publications

under review - accepted - articles - in limbo - conference proceedings

: abstract - : BibTeX - : arXiv preprint - : published manuscript

under review

1. T. Erdoğan, T. Kann, A. Nosratinia, and M. R. Bloch, “Covert Communication over Physically-Degraded Alarm Two-Way Channels.” submitted to IEEE Transactions on Information Theory, Jun. 2025.

   @misc{Erdogan2025Covert, author = {Erdoğan, Tuna and Kann, Tyler; and Nosratinia, Aria and Bloch, Matthieu R.}, howpublished = {submitted to \emph{IEEE Transactions on Information Theory}}, month = jun, title = {Covert Communication over Physically-Degraded Alarm Two-Way Channels}, year = {2025}, eprint = {2506.16581} }

2. M.-C. Chang and M. R. Bloch, “Covert Sequential Sensing.” submitted to IEEE Journal of Selected Areas in Communications, Apr. 2025.

   @misc{Chang2025Covert, author = {Chang, Meng-Che and Bloch, Matthieu R.}, howpublished = {submitted to \emph{IEEE Journal of Selected Areas in Communications}}, month = apr, title = {Covert Sequential Sensing}, year = {2025}, groups = {NSF1955401} }

3. S. Bakirtas, M. R. Bloch, and E. Erkip, “Covert Communications of Wireless Hardware Trojans: Positive Rates Through Pilot Manipulation.” submitted to IEEE Journal of Selected Areas in Communications, Apr. 2025.

   @misc{Bakirtas2025Covert, author = {Bakirtas, Serhat and Bloch, Matthieu R. and Erkip, Elza}, howpublished = {submitted to \emph{IEEE Journal of Selected Areas in Communications}}, month = apr, title = {Covert Communications of Wireless Hardware Trojans: Positive Rates Through Pilot Manipulation}, year = {2025}, groups = {NSF2148400} }

accepted

1. S. Guo and M. R. Bloch, “Rate-Reliability Region of Sequential Beam Alignment and Communication.” accepted to IEEE Information Theory Workshop, Jun. 2025.

   @misc{Guo2025Rate, author = {Guo, Sidong and Bloch, Matthieu R.}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, month = jun, title = {Rate-Reliability Region of Sequential Beam Alignment and Communication}, year = {2025}, groups = {NSF2148400} }

2. C. Bouette, L. Luzzi, and M. Bloch, “Covert Capacity of AWGN Channelsunder Average Probability of Error.” accepted to IEEE International Symposium on Information Theory, Apr. 2025.

   @misc{Bouette2025Covert, author = {Bouette, C\'ecile and Luzzi, Laura and Bloch, Matthieu}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, month = apr, title = {Covert Capacity of AWGN Channelsunder Average Probability of Error}, year = {2025}, eprint = {2506.14483} }

3. C. P. Lindstrom and M. R. Bloch, “Rate Distortion Approach to Joint Communicationand Sensing with Markov States: Open Loop Case.” accepted to IEEE International Symposium on Information Theory, Apr. 2025.

   @misc{Lindstrom2025Rate, author = {Lindstrom, Colton P. and Bloch, Matthieu R.}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, month = apr, title = {Rate Distortion Approach to Joint Communicationand Sensing with Markov States: Open Loop Case}, year = {2025}, groups = {NSF2148400} }

4. Y.-F. Lo and M. R. Bloch, “Active Hypothesis Testing for Quantum Detection of Phase-Shift Keying Coherent States.” accepted to IEEE International Symposium on Information Theory, Apr. 2025.

   @misc{Lo2025Active, author = {Lo, Yun-Feng and Bloch, Matthieu R.}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, month = apr, title = {Active Hypothesis Testing for Quantum Detection of Phase-Shift Keying Coherent States}, year = {2025}, eprint = {2501.16218} }

articles

1. R. Chou and M. R. Bloch, “Multiuser Commitment over Noisy Channels,” IEEE Transactions on Information Theory, vol. 71, no. 11, pp. 1557–9654, Nov. 2025.

   @article{Chou2024Multiuser, author = {Chou, R\'emi and Bloch, Matthieu R.}, journal = {IEEE Transactions on Information Theory}, title = {Multiuser Commitment over Noisy Channels}, year = {2025}, month = nov, number = {11}, pages = {1557-9654}, volume = {71}, doi = {10.1109/TIT.2025.3608081}, eprint = {2411.05987}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

2. N. Blinn and M. R. Bloch, “Multi-Armed Bandit Dynamic Beam Zooming for mmWave Alignment and Tracking,” IEEE Transactions on Wireless Communications, vol. 24, no. 9, pp. 7908–7922, Sep. 2025.

   @article{Blinn2024Multi, author = {Blinn, Nathan and Bloch, Matthieu R.}, journal = {IEEE Transactions on Wireless Communications}, title = {Multi-Armed Bandit Dynamic Beam Zooming for mmWave Alignment and Tracking}, year = {2025}, month = sep, number = {9}, pages = {7908-7922}, volume = {24}, doi = {10.1109/TWC.2025.3563409}, eprint = {2209.02896}, groups = {NSF2148400}, howpublished = {accepted to \emph{IEEE Transactions on Wireless Communications}} }

3. S.-Y. Wang, K. S. K. Arumugam, and M. R. Bloch, “Bounds on Covert Capacity with Sub-Exponential Random Slot Selection,” ieee_j_it, vol. 71, no. 9, pp. 6586–6601, Sep. 2025.

   We consider the problem of covert communication with random slot selection over binary-input Discrete Memoryless Channels (DMCs) and Additive White Gaussian Noise (AWGN) channels, in which a transmitter attempts to reliably communicate with a legitimate receiver while simultaneously maintaining covertness with respect to (w.r.t.) an eavesdropper. Covertness refers to the inability of the eavesdropper to distinguish the transmission of a message from the absence of communication, modeled by the transmission of a fixed channel input. Random slot selection refers to the transmitter’s ability to send a codeword in a time slot with known boundaries selected uniformly at random among a predetermined number of slots. Our main contribution is to develop bounds for the information-theoretic limit of communication in this model, called the covert capacity, when the number of time slots scales sub-exponentially with the codeword length. Our upper and lower bounds for the covert capacity are within a multiplicative factor of √2 independent of the channel. This result partially fills a characterization gap between the covert capacity without random slot selection and the covert capacity with random selection among an exponential number of slots in the codeword length. Our key technical contributions consist of i) a tight upper bound for the relative entropy characterizing the effect of random slot selection on the covertness constraint in our achievability proof; ii) a careful converse analysis to characterize the maximum allowable weight or power of codewords to meet the covertness constraint. Our results suggest that, unlike the case without random slot selection, the choice of covertness metric does not change the covert capacity in the presence of random slot selection.

   @article{Wang2024Bounds, author = {Wang, Shi-Yuan and Arumugam, Keerthi Suria Kumar and Bloch, Matthieu R.}, journal = ieee_j_it, title = {Bounds on Covert Capacity with Sub-Exponential Random Slot Selection}, year = {2025}, month = sep, number = {9}, pages = {6586-6601}, volume = {71}, doi = {10.1109/TIT.2025.3589575}, eprint = {2409.07777}, groups = {Steganography and covert communications, NSF1955401}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

4. Z. J. Zhang, M. Bloch, J. Pan, and M. Saeedifard, “A Passive-Active Intrusion Detection Scheme for Multi-Terminal HVDC Grid Line Protection Attacks,” IEEE Transaction on Industrial Electronics, vol. 72, no. 5, pp. 4331–4342, May 2025.

   Emerging multiterminal dc (MTdc) grids are envisioned to be highly reliant on information communication technology, making them vulnerable to cyber-security threats. In particular, digital substations that house dc-side line fault protection schemes can be compromised by manipulated measurement signals that resemble actual faults, resulting in outages of dc transmission lines. Therefore, it is imperative to defend against such cyber-attacks. To this end, this article proposes an intrusion detection scheme (IDS) for dc line protection schemes. The IDS comprises two stages, passive and active, that operate sequentially. In the first passive stage, the IDS analyzes voltage and current measurements to detect potential cyber-attacks. In the second active stage, the hybrid solid-state dc circuit breaker is actively controlled to identify attacks that evade the passive stage and achieve a moving target defense. The IDS i) conforms with the MTdc grid protection requirements, ii) only utilizes local measurements, and iii) is universal as different algorithms can be incorporated in this scheme while its hybrid passive and active structure stays intact. Off-line simulation and experimental performance evaluation results demonstrate that the IDS is able to detect a variety of cyber-attacks, including the fully-synchronized replay attack (one of the most sophisticated and stealthiest attacks).

   @article{Zhang2024Passive, author = {Zhang, Zhi Jin and Bloch, Matthieu and Pan, Jiuping and Saeedifard, Maryam}, journal = {IEEE Transaction on Industrial Electronics}, title = {A Passive-Active Intrusion Detection Scheme for Multi-Terminal HVDC Grid Line Protection Attacks}, year = {2025}, month = may, number = {5}, pages = {4331-4342}, volume = {72}, doi = {10.1109/TIE.2024.3468621}, howpublished = {accepted to \emph{IEEE Transactions on Industrial Electronics}} }

5. M. Mittelbach, R. F. Schaefer, M. Bloch, A. Yener, and O. Günlü, “Sensing-Assisted Secure Communications over Correlated Rayleigh Fading Channels,” Entropy, vol. 27, no. 3, Feb. 2025.

   We consider a secure integrated sensing and communication (ISAC) scenario, where a signal is transmitted through a state-dependent wiretap channel with one legitimate receiver with which the transmitter communicates and one honest-but-curious target that the transmitter wants to sense. The secure ISAC channel is modeled as two state-dependent fast-fading channels with correlated Rayleigh fading coefficients and independent additive Gaussian noise components. Delayed channel outputs are fed back to the transmitter to improve the communication performance and to estimate the channel state sequence. We establish and illustrate an achievable secrecy-distortion region for degraded secure ISAC channels under correlated Rayleigh fading, for which we show that the signal-to-interference-plus-noise is not a sufficient statistic. We also evaluate the inner bound for a large set of parameters to derive practical design insights. The presented results include parameter ranges for which the secrecy capacity of a classical wiretap channel setup is surpassed and for which the channel capacity is approached. Thus, we illustrate for correlated Rayleigh fading cases that our secure ISAC methods can (i) eliminate the need for the legitimate receiver to have a statistical advantage over the eavesdropper and (ii) provide communication security with minimal rate penalty.

   @article{Mittelbach2024Secure, author = {Mittelbach, Martin and Schaefer, Rafael F. and Bloch, Matthieu and Yener, Aylin and G\"{u}nl\"{u}, Onur}, journal = {Entropy}, title = {Sensing-Assisted Secure Communications over Correlated Rayleigh Fading Channels}, year = {2025}, month = feb, number = {3}, volume = {27}, doi = {10.3390/e27030225}, groups = {NSF2148400}, howpublished = {accepted to \emph{Entropy}} }

6. M. E. Cao, M. Bloch, and S. Coogan, “An Optimistic Approach to Cost-Aware Predictive Control,” Automatica, vol. 176, p. 112263, 2025.

   We consider continuous-time systems subject to a priori unknown state-dependent disturbance inputs. Given a target goal region, our first approach consists of a control scheme that avoids unsafe regions of the state space and observes the disturbance behavior until the goal is reachable with high probability. We leverage collected observations and the mixed monotonicity property of dynamical systems to efficiently obtain high-probability overapproximations of the system’s reachable sets. These overapproximations improve as more observations are collected. For our second approach, we consider the problem of minimizing cost while navigating toward the goal region and modify our previous formulation to allow for the estimated confidence bounds on the disturbance to be adjusted based on what would reduce the overall cost. We explicitly consider the additional cost incurred through exploration and develop a formulation wherein the amount of exploration performed can be directly tuned. We show theoretical results confirming that this confidence bound modification strategy outperforms the previously developed strategy on a simplified system. We demonstrate the first approach on an example of a motorboat navigating a river, then showcase a Monte Carlo simulation comparison of both approaches on a planar multirotor navigating toward a goal region through an unknown wind field.

   @article{Cao2025Optimistic, author = {Cao, Michael Enqi and Bloch, Matthieu and Coogan, Samuel}, journal = {Automatica}, title = {An Optimistic Approach to Cost-Aware Predictive Control}, year = {2025}, pages = {112263}, volume = {176}, doi = {10.1016/j.automatica.2025.112263} }

7. B. Martin Urcelay, M. Bloch, and C. Rozell, “Online Machine Teaching under Learner Uncertainty: Gradient Descent Learners of a Quadratic Loss,” SIAM Journal on Mathematics of Data Science, vol. 7, no. 3, pp. 884–905, 2025.

   We revisit the framework of online machine teaching, a special case of active learning in which a teacher with full knowledge of a model attempts to train a learner by adaptively presenting examples. While online machine teaching example selection strategies are typically designed assuming omniscience, i.e., the teacher has absolute knowledge of the learner state, we show that efficient machine teaching is possible even when the teacher is uncertain about the learner initialization. Specifically, we consider the case of learners that perform gradient descent of a quadratic loss to learn a linear classifier, and we propose an online machine teaching algorithm in which the teacher simultaneously learns the learner state while teaching the learner. We theoretically show that the learner’s mean square error decreases exponentially with the number of examples, thus achieving a performance similar to the omniscient case and outperforming two stage strategies that first attempt to make the teacher omniscient before teaching. We empirically illustrate our approach in the context of a cross-lingual sentiment analysis problem.

   @article{Urcelay2023Online, author = {{Martin Urcelay}, B\'elen and Bloch, Matthieu and Rozell, Chris}, journal = {SIAM Journal on Mathematics of Data Science}, title = {Online Machine Teaching under Learner Uncertainty: Gradient Descent Learners of a Quadratic Loss}, year = {2025}, number = {3}, pages = {884-905}, volume = {7}, doi = {10.1137/24M1657997}, howpublished = {accepted to \emph{SIAM Journal on Mathematics of Data Science}} }

8. L. Luzzi, C. Ling, and M. R. Bloch, “Optimal rate-limited secret key generation from Gaussian sources using lattices,” ieee_j_it, vol. 69, no. 8, pp. 4944–4960, Aug. 2023.

   We propose a lattice-based scheme for secret key generation from Gaussian sources in the presence of an eavesdropper, and show that it achieves the strong secret key capacity in the case of degraded source models, as well as the optimal secret key / public communication rate trade-off. The key ingredients of our scheme are a lattice extractor to extract the channel intrinsic randomness, based on the notion of flatness factor, together with a randomized lattice quantization technique to quantize the continuous source. Compared to previous works, we introduce two new notions of flatness factor based on L1 distance and KL divergence, respectively, which are of independent interest. We prove the existence of secrecy-good lattices under L1 distance and KL divergence, whose L1 and KL flatness factors vanish for volume-to-noise ratios up to 2πe. This improves upon the volume-to-noise ratio threshold 2π of the L∞ flatness factor.

   @article{Luzzi2022Secret, author = {Luzzi, Laura and Ling, Cong and Bloch, Matthieu R.}, journal = ieee_j_it, title = {Optimal rate-limited secret key generation from Gaussian sources using lattices}, year = {2023}, month = aug, number = {8}, pages = {4944-4960}, volume = {69}, doi = {10.1109/TIT.2023.3266033}, eprint = {2206.10443}, file = {:2023-Luzzi-IEEETransIT-Optimal Rate-Limited Secret Key Generation From Gaussian Sources Using Lattices.pdf:PDF}, groups = {NSF1955401, NSF2148400}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

9. M.-C. Chang, S.-Y. Wang, T. Erdoğan, and M. R. Bloch, “Rate and Detection-Error Exponent Tradeoff for Joint Communication and Sensing of Fixed Channel States,” ieee_j_sait, vol. 4, pp. 245–259, May 2023.

   We study the information-theoretic limits of joint communication and sensing when the sensing task is modeled as the estimation of a discrete channel state fixed during the transmission of an entire codeword. This setting captures scenarios in which the time scale over which sensing happens is significantly slower than the time scale over which symbol transmission occurs. The tradeoff between communication and sensing then takes the form of a tradeoff region between the rate of reliable communication and the state detection-error exponent. We investigate such tradeoffs for both mono-static and bi-static scenarios, in which the sensing task is performed at the transmitter or receiver, respectively. In the mono-static case, we develop an exact characterization of the tradeoff in open-loop, when the sensing is not used to assist the communication. We also show the strict improvement brought by a closed-loop operation, in which the sensing informs the communication. In the bi-static case, we develop an achievable tradeoff region that highlights the fundamentally different nature of the bi-static scenario. Specifically, the rate of communication plays a key role in the characterization of the tradeoff and we show how joint strategies, which simultaneously estimate message and state, outperform successive strategies, which only estimate the state after decoding the transmitted message.

   @article{Chang2022Ratea, author = {Chang, Meng-Che and Wang, Shi-Yuan and Erdo\u{g}an, Tuna and Bloch, Matthieu R.}, journal = ieee_j_sait, title = {Rate and Detection-Error Exponent Tradeoff for Joint Communication and Sensing of Fixed Channel States}, year = {2023}, month = may, pages = {245-259}, volume = {4}, doi = {10.1109/JSAIT.2023.3275877}, eprint = {2210.07963}, file = {:2023-Chang-JSAIT-Rate and Detection-Error Exponent Tradeoff for Joint Communication and Sensing of Fixed Channel States.pdf:PDF}, groups = {NSF2148400, NSF1955401}, howpublished = {accepted to \emph{IEEE Journal on Selected Areas in Information Theory}} }

10. O. Günlü, M. R. Bloch, R. F. Schaefer, and A. Yener, “Secure Integrated Sensing and Communication,” ieee_j_sait, vol. 4, pp. 40–53, May 2023.

    This work considers the problem of mitigating information leakage between communication and sensing in systems jointly performing both operations. Specifically, a discrete memoryless state-dependent broadcast channel model is studied in which (i) the presence of feedback enables a transmitter to convey information, while simultaneously performing channel state estimation; (ii) one of the receivers is treated as an eavesdropper whose state should be estimated but which should remain oblivious to part of the transmitted information. The model abstracts the challenges behind security for joint communication and sensing if one views the channel state as a sensitive attribute, e.g., location. For independent and identically distributed states, perfect output feedback, and when part of the transmitted message should be kept secret, a partial characterization of the secrecy-distortion region is developed. The characterization is exact when the broadcast channel is either physically-degraded or reversely-physically-degraded. The partial characterization is also extended to the situation in which the entire transmitted message should be kept secret. The benefits of a joint approach compared to separation-based secure communication and state-sensing methods are illustrated with binary joint communication and sensing models.

    @article{Guenlue2022SecureJSAIT, author = {G\"unl\"u, Onur and Bloch, Matthieu R. and Schaefer, Rafael F. and Yener, Aylin}, journal = ieee_j_sait, title = {Secure Integrated Sensing and Communication}, year = {2023}, month = may, pages = {40-53}, volume = {4}, doi = {10.1109/JSAIT.2023.3275048}, eprint = {2303.11350}, file = {:2023-Gunlu-JSAIT-Secure Integrated Sensing and Communication.pdf:PDF}, groups = {NSF1955401, NSF2148400}, howpublished = {accepted to \emph{IEEE Journal on Special Areas in Information Theory}} }

11. O. Günlü, M. R. Bloch, and R. Schaeffer, “Private Remote Sources for Secure Multi-Function Computation,” ieee_j_it, vol. 10, no. 68, pp. 1557–9654, Oct. 2022.

    We consider a distributed function computation problem in which parties observing noisy versions of a remote source facilitate the computation of a function of their observations at a fusion center through public communication. The distributed function computation is subject to constraints, including not only reliability and storage but also privacy and secrecy. Specifically, 1) the remote source should remain private from an eavesdropper and the fusion center, measured in terms of the information leaked about the remote source; 2) the function computed should remain secret from the eavesdropper, measured in terms of the information leaked about the arguments of the function, to ensure secrecy regardless of the exact function used. We derive the exact rate regions for lossless and lossy single-function computation and illustrate the lossy single-function computation rate region for an information bottleneck example, in which the optimal auxiliary random variables are characterized for binary-input symmetric-output channels. We extend the approach to lossless and lossy asynchronous multiple-function computations with joint secrecy and privacy constraints, in which case inner and outer bounds for the rate regions differing only in the Markov chain conditions imposed are characterized.

    @article{Guenlue2021a, author = {G\"unl\"u, Onur and Bloch, Matthieu R and Schaeffer, Rafael}, journal = ieee_j_it, title = {Private Remote Sources for Secure Multi-Function Computation}, year = {2022}, month = oct, number = {68}, pages = {1557-9654}, volume = {10}, doi = {10.1109/TIT.2022.3182416}, eprint = {2106.09485}, file = {:2022-Gunlu-IEEETransIT-Private Remote Sources for Secure Multi-Function Computation.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

12. M. E. Cao, M. R. Bloch, and S. Coogan, “Efficient Learning of Hyperrectangular Invariant Sets using Gaussian Processes,” IEEE Open Journal of Control Systems, pp. 223–236, Sep. 2022.

    @article{Cao2022Efficient, author = {Cao, Michael E. and Bloch, Matthieu R. and Coogan, Samuel}, journal = {IEEE Open Journal of Control Systems}, title = {Efficient Learning of Hyperrectangular Invariant Sets using Gaussian Processes}, year = {2022}, month = sep, pages = {223 - 236}, doi = {10.1109/OJCSYS.2022.3206083}, file = {:2022-Cao-OJCS-Efficient_Learning_of_Hyperrectangular_Invariant_Sets_Using_Gaussian_Processes.pdf:PDF}, howpublished = {accepted to \emph{Open Journal of Control Systems}} }

13. H. Zivari-Fard, M. Bloch, and A. Nosratinia, “Keyless Covert Communication via Channel State Information,” ieee_j_it, vol. 68, no. 8, pp. 5440–5474, Aug. 2022.

    We consider the problem of covert communication over a state-dependent channel when the channel state is available either non-causally, causally, or strictly causally, either at the transmitter alone or at both transmitter and receiver. Covert communication with respect to an adversary, called warden, is one in which, despite communication over the channel, the warden’s observation remains indistinguishable from an output induced by innocent channel-input symbols. Covert communication involves fooling an adversary in part by a proliferation of codebooks; for reliable decoding at the legitimate receiver, the codebook uncertainty is typically removed via a shared secret key that is unavailable to the warden. In contrast to previous work, we do not assume the availability of a shared key at the transmitter and legitimate receiver. Instead, shared randomness is extracted from the channel state in a manner that keeps it secret from the warden, despite the influence of the channel state on the warden’s output. When channel state is available at the transmitter and receiver, we derive the covert capacity region. When channel state is only available at the transmitter, we derive inner and outer bounds on the covert capacity. We provide examples for which the covert capacity is positive with knowledge of channel state information but is zero without it.

    @article{ZivariFard2020, author = {Zivari-Fard, Hassan and Bloch, Matthieu and Nosratinia, Aria}, journal = ieee_j_it, title = {Keyless Covert Communication via Channel State Information}, year = {2022}, month = aug, number = {8}, pages = {5440-5474}, volume = {68}, doi = {10.1109/TIT.2021.3135291}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

14. N. S. Mannem, T.-Y. Huang, E. Erfani, S. Li, M. Bloch, and H. Wang, “A 25–34-GHz Eight-Element MIMO Transmitter for Keyless High Throughput Directionally Secure Communication,” IEEE Journal of Solid-State Circuits, vol. 57, no. 5, pp. 1244–1256, May 2022.

    A primary advantage of antenna arrays is their spatial selectivity, which has been widely utilized to support various applications, such as beam-steering, blocker rejection, massive multi-in–multi-out (MIMO), targeting communication, radar, and imaging. In this article, we exploit and engineer this spatial selectivity in an MIMO array for directionally secured wireless communication. We propose constellation decomposition array (CDA) and spatial carrier aggregation (SCA) schemes to achieve high throughput keyless physical layer security using antenna arrays. In CDA, lower order quadratic-amplitude modulation (QAM) signals are fed into an MIMO array and are spatially combined in the target direction to realize desired higher order QAM signals but distort the modulation in unintended directions. In SCA, we feed different carriers to different elements in an MIMO array to perform spectral carrier aggregation spatially. In addition, we adopt temporal swapping to further enhance security by creating one-to-many symbol mapping in unintended directions. The concept is demonstrated on an eight-channel MIMO transmitter (TX) fabricated in 45-nm CMOS silicon on insulator (SOI) and on-board antenna array for over-the-air (OTA) measurements. Using four channels of the TX array in the CDA mode, an information beamwidth of 5°/10° is realized by spatially constructing a single carrier 64QAM signal using three QPSK signals or one QPSK signal plus one 16QAM signal with a total 64QAM data rate up to 3 Gb/s. Using SCA with two carriers of 64QAM signals and temporal swapping, an rms error vector magnitude (EVM) of 6.3% at broadside with an aggregated data rate of 1.2 Gb/s is achieved, in contrast to greatly distorted rms EVM of 10% at only 4° angle.

    @article{Mannem2021CDA, author = {Mannem, Naga Sasikanth and Huang, Tzu-Yuan and Erfani, Elham and Li, Sensen and Bloch, Matthieu and Wang, Hua}, journal = {IEEE Journal of Solid-State Circuits}, title = {A 25–34-GHz Eight-Element MIMO Transmitter for Keyless High Throughput Directionally Secure Communication}, year = {2022}, issn = {1558-173X}, month = may, number = {5}, pages = {1244-1256}, volume = {57}, doi = {10.1109/JSSC.2021.3135481}, howpublished = {accepted to \emph{IEEE Journal of Solid State Circuits}} }

15. J. Sun, S. Debnath, M. R. Bloch, and M. Saeedifard, “A Hybrid DC Fault Primary Protection Algorithm for Multi-Terminal HVdc Systems,” IEEE Transactions on Power Delivery, vol. 37, no. 2, pp. 1285–1294, Apr. 2022.

    Protection against dc faults is one of the main technical hurdles faced when operating converter-based HVdc systems. Protection becomes even more challenging for multi-terminal dc (MTdc) systems with more than two terminals/converter stations. In this paper, a hybrid primary fault detection algorithm for MTdc systems is proposed to detect a broad range of failures. Sensor measurements, i.e., line currents and dc reactor voltages measured at local terminals, are first processed by a top-level context clustering algorithm. For each cluster, the best fault detector is selected among a detector pool according to a rule resulting from a learning algorithm. The detector pool consists of existing detection algorithms, each performing differently across fault scenarios. The proposed detection algorithm: i) offers superior performance compared to an individual detector through a data-driven approach; ii) detects all major fault types including pole-to-pole (P2P), pole-to-ground (P2G), and external dc faults; iii) identifies faults with various fault locations and impedances; iv) is more robust to noisy sensor measurements compared to existing methods; v) does not require exhaustive simulation and sampling for training the model. Performance and effectiveness of the proposed algorithm are evaluated and verified based on time-domain simulations in the PSCAD/EMTDC software environment.

    @article{Sun2021, author = {Sun, Jingfan and Debnath, Suman and Bloch, Matthieu R and Saeedifard, Maryam}, journal = {IEEE Transactions on Power Delivery}, title = {A Hybrid DC Fault Primary Protection Algorithm for Multi-Terminal HVdc Systems}, year = {2022}, month = apr, number = {2}, pages = {1285--1294}, volume = {37}, doi = {10.1109/TPWRD.2021.3083642}, howpublished = {accepted to \emph{IEEE Transactions on Power Delivery}} }

16. S.-Y. Wang and M. R. Bloch, “Covert MIMO Communications under Variational Distance Constraint,” ieee_j_ifs, vol. 16, pp. 4605–4620, Sep. 2021.

    The problem of covert communication over Multiple-Input Multiple-Output (MIMO) Additive White Gaussian Noise (AWGN) channels is investigated, in which a transmitter attempts to reliably communicate with a legitimate receiver while avoiding detection by a passive adversary. The covert capacity of the MIMO AWGN channel is characterized under a variational distance covertness constraint when the MIMO channel matrices are static and known. The characterization of the covert capacity is also extended to a class of channels in which the legitimate channel matrix is known but the adversary’s channel matrix is only known up to a rank and a spectral norm constraint.

    @article{Wang2021, author = {Wang, Shi-Yuan and Bloch, Matthieu R}, journal = ieee_j_ifs, title = {Covert MIMO Communications under Variational Distance Constraint}, year = {2021}, month = sep, pages = {4605 - 4620}, volume = {16}, doi = {10.1109/TIFS.2021.3110048}, eprint = {2102.11336}, file = {:2021-Wang-IEEETransIFS-Covert MIMO Communications under Variational Distance Constraint.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}} }

17. R. A. Chou, M. Bloch, and A. Yener, “Universal Covertness for Discrete Memoryless Sources,” ieee_j_it, vol. 67, no. 8, pp. 1557–9654, Aug. 2021.

    Consider a sequence Xn of length n emitted by a Discrete Memoryless Source (DMS) with unknown distribution pX. The objective is to construct a lossless source code that maps Xn to a sequence Yˆm of length m that is indistinguishable, in terms of Kullback-Leibler divergence, from a sequence emitted by another DMS with known distribution pY. The main result is the existence of a coding scheme that performs this task with an optimal ratio m/n equal to H(X)/H(Y), the ratio of the Shannon entropies of the two distributions, as n goes to infinity. The coding scheme overcomes the challenges created by the lack of knowledge about pX by relying on a sufficiently fine estimation of H(X), followed by an appropriately designed type-based source coding that jointly performs source resolvability and universal lossless source coding. The result recovers and extends previous results that either assume pX or pY uniform, or pX known. The price paid for these generalizations is the use of common randomness with vanishing rate, whose length roughly scales as the square root of n. By allowing common randomness strictly larger than the square root of n but still negligible compared to n, a constructive low-complexity encoding and decoding counterpart to the main result is also provided for binary sources by means of polar codes.

    @article{Chou2018, author = {Chou, R\'emi A. and Bloch, Matthieu and Yener, Aylin}, journal = ieee_j_it, title = {Universal Covertness for Discrete Memoryless Sources}, year = {2021}, month = aug, number = {8}, pages = {1557-9654}, volume = {67}, doi = {10.1109/TIT.2021.3091381}, eprint = {1808.05612}, file = {:2021-Chou-IEEETransIT-Universal Covertness for Discrete Memoryless Sources.pdf:PDF}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

18. M.-C. Chang and M. R. Bloch, “Evasive Active Hypothesis Testing,” IEEE Journal on Selected Areas in Information Theory, vol. 2, no. 2, pp. 735–746, Jun. 2021.

    We consider a situation in which a decision maker takes sequential and adaptive sensing actions to collect measurements and estimate an unknown parameter taking finitely many values, in the presence of an adversary who also collects measurements whenever a sensing action is taken. This situation can be viewed as an abstraction in which to analyze the mitigation of information leakage inherent to control actions in systems with feedback, such as cyber-physical systems. Specifically, we formulate an evasive active hypothesis problem in which the objective is for the decision maker to control the risk of its test while minimizing the detection ability of the adversary, measured in terms of the asymptotic error exponent ratio between the adversary and the decision maker. We develop bounds on the exponent ratio that offer insight into optimal strategies that the decision maker can deploy to evade the adversary’s detection. We illustrate the results with a numerical example corresponding to the detection of a wireless transmission.

    @article{Chang2020a, author = {Chang, Meng-Che and Bloch, Matthieu R.}, journal = {IEEE Journal on Selected Areas in Information Theory}, title = {Evasive Active Hypothesis Testing}, year = {2021}, month = jun, number = {2}, pages = {735-746}, volume = {2}, doi = {10.1109/JSAIT.2021.3074156}, file = {:2021-Chang-IEEEJSAIT-Evasive Active Hypothesis Testing.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Journal of Selected Areas in Information Theory}} }

19. M. Tahmasbi and M. R. Bloch, “On Covert Quantum Sensing and the Benefits of Entanglement,” IEEE Journal on Selected Areas in Information Theory, vol. 2, no. 1, pp. 352–365, Mar. 2021.

    Motivated by applications to covert quantum radar, we analyze a covert quantum sensing problem, in which a legitimate user aims at estimating an unknown parameter taking finitely many values by probing a quantum channel while remaining undetectable from an adversary receiving the probing signals through another quantum channel. When channels are classical-quantum, we characterize the optimal error exponent under a covertness constraint for sensing strategies in which probing signals do not depend on past observations. When the legitimate user’s channel is a unitary depending on the unknown parameter, we provide achievability and converse results that show how one can significantly improve covertness using an entangled input state.

    @article{Tahmasbi2020c, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, journal = {IEEE Journal on Selected Areas in Information Theory}, title = {On Covert Quantum Sensing and the Benefits of Entanglement}, year = {2021}, issn = {2641-8770}, month = mar, number = {1}, pages = {352-365}, volume = {2}, doi = {10.1109/JSAIT.2021.3056640}, eprint = {2008.01264}, file = {:/Users/mbloch/Downloads/2021-Tahmasbi-JSAIT-On covert quantum sensing and the benefits of entanglement-pdfa.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Journal of Selected Areas in Information Theory}}, keywords = {Sensors;Quantum channel;Testing;Quantum entanglement;Channel estimation;Quantum state;Tensors;Quantum sensing;covert communication} }

20. M. Bloch et al., “An Overview of Information-Theoretic Security and Privacy: Metrics, Limits and Applications,” IEEE Journal on Selected Areas in Information Theory, vol. 2, no. 1, pp. 5–22, Mar. 2021.

    @article{Bloch2021, author = {Bloch, Matthieu and Gunlu, Onur and Yener, Aylin and Oggier, Frederique and Poor, H. Vincent and Sankar, Lalitha and Schaefer, Rafael F.}, journal = {{IEEE} Journal on Selected Areas in Information Theory}, title = {An Overview of Information-Theoretic Security and Privacy: Metrics, Limits and Applications}, year = {2021}, month = mar, number = {1}, pages = {5--22}, volume = {2}, doi = {10.1109/jsait.2021.3062755}, file = {:2021-Bloch-JSAIT-An Overview of Information-Theoretic Security and Privacy Metrics, Limits and Applications.pdf:PDF}, groups = {NSF1955401}, publisher = {Institute of Electrical and Electronics Engineers ({IEEE})} }

21. M. Le Treust and M. R. Bloch, “State Leakage and Coordination of Actions: Core of the Receiver’s Knowledge,” ieee_j_it, vol. 67, no. 2, pp. 805–823, Feb. 2021.

    We revisit the problems of state masking and state amplification through the lens of empirical coordination by considering a state-dependent channel in which the encoder has causal and strictly causal state knowledge. We show that the problem of empirical coordination provides a natural framework in which to jointly study the problems of reliable communication, state masking, and state amplification. We characterize the regions of rate-equivocation-coordination trade-offs for several channel models with causal and strictly causal state knowledge. We introduce the notion of “core of the receiver’s knowledge” to capture what the decoder can infer about all the signals involved in the model. We exploit this result to solve a channel state estimation zero-sum game in which the encoder prevents the decoder to estimate the channel state accurately.

    @article{LeTreust2018, author = {{Le Treust}, Ma\"el and Bloch, Matthieu R}, journal = ieee_j_it, title = {State Leakage and Coordination of Actions: Core of the Receiver's Knowledge}, year = {2021}, month = feb, number = {2}, pages = {805-823}, volume = {67}, doi = {10.1109/TIT.2020.3036987}, eprint = {1812.07026}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

22. H. Zivari-Fard, M. Bloch, and A. Nosratinia, “Two-Multicast Channel with Confidential Messages,” ieee_j_ifs, vol. 16, pp. 2743–2758, 2021.

    Motivated in part by the problem of secure multicast distributed storage, we analyze secrecy rates for a channel in which two transmitters simultaneously multicast to two receivers in the presence of an eavesdropper. Achievable rates are calculated via extensions of a technique due to Chia and El Gamal and the method of output statistics of random binning. Outer bounds are derived for both the degraded and non-degraded versions of the channel, and examples are provided in which the inner and outer bounds meet. The inner bounds recover known results for the multiple-access wiretap channel, broadcast channel with confidential messages, and the compound MAC channel. An auxiliary result is also produced that derives an inner bound on the minimal randomness necessary to achieve secrecy in multiple-access wiretap channels.

    @article{Zivari-Fard2018, author = {Zivari-Fard, Hassan and Bloch, Matthieu and Nosratinia, Aria}, journal = ieee_j_ifs, title = {Two-Multicast Channel with Confidential Messages}, year = {2021}, issn = {1556-6021}, pages = {2743-2758}, volume = {16}, doi = {10.1109/TIFS.2021.3055031}, eprint = {1902.08657}, file = {:2021-ZivariFard-IEEETransIFS-Two-Multicast Channel With Confidential Messages.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}}, keywords = {Encoding;Decoding;Receivers;Random variables;Compounds;Interference channels;US Government;Multicasting;compound channel;confidential messages;randomness constraint;stochastic encoder;wire-tap channel} }

23. M. Tahmasbi and M. R. Bloch, “Covert and secret key expansion over quantum channels under collective attacks,” ieee_j_it, vol. 66, no. 11, pp. 7113–7131, Nov. 2020.

    We consider an enhanced measure of security for a quantum key distribution protocol, in which we require not only that the adversary obtains no information about the key but also remains unaware that a key generation protocol has been executed. When the adversary applies the same quantum channel independently to each transmitted quantum state, akin to a collective attack in the quantum key distribution literature, we propose a protocol that achieves covert and secret key expansion under mild restrictions. A crucial component of the protocol is a covert estimation stage, which is then combined with universal channel coding for reliability and resolvability in the covert regime.

    @article{Tahmasbi2019a, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R}, journal = ieee_j_it, title = {Covert and secret key expansion over quantum channels under collective attacks}, year = {2020}, issn = {1557-9654}, month = nov, number = {11}, pages = {7113-7131}, volume = {66}, doi = {10.1109/TIT.2020.3021595}, file = {:2020-Tahmasbi-IEEETransIT-b.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

24. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Multilevel-Coded Pulse-Position Modulation for Covert Communications over Binary-Input Discrete Memoryless Channels,” ieee_j_it, vol. 66, no. 10, pp. 6001–6023, Oct. 2020.

    We consider the problem of coding to ensure covert communication, which involves ensuring reliable communication between two legitimate parties while simultaneously guaranteeing a low probability of detection by an eavesdropper. Specifically, we develop an optimal low-complexity coding scheme that achieves the information-theoretic limits of covert communications over binary-input discrete memoryless channels (BI-DMCs). To justify our design, we first consider a regime in which information theory proves the possibility of covert communication without shared secret key and show the impossibility of achieving information-theoretic limits using linear codes without secret key. We then circumvent this impossibility by introducing non-linearity into the coding scheme through the use of pulse position modulation (PPM) and multilevel coding (MLC). This MLC-PPM scheme exhibits several appealing properties; in particular, for an appropriate decoder, the channel at a given level is independent of the total number of levels and the codeword length. We exploit these properties to show how one can use families of channel capacity- and channel resolvability-achieving codes to concretely instantiate a covert communication scheme.

    @article{Kadampot2018a, author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R}, journal = ieee_j_it, title = {Multilevel-Coded Pulse-Position Modulation for Covert Communications over Binary-Input Discrete Memoryless Channels}, year = {2020}, month = oct, number = {10}, pages = {6001-6023}, volume = {66}, doi = {10.1109/TIT.2020.3019996}, eprint = {1811.09695}, file = {:2020-Kadampot-IEEETransIT.pdf:PDF} }

25. N. Helal, M. Bloch, and A. Nosratinia, “Cooperative Resolvability and Secrecy in the Cribbing Multiple-Access Channel,” ieee_j_it, vol. 66, no. 9, pp. 5429–5447, Sep. 2020.

    We study channel resolvability for the discrete memoryless multiple-access channel with cribbing, i.e., the characterization of the amount of randomness required at the inputs to approximately produce a chosen i.i.d. output distribution according to Kullback-Leibler divergence. We analyze resolvability rates when one encoder cribs (i) the input of the other encoder; or the output of the other encoder, (ii) non-causally, (iii) causally, or (iv) strictly-causally. For scenarios (i)-(iii), we exactly characterize the channel resolvability region. For (iv), we provide inner and outer bounds for the channel resolvability region; the crux of our achievability result is to handle the strict causality constraint with a block-Markov coding scheme in which dependencies across blocks are suitably hidden. Finally, we leverage the channel resolvability results to derive achievable secrecy rate regions for each of the cribbing scenarios under strong secrecy constraints.We study channel resolvability for the discrete memoryless multiple-access channel with cribbing, i.e., the characterization of the amount of randomness required at the inputs to approximately produce a chosen i.i.d. output distribution according to Kullback-Leibler divergence. We analyze resolvability rates when one encoder cribs (i) the input of the other encoder; or the output of the other encoder, (ii) non-causally, (iii) causally, or (iv) strictly-causally. For scenarios (i)-(iii), we exactly characterize the channel resolvability region. For (iv), we provide inner and outer bounds for the channel resolvability region; the crux of our achievability result is to handle the strict causality constraint with a block-Markov coding scheme in which dependencies across blocks are suitably hidden. Finally, we leverage the channel resolvability results to derive achievable secrecy rate regions for each of the cribbing scenarios under strong secrecy constraints.

    @article{Helhal2018a, author = {Helal, Noha and Bloch, Matthieu and Nosratinia, Aria}, journal = ieee_j_it, title = {Cooperative Resolvability and Secrecy in the Cribbing Multiple-Access Channel}, year = {2020}, month = sep, number = {9}, pages = {5429-5447}, volume = {66}, doi = {10.1109/TIT.2020.2995565}, eprint = {1811.11649}, file = {:2020-Helal-IEEETransIT-Cooperative Resolvability and Secrecy in the Cribbing Multiple-Access Channel.pdf:PDF}, howpublished = {accepted for \emph{IEEE Transactions on Information Theory}} }

26. G. Cervia, L. Luzzi, M. Le Treust, and M. Bloch, “Strong Coordination of Signals and Actions over Noisy Channels with two-sided State Information,” ieee_j_it, vol. 66, no. 8, pp. 4681–4708, Aug. 2020.

    We consider a network of two nodes separated by a noisy channel with two-sided state information, in which the input and output signals have to be coordinated with the source and its reconstruction. In the case of non-causal encoding and decoding, we propose a joint source-channel coding scheme and develop inner and outer bounds for the strong coordination region. While the inner and outer bounds do not match in general, we provide a complete characterization of the strong coordination region in three particular cases: i) when the channel is perfect; ii) when the decoder is lossless; and iii) when the random variables of the channel are independent from the random variables of the source. Through the study of these special cases, we prove that the separation principle does not hold for joint source-channel strong coordination. Finally, in the absence of state information, we show that polar codes achieve the best known inner bound for the strong coordination region, which therefore offers a constructive alternative to random binning and coding proofs.

    @article{Cervia2018, author = {Cervia, Giulia and Luzzi, Laura and {Le Treust}, Ma\"el and Bloch, Matthieu}, title = {Strong Coordination of Signals and Actions over Noisy Channels with two-sided State Information}, journal = ieee_j_it, year = {2020}, volume = {66}, number = {8}, pages = {4681-4708}, month = aug, doi = {10.1109/TIT.2020.2984345}, eprint = {1801.10543}, file = {:2020-Cervia-IEEETransIT.pdf:PDF}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

27. M. Tahmasbi and M. R. Bloch, “Towards Undetectable Quantum Key Distribution over Bosonic Channels,” IEEE Journal on Selected Areas in Information Theory, vol. 1, no. 2, pp. 585–598, Aug. 2020.

    We propose a protocol based on pulse-position modulation and multi-level coding that allows one to bootstrap traditional quantum key distribution protocols while ensuring covertness, in the sense that no statistical test by the adversary can detect the presence of communication over the quantum channel better than a random guess. When run over a bosonic channel, our protocol can leverage existing discrete-modulated continuous-variable protocols. Since existing techniques to bound Eve’s information do not directly apply, we develop a new bound that results in positive, although very low, throughput for a range of channel parameters. The analysis of the protocol performance shows that covert secret key expansion is possible using a public authenticated classical channel and a quantum channel largely but not fully under the control of an adversary, which we precisely define. We also establish a converse result showing that, under the golden standard of quantum key distribution, by which the adversary completely controls the quantum channel, no covert key generation is possible.We propose a protocol based on pulse-position modulation and multi-level coding that allows one to bootstrap traditional quantum key distribution protocols while ensuring covertness, in the sense that no statistical test by the adversary can detect the presence of communication over the quantum channel better than a random guess. When run over a bosonic channel, our protocol can leverage existing discrete-modulated continuous-variable protocols. Since existing techniques to bound Eve’s information do not directly apply, we develop a new bound that results in positive, although very low, throughput for a range of channel parameters. The analysis of the protocol performance shows that covert secret key expansion is possible using a public authenticated classical channel and a quantum channel largely but not fully under the control of an adversary, which we precisely define. We also establish a converse result showing that, under the golden standard of quantum key distribution, by which the adversary completely controls the quantum channel, no covert key generation is possible.

    @article{Tahmasbi2020, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, journal = {IEEE Journal on Selected Areas in Information Theory}, title = {Towards Undetectable Quantum Key Distribution over Bosonic Channels}, year = {2020}, month = aug, number = {2}, pages = {585-598}, volume = {1}, doi = {10.1109/JSAIT.2020.3017212}, eprint = {1904.12363}, file = {:2020-Tahmasbi-IEEEJSAIT-Towards Undetectable Quantum Key Distribution Over Bosonic Channels.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Journal of Selected Topics in Information Theory}} }

28. M. Tahmasbi and M. R. Bloch, “Steganography Protocols for Quantum Channels,” Journal of Mathematical Physics, vol. 61, no. 8, p. 082201, Aug. 2020.

    We study several versions of a quantum steganography problem in which two legitimate parties attempt to conceal a cypher in a quantum cover transmitted over a quantum channel without arising suspicion from a warden who intercepts the cover. In all our models, we assume that the warden has an inaccurate knowledge of the quantum channel and we formulate several variations of the steganography problem depending on the tasks used as the cover and the cypher task. In particular, when the cover task is classical communication, we show that the cypher task can be classical communication or entanglement sharing; when the cover task is entanglement sharing and the main channel is noiseless, we show that the cypher task can be randomness sharing; when the cover task is quantum communication and the main channel is noiseless, we show that the cypher task can be classical communication. In the latter case, our results improve earlier ones by relaxing the need for a shared key between the transmitter and the receiver and hold under milder assumptions on the cover quantum communication code. We study several versions of a quantum steganography problem in which two legitimate parties attempt to conceal a cypher in a quantum cover transmitted over a quantum channel without arising suspicion from a warden who intercepts the cover. In all our models, we assume that the warden has an inaccurate knowledge of the quantum channel and we formulate several variations of the steganography problem depending on the tasks used as the cover and the cypher task. In particular, when the cover task is classical communication, we show that the cypher task can be classical communication or entanglement sharing; when the cover task is entanglement sharing and the main channel is noiseless, we show that the cypher task can be randomness sharing; when the cover task is quantum communication and the main channel is noiseless, we show that the cypher task can be classical communication. In the latter case, our results improve earlier ones by relaxing the need for a shared key between the transmitter and the receiver and hold under milder assumptions on the cover quantum communication code.

    @article{Tahmasbi2020a, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R}, journal = {Journal of Mathematical Physics}, title = {Steganography Protocols for Quantum Channels}, year = {2020}, month = aug, number = {8}, pages = {082201}, volume = {61}, doi = {10.1063/5.0004731}, eprint = {1907.09602}, file = {:2020-Tahmasbi-JMP.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{Journal of Mathematical Physics}} }

29. E. Shipilova, M. Barret, M. Bloch, J.-L. Boelle, and J.-L. Collette, “Simultaneous seismic sources separation based on Matrioshka Orthogonal Matching Pursuit, Application in Oil and Gas Exploration,” IEEE Transactions on Geoscience and Remote Sensing, vol. 58, no. 7, pp. 4529–4546, Jul. 2020.

    We present Matrioshka orthogonal matching pursuit (OMP), a method consisting of two nested OMPs for separating seismic sources at an early stage of the signal processing chain. Matrioshka OMP is based on models of sensor signals that place nonrestrictive assumptions on the seismic survey using simultaneous sources. Our seismic event model is based on the spatial coherence of signals, which results in a straight or slightly curved feature in the trace representation of the data with a specific wavelet, whose magnitude can linearly vary according to the offset. We demonstrate the effectiveness of the approach on synthetic and real data.We present Matrioshka orthogonal matching pursuit (OMP), a method consisting of two nested OMPs for separating seismic sources at an early stage of the signal processing chain. Matrioshka OMP is based on models of sensor signals that place nonrestrictive assumptions on the seismic survey using simultaneous sources. Our seismic event model is based on the spatial coherence of signals, which results in a straight or slightly curved feature in the trace representation of the data with a specific wavelet, whose magnitude can linearly vary according to the offset. We demonstrate the effectiveness of the approach on synthetic and real data.

    @article{Shipilova2019, author = {Shipilova, Ekaterina and Barret, Michel and Bloch, Matthieu and Boelle, Jean-Luc and Collette, Jean-Luc}, title = {Simultaneous seismic sources separation based on Matrioshka Orthogonal Matching Pursuit, Application in Oil and Gas Exploration}, journal = {IEEE Transactions on Geoscience and Remote Sensing}, year = {2020}, volume = {58}, number = {7}, pages = {4529-4546}, month = jul, doi = {10.1109/TGRS.2019.2959650}, file = {:2020-Shipilova-IEEETransGSRS.pdf:PDF}, howpublished = {accepted to \emph{IEEE Transactions on Geoscience and Remote Sensing}} }

30. M. Tahmasbi and M. R. Bloch, “Covert Secret Key Generation with an Active Warden,” ieee_j_ifs, vol. 15, pp. 1026–1039, Jun. 2020.

    We investigate the problem of covert and secret key generation over a state-dependent discrete memoryless channel with one-way public discussion in which an adversary, the warden, may arbitrarily choose the channel state. We develop an adaptive protocol that, under conditions that we explicitly specify, not only allows the transmitter and the legitimate receiver to exchange a secret key but also conceals from the active warden whether the protocol is being run. When specialized to passive adversaries that do not control the channel state, we partially characterize the covert secret key capacity. In particular, the covert secret key capacity is sometimes equal to the covert capacity of the channel, so that secrecy comes "for free."

    @article{Tahmasbi2019, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R}, journal = ieee_j_ifs, title = {Covert Secret Key Generation with an Active Warden}, year = {2020}, month = jun, pages = {1026-1039}, volume = {15}, doi = {10.1109/TIFS.2019.2932906}, doneatgt = {yes}, eprint = {1901.02044}, file = {:2020-Tahmasbi-IEEETransIFS.pdf:PDF}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}} }

31. M. Tahmasbi, A. Savard, and M. R. Bloch, “Covert Capacity of Non-Coherent Rayleigh-Fading Channels,” ieee_j_it, vol. 66, no. 4, pp. 1979–2005, Apr. 2020.

    The covert capacity is characterized for a non-coherent fast Rayleigh-fading wireless channel, in which a legitimate user wishes to communicate reliably with a legitimate receiver while escaping detection from a warden. It is shown that the covert capacity is achieved with an amplitude-constrained input distribution that consists of a finite number of mass points including one at zero and numerically tractable bounds are provided. It is also conjectured that distributions with two mass points in fixed locations are optimal.

    @article{Tahmasbi2018a, author = {Tahmasbi, Mehrdad and Savard, Anne and Bloch, Matthieu R}, journal = ieee_j_it, title = {Covert Capacity of Non-Coherent Rayleigh-Fading Channels}, year = {2020}, issn = {0018-9448}, month = apr, number = {4}, pages = {1979-2005}, volume = {66}, doi = {10.1109/TIT.2019.2956489}, eprint = {1810.07687}, file = {:2020-Tahmasbi-IEEETransIT.pdf:PDF}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

32. M. Tahmasbi, M. R. Bloch, and A. Yener, “Learning an Adversary’s Actions for Secret Communication,” ieee_j_it, vol. 66, no. 3, pp. 1607–1624, Mar. 2020.

    Secure communication over a wiretap channel is investigated, in which an active adversary modifies the state of the channel and the legitimate transmitter has the opportunity to sense and learn the adversary’s actions. The adversary has the ability to switch the channel state and observe the corresponding output at every channel use while the encoder has causal access to observations that depend on the adversary’s actions. A joint learning/transmission scheme is developed in which the legitimate users learn and adapt to the adversary’s actions. For some channel models, it is shown that the achievable rates, defined precisely for the problem, are arbitrarily close to those obtained with hindsight, had the transmitter known the actions ahead of time. This initial study suggests that there is much to exploit and gain in physical-layer security by learning the adversary, e.g., monitoring the environment.

    @article{Tahmasbi2018, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R. and Yener, Aylin}, journal = ieee_j_it, title = {Learning an Adversary's Actions for Secret Communication}, year = {2020}, month = mar, number = {3}, pages = {1607--1624}, volume = {66}, doi = {10.1109/TIT.2019.2940960}, eprint = {1807.08670}, file = {:2020-Tahmasbi-IEEETransIT-a.pdf:PDF}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

33. K. S. K. Arumugam and M. R. Bloch, “Covert Communication over a K-User Multiple Access Channel,” ieee_j_it, vol. 65, no. 11, pp. 7020–7044, Nov. 2019.

    We consider a scenario in which K transmitters attempt to communicate covert messages reliably to a legitimate receiver over a discrete memoryless multiple-access channel (MAC) while simultaneously escaping detection from an adversary who observes their communication through another discrete memoryless MAC. We assume that each transmitter may use a secret key that is shared only between itself and the legitimate receiver. We show that each of the K transmitters can transmit on the order of sqrt(n) reliable and covert bits per n channel uses, exceeding which, the warden will be able to detect the communication. We identify the optimal pre-constants of the scaling, which leads to a complete characterization of the covert capacity region of the K-user binary-input MAC. We show that, asymptotically, all sum-rate constraints are inactive unlike the traditional MAC capacity region. We also characterize the channel conditions that have to be satisfied for the transmitters to operate without a secret key.

    @article{Arumugam2018a, author = {Arumugam, Keerthi Suria Kumar and Bloch, Matthieu R}, title = {Covert Communication over a K-User Multiple Access Channel}, journal = ieee_j_it, year = {2019}, volume = {65}, number = {11}, pages = {7020-7044}, month = nov, issn = {0018-9448}, doi = {10.1109/TIT.2019.2930484}, eprint = {1803.06007}, file = {:2019-Arumugam-TransIT.pdf:PDF} }

34. K. S. K. Arumugam and M. R. Bloch, “Embedding Covert Information in Broadcast Communications,” ieee_j_ifs, vol. 14, no. 10, pp. 2787–2801, Oct. 2019.

    We analyze a two-receiver binary-input discrete memoryless broadcast channel, in which the transmitter communicates a common message simultaneously to both receivers and a covert message to only one of them. The unintended recipient of the covert message is treated as an adversary who attempts to detect the covert transmission. This model captures the problem of embedding covert messages in an innocent codebook and generalizes previous covert communication models in which the innocent behavior corresponds to the absence of communication between legitimate users. We identify the exact asymptotic behavior of the number of covert bits that can be transmitted when the rate of the innocent codebook is close to the capacity of the channel to the adversary. Our results also identify the dependence of the number of covert bits on the channel parameters and the characteristics of the innocent codebook.

    @article{Arumugam2018b, author = {Arumugam, Keerthi Suria Kumar and Bloch, Matthieu R.}, title = {Embedding Covert Information in Broadcast Communications}, journal = ieee_j_ifs, year = {2019}, volume = {14}, number = {10}, pages = {2787--2801}, month = oct, doi = {10.1109/TIFS.2019.2907190}, eprint = {1808.09556}, file = {:2019-Arumugam-IEEETransIFS.pdf:PDF}, groups = {Steganography and covert communications} }

35. M. Tahmasbi and M. R. Bloch, “Framework for covert and secret key expansion over classical-quantum channels,” Physical Review A, vol. 99, no. 5, p. 052329, May 2019.

    Covert and secret quantum key distribution aims at generating information-theoretically secret bits between distant legitimate parties in a manner that remains provably undetectable by an adversary. We propose a framework in which to precisely define and analyze such an operation, and we show that covert and secret key expansion is possible. For fixed and known classical-quantum wiretap channels, we develop and analyze protocols based on forward and reverse reconciliation. The crux of our approach is the use of information reconciliation and privacy amplification techniques that are able to process the sparse signals required for covert operation and the Shannon entropy of which scales as the square root of their length. In particular, our results show that the coordination required between legitimate parties to achieve covert communication can be achieved with a negligible number of secret key bits.

    @article{Tahmasbi2018b, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, journal = {Physical Review A}, title = {Framework for covert and secret key expansion over classical-quantum channels}, year = {2019}, month = may, pages = {052329}, volume = {99}, doi = {10.1103/PhysRevA.99.052329}, eprint = {1811.05626}, file = {:2019-Tahmasbi-PRA.pdf:PDF}, groups = {Quantum information science}, issue = {5}, numpages = {11}, publisher = {American Physical Society} }

36. M. Tahmasbi and M. R. Bloch, “First and Second Order Asymptotics in Covert Communication,” ieee_j_it, vol. 65, no. 4, pp. 2190–2212, Apr. 2019.

    We study the first- and second-order asymptotics of covert communication over binary-input DMC for three different covertness metrics and under maximum probability of error constraint. When covertness is measured in terms of the relative entropy between the channel output distributions induced with and without communication, we characterize the exact first- and second-order asymptotics of the number of bits that can be reliably transmitted with a maximum probability of error less than εand a relative entropy less than δ. When covertness is measured in terms of the variational distance between the channel output distributions or in terms of the probability of missed detection for fixed probability of false alarm, we establish the exact first-order asymptotics and bound the second-order asymptotics. PPM achieves the optimal first-order asymptotics for all three metrics, as well as the optimal second-order asymptotics for relative entropy. The main conceptual contribution of this paper is to clarify how the choice of a covertness metric impacts the information-theoretic limits of covert communications. The main technical contribution underlying our results is a detailed expurgation argument to show the existence of a code satisfying the reliability and covertness criteria.

    @article{Tahmasbi2017, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R}, journal = ieee_j_it, title = {First and Second Order Asymptotics in Covert Communication}, year = {2019}, month = apr, number = {4}, pages = {2190 --2212}, volume = {65}, doi = {10.1109/TIT.2018.2878526}, eprint = {1703.01362}, file = {:2019-Tahmasbi-IEEETransIT.pdf:PDF}, groups = {Steganography and covert communications} }

37. R. A. Chou, M. R. Bloch, and J. Kliewer, “Empirical and Strong Coordination via Soft Covering with Polar Codes,” ieee_j_it, vol. 64, no. 7, pp. 5087–5100, Jul. 2018.

    We design polar codes for empirical coordination and strong coordination in two-node networks. Our constructions hinge on the fact that polar codes enable explicit low-complexity schemes for soft covering. We leverage this property to propose explicit and low-complexity coding schemes that achieve the capacity regions of both empirical coordination and strong coordination for sequences of actions taking value in an alphabet of prime cardinality. Our results improve previously known polar coding schemes, which (i) were restricted to uniform distributions and to actions obtained via binary symmetric channels for strong coordination, (ii) required a non-negligible amount of common randomness for empirical coordination, and (iii) assumed that the simulation of discrete memoryless channels could be perfectly implemented. As a by-product of our results, we obtain a polar coding scheme that achieves channel resolvability for an arbitrary discrete memoryless channel whose input alphabet has prime cardinality.

    @article{Chou2016a, author = {Chou, R\'emi A. and Bloch, Matthieu R. and Kliewer, Joerg}, journal = ieee_j_it, title = {Empirical and Strong Coordination via Soft Covering with Polar Codes}, year = {2018}, issn = {0018-9448}, month = jul, number = {7}, pages = {5087-5100}, volume = {64}, doi = {10.1109/TIT.2018.2817519}, eprint = {1608.08474}, groups = {Coordination of networks, Polar codes}, howpublished = {accepted to \emph{IEEE Transactions on Information Theory}} }

38. B. Larrousse, S. Lasaulce, and M. Bloch, “Coordination in distributed networks via coded actions with application to power control,” ieee_j_it, vol. 64, no. 5, pp. 3633–3654, May 2018.

    This paper investigates the problem of coordinating several agents through their actions. Although the methodology applies to general scenarios, the present work focuses on a situation with an asymmetric observation structure that only involves two agents. More precisely, one of the agents knows the past, present, and future realizations of a state (the system state) that affects the common payoff function of the agents; in contrast, the second agent is assumed either to know the past realizations of the system state or to have no knowledge of it. In both cases, the second agent has access to some strictly causal observations of the first agent’s actions, which enables the two agents to coordinate. These scenarios are applied to the problem of distributed power control; the key idea is that a transmitter may embed information about the wireless channel state into its transmit power levels so that an observation of these levels, e.g. the signal-to-interference plus noise ratio, allows the other transmitter to coordinate its power levels. The main contributions of this paper are twofold. First, we provide a characterization of the set of feasible average payoffs when the agents repeatedly take long sequences of actions and the realizations of the system state are \acsiid. Second, we exploit these results in the context of distributed power control and introduce the concept of coded power control. We carry out an extensive numerical analysis of the benefits of coded power control over alternative power control policies, and highlight a simple yet non-trivial example of a power control code.

    @article{Larrousse2014, author = {Larrousse, Benjamin and Lasaulce, Samson and Bloch, Matthieu}, journal = ieee_j_it, title = {Coordination in distributed networks via coded actions with application to power control}, year = {2018}, month = may, number = {5}, pages = {3633--3654}, volume = {64}, creationdate = {2014-10-31T00:00:00}, doi = {10.1109/TIT.2018.2809008}, eprint = {1501.03685}, howpublished = {accepted in \emph{IEEE Transactions on Information Theory}}, owner = {mattbloch} }

39. B. N. Vellambi, J. Kliewer, and M. R. Bloch, “Strong Coordination Over Multi-Hop Line Networks Using Channel Resolvability Codebooks,” ieee_j_it, vol. 64, no. 2, pp. 1132–1162, Feb. 2018.

    We analyze the problem of strong coordination over a multi-hop line network in which the node initiating the coordination is a terminal network node. We assume that each node has access to a certain amount of randomness that is local to the node, and that the nodes also have shared common randomness, which are used together with explicit hop-by-hop communication to achieve information-theoretic strong coordination. We derive the trade-offs among the required rates of communication on the network links, the rates of local randomness available at network nodes, and the rate of common randomness to realize strong coordination. We present an achievable coding scheme built using multiple layers of channel resolvability codes, and establish several settings in which this scheme offers the best possible trade-offs among network resources.

    @article{Vellambi2016a, author = {Vellambi, Badri N. and Kliewer, Joerg and Bloch, Matthieu R}, journal = ieee_j_it, title = {Strong Coordination Over Multi-Hop Line Networks Using Channel Resolvability Codebooks}, year = {2018}, issn = {0018-9448}, month = feb, number = {2}, pages = {1132-1162}, volume = {64}, creationdate = {2016-04-09T00:00:00}, doi = {10.1109/TIT.2017.2768529}, eprint = {1602.09001}, file = {:2018-Vellambi-IEEETransIT-Strong Coordination Over Multi-Hop LineNetworks Using Channel Resolvability Codebooks.pdf:PDF}, groups = {Coordination of networks}, keywords = {Communication system signaling;Encoding;Indexes;Random variables;Robot kinematics;Spread spectrum communication;Strong coordination;channel resolvability;channel synthesis;line network}, owner = {mattbloch} }

40. G. Frèche, M. Bloch, and M. Barret, “Polar Codes for Covert Communications over Asynchronous Discrete Memoryless Channels,” Entropy, vol. 20, no. 1, p. 3, Dec. 2017.

    This paper introduces an explicit covert communication code for binary-input asynchronous discrete memoryless channels based on binary polar codes, in which legitimate parties exploit uncertainty created by both the channel noise and the time of transmission to avoid detection by an adversary. The proposed code jointly ensures reliable communication for a legitimate receiver and low probability of detection with respect to the adversary, both observing noisy versions of the codewords. Binary polar codes are used to shape the weight distribution of codewords and ensure that the average weight decays as the block length grows. The performance of the proposed code is severely limited by the speed of polarization, which in turn controls the decay of the average codeword weight with the block length. Although the proposed construction falls largely short of achieving the performance of random codes, it inherits the low-complexity properties of polar codes.

    @article{Freche2017, author = {Fr\`eche, Guillaume and Bloch, Matthieu and Barret, Michel}, title = {Polar Codes for Covert Communications over Asynchronous Discrete Memoryless Channels}, journal = {Entropy}, year = {2017}, volume = {20}, number = {1}, pages = {3}, month = dec, issn = {1099-4300}, doi = {10.3390/e20010003}, file = {:2017-Freche-Entropy.pdf:PDF}, groups = {Steganography and covert communications, Polar codes} }

41. R. A. Chou, B. N. Vellambi, M. R. Bloch, and J. Kliewer, “Coding Schemes for Achieving Strong Secrecy at Negligible Cost,” ieee_j_it, vol. 63, no. 3, pp. 1858–1873, Mar. 2017.

    We study the problem of achieving strong secrecy over wiretap channels at negligible cost, in the sense of maintaining the overall communication rate of the same channel without secrecy constraints. Specifically, we propose and analyze two source-channel coding architectures, in which secrecy is achieved by multiplexing public and confidential messages. In both cases, our main contribution is to show that secrecy can be achieved without compromising communication rate and by requiring only randomness of asymptotically vanishing rate. Our first source-channel coding architecture relies on a modified wiretap channel code, in which randomization is performed using the output of a source code. In contrast, our second architecture relies on a standard wiretap code combined with a modified source code termed uniform compression code, in which a small shared secret seed is used to enhance the uniformity of the source code output. We carry out a detailed analysis of uniform compression codes and characterize the optimal size of the shared seed.

    @article{Chou2014b, author = {Chou, R\'emi A. and Vellambi, B. N. and Bloch, M. R. and Kliewer, J.}, journal = ieee_j_it, title = {Coding Schemes for Achieving Strong Secrecy at Negligible Cost}, year = {2017}, issn = {0018-9448}, month = mar, number = {3}, pages = {1858-1873}, volume = {63}, creationdate = {2014-06-15T00:00:00}, doi = {10.1109/TIT.2016.2645225}, eprint = {1508.07920}, groups = {Wiretap channels}, keywords = {channel coding;cryptography;message authentication;multiplexing;source coding;telecommunication security;asymptotically vanishing rate randomness;confidential messages;modified source code;modified wiretap channel code;multiplexing;optimal size characterization;public messages;shared secret seed;source code output uniformity enhancement;source-channel coding architectures;strong secrecy problem;uniform compression code;Channel models;Decoding;Encoding;Multiplexing;Physical layer;Security;Virtual private networks;Wiretap channel;multiplexing;physical-layer security;source coding}, owner = {mattbloch} }

42. M. R. Bloch, “Covert Communication over Noisy Channels: A Resolvability Perspective,” ieee_j_it, vol. 62, no. 5, pp. 2334–2354, May 2016.

    We consider the situation in which a transmitter attempts to communicate reliably over a discrete memoryless channel, while simultaneously ensuring covertness (low probability of detection) with respect to a warden, who observes the signals through another discrete memoryless channel. We develop a coding scheme based on the principle of channel resolvability, which generalizes and extends prior work in several directions. First, it shows that irrespective of the quality of the channels, it is possible to communicate on the order of \sqrt n reliable and covert bits over n channel uses if the transmitter and the receiver share on the order of \sqrt n key bits. This improves upon earlier results requiring on the order of \sqrt n\log n key bits. Second, it proves that if the receiver’s channel is better than the warden’s channel in a sense that we make precise, it is possible to communicate on the order of \sqrt n reliable and covert bits over n channel uses without a secret key. This generalizes earlier results established for binary symmetric channels. We also identify the fundamental limits of covert and secret communications in terms of the optimal asymptotic scaling of the message size and key size, and we extend the analysis to Gaussian channels. The main technical problem that we address is how to develop concentration inequalities for low-weight sequences. The crux of our approach is to define suitably modified typical sets that are amenable to concentration inequalities.t

    @article{Bloch2015b, author = {Bloch, Matthieu R.}, journal = ieee_j_it, title = {Covert Communication over Noisy Channels: A Resolvability Perspective}, year = {2016}, issn = {0018-9448}, month = may, number = {5}, pages = {2334-2354}, volume = {62}, creationdate = {2015-03-31T00:00:00}, doi = {10.1109/TIT.2016.2530089}, eprint = {1503.08778}, file = {:2016-Bloch-IEEETransIT.pdf:PDF}, groups = {Steganography and covert communications}, keywords = {AWGN channels;Encoding;Memoryless systems;Noise measurement;Reliability theory;Covert communications;Shannon theory;low probability of detection;physical-layer security}, owner = {mattbloch} }

43. R. A. Chou and M. R. Bloch, “Polar Coding for the Broadcast Channel with Confidential Messages: A Random Binning Analogy,” ieee_j_it, vol. 62, no. 5, pp. 2410–2429, May 2016.

    We develop a low-complexity polar coding scheme for the discrete memoryless broadcast channel with confidential messages under strong secrecy and randomness constraints. Our scheme extends previous work by using an optimal rate of uniform randomness in the stochastic encoder, and avoiding assumptions regarding the symmetry or degraded nature of the channels. The price paid for these extensions is that the encoder and the decoders are required to share a secret seed of negligible size and to increase the block length through chaining. We also highlight a close conceptual connection between the proposed polar coding scheme and a random binning proof of the secrecy capacity region.

    @article{Chou2014d, author = {Chou, R\'emi A. and Bloch, Matthieu R}, journal = ieee_j_it, title = {Polar Coding for the Broadcast Channel with Confidential Messages: A Random Binning Analogy}, year = {2016}, issn = {0018-9448}, month = may, number = {5}, pages = {2410-2429}, volume = {62}, creationdate = {2014-10-31T00:00:00}, doi = {10.1109/TIT.2016.2539145}, eprint = {1411.0281}, file = {:2016-Chou-IEEETransIT.pdf:PDF}, groups = {Polar codes, Wiretap codes}, keywords = {Channel models;Decoding;Degradation;Encoding;Random variables;Security;Stochastic processes;Polar codes;physical-layer security;random binning;strong secrecy;wiretap channel}, owner = {mattbloch} }

44. R. A. Chou, M. R. Bloch, and E. Abbe, “Polar Coding for Secret-Key Generation,” ieee_j_it, vol. 61, no. 11, pp. 6213–6237, Nov. 2015.

    Practical implementations of secret-key generation are often based on sequential strategies, which handle reliability and secrecy in two successive steps, called reconciliation and privacy amplification. In this paper, we propose an alternative approach based on polar codes that jointly deals with reliability and secrecy. Specifically, we propose secret-key capacityachieving polar coding schemes for the following models: (i) the degraded binary memoryless source (DBMS) model with rateunlimited public communication, (ii) the DBMS model with oneway rate-limited public communication, (iii) the 1-to-m broadcast model and (iv) the Markov tree model with uniform marginals. For models (i) and (ii) our coding schemes remain valid for nondegraded sources, although they may not achieve the secret-key capacity. For models (i), (ii) and (iii), our schemes rely on preshared secret seed of negligible rate; however, we provide special cases of these models for which no seed is required. Finally, we show an application of our results to secrecy and privacy for biometric systems. We thus provide the first examples of lowcomplexity secret-key capacity-achieving schemes that are able to handle vector quantization for model (ii), or multiterminal communication for models (iii) and (iv).

    @article{Chou2013b, author = {Chou, R\'emi A. and Bloch, Matthieu R and Abbe, Emmanuel}, journal = ieee_j_it, title = {Polar Coding for Secret-Key Generation}, year = {2015}, issn = {0018-9448}, month = nov, number = {11}, pages = {6213-6237}, volume = {61}, creationdate = {2013-10-09T00:00:00}, doi = {10.1109/TIT.2015.2471179}, eprint = {1305.4746}, file = {:2015-Chou-IEEETransIT-Polar Coding for Secret-Key Generation.pdf:PDF}, groups = {Secret key agreement, Polar codes}, keywords = {Biological system modeling;Decoding;Encoding;Markov processes;Privacy;Protocols;Reliability}, owner = {mattbloch} }

45. M. R. Bloch, M. Hayashi, and A. Thangaraj, “Error-Control Coding for Physical-Layer Secrecy,” Proceedings of IEEE, vol. 103, no. 10, pp. 1725–1746, Oct. 2015.

    The renewed interest for physical-layer security techniques has put forward a new role for error-control codes. In addition to ensuring reliability, carefully designed codes have been shown to provide a level of information-theoretic secrecy, by which the amount of information leaked to an adversary may be controlled. The ability to achieve information-theoretic secrecy relies on the study of alternative coding mechanisms, such as channel resolvability and privacy amplification, in which error-control codes are exploited as a means to shape the distribution of stochastic processes. This use of error-control codes, which goes much beyond that of correcting errors, creates numerous new design challenges. The objective of this paper is threefold. First, the paper aims at providing system engineers with explicit tools to build simple secrecy codes in order to stimulate interest and foster their integration in communication system prototypes. Second, it aims at providing coding and information theorists with a synthetic overview of the theoretical concepts and techniques for secrecy. Finally, it aims at highlighting the open challenges and opportunities faced for the integration of these codes in practical systems.

    @article{Bloch2015a, author = {Bloch, Matthieu R and Hayashi, Masahito and Thangaraj, Andrew}, journal = {{P}roceedings of {IEEE}}, title = {Error-Control Coding for Physical-Layer Secrecy}, year = {2015}, issn = {0018-9219}, month = oct, number = {10}, pages = {1725-1746}, volume = {103}, creationdate = {2015-01-27T00:00:00}, doi = {10.1109/JPROC.2015.2463678}, groups = {Wiretap codes}, keywords = {Channel coding;Communication system security;Cryptography;Decoding;Error analysis;Physical layer;Security;Semantics;Telecommunication services;Channel resolvability;error-control coding;physical-layer security;privacy amplification}, owner = {mattbloch} }

46. V. Y. F. Tan and M. R. Bloch, “Information Spectrum Approach to Strong Converse Theorems for Degraded Wiretap Channels,” ieee_j_ifs, vol. 10, no. 9, pp. 1891–1904, Sep. 2015.

    We consider block codes for degraded wiretap channels in which the legitimate receiver decodes the message with an asymptotic error probability no larger than epsilon but the leakage to the eavesdropper vanishes. For discrete memoryless and Gaussian wiretap channels, we show that the maximum rate of transmission does not depend on epsilon in [0, 1), i.e., such channels possess the partial strong converse property. Furthermore, we derive sufficient conditions for the partial strong converse property to hold for memoryless but nonstationary symmetric and degraded wiretap channels. Our proof techniques leverage the information spectrum method, which allows us to establish a necessary and sufficient condition for the partial strong converse to hold for general wiretap channels without any information stability assumptions.

    @article{Tan2014a, author = {Tan, V.Y.F. and Bloch, M.R.}, journal = ieee_j_ifs, title = {Information Spectrum Approach to Strong Converse Theorems for Degraded Wiretap Channels}, year = {2015}, issn = {1556-6013}, month = sep, number = {9}, pages = {1891-1904}, volume = {10}, creationdate = {2015-01-06T00:00:00}, doi = {10.1109/TIFS.2015.2434592}, eprint = {1406.6758}, groups = {Wiretap channels}, keywords = {Gaussian channels;block codes;error statistics;telecommunication security;wireless channels;Gaussian wiretap channels;asymptotic error probability;block codes;degraded wiretap channels;discrete memoryless wiretap channels;eavesdropper;information spectrum method;legitimate receiver;partial strong converse property;Error probability;Manganese;Measurement;Mutual information;Random variables;Receivers;Zinc;Degraded wiretap channels;Information spectrum method;Information-theoretic security;Strong converse;degraded wiretap channels;information spectrum method;information-theoretic security}, owner = {mattbloch} }

47. R. A. Chou and M. R. Bloch, “Separation of Reliability and Secrecy in Rate-Limited Secret Key-Distillation,” ieee_j_it, vol. 60, no. 8, pp. 4941–4957, Aug. 2014.

    For a discrete or a continuous source model, we study the problem of secret-key generation with one round of rate-limited public communication between two legitimate users. Although we do not provide new bounds on the wiretap secret-key (WSK) capacity for the discrete source model, we use an alternative achievability scheme that may be useful for practical applications. As a side result, we conveniently extend known bounds to the case of a continuous source model. Specifically, we consider a sequential key-generation strategy, that implements a rate-limited reconciliation step to handle reliability, followed by a privacy amplification step performed with extractors to handle secrecy. We prove that such a sequential strategy achieves the best known bounds for the rate-limited WSK capacity (under the assumption of degraded sources in the case of two-way communication). However, we show that, unlike the case of rate-unlimited public communication, achieving the reconciliation capacity in a sequential strategy does not necessarily lead to achieving the best known bounds for the WSK capacity. Consequently, reliability and secrecy can be treated successively but not independently, thereby exhibiting a limitation of sequential strategies for rate-limited public communication. Nevertheless, we provide scenarios for which reliability and secrecy can be treated successively and independently, such as the two-way rate-limited SK capacity, the one-way rate-limited WSK capacity for degraded binary symmetric sources, and the one-way rate-limited WSK capacity for Gaussian degraded sources.

    @article{Chou2012a, author = {Chou, R\'emi A. and Bloch, Matthieu R}, journal = ieee_j_it, title = {Separation of Reliability and Secrecy in Rate-Limited Secret Key-Distillation}, year = {2014}, month = aug, number = {8}, pages = {4941--4957}, volume = {60}, citeseerurl = {1210.4482}, creationdate = {2012-09-24T00:00:00}, doi = {10.1109/TIT.2014.2323246}, eprint = {1210.4482}, groups = {Secret key agreement}, owner = {mattbloch} }

48. N. Li et al., “Two approaches for ultrafast random bit generation based on the chaotic dynamics of a semiconductor laser,” Optics Express, vol. 22, no. 6, pp. 6634–6646, Mar. 2014.

    This paper reports the experimental investigation of two different approaches to random bit generation based on the chaotic dynamics of a semiconductor laser with optical feedback. By computing high-order finite differences of the chaotic laser intensity time series, we obtain time series with symmetric statistical distributions that are more conducive to ultrafast random bit generation. The first approach is guided by information-theoretic considerations and could potentially reach random bit generation rates as high as 160 Gb/s by extracting 4 bits per sample. The second approach is based on pragmatic considerations and could lead to rates of 2.2 Tb/s by extracting 55 bits per sample. The randomness of the bit sequences obtained from the two approaches is tested against three standard randomness tests (ENT, Diehard, and NIST tests), as well as by calculating the statistical bias and the serial correlation coefficients on longer sequences of random bits than those used in the standard tests.

    @article{Li2013, author = {Li, Nianqiang and Kim, Byungchil and Chizhevsky, V. N. and Locquet, A. and Bloch, M. and Citrin, D. S. and Pan, Wei}, journal = {{O}ptics {E}xpress}, title = {Two approaches for ultrafast random bit generation based on the chaotic dynamics of a semiconductor laser}, year = {2014}, month = mar, number = {6}, pages = {6634--6646}, volume = {22}, doi = {10.1364/OE.22.006634}, groups = {Physical random number generation}, keywords = {Fiber optics and optical communications; Chaos; Semiconductor lasers; Instabilities and chaos}, publisher = {OSA} }

49. M. R. Bloch and J. N. Laneman, “Strong Secrecy from Channel Resolvability,” ieee_j_it, vol. 59, no. 12, pp. 8077–8098, Dec. 2013.

    We analyze physical-layer security based on the premise that the coding mechanism for secrecy over noisy channels is tied to the notion of channel resolvability. Instead of considering capacity-based constructions, which associate to each message a subcode that operates just below the capacity of the eavesdropper’s channel, we consider channel-resolvability-based constructions, which associate to each message a subcode that operates just above the resolvability of the eavesdropper’s channel. Building upon the work of Csiszár and Hayashi, we provide further evidence that channel resolvability is a powerful and versatile coding mechanism for secrecy by developing results that hold for strong secrecy metrics and arbitrary channels. Specifically, we show that at least for symmetric wiretap channels, random capacity-based constructions fail to achieve the strong secrecy capacity, while channel-resolvability-based constructions achieve it. We then leverage channel resolvability to establish the secrecy-capacity region of arbitrary broadcast channels with confidential messages and a cost constraint for strong secrecy metrics. Finally, we specialize our results to study the secrecy capacity of wireless channels with perfect channel state information (CSI), mixed channels, and compound channels with receiver CSI, as well as the secret-key capacity of source models for secret-key agreement. By tying secrecy to channel resolvability, we obtain achievable rates for strong secrecy metrics with simple proofs.

    @article{Bloch2011e, author = {Bloch, Matthieu R. and Laneman, J. Nicholas}, journal = ieee_j_it, title = {Strong Secrecy from Channel Resolvability}, year = {2013}, issn = {0018-9448}, month = dec, number = {12}, pages = {8077-8098}, volume = {59}, citeseerurl = {1105.5419}, creationdate = {2009-07-12T00:00:00}, doi = {10.1109/TIT.2013.2283722}, eprint = {1105.5419}, file = {:2013-Bloch-IEEETransIT-Strong Secrecy From Channel Resolvability.pdf:PDF}, groups = {Wiretap channels}, keywords = {Channel capacity;Encoding;Entropy;Measurement;Mutual information;Random variables;Security;Channel resolvability;information-spectrum;information-theoretic security;secret-key agreement;wireless channels;wiretap channel}, owner = {matthieu} }

50. W. K. Harrison, J. Almeida, M. R. Bloch, S. W. McLaughlin, and J. Barros, “Coding for Secrecy: An Overview of Error-Control Coding Techniques for Physical-Layer Security,” IEEE Signal Processing Magazine, vol. 30, no. 5, pp. 41–50, Sep. 2013.

    While secrecy in communication systems has historically been obtained through cryptographic means in the upper layers, recent research efforts have focused on the physical layer and have unveiled ample opportunities for security design. In particular, the combination of signal processing techniques with channel coding for secrecy has been central to the development of physical-layer security efforts. Although implicit coding techniques for secrecy have been known since the 1970s, explicit code constructions have only been discovered within the last decade. The purpose of this article is to provide a synopsis of the state of the art in coding for secrecy. We discuss the general principles of coding, and we illustrate them with several examples. In particular, we discuss the importance of a nested code structure and stochastic encoding, which allow for both data reliability and security.

    @article{Harrison2013, author = {Harrison, Willie K. and Almeida, Joao and Bloch, Matthieu R. and McLaughlin, Steven W. and Barros, Joao}, journal = {{IEEE} {S}ignal {P}rocessing {M}agazine}, title = {Coding for Secrecy: An Overview of Error-Control Coding Techniques for Physical-Layer Security}, year = {2013}, month = sep, number = {5}, pages = {41--50}, volume = {30}, creationdate = {2013-01-20T00:00:00}, doi = {10.1109/MSP.2013.2265141}, file = {:Users/mattbloch/Documents/Publications/2013-Harrison-IEEESPMag.pdf:PDF}, groups = {Wiretap codes}, howpublished = {accepted to \emph{Signal Processing Magazine}}, owner = {mattbloch}, quality = {1} }

51. M. R. Bloch and J. N. Laneman, “Exploiting Partial Channel State Information for Secrecy over Wireless Channels,” IEEE Journal on Selected Areas in Communications, vol. 31, no. 9, pp. 1840–1849, Sep. 2013.

    In this paper, we investigate the effect of partial channel state information on the achievable secure communication rates and secret-key generation rates over ergodic fading channels. In particular, we establish the strong secret-key capacity as well as lower bounds for the strong secrecy capacity of ergodic and block-ergodic fading channels with partial Channel State Information at the Transmitter(CSIT). Our analysis sheds light on the usefulness of CSIT to harness the benefits of fading for secrecy and allows us to quantify the penalty incurred by the lack of full CSIT. In particular, we numerically illustrate situations in which little CSIT is required to recover most of the benefits of fading and in which the legitimate terminals have an incentive to precisely characterize their channel.

    @article{Bloch2012b, author = {Bloch, Matthieu R. and Laneman, J. Nicholas}, journal = {{IEEE} {J}ournal on {S}elected {A}reas in {C}ommunications}, title = {Exploiting Partial Channel State Information for Secrecy over Wireless Channels}, year = {2013}, issn = {0733-8716}, month = sep, number = {9}, pages = {1840-1849}, volume = {31}, doi = {10.1109/JSAC.2013.130916}, file = {:Users/mattbloch/Documents/Publications/2013-Bloch-IEEEJSAC.pdf:PDF}, groups = {Secret key agreement}, keywords = {Channel state information;Coherence;Communication system security;Encoding;Fading;Resource management;Wireless communication;channels state information;secrecy capacity;secret-key capacity;wireless fading channel} }

52. R. Bassily et al., “Cooperative Security at the Physical Layer: A Summary of Recent Advances,” IEEE Signal Processing Magazine, vol. 30, no. 5, pp. 16–28, Sep. 2013.

    Wireless communications systems are particularly vulnerable to security attacks because of the inherent openness of the transmission medium. In this article, we focus on guaranteeing confidentiality against eavesdropping attacks where an unauthorized entity aims to intercept an ongoing wireless communication, and we provide a comprehensive summary of recent advances in the area of physical-layer security that guarantees confidentiality by using cooperative techniques unique to the wireless medium. These cooperative techniques consist of carefully designed coding and signaling schemes that are able to harness the properties of the physical layer and to ensure some level of information-theoretic security.

    @article{Bassily2013, author = {Bassily, Raef and Ekrem, Ersen and He, Xiang and Tekin, Ender and Xie, Jianwei and Bloch, Matthieu and Ulukus, Sennur and Yener, Aylin}, journal = {{IEEE} {S}ignal {P}rocessing {M}agazine}, title = {Cooperative Security at the Physical Layer: A Summary of Recent Advances}, year = {2013}, month = sep, number = {5}, pages = {16--28}, volume = {30}, creationdate = {2013-01-20T00:00:00}, doi = {10.1109/MSP.2013.2260875}, file = {:2013-Bassily-IEEESPMag.pdf:PDF}, groups = {Cooperative jamming}, howpublished = {accepted to \emph{Signal Processing Magazine}}, owner = {mattbloch}, quality = {1} }

53. F. Renna, M. R. Bloch, and N. Laurenti, “Semi-blind Key-Agreement over MIMO Fading Channels,” IEEE Transactions on Communications, vol. 61, no. 2, pp. 620–627, Feb. 2013.

    In this paper, we study the fundamental limits of secret-key agreement over MIMO quasi-static fading channels. We provide closed-form expressions for the secret-key capacity in both the asymptotic high-power and low-power regimes. The optimal signaling strategy for the low-power regime is shown to be independent of the eavesdropper’s channel and secret-key capacity is achieved by transmitting random Gaussian symbols along the direction corresponding to the maximal eigenvalue of the legitimate channel matrix. Hence, by beamforming and waterfilling over the main channel alone, one obtains a semi-blind key-agreement strategy in which the knowledge of the eavesdropper’s channel is only required for privacy amplification. We also derive the probability that a target secret-key rate is not achieved by the optimal low-power signaling when assuming only statistical CSI about the eavesdropper’s channel.

    @article{Renna2012, author = {Renna, Francesco and Bloch, Matthieu R. and Laurenti, Nicola}, journal = {{IEEE} {T}ransactions on {C}ommunications}, title = {{S}emi-blind Key-Agreement over {MIMO} Fading Channels}, year = {2013}, month = feb, number = {2}, pages = {620--627}, volume = {61}, creationdate = {2012-01-29T00:00:00}, doi = {10.1109/TCOMM.2012.102512.120084}, file = {:../Publications/2013-Renna-IEEETransCom.pdf:PDF}, groups = {Secret key agreement}, howpublished = {accepted to \emph{IEEE Transactions on Communications}}, owner = {mattbloch} }

54. A. J. Pierrot and M. R. Bloch, “Strongly Secure Communications Over the Two-Way Wiretap Channel,” ieee_j_ifs, vol. 6, no. 3, pp. 595–605, Sep. 2011.

    We consider the problem of secure communications over the two-way wiretap channel under a strong secrecy criterion. We improve existing results by developing an achievable region based on strategies that exploit both the interference at the eavesdropper’s terminal and cooperation between legitimate users. We leverage the notion of channel resolvability for the multiple-access channel to analyze cooperative jamming and we show that the artificial noise created by cooperative jamming induces a source of common randomness that can be used for secret-key agreement. We illustrate the gain provided by this coding technique in the case of the Gaussian two-way wiretap channel, and we show significant improvements for some channel configurations.

    @article{Pierrot2011a, author = {Pierrot, Alexandre J. and Bloch, Matthieu R.}, journal = ieee_j_ifs, title = {{S}trongly Secure Communications Over the Two-Way Wiretap Channel}, year = {2011}, month = sep, number = {3}, pages = {595--605}, volume = {6}, citeseerurl = {1010.0177}, creationdate = {2010-08-29T00:00:00}, doi = {10.1109/TIFS.2011.2158422}, file = {:2011-Pierrot-IEEETransIFS.pdf:PDF}, groups = {Wiretap channels}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}}, owner = {matthieu} }

55. A. Subramanian, A. Thangaraj, M. Bloch, and S. McLaughlin, “Strong Secrecy on the Binary Erasure Wiretap Channel Using Large-Girth LDPC Codes,” ieee_j_ifs, vol. 6, no. 3, pp. 585–594, Sep. 2011.

    For an arbitrary degree distribution pair (DDP), we construct a sequence of low-density parity-check (LDPC) code ensembles with girth growing logarithmically in block-length using Ramanujan graphs. When the DDP has minimum left degree at least three, we show using density evolution analysis that the expected bit-error probability of these ensembles, when passed through a binary erasure channel with erasure probability ε, decays as O (exp(-( c 1 ) n(c 2 ))) with the block-length n for positive constants c 1 and c 2 , as long as εis less than the erasure threshold εth of the DDP. This guarantees that the coset coding scheme using the dual sequence provides strong secrecy over the binary erasure wiretap channel for erasure probabilities greater than 1-\epsilonth .

    @article{Subramanian2011, author = {Subramanian, Arunkumar and Thangaraj, Andrew and Bloch, Matthieu and McLaughlin, Steven}, journal = ieee_j_ifs, title = {{S}trong Secrecy on the Binary Erasure Wiretap Channel Using Large-Girth {LDPC} Codes}, year = {2011}, month = sep, number = {3}, pages = {585--594}, volume = {6}, citeseerurl = {1009.3130}, creationdate = {2010-09-19T00:00:00}, doi = {10.1109/TIFS.2011.2148715}, file = {:2011-Subramanian-IEEETransIFS.pdf:PDF}, groups = {Wiretap codes}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}}, owner = {matthieu} }

56. J. P. Vilela, M. Bloch, J. Barros, and S. W. McLaughlin, “Wireless Secrecy Regions with Friendly Jamming,” ieee_j_ifs, vol. 6, no. 2, pp. 256–266, Jun. 2011.

    Inspired by recent results on information-theoretic security, we consider the transmission of confidential messages over wireless networks, in which the legitimate communication partners are aided by friendly jammers. We characterize the security level of a confined region in a quasi-static fading environment by computing the probability of secrecy outage in connection with two new measures of physical-layer security: the jamming coverage and the jamming efficiency. Our analysis for various jamming strategies based on different levels of channel state information provides insight into the design of optimal jamming configurations and shows that a single jammer is not sufficient to maximize both figures of merit simultaneously. Moreover, a single jammer requires full channel state information to provide security gains in the vicinity of the legitimate receiver.

    @article{Vilela2011, author = {Vilela, Joao Paulo and Bloch, Matthieu and Barros, Joao and McLaughlin, Steven W.}, journal = ieee_j_ifs, title = {{W}ireless Secrecy Regions with Friendly Jamming}, year = {2011}, month = jun, number = {2}, pages = {256--266}, volume = {6}, creationdate = {2009-11-17T00:00:00}, doi = {10.1109/TIFS.2011.2111370}, file = {:2011-Vilela-IEEETransIFS.pdf:PDF;:Vilela2011 - {W}ireless Secrecy Regions with Friendly Jamming.pdf:PDF}, groups = {Wiretap channels}, howpublished = {accepted to \emph{IEEE Transactions on Information Forensics and Security}}, owner = {matthieu} }

57. T. F. Wong, M. Bloch, and J. M. Shea, “Secret Sharing over Fast-Fading MIMO Wiretap Channels,” EURASIP Journal on Wireless Communications and Networking, vol. 2009, pp. 506973/1–17, 2009.

    Secret sharing over the fast-fading MIMO wiretap channel is considered. A source and a destination try to share secret information over a fast-fading MIMO channel in the presence of an eavesdropper who also makes channel observations that are different from but correlated to those made by the destination. An interactive, authenticated public channel with unlimited capacity is available to the source and destination for the secret sharing process. This situation is a special case of the "channel model with wiretapper" considered by Ahlswede and Csiszár. An extension of their result to continuous channel alphabets is employed to evaluate the key capacity of the fast-fading MIMO wiretap channel. The effects of spatial dimensionality provided by the use of multiple antennas at the source, destination, and eavesdropper are then investigated.

    @article{Wong2009, author = {Wong, Tan F. and Bloch, Matthieu and Shea, John M.}, journal = {{EURASIP} {J}ournal on {W}ireless {C}ommunications and {N}etworking}, title = {{S}ecret Sharing over Fast-Fading {MIMO} Wiretap Channels}, year = {2009}, pages = {506973/1-17}, volume = {2009}, citeseerurl = {cs.IT/0812.2719}, creationdate = {2009-09-10T00:00:00}, doi = {10.1155/2009/506973}, file = {:2009-Wong-EURASIP.pdf:PDF}, groups = {Secret key agreement, Wireless security}, howpublished = {accepted to EURASIP Journal on Wireless Communications and Networking}, owner = {matthieu} }

58. M. Bloch, R. Narasimha, and S. W. McLaughlin, “Network Security for Client-Server Architecture using Wiretap Codes,” ieee_j_ifs, vol. 3, no. 3, pp. 404–413, Sep. 2008.

    We propose a method that provides information-theoretic security for client-server communications. By introducing an appropriate encoding scheme, we show how a client-server architecture under active attacks can be modeled as a binary-erasure wiretap channel. The secrecy capacity of the equivalent wiretap channel is then used as a metric to optimize the architecture and limit the impact of the attacks. Upper and lower bounds of the optimal secrecy capacity are derived and analyzed. While still mostly of theoretical interest, our analysis sheds some light on the practical design of resistant and secure client-server architectures.

    @article{Bloch2008d, author = {Bloch, Matthieu and Narasimha, Rajesh and McLaughlin, Steven W.}, journal = ieee_j_ifs, title = {{N}etwork Security for Client-Server Architecture using Wiretap Codes}, year = {2008}, month = sep, number = {3}, pages = {404--413}, volume = {3}, creationdate = {2007-10-01T00:00:00}, doi = {10.1109/TIFS.2008.927688}, file = {:2008-Bloch-IEEETransIFS.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

59. M. Bloch, J. Barros, M. R. D. Rodrigues, and S. W. McLaughlin, “Wireless Information-Theoretic Security,” ieee_j_it, vol. 54, no. 6, pp. 2515–2534, Jun. 2008.

    This paper considers the transmission of confidential data over wireless channels. Based on an information-theoretic formulation of the problem, in which two legitimates partners communicate over a quasi-static fading channel and an eavesdropper observes their transmissions through a second independent quasi-static fading channel, the important role of fading is characterized in terms of average secure communication rates and outage probability. Based on the insights from this analysis, a practical secure communication protocol is developed, which uses a four-step procedure to ensure wireless information-theoretic security: (i) common randomness via opportunistic transmission, (ii) message reconciliation, (iii) common key generation via privacy amplification, and (iv) message protection with a secret key. A reconciliation procedure based on multilevel coding and optimized low-density parity-check (LDPC) codes is introduced, which allows to achieve communication rates close to the fundamental security limits in several relevant instances. Finally, a set of metrics for assessing average secure key generation rates is established, and it is shown that the protocol is effective in secure key renewal-even in the presence of imperfect channel state information.

    @article{Bloch2008c, author = {Bloch, Matthieu and Barros, Jo{\~a}o and Rodrigues, Miguel R. D. and McLaughlin, Steven W.}, journal = ieee_j_it, title = {{W}ireless Information-Theoretic Security}, year = {2008}, month = jun, number = {6}, pages = {2515--2534}, volume = {54}, citeseerurl = {cs.IT/0611120,cs.IT/0611121}, comment = {Preprint cited 3 times 1. The Wiretap Channel with Feedback: Encryption over the Channel, Lai, L.; Gamal, H. E. & Poor, H. V., 2007 Allerton Conference on Communication, Control and Computing. 2. The Secrecy Capacity of the MIMO wiretap channel, Oggier, F. & Hassibi, B., 2007 Allerton Conference on Communication, Control and Computing. 3. Dense Parity Check Based Secrecy Sharing in Wireless Communications, Xiao S; Pishro-Nik,H & Gong, W., 2007 Globecom conference.}, creationdate = {2007-10-01T00:00:00}, doi = {10.1109/TIT.2008.921908}, file = {:2008-Bloch-IEEETransIT.pdf:PDF}, groups = {Wireless security}, owner = {matthieu} }

60. J. Lodewyck et al., “Quantum key distribution over 25 km with an all-fiber continuous-variable system,” Physical Review A, vol. 76, pp. 042305/1–10, Oct. 2007.

    We report on the implementation of a reverse-reconciliated coherent-state continuous-variable quantum key distribution system, with which we generated secret keys at a rate of more than 2 kb/s over 25 km of optical fiber. Time multiplexing is used to transmit both the signal and phase reference in the same optical fiber. Our system includes all experimental aspects required for a field implementation of a quantum key distribution setup. Real-time reverse reconciliation is achieved by using fast and efficient LDPC error correcting codes.

    @article{Lodewyck2007, author = {Lodewyck, J\'erome and Bloch, Matthieu and Garc\'ia-Patr\'on, Ra\'ul and Fossier, Simon and Karpov, Evgueni and Diamanti, Eleni and Debuisschert, Thierry and Cerf, Nicolas J. and Tualle-Brouri, Rosa and McLaughlin, Steven W. and Grangier, Philippe}, journal = {{P}hysical {R}eview {A}}, title = {{Q}uantum key distribution over 25 km with an all-fiber continuous-variable system}, year = {2007}, month = oct, pages = {042305/1-10}, volume = {76}, citeseerurl = {0706.4255}, comment = {Cited 2 times 1. Experimental study on the Gaussian-modulated coherent-state quantum key distribution over standard telecommunication fibers, Bing Qi, Lei-Lei Huang, Li Qian, and Hoi-Kwong Lo, Phys. Rev. A, 76, 052323, 2007 2. Two-way quantum key distribution at telecommunication wavelength, Rupesh Kumar, Marco Lucamarini, Giovanni Di Giuseppe, Riccardo Natali, Giorgio Mancini, and Paolo Tombesi, Phys. Rev. A, 77, 022304, 2008}, creationdate = {2007-10-01T00:00:00}, doi = {10.1103/PhysRevA.76.042305}, file = {:Users/matthieu/Documents/publications/2007-Lodewyck-PhysRevA.pdf:PDF}, groups = {Quantum information science}, owner = {matthieu} }

61. M. Bloch, S. W. McLaughlin, F. Patois, and J.-M. Merolla, “Frequency-Coded Quantum Key Distribution,” Optics Letters, vol. 32, no. 3, pp. 301–303, Feb. 2007.

    We report an intrinsically stable quantum key distribution scheme based on genuine frequency-coded quantum states. The qubits are efficiently processed without fiber interferometers by fully exploiting the nonlinear interaction occurring in electro-optic phase modulators. The system requires only integrated off-the-shelf devices and could be used with a true single-photon source. Preliminary experiments have been performed with weak laser pulses and have demonstrated the feasibility of this new setup.

    @article{Bloch2007, author = {Bloch, Matthieu and McLaughlin, Steven W. and Patois, Fr\'ed\'eric and Merolla, Jean-Marc}, journal = {{O}ptics {L}etters}, title = {{F}requency-Coded Quantum Key Distribution}, year = {2007}, month = feb, number = {3}, pages = {301--303}, volume = {32}, creationdate = {2006-11-15T00:00:00}, doi = {doi:10.1364/OL.32.000301}, file = {:Users/matthieu/Documents/publications/2007-Bloch-OptLett.pdf:PDF;2007-Bloch-OptLett.pdf:2007-Bloch-OptLett.pdf:PDF}, groups = {Quantum comm experiments, Quantum information science}, keywords = {Fiber optics and optical communications Quantum optics}, owner = {Matthieu} }

62. S. Donnet, A. Thangaraj, M. Bloch, J. Cussey, J.-M. Merolla, and L. Larger, “Security of Y-00 under heterodyne measurement and fast correlation attack,” Physics Letters A, vol. 356, no. 6, pp. 406–410, Aug. 2006.

    We provide a security analysis of the Y-00 protocol under heterodyne measurement and correlation attack. We show that the secrecy of the data encryption scheme is extremely sensitive to the running-key generation process. In many situations our simple attack succeeds in recovering the initial shared secret key. Our simulation results suggest that a truly secure implementation of the protocol should take into account the effective key generation method.

    @article{Donnet2006, author = {Donnet, St\'ephane and Thangaraj, Andrew and Bloch, Matthieu and Cussey, Johann and Merolla, Jean-Marc and Larger, Laurent}, journal = {{P}hysics {L}etters {A}}, title = {{S}ecurity of {Y}-00 under heterodyne measurement and fast correlation attack}, year = {2006}, month = aug, number = {6}, pages = {406--410}, volume = {356}, comment = {Cited 4 times 1. Ahn C, Birnbaum K Exposed-key weakness of alpha eta PHYSICS LETTERS A 370(2) 2007 2. Hirota O Practical security analysis of a quantum stream cipher by the Yuen 2000 protocol PHYSICAL REVIEW A 3 76(3) 2007 3. Mihaljevic MJ Generic framework for the secure Yuen 2000 quantum-encryption protocol employing the wire-tap channel approach PHYSICAL REVIEW A 75(5) 2007 4. Yuen HP, Nair R On the security of Y-00 under fast correlation and other attacks on the key PHYSICS LETTERS A, 364(2), 2007}, creationdate = {2006-11-15T00:00:00}, doi = {10.1016/j.physleta.2006.04.002}, file = {:Users/matthieu/Documents/publications/2006-Donnet-PhysLettA.pdf:PDF;2006-Donnet-PhysLettA.pdf:2006-Donnet-PhysLettA.pdf:PDF}, groups = {Quantum information science}, owner = {Matthieu} }

in limbo

1. T. Erdoğan, S.-Y. Wang, S.-J. Su, and M. Bloch, “Joint Communication and Sensing with Bipartite Entanglement over Bosonic Channels.” in limbos, Apr. 2025.

   @misc{Erdogan2025Joint, author = {Erdo\u{g}an, Tuna and Wang, Shi-Yuan and Su, Shang-Jen and Bloch, Matthieu}, howpublished = {in limbos}, month = apr, title = {Joint Communication and Sensing with Bipartite Entanglement over Bosonic Channels}, year = {2025}, eprint = {2501.15675}, groups = {NSF2148400} }

2. N. Blinn and M. R. Bloch, “Track-and-Stop for mmWave Initial Alignment and Tracking.” in limbos, Nov. 2024.

   @misc{Blinn2024Track, author = {Blinn, Nathan and Bloch, Matthieu R.}, howpublished = {in limbos}, month = nov, title = {Track-and-Stop for mmWave Initial Alignment and Tracking}, year = {2024} }

3. U. Pereg, R. Ferrara, and M. R. Bloch, “Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels.” in limbo, May 2021.

   @misc{Pereg2021Key, author = {Pereg, Uzi and Ferrara, Roberto and Bloch, Matthieu R.}, howpublished = {in limbo}, month = may, title = {Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels}, year = {2021}, eprint = {2105.04033} }

4. E. Zhang, M. Bloch, M. Bakshi, and S. Jaggi, “Undetectable Radios: Covert Communication under Spectral Mask Constraints.” in limbo, Dec. 2019.

   @misc{Zhang2019b, author = {Zhang, Eric and Bloch, Matthieu and Bakshi, Mayank and Jaggi, Siddarth}, howpublished = {in limbo}, month = dec, title = {Undetectable Radios: Covert Communication under Spectral Mask Constraints}, year = {2019} }

5. S. Salimi, M. Bloch, F. Gabry, M. Skoglund, and P. Papadimitratos, “Strong Secrecy in Pairwise Key Agreement over a Generalized Multiple Access Channel.” in limbo, Mar. 2016.

   @misc{Salimi2016, author = {Salimi, Somayeh and Bloch, Matthieu and Gabry, Fr\'ed\'eric and Skoglund, Mikael and Papadimitratos, Panagiotis}, howpublished = {in limbo}, month = mar, title = {Strong Secrecy in Pairwise Key Agreement over a Generalized Multiple Access Channel}, year = {2016}, creationdate = {2016-03-15T00:00:00}, eprint = {1603.05399}, groups = {Secret key agreement}, owner = {mattbloch} }

6. A. J. Pierrot, R. A. Chou, and M. R. Bloch, “The Effect of Eavesdropper’s Statistics in Experimental Wireless Secret-Key Generation.” in limbo, Jun. 2014.

   @misc{Pierrot2013c, author = {Pierrot, Alexandre J. and Chou, R\'emi A. and Bloch, Matthieu R.}, howpublished = {in limbo}, month = jun, title = {The Effect of Eavesdropper's Statistics in Experimental Wireless Secret-Key Generation}, year = {2014}, creationdate = {2013-12-11T00:00:00}, eprint = {1312.3304}, groups = {Experimental systems}, owner = {mattbloch} }

conference proceedings

1. B. Martin Urcelay, C. J. Rozell, and M. R. Bloch, “Enhancing Human-in-the-Loop Learning for Binary Sentiment Word Classification,” in Proc. of IEEE Conference on Decision and Control, Milan, Italy, Dec. 2024, pp. 2293–2298.

   While humans intuitively excel at classifying words according to their connotation, transcribing this innate skill into algorithms remains challenging. We present a human-guided methodology to learn binary word sentiment classifiers from fewer interactions with humans. We introduce a human perception model that relates the perceived sentiment of a word to the distance between the word and the unknown classifier. Our model informs the design of queries that capture more nuanced information than traditional queries solely requesting labels. Together with active learning strategies, our approach reduces human effort without sacrificing learning fidelity. We validate our method through experiments with human data, demonstrating improved accuracy in binary sentiment word classification.

   @inproceedings{MartinUrcelay2024Enhancing, author = {{Martin Urcelay}, B\'elen and Rozell, Christopher J. and Bloch, Matthieu R.}, booktitle = {Proc. of IEEE Conference on Decision and Control}, title = {Enhancing Human-in-the-Loop Learning for Binary Sentiment Word Classification}, year = {2024}, address = {Milan, Italy}, month = dec, pages = {2293-2298}, doi = {10.1109/CDC56724.2024.10885942}, howpublished = {accepted to \emph{Conference on Decision and Control}} }

2. T. Kann, S. Kudekar, and M. Bloch, “A Path Metric Based Construction of Polarization-Adjusted Convolutional Codes,” in ieee_isit, Athens, Greece, Jul. 2024, pp. 2406–2411.

   @inproceedings{Kann2024Path, author = {Kann, Tyler and Kudekar, Shrinivas and Bloch, Matthieu}, booktitle = ieee_isit, title = {A Path Metric Based Construction of Polarization-Adjusted Convolutional Codes}, year = {2024}, address = {Athens, Greece}, month = jul, pages = {2406--2411}, doi = {10.1109/ISIT57864.2024.10619693}, groups = {NSF2148400}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

3. S. Bakirtas, M. Bloch, and E. Erkip, “Pilot-Attacks Can Enable Positive-Rate Covert Communications of Wireless Hardware Trojans,” in Proc. of IEEE Global Communications Conference, Jul. 2024, pp. 1341–1346.

   Hardware Trojans can inflict harm on wireless networks by exploiting the link margins inherent in communication systems. We investigate a setting in which, alongside a legitimate communication link, a hardware Trojan embedded in the legitimate transmitter attempts to establish communication with its intended rogue receiver. To illustrate the susceptibility of wireless networks against pilot attacks, we examine a two-phased scenario. In the channel estimation phase, the Trojan carries out a covert pilot scaling attack to corrupt the channel estimation of the legitimate receiver. Subsequently, in the communication phase, the Trojan exploits the ensuing imperfect channel estimation to covertly communicate with its receiver. By analyzing the corresponding hypothesis tests conducted by the legitimate receiver in both phases, we establish that the pilot scaling attack allows the Trojan to operate in the so-called "linear regime" i.e., covertly and reliably transmitting at a positive rate to the rogue receiver. Our results highlight the vulnerability of the channel estimation process in wireless communication systems against hardware Trojans.

   @inproceedings{Bakirtas2024Pilot, author = {Bakirtas, Serhat and Bloch, Matthieu and Erkip, Elza}, booktitle = {Proc. of IEEE Global Communications Conference}, title = {Pilot-Attacks Can Enable Positive-Rate Covert Communications of Wireless Hardware Trojans}, year = {2024}, month = jul, pages = {1341-1346}, doi = {10.1109/GLOBECOM52923.2024.10901523}, groups = {Steganography and covert communications, NSF2148400}, howpublished = {accepted to \emph{IEEE GLOBECOM}} }

4. S.-Y. Wang, S.-J. Su, and M. R. Bloch, “Resource-Efficient Entanglement-Assisted Covert Communications over Bosonic Channels,” in ieee_isit, Athens, Greece, Jul. 2024, pp. 3106–3111.

   @inproceedings{Wang2024Resource, author = {Wang, Shi-Yuan and Su, Shang-Jen and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Resource-Efficient Entanglement-Assisted Covert Communications over Bosonic Channels}, year = {2024}, address = {Athens, Greece}, month = jul, pages = {3106-3111}, doi = {10.1109/ISIT57864.2024.10619663}, file = {:2024-Wang-ISIT-Resource-Efficient Entanglement-Assisted Covert Communications over Bosonic Channels.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

5. O. Günlü, M. Bloch, and and A. Y. Rafael F. Schaefer, “Nonasymptotic performance limits of low-latency secure integrated sensing and communication systems,” in Proc. of IEEE International Conference on Acoustics, Speech and Signal Processing, Seoul, Korea, Apr. 2024.

   @inproceedings{Guenlue2024Nonasymptotic, author = {Günlü, Onur and Bloch, Matthieu and Rafael F. Schaefer, and Aylin Yener}, booktitle = {Proc. of IEEE International Conference on Acoustics, Speech and Signal Processing}, title = {Nonasymptotic performance limits of low-latency secure integrated sensing and communication systems}, year = {2024}, address = {Seoul, Korea}, month = apr, doi = {10.1109/ICASSP48485.2024.10448166}, file = {:2024-Gunlu-ICASSP-Nonasymptotic Performance Limits of Low-Latency Secure Integrated Sensing and Communication Systems.pdf:PDF}, groups = {NSF2148400, NSF1955401} }

6. S.-Y. Wang, M.-C. Chang, and M. R. Bloch, “Covert Joint Communication and Sensing Under Variational Distance Constraint,” in Proc. of 58th Annual Conference on Information Sciences and Systems, Princeton, JN, Mar. 2024.

   @inproceedings{Wang2024Covert, author = {Wang, Shi-Yuan and Chang, Meng-Che and Bloch, Matthieu R.}, booktitle = {Proc. of 58th Annual Conference on Information Sciences and Systems}, title = {Covert Joint Communication and Sensing Under Variational Distance Constraint}, year = {2024}, address = {Princeton, JN}, month = mar, doi = {10.1109/CISS59072.2024.10480161}, file = {:2024-Wang-CISS-Covert Joint Communication and Sensing under Variational Distance Constraint.pdf:PDF}, groups = {NSF1910859, NSF2148400}, howpublished = {accepted to \emph{58th Annual Conference on Information Sciences and Systems}} }

7. T. Kann, S. Kudekar, and M. R. Bloch, “Source Polarization-Adjusted Convolutional Codes,” in ieee_isit, Taipei, Taiwan, Jun. 2023, pp. 1896–1901.

   Motivated by applications to low-latency secret key generation in physical-layer security, we study Polarization-Adjusted Convolutional (PAC) codes for source coding with side information. Source PAC codes operate in a dual manner to channel PAC codes by introducing a rate-one convolutional code after the polarization transform. The decoding of source PAC codes requires a careful scheduling of the successive cancellation decoder and a careful optimization of the rate profiling. Our empirical results demonstrate the improved performance of source PAC codes over regular polar codes using Successive Cancellation List (SCL) decoding. We illustrate the performance in terms for key generation rate in a secret-key generation setup over an Additive White Gaussian Noise (AWGN) channel, suggesting that PAC codes could improve the performance of physical-layer security schemes at short blocklength.

   @inproceedings{Kann2023Source, author = {Kann, Tyler and Kudekar, Shrinivas and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Source Polarization-Adjusted Convolutional Codes}, year = {2023}, address = {Taipei, Taiwan}, month = jun, pages = {1896-1901}, doi = {10.1109/ISIT54713.2023.10206454}, file = {:2021-Kann-ISIT-Source Polarization-Adjusted Convolutional Codes.pdf:PDF}, groups = {NSF2148400}, howpublished = {accepted to \emph{2023 IEEE International Symposium on Information Theory}} }

8. M.-C. Chang and M. R. Bloch, “Distributed Stochastic Bandits with Corrupted and Defective Input Commands,” in ieee_isit, Taipei, Taiwan, Jun. 2023, pp. 1318–1323.

   We analyze a distributed stochastic bandit model in which an agent controls multiple independent stochastic bandit machines. At each time step, the agent selects several machines for parallel exploitation but the arm pulled by each machine may differ from the command received either randomly (defective command) or adversarially (corrupted command). Machines that faithfully execute commands are called honest. We study situations in which the number of honest machines is either known or unknown and define appropriate notions of regret. With at least one honest machine and a known number of honest bandits, we provide a simple algorithm that achieves \tilde O\left( n^1/2 \right) regrets when commands are corrupted. Lower bounds on regret established by drawing connections to the problem of "low probability of detection," show the near optimality of the regret achieved by the algorithms.

   @inproceedings{Chang2023Distributed, author = {Chang, Meng-Che and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Distributed Stochastic Bandits with Corrupted and Defective Input Commands}, year = {2023}, address = {Taipei, Taiwan}, month = jun, pages = {1318-1323}, doi = {10.1109/ISIT54713.2023.10206787}, file = {:2023-Chang-ISIT-Distributed Stochastic Bandits with Corrupted and Defective Input Commands.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{2023 IEEE International Symposium on Information Theory}} }

9. M.-C. Chang, S.-Y. Wang, and M. R. Bloch, “Sequential Joint Communication and Sensing of Fixed Channel States,” in ieee_itw, Saint-Malo, France, Apr. 2023, pp. 462–467.

   We consider a communication model in which a transmitter attempts to communicate with a receiver over a state-dependent channel and simultaneously estimates the state using strictly causal noisy state observations. The state is assumed to remain constant over the duration of the transmission. We analyze the trade-off between the state-error exponent and the communication rate in the sequential setting, in which the transmitter determines what and how many symbols to transmit in an online manner.

   @inproceedings{Chang2023Sequential, author = {Chang, Meng-Che and Wang, Shi-Yuan and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Sequential Joint Communication and Sensing of Fixed Channel States}, year = {2023}, address = {Saint-Malo, France}, month = apr, pages = {462--467}, doi = {10.1109/ITW55543.2023.10161688}, file = {:2023-Chang-ITW-Sequential Joint Communication and Sensing of Fixed Channel States.pdf:PDF}, groups = {NSF2148400}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

10. R. A. Chou and M. R. Bloch, “Retractable Commitment,” in ieee_itw, Saint-Malo, France, Apr. 2023, pp. 260–265.

    Consider a commitment protocol between two parties, Alice and Bob, in which Alice may (i) commit to a message using a non-redundant discrete memoryless channel whose outputs are observed by Bob; and (ii) later reveal her committed message to Bob who must decide whether Alice is revealing the message she actually committed to. A commitment protocol should meet three standard requirements: concealment, bindingness, and soundness, to ensure that no party may act dishonestly. Our objective is to study whether one can enforce a fourth requirement that would allow Alice to retract a commitment before the reveal phase starts without Bob detecting that she ever participated in the commit phase of the protocol. We positively answer this question and characterize the commitment capacity for such a setting by relying on tools developed for covert communication.

    @inproceedings{Chou2023Retractable, author = {Chou, R\'emi A. and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Retractable Commitment}, year = {2023}, address = {Saint-Malo, France}, month = apr, pages = {260--265}, doi = {10.1109/ITW55543.2023.10161683}, file = {:2023-Chou-ITW-Retractable Commitment over Noisy Channels.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

11. O. Günlü, M. Bloch, R. Schaeffer, and A. Yener, “Secure Integrated Sensing and Communication for Binary-Modulated Input Additive White Gaussian Noise Channels,” in Proc. of IEEE 3rd International Symposium on Joint Communications & Sensing, Seefeld, Austria, Mar. 2023, pp. 1–6.

    @inproceedings{Guenlue2022Securea, author = {G\"unl\"u, Onur and Bloch, Matthieu and Schaeffer, Rafael and Yener, Aylin}, booktitle = {Proc. of IEEE 3rd International Symposium on Joint Communications \& Sensing}, title = {Secure Integrated Sensing and Communication for Binary-Modulated Input Additive White Gaussian Noise Channels}, year = {2023}, address = {Seefeld, Austria}, month = mar, pages = {1--6}, doi = {10.1109/JCS57290.2023.10107461}, file = {:2023-Gunlu-ISJCS-Secure Integrated Sensing and Communication for Binary Input Additive White Gaussian Noise Channels.pdf:PDF}, howpublished = {accepted to \emph{International Symposium on Joint Communication and Sensing}} }

12. Z. J. Zhang, M. Bloch, and M. Saeedifard, “Load Redistribution Attacks in Multi-Terminal DC Grids,” in Proc. of IEEE Energy Conversion Congress and Exposition, Detroit, MI, Oct. 2022.

    The modernization of legacy power grids relies on the prevalence of information technology (IT). While the benefits are multi-fold and include increased reliability, more accurate monitoring, etc., the reliance on IT increases the attack surface of power grids by making them vulnerable to cyber-attacks. One of the modernization paths is the emergence of multi-terminal dc systems that offer numerous advantages over traditional ac systems. Therefore, cyber-security issues surrounding dc networks need to be investigated. Contributing to this effort, a class of false data injection attacks, called load redistribution (LR) attacks, that targets dc grids is proposed. These attacks aim to compromise the system load data and lead the system operator to dispatch incorrect power flow commands that lead to adverse consequences. Although similar attacks have been recently studied for ac systems, their feasibility in the converter-based dc grids has yet to be demonstrated. Such an attack assessment is necessary because the dc grids have a much smaller control timescale and are more dependent on IT than their traditional ac counterparts. Hence, this work formulates and evaluates dc grid LR attacks by incorporating voltage-sourced converter (VSC) control strategies that appropriately delineate dc system operations. The proposed attack strategy is solved with Gurobi, and the results show that both control and system conditions can affect the success of an LR attack.

    @inproceedings{Zhang2022Load, author = {Zhang, Zhi Jin and Bloch, Matthieu and Saeedifard, Maryam}, booktitle = {Proc. of IEEE Energy Conversion Congress and Exposition}, title = {Load Redistribution Attacks in Multi-Terminal DC Grids}, year = {2022}, address = {Detroit, MI}, month = oct, doi = {10.1109/ECCE50734.2022.9948106} }

13. R. Chou and M. R. Bloch, “Commitment over Multiple-Access Channels,” in Proc. of 58th Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2022.

    The problem of multi-user commitment is one in which multiple users first commit to individual messages with a bookmaker and later reveal their messages. The objective of the bookmaker is then to decide whether the revealed messages correspond to the committed messages. We study a specific multi-user commitment model in which the users and the bookmaker have access to a noiseless channel, as well as a noisy multiple-access channel whose inputs are controlled by the users and whose output is observed by the bookmaker. When the users are non-colluding and the channel is non-redundant, we fully characterize the commitment capacity region. When the users are colluding, we derive an achievable region and a tight converse for the sum-rate. In both cases our proposed achievable commitment schemes are constructive.

    @inproceedings{Chou2022Commitment, author = {Chou, R\'emi and Bloch, Matthieu R.}, booktitle = {Proc. of 58th Annual Allerton Conference on Communication, Control, and Computing}, title = {Commitment over Multiple-Access Channels}, year = {2022}, address = {Monticello, IL}, month = sep, doi = {10.1109/Allerton49937.2022.9929405}, file = {:2022-Chou-Allerton-Commitment over Multiple-Access Channels.pdf:PDF}, howpublished = {accepted to \emph{Allerton conference}} }

14. M.-C. Chang, S.-Y. Wang, and M. R. Bloch, “Controlled Sensing with Corrupted Commands,” in Proc. of 58th Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2022.

    We consider a non-adaptive controlled sensing sce-nario in which the actions of the decision maker are corrupted by an adversary. The objective of the decision maker is to either detect the presence of the corruption or make a correct decision. Accordingly, the performance of a controlled sensing strategy is measured in terms of the error probability when there is no adversary, denoted PE,0 , and the error probability when an adversary is present, denoted PE,1 . Our main result is Stein-lemma like characterization of the optimal achievable error exponent of PE,0 subject to a constraint on PE,1 . We also illustrate the result with numerical examples.

    @inproceedings{Chang2022Controlled, author = {Chang, Meng-Che and Wang, Shi-Yuan and Bloch, Matthieu R.}, booktitle = {Proc. of 58th Annual Allerton Conference on Communication, Control, and Computing}, title = {Controlled Sensing with Corrupted Commands}, year = {2022}, address = {Monticello, IL}, month = sep, doi = {10.1109/Allerton49937.2022.9929364}, file = {:2022-Chang-Allerton-Controlled Sensing with Corrupted Commands.pdf:PDF}, groups = {NSF1955401, NSF1910859}, howpublished = {accepted to \emph{Allerton conference}} }

15. S.-Y. Wang, T. Erdoğan, U. Pereg, and M. R. Bloch, “Joint Quantum Communication and Sensing,” in ieee_itw, Aug. 2022, pp. 506–511.

    @inproceedings{Wang2022Joint, author = {Wang, Shi-Yuan and Erdo\u{g}an, Tuna and Pereg, Uzi and Bloch, Matthieu R}, booktitle = ieee_itw, title = {Joint Quantum Communication and Sensing}, year = {2022}, month = aug, pages = {506-511}, doi = {10.1109/ITW54588.2022.9965810}, file = {:2022-Wang-ITW-Joint Quantum Communication and Sensing.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

16. O. Günlü, M. R. Bloch, R. Schaefer, and A. Yener, “Secure Joint Communication and Sensing,” in ieee_isit, Helskinki, Finland, Jun. 2022, pp. 844–849.

    @inproceedings{Guenlue2022Secure, author = {G\"unl\"u, Onur and Bloch, Matthieu R. and Schaefer, Rafael and Yener, Aylin}, booktitle = ieee_isit, title = {Secure Joint Communication and Sensing}, year = {2022}, address = {Helskinki, Finland}, month = jun, pages = {844-849}, doi = {10.1109/ISIT50566.2022.9834748}, file = {:2022-Gunlu-ISIT-Secure_Joint_Communication_and_Sensing.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

17. M.-C. Chang and M. R. Bloch, “Covert Best Arm Identification of Stochastic Bandits,” in ieee_isit, Helsinki, Finland, Jun. 2022, pp. 324–329.

    We study the covert best arm identification problem in which an agent tries to identify the best arm while escaping detection from an adversary. Specifically, the agent should identify the best arm of the bandit with accuracy higher than a predefined requirement as soon as possible and, simultaneously, the adversary’s observations induced by pulling effective arms should remain indistinguishable from the observations obtained when no effective arm is pulled. Our main result is the characterization of the exponent γ, which captures the asymptotic exponential decrease of the confidence level with the square-root of the averaged stopping time.

    @inproceedings{Chang2022Covert, author = {Chang, Meng-Che and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Covert Best Arm Identification of Stochastic Bandits}, year = {2022}, address = {Helsinki, Finland}, month = jun, pages = {324-329}, doi = {10.1109/ISIT50566.2022.9834559}, file = {:2022-Chang-ISIT-Covert Best Arm Identification of Stochastic Bandits.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

18. S.-Y. Wang, T. Erdoğan, and M. R. Bloch, “Towards a Characterization of the Covert Capacity of Bosonic Channels under Trace Distance,” in ieee_isit, Helsinki, Finland, Jun. 2022, pp. 354–359.

    @inproceedings{Wang2022Towards, author = {Wang, Shi-Yuan and Erdo\u{g}an, Tuna and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Towards a Characterization of the Covert Capacity of Bosonic Channels under Trace Distance}, year = {2022}, address = {Helsinki, Finland}, month = jun, pages = {354--359}, doi = {10.1109/ISIT50566.2022.9834394}, file = {:2022-Wang-ISIT-Towards a Characterization of the Covert Capacity of Bosonic Channels under Trace Distance.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

19. H. Zivari-Fard, M. R. Bloch, and A. Nosratinia, “Covert Communication in the Presence of an Uninformed, Informed, and Coordinated Jammer,” in ieee_isit, Helsinki, Finland, Jun. 2022.

    This paper investigates covert communication in the presence of a cooperative jammer. Covert communication refers to the inability of an adversary to distinguish data transmission from a so-called innocent symbol at the input. We consider three related problems: (1) a jammer without direct communication or coordination with the transmitter, (2) a jammer that cribs the output of the transmitter, and (3) a jammer that is able to coordinate with the transmitter via a secret key that is also shared with the legitimate receiver. For each model, we derive inner and outer bounds on the capacity region that are tight in some special cases. Unlike prior results in the literature, the jammer in our model does not have access to unlimited local randomness. In fact, uncovering the fundamental interplay between the covert communication rate, local randomness, and secret key rate, is one of the distinctions and contributions of the present work. In the context of a few specific channels, we calculate achievable covert rates to illuminate our results.

    @inproceedings{ZivariFard2022Covert, author = {Zivari-Fard, Hassan and Bloch, Matthieu R. and Nosratinia, Aria}, booktitle = ieee_isit, title = {Covert Communication in the Presence of an Uninformed, Informed, and Coordinated Jammer}, year = {2022}, address = {Helsinki, Finland}, month = jun, doi = {10.1109/ISIT50566.2022.9834682}, file = {:2022-ZivariFard-ISIT-Covert Communication in the Presence of an Uninformed Informed and Coordinated Jammer.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

20. M.-C. Chang, T. Erdoğan, S.-Y. Wang, and M. R. Bloch, “Rate and Detection Error-Exponent Tradeoffs of Joint Communication and Sensing,” in Proc. of IEEE International Symposium on Joint Communications & Sensing, Vienna, Austria, Mar. 2022, pp. 1–6.

    We consider a communication model in which a transmitter attempts to communicate with a receiver over a state-dependent channel and simultaneously estimate the state using strictly causal noisy state observations. Motivated by joint communication and sensing scenarios in which the physical phenomenon of interest for sensing evolves at a much slower rate than the rate of communication, the state is assumed to remain constant over the duration of the transmission. We derive a complete characterization of the optimal asymptotic trade-off between communication rate and detection-error exponent when coding strategies are open loop. We also show that closed-loop strategies result in strict improvements of the trade-offs.

    @inproceedings{Chang2022Rate, author = {Chang, Meng-Che and Erdo\u{g}an, Tuna and Wang, Shi-Yuan and Bloch, Matthieu R.}, booktitle = {Proc. of IEEE International Symposium on Joint Communications \& Sensing}, title = {Rate and Detection Error-Exponent Tradeoffs of Joint Communication and Sensing}, year = {2022}, address = {Vienna, Austria}, month = mar, pages = {1--6}, doi = {10.1109/JCS54387.2022.9743498}, file = {:2022-Chang-ISJCS-Rate and Detection Error-Exponent Tradeoffs of Joint Communication and Sensing.pdf:PDF}, groups = {Joint communication and sensing, NSF1955401, NSF1910859}, howpublished = {accepted to the \emph{IEEE International Hybrid Symposium on Joint Communications \& Sensing}} }

21. M. E. Cao, M. Bloch, and S. Coogan, “Estimating High Probability Reachable Sets using Gaussian Processes,” in Proc. of IEEE Conference on Decision and Control, Dec. 2021.

    We present a method for computing reachable sets and forward invariant sets for systems with dynamics that include unknown components. Our main assumption is that, given any hyperrectangle of states, lower and upper bounds for the unknown components that hold with high probability are available. We then show that this assumption is well-suited when the unknown terms are modeled as state-dependent Gaussian processes. Under this assumption, we leverage the theory of mixed monotone systems and propose an efficient method for computing a hyperrectangular set that over-approximates the reachable set of the system with high probability. We then show a related approach that leads to sufficient conditions for identifying sets that are forward invariant for the dynamics with high probability. These theoretical results lead to practical algorithms for efficient computation of high probability reachable sets and invariant sets. A major advantage of our approach is that it leads to tractable computations for systems up to moderately high dimension that are subject to low dimensional uncertainty modeled as Gaussian Processes, a class of systems that appears often in practice. We demonstrate our results on an example of a six-dimensional model of a multirotor aerial vehicle.

    @inproceedings{Cao2021, author = {Cao, Michael Enqi and Bloch, Matthieu and Coogan, Samuel}, booktitle = {Proc. of IEEE Conference on Decision and Control}, title = {Estimating High Probability Reachable Sets using Gaussian Processes}, year = {2021}, month = dec, doi = {10.1109/CDC45484.2021.9682962}, howpublished = {accepted to \emph{IEEE Conference on Decision and Control}} }

22. M.-C. Chang and M. R. Bloch, “Covert Sequential Hypothesis Testing,” in ieee_itw, Oct. 2021, pp. 1–6.

    @inproceedings{Chang2021a, author = {Chang, Meng-Che and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Covert Sequential Hypothesis Testing}, year = {2021}, month = oct, pages = {1-6}, doi = {10.1109/ITW48936.2021.9611391}, file = {:2021-Chang-ITW-Covert sequential hypothesis testing.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

23. U. Pereg, R. Ferrara, and M. R. Bloch, “Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels,” in ieee_itw, Oct. 2021, pp. 1–6.

    @inproceedings{Pereg2021, author = {Pereg, Uzi and Ferrara, Roberto and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels}, year = {2021}, month = oct, pages = {1-6}, doi = {10.1109/ITW48936.2021.9611359}, file = {:2021-Pereg-ITW-Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

24. H. ZivariFard, M. R. Bloch, and A. Nosratinia, “Covert Communication via Non-Causal Cribbing from a Cooperative Jammer,” in ieee_isit, Jul. 2021, pp. 202–207.

    We consider the problem of covert communication in the presence of a cooperative jammer. Covert communication refers to communication that is undetectable by an adversary, i.e., a scenario in which, despite ongoing communication, the output distribution observed by an adversary called the “warden” is indistinguishable from the distribution that would have been induced by an innocent channel-input symbol. It is known that in general, a transmitter and a receiver can communicate only O(n−−√) covert bits over n channel uses, i.e., zero rate. This paper shows that a cooperative jammer can facilitate the communication of positive covert rates, subject to the transmitter having non-causal access to the jammer signal. An achievable rate region is calculated that highlights the relation between the covert communication rate, jammer’s randomness (expressed as a rate), and rate of a secret key shared between transmitter and receiver.

    @inproceedings{ZivariFard2021, author = {ZivariFard, Hassan and Bloch, Matthieu R. and Nosratinia, Aria}, booktitle = ieee_isit, title = {Covert Communication via Non-Causal Cribbing from a Cooperative Jammer}, year = {2021}, month = jul, pages = {202-207}, doi = {10.1109/ISIT45174.2021.9517883}, file = {:2021-ZivariFard-ISIT-Covert Communication via Non-Causal Cribbing from a Cooperative Jammer.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

25. M. Tahmasbi, B. Bash, S. Guha, and M. R. Bloch, “Signaling for Covert Quantum Sensing,” in ieee_isit, Jul. 2021, pp. 1041–1045.

    @inproceedings{Tahmasbi2021, author = {Tahmasbi, Mehrdad and Bash, Boulat and Guha, Saikat and Bloch, Matthieu R}, booktitle = ieee_isit, title = {Signaling for Covert Quantum Sensing}, year = {2021}, month = jul, pages = {1041-1045}, doi = {10.1109/ISIT45174.2021.9517722}, file = {:2021-Tahmasbi-ISIT-Signaling for Covert Quantum Sensing.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

26. O. Günlü, M. Bloch, and R. F. Schaefer, “Secure Multi-Function Computation with Private Remote Sources,” in ieee_isit, Jul. 2021, pp. 1403–1408.

    We consider a distributed function computation problem in which parties observing noisy versions of a remote source facilitate the computation of a function of their observations at a fusion center through public communication. The distributed function computation is subject to constraints, including not only reliability and storage but also privacy and secrecy. Specifically, 1) the remote source should remain private from an eavesdropper and the fusion center, measured in terms of the information leaked about the remote source; 2) the function computed should remain secret from the eavesdropper, measured in terms of the information leaked about the arguments of the function, to ensure secrecy regardless of the exact function used. We derive the exact rate regions for lossless and lossy single-function computation and illustrate the lossy single-function computation rate region for an information bottleneck example, in which the optimal auxiliary random variables are characterized for binary input symmetric output channels. We extend the approach to lossless and lossy asynchronous multiple-function computations with joint secrecy and privacy constraints, in which case inner and outer bounds for the rate regions differing only in the Markov chain conditions imposed are characterized.

    @inproceedings{Guenlue2021, author = {G\"unl\"u, Onur and Bloch, Matthieu and Schaefer, Rafael F.}, booktitle = ieee_isit, title = {Secure Multi-Function Computation with Private Remote Sources}, year = {2021}, month = jul, pages = {1403-1408}, doi = {10.1109/ISIT45174.2021.9518019}, file = {:2021-Gunlu-ISIT-Secure Multi-Function Computation with Private Remote Sources.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

27. M.-C. Chang and M. R. Bloch, “Covert Authentication Against a Myopic Adversary,” in ieee_isit, Jul. 2021, pp. 196–201.

    We consider the problem of authenticating communication over a Myopic Binary Adversarial Channel (MBAC) while maintaining covertness with respect to the myopic adversary. When the main channel between legitimate parties is degraded with respect to the adversary’s channel, we show the existence of an integrated scheme that simultaneously exploits secret keys to ensure covertness and authentication. The main technical challenge we address is showing that authentication may be ensured against myopic attacks when using the low-weight codewords mandated by covert communication.

    @inproceedings{Chang2021, author = {Chang, Meng-Che and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Covert Authentication Against a Myopic Adversary}, year = {2021}, month = jul, pages = {196-201}, doi = {10.1109/ISIT45174.2021.9518165}, file = {:2021-Chang-ISIT-Covert Authentication Against a Myopic Adversary.pdf:PDF}, groups = {NSF1955401}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

28. S.-Y. Wang and M. R. Bloch, “Explicit Design of Provably Covert Channel Codes,” in ieee_isit, Jul. 2021, pp. 190–195.

    @inproceedings{Wang2021a, author = {Wang, Shi-Yuan and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Explicit Design of Provably Covert Channel Codes}, year = {2021}, month = jul, pages = {190-195}, doi = {10.1109/ISIT45174.2021.9517930}, file = {:2021-Wang-ISIT-Explicit Design of Provably Covert Channel Codes.pdf:PDF}, groups = {NSF1910859}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

29. N. Blinn, J. Boerger, and M. R. Bloch, “mmWave Beam Steering with Hierarchical Optimal Sampling for Unimodal Bandits,” in IEEE International Conference on Communications, Jun. 2021, pp. 1–6.

    We propose a Multi-Armed Bandit algorithm for mmWave beam steering that approaches the performance of state-of-the-art Bayesian algorithms at a fraction of the complexity and without requiring Channel State Information. The algorithm, called Hierarchical Optimal Sampling of Unimodal Bandits, simultaneously exploits the benefits of hierarchical codebooks and the approximate unimodality of rewards to achieve fast beam steering, in a sense that we precisely define to provide fair comparison with existing algorithms. Extensive simulations over slow fading channels demonstrate the appealing performance versus complexity trade-off struck by the algorithm across a wide range of Signal-to-Noise Ratios.

    @inproceedings{Blinn2021, author = {Blinn, Nathan and Boerger, Jana and Bloch, Matthieu R}, booktitle = {IEEE International Conference on Communications}, title = {mmWave Beam Steering with Hierarchical Optimal Sampling for Unimodal Bandits}, year = {2021}, month = jun, pages = {1-6}, doi = {10.1109/ICC42927.2021.9500373}, file = {:2021-Blinn-ICC-mmWave_Beam_Steering_with_Hierarchical_Optimal_Sampling_for_Unimodal_Bandits.pdf:PDF}, groups = {mmWave}, howpublished = {accepted to the \emph{IEEE 2021 IEEE International Conference on Communications}} }

30. G. Canal, M. R. Bloch, and C. Rozell, “Feedback Coding for Active Learning,” in Proc. of The 24th International Conference on Artificial Intelligence and Statistics, Jan. 2021, vol. 130, pp. 1468–1476.

    The iterative selection of examples for labeling in active machine learning is conceptually similar to feedback channel coding in information theory: in both tasks, the objective is to seek a minimal sequence of actions to encode information in the presence of noise. While this high-level overlap has been previously noted, there remain open questions on how to best formulate active learning as a communications system to leverage existing analysis and algorithms in feedback coding. In this work, we formally identify and leverage the structural commonalities between the two problems, including the characterization of encoder and noisy channel components, to design a new algorithm. Specifically, we develop an optimal transport-based feedback coding scheme called Approximate Posterior Matching (APM) for the task of active example selection and explore its application to Bayesian logistic regression, a popular model in active learning. We evaluate APM on a variety of datasets and demonstrate learning performance comparable to existing active learning methods, at a reduced computational cost. These results demonstrate the potential of directly deploying concepts from feedback channel coding to design efficient active learning strategies.

    @inproceedings{Canal2021, author = {Canal, Greg and Bloch, Matthieu R and Rozell, Chris}, booktitle = {Proc. of The 24th International Conference on Artificial Intelligence and Statistics}, title = {Feedback Coding for Active Learning}, year = {2021}, editor = {Banerjee, Arindam and Fukumizu, Kenji}, month = jan, pages = {1468--1476}, publisher = {PMLR}, series = {Proceedings of Machine Learning Research}, volume = {130}, eprint = {2103.00654}, howpublished = {accepted to {AISTATS}}, pdf = {http://proceedings.mlr.press/v130/canal21a/canal21a.pdf}, url = {http://proceedings.mlr.press/v130/canal21a.html} }

31. H. Zivari-Fard, M. Bloch, and A. Nosratinia, “Keyless Covert Communication in the Presence of Channel State Information,” in ieee_isit, Los Angeles, CA, Jun. 2020, pp. 834–839.

    We consider the problem of covert communication when Channel State Information (CSI) is available non-causally, causally, and strictly causally at both transmitter and receiver, as well as the case when channel state information is only available at the transmitter. Covert communication with respect to an adversary referred to as the "warden", is one in which the distribution induced during communication at the channel output observed by the warden is identical to the output distribution conditioned on an innocent channel-input symbol. In contrast to previous work, we do not assume the availability of a shared key at the transmitter and legitimate receiver; instead shared randomness is extracted from the channel state, in a manner that keeps it secret from the warden despite the influence of the channel state on the warden’s output. When CSI is available at both transmitter and receiver, we derive the covert capacity region; when CSI is only available at the transmitter, we derive inner and outer bounds on the covert capacity. We also derive the covert capacity when the warden’s channel is less noisy with respect to the legitimate receiver. We provide examples for which covert capacity is zero without channel state information, but is positive in the presence of channel state information.

    @inproceedings{ZivariFard2020a, author = {Zivari-Fard, Hassan and Bloch, Matthieu and Nosratinia, Aria}, booktitle = ieee_isit, title = {Keyless Covert Communication in the Presence of Channel State Information}, year = {2020}, address = {Los Angeles, CA}, month = jun, pages = {834-839}, doi = {10.1109/ISIT44484.2020.9174089}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

32. S.-Y. Wang and M. R. Bloch, “Covert MIMO Communications under Variational Distance Constraint,” in ieee_isit, Los Angeles, CA, Jun. 2020, pp. 828–833.

    We consider the problem of covert communication over Multiple-Input Multiple-Output (MIMO) Additive White Gaussian Noise (AWGN) channels, in which a transmitter attempts to reliably communicate with a legitimate receiver while ensuring a low probability of detection by an adversary. We exactly characterize the covert capacity under a variational distance covertness constraint when MIMO channel matrices are static and known to all parties. We also characterize the covert capacity for a class of channels in which the legitimate channel matrix is known but the adversary’s channel matrix is only known to satisfy a rank and a spectral norm constraint.

    @inproceedings{Wang2020, author = {Wang, Shi-Yuan and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Covert {MIMO} Communications under Variational Distance Constraint}, year = {2020}, address = {Los Angeles, CA}, month = jun, pages = {828-833}, doi = {10.1109/ISIT44484.2020.9174387}, howpublished = {accepted to \emph{IEEE International Sympsoium on Information Theory}} }

33. N. Helal, M. Bloch, and A. Nosratinia, “Resolvability of the Multiple Access Channel with Two-Sided Cooperation,” in ieee_isit, Los Angeles, CA, Jun. 2020.

    We study the randomness required at the inputs of a multiple access channel in order to produce a desired, approximately i.i.d., output distribution, subject to cooperation in one of the following forms: (i) a common message, (ii) conferencing, (iii) feedback and (iv) generalized feedback. For the cases (i)-(iii), we characterize the channel resolvability via matching inner and outer bounds, and for generalized feedback we provide two inner bounds representing the role of decoding and randomness extraction, which can also be combined. One of the main contributions of this work is to show that resolvability rates of the multiple access channel are not improved with feedback, unlike the multiple access channel capacity which is improved by feedback.

    @inproceedings{Helal2020, author = {Helal, Noha and Bloch, Matthieu and Nosratinia, Aria}, booktitle = ieee_isit, title = {Resolvability of the Multiple Access Channel with Two-Sided Cooperation}, year = {2020}, address = {Los Angeles, CA}, month = jun, doi = {10.1109/ISIT44484.2020.9174302}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

34. M.-C. Chang and M. Bloch, “Evasive Active Hypothesis Testing,” in ieee_isit, Los Angeles, CA, Jun. 2020, pp. 1248–1253.

    We consider an active hypothesis testing scenario in which an adversary obtains observations while legitimate parties engage in a sequential adaptive control policy to estimate an unknown parameter. The objective is for the legitimate parties to evade the adversary by controlling the risk of their test while minimizing the detection ability of the adversary, measured in terms of its error exponent. We develop bounds on the adversary’s error exponent that offer insight into how legitimate adversaries can best evade the adversary’s detection. We illustrate the results in a wireless transmission detection example.

    @inproceedings{Chang2020, author = {Chang, Meng-Che and Bloch, Matthieu}, booktitle = ieee_isit, title = {Evasive Active Hypothesis Testing}, year = {2020}, address = {Los Angeles, CA}, month = jun, pages = {1248-1253}, doi = {10.1109/ISIT44484.2020.9174021}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

35. M. Tahmasbi and M. R. Bloch, “Active Covert Sensing,” in ieee_isit, Los Angeles, CA, Jun. 2020, pp. 840–845.

    We formalize the problem of active covert sensing, in which a legitimate user wants to not only sense an unknown parameter but also remain undetectable from an adversary by actively controlling the actions that generate observations. We characterize the optimal achievable error exponent when the actions of the legitimate user do not depend on the past observations. When the actions are allowed to depend on the past observations, we provide an example showing the benefits of adaptivity.

    @inproceedings{Tahmasbi2020b, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R}, booktitle = ieee_isit, title = {Active Covert Sensing}, year = {2020}, address = {Los Angeles, CA}, month = jun, pages = {840-845}, doi = {10.1109/ISIT44484.2020.9174220}, file = {:2020-Tahmasbi-ISIT-Active Covert Sensing.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

36. A. Benevento, M. Santos, G. Notarstefano, K. Paynabar, M. Bloch, and M. Egerstedt, “Multi-Robot Coordination for Estimation and Coverage of Unknown Spatial Fields,” in Proc. of IEEE International Conference on Robotics and Automation, Paris, France, May 2020, pp. 7740–7746.

    @inproceedings{Benevento2019, author = {Benevento, Alessia and Santos, Mar\'ia and Notarstefano, Giuseppe and Paynabar, Kamran and Bloch, Matthieu and Egerstedt, Magnus}, booktitle = {Proc. of IEEE International Conference on Robotics and Automation}, title = {Multi-Robot Coordination for Estimation and Coverage of Unknown Spatial Fields}, year = {2020}, address = {Paris, France}, month = may, pages = {7740-7746}, doi = {10.1109/ICRA40945.2020.9197487}, file = {:2020-Benevento-ICRA.pdf:PDF}, groups = {Multi-agent systems, Gaussian Processes}, howpublished = {accepted to \emph{IEEE International Conference on Robotics and Automation}} }

37. M. Tahmasbi and M. R. Bloch, “Covert Communication with Unknown Code at the Warden,” in Proc. of Allerton Conference on Communication, Control and Computing, Monticello, IL, Sep. 2019, pp. 1060–1067.

    In covert communication, a transmitter attempts to send a message over a channel while avoiding detection from a warden. We investigate here how the warden’s knowledge of the code used by the transmitter and the receiver influences the optimal number of bits that can be covertly and reliably sent. We formulate the problem in three scenarios: the warden completely knows the code, the warden knows only the rate and an upper-bound on the probability of error at the decoder, and the warden has access to previous samples of its channel when the code was used. The first scenario corresponds to the standard model in covert communication. For the second scenario, we characterize the number of bits that can be transmitted reliably subject to a covertness constraint up to the first-order of asymptotics. Finally, for the third scenario, we provide lower-and upper-bound on the number of bits that can be transmitted reliably subject to a covertness constraint for two scalings of the number of observed samples.

    @inproceedings{Tahmasbi2019d, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, booktitle = {Proc. of Allerton Conference on Communication, Control and Computing}, title = {Covert Communication with Unknown Code at the Warden}, year = {2019}, address = {Monticello, IL}, month = sep, pages = {1060--1067}, doi = {10.1109/ALLERTON.2019.8919792}, file = {:2019-Tahmasbi-Allerton.pdf:PDF}, groups = {Steganography and covert communications}, isbn = {978-1-7281-3152-8}, keywords = {Reliability, Transmitters, Receivers, Zinc, Decoding, Standards, AWGN channels}, location = {Monticello, IL, USA} }

38. H. Zivari-Fard, M. Bloch, and A. Nosratinia, “Keyless Covert Communication in the Presence of Non-causal Channel State Information,” in ieee_itw, Visby, Sweden, Aug. 2019, pp. 1–5.

    @inproceedings{ZivariFard2019, author = {Zivari-Fard, Hassan and Bloch, Matthieu and Nosratinia, Aria}, booktitle = ieee_itw, title = {Keyless Covert Communication in the Presence of Non-causal Channel State Information}, year = {2019}, address = {Visby, Sweden}, month = aug, pages = {1-5}, doi = {10.1109/ITW44776.2019.8989317}, file = {:2019-ZivariFard-ITW.pdf:PDF}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

39. N. Helal, M. R. Bloch, and A. Nostratinia, “Channel Resolvability with a Full-Duplex Decode-and-Forward Relay,” in ieee_itw, Visby, Sweden, Aug. 2019, pp. 1–5.

    @inproceedings{Helhal2019, author = {Helal, Noha and Bloch, Matthieu R and Nostratinia, Aria}, booktitle = ieee_itw, title = {Channel Resolvability with a Full-Duplex Decode-and-Forward Relay}, year = {2019}, address = {Visby, Sweden}, month = aug, pages = {1--5}, doi = {10.1109/ITW44776.2019.8989307}, file = {:2019-Helal-ITW.pdf:PDF}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

40. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Forward Reconciliation for Covert Key Generation,” in ieee_itw, Visby, Sweden, Aug. 2019, pp. 1–5.

    @inproceedings{Kadampot2019a, author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Forward Reconciliation for Covert Key Generation}, year = {2019}, address = {Visby, Sweden}, month = aug, pages = {1--5}, doi = {10.1109/ITW44776.2019.8989274}, file = {:2019-Kadampot-ITW.pdf:PDF}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}} }

41. M. Tahmasbi and M. Bloch, “Steganography Protocols for Quantum Channels,” in ieee_isit, Paris, France, Jul. 2019, pp. 2179–2183.

    @inproceedings{Tahmasbi2019b, author = {Tahmasbi, Mehrdad and Bloch, Matthieu}, booktitle = ieee_isit, title = {Steganography Protocols for Quantum Channels}, year = {2019}, address = {Paris, France}, month = jul, pages = {2179-2183}, file = {:2019-Tahmasbi-ISIT.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

42. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Codes for Covert Communication over Additive White Gaussian Noise Channels,” in ieee_isit, Paris, France, Jul. 2019, pp. 977–981.

    We propose a coding scheme for covert communication over additive white Gaussian noise channels, which extends a previous construction for discrete memoryless channels. We first show how sparse signaling with On-Off keying fails to achieve the covert capacity but that a modification allowing the use of binary phase-shift keying for "on" symbols recovers the loss. We then construct a modified pulse-position modulation scheme that, combined with multilevel coding, can achieve the covert capacity with low-complexity error-control codes. The main contribution of this work is to reconcile the tension between diffuse and sparse signaling suggested by earlier information-theoretic results.

    @inproceedings{Kadampot2019, author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R}, title = {Codes for Covert Communication over Additive White Gaussian Noise Channels}, booktitle = ieee_isit, year = {2019}, pages = {977-981}, address = {Paris, France}, month = jul, doi = {10.1109/ISIT.2019.8849662}, file = {:2019-Kadampot-ISIT.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

43. W. Harrison and M. R. Bloch, “Attributes of Generator Matrices for Best Finite Blocklength Wiretap Codes,” in ieee_isit, Paris, France, Jul. 2019, pp. 827–831.

    @inproceedings{Harrison2019, author = {Harrison, Willie and Bloch, Matthieu R}, booktitle = ieee_isit, title = {Attributes of Generator Matrices for Best Finite Blocklength Wiretap Codes}, year = {2019}, address = {Paris, France}, month = jul, pages = {827-831}, doi = {10.1109/ISIT.2019.8849625}, file = {:2019-Harrison-ISIT.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

44. M. Tahmasbi, M. Bloch, and A. Yener, “In-Band Sensing of the Adversary’s Channel for Secure Communication in Wireless Channels,” in ieee_isit, Paris, France, Jul. 2019, pp. 2184–2188.

    We propose a model of secure communication over wireless channels in which the legitimate parties leverage Radio Tomographic Imaging (RTI) to learn the adversary. Specifically, we model the results of RTI as an "in band" sensing channel that provides causal information about the eavesdropper’s path-loss to the transmitter. This ability to learn the path-loss is exploited to achieve secrecy, even in presence of an eavesdropper that moves to optimize its path-loss and improves its eavesdropping. We show that the secrecy rates achieved are the same as those that would have been obtained with hindsight, had the transmitter known the average path-loss ahead of time.

    @inproceedings{Tahmasbi2019c, author = {Tahmasbi, Mehrdad and Bloch, Matthieu and Yener, Aylin}, title = {In-Band Sensing of the Adversary's Channel for Secure Communication in Wireless Channels}, booktitle = ieee_isit, year = {2019}, pages = {2184-2188}, address = {Paris, France}, month = jul, doi = {10.1109/ISIT.2019.8849506}, file = {:2019-Tahmasbi-ISIT2.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

45. Q. Zhang, M. Bloch, M. Bakshi, and S. Jaggi, “Undetectable Radios: Covert Communication under Spectral Mask Constraints,” in ieee_isit, Paris, France, Jul. 2019, pp. 992–996.

    We consider the problem of covert communication over continuous-time additive white Gaussian noise (AWGN) channels under spectral mask constraints. In addition to requiring the legitimate receiver to reliably decode, covert communication also requires that the warden is unable to estimate whether or not communication is taking place. The spectral mask at the transmitter restricts excessive radiation beyond the bandwidth of interest. We develop a communication scheme with theoretical guarantees for both covertness and reliability, based on pulse amplitude modulation (PAM) with Binary Phase Shift Keying (BPSK) and root raised cosine (RRC) carrier pulses. Given a fixed time T and a spectral mask with bandwidth parameter W, we show that one can transmit \mathcalO\left( \sqrt WT \right) bits of information covertly and reliably, and our proposed scheme provides a lower bound on the covert capacity.

    @inproceedings{Zhang2019, author = {Zhang, Qiaosheng and Bloch, Matthieu and Bakshi, Mayank and Jaggi, Sidharth}, booktitle = ieee_isit, title = {Undetectable Radios: Covert Communication under Spectral Mask Constraints}, year = {2019}, address = {Paris, France}, month = jul, pages = {992-996}, doi = {10.1109/ISIT.2019.8849818}, file = {:2019-Zhang-ISIT.pdf:PDF}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

46. G. Cervia, L. Luzzi, M. Le Treust, and M. R. Bloch, “Strong coordination over noisy channels with strictly causal encoding,” in Proc. of 56th Annual Allerton Conference on Communication, Control, and Computing, Oct. 2018, pp. 519–526.

    We consider a network of two nodes separated by a noisy channel, in which the input and output signals have to be coordinated with the source and its reconstruction. In the case of strictly causal encoding and non-causal decoding, we prove inner and outer bounds for the strong coordination region and show that the inner bound is achievable with polar codes.

    @inproceedings{Cervia2018a, author = {Cervia, Giulia and Luzzi, Laura and {Le Treust}, Mael and Bloch, Matthieu R}, title = {Strong coordination over noisy channels with strictly causal encoding}, booktitle = {Proc. of 56th Annual Allerton Conference on Communication, Control, and Computing}, year = {2018}, pages = {519-526}, month = oct, doi = {10.1109/ALLERTON.2018.8635991}, eprint = {1809.10934}, groups = {Coordination of networks}, keywords = {Decoding;Encoding;Noise measurement;Memoryless systems;Markov processes;Communication networks} }

47. W. K. Harrison and M. R. Bloch, “On Dual Relationships of Secrecy Codes,” in Proc. of 56th Annual Allerton Conference on Communication, Control, and Computing, Oct. 2018, pp. 366–372.

    We investigate properties of finite blocklength codes and their duals when used for coset coding over the binary era- sure wiretap channel (BEWC). We identify sufficient conditions, related to the ranks of sub-matrices of a generator matrix that codes may satisfy to achieve the maximum equivocation among all codes with given blocklength and dimension, irrespective of the eavesdropper’s channel erasure probability. We point out that binary maximum distance separable (MDS) codes are optimal for secrecy and we also show that simplex codes (and Hamming codes) have higher equivocation than families of codes with a single repeated column in the generator matrix (parity-check matrix). We conjecture that simplex and Hamming codes are optimal when used as the base linear code in a coset coding scheme for secrecy over the BEWC.

    @inproceedings{Harrison2018, author = {Harrison, Willie K. and Bloch, Matthieu R.}, title = {On Dual Relationships of Secrecy Codes}, booktitle = {Proc. of 56th Annual Allerton Conference on Communication, Control, and Computing}, year = {2018}, pages = {366-372}, month = oct, doi = {10.1109/ALLERTON.2018.8635841}, groups = {Wiretap codes} }

48. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Multilevel-Coded Pulse Position Modulation for Covert Communications,” in ieee_isit, Vail, CO, Jun. 2018, pp. 1864–1868.

    We develop a low-complexity coding scheme to achieve covert communications over binary symmetric channels. We circumvent the impossibility of covert communication with linear codes by introducing non-linearity through the use of pulse-position modulation (PPM) and multilevel coding (MLC). We show that the MLC-PPM scheme exhibits many appealing properties, in particular, the channel at a given index level remains the same as the number of level increases, which allows one to use families of capacity- and resolvability-achieving codes to concretely instantiate the covert communication scheme.

    @inproceedings{Kadampot2018, author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R.}, title = {Multilevel-Coded Pulse Position Modulation for Covert Communications}, booktitle = ieee_isit, year = {2018}, pages = {1864--1868}, address = {Vail, CO}, month = jun, doi = {10.1109/ISIT.2018.8437587}, file = {:2018-Kadampot-ISIT.pdf:PDF}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

49. N. Helal, M. R. Bloch, and A. Nosratinia, “Multiple-Access Channel Resolvability with Cribbing,” in ieee_isit, Vail, CO, Jun. 2018, pp. 2052–2056.

    We study channel resolvability for the discrete memoryless multiple access channel with cribbing, i.e., the characterization of the amount of randomness required to approximate an i.i.d. output distribution in terms of Kullback-Leibler divergence. We analyze the cases in which one encoder cribs (i) the input of the other encoder; or the output of the other encoder (ii) noncausally, (iii) causally, or (iv) strictly-causally. For cases (i)-(iii), we exactly characterize the channel resolvability region. For case (iv), we provide inner and outer bounds for the channel resolvability region; our achievability result handles the strict causality constraint with a block-Markov coding scheme in which dependencies across blocks are suitably hidden.

    @inproceedings{Helhal2018, author = {Helal, Noha and Bloch, Matthieu R and Nosratinia, Aria}, title = {Multiple-Access Channel Resolvability with Cribbing}, booktitle = ieee_isit, year = {2018}, pages = {2052--2056}, address = {Vail, CO}, month = jun, doi = {10.1109/ISIT.2018.8437580}, file = {:2018-Helal-ISIT.pdf:PDF}, groups = {Randomness processing}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, issn = {2157-8117}, keywords = {channel capacity;channel coding;Markov processes;memoryless systems;multi-access systems;discrete memoryless multiple access channel;cribbing;output distribution;Kullback-Leibler divergence;encoder cribs;channel resolvability region;strict causality constraint;multiple-access channel resolvability;block-Markov coding scheme;Encoding;Zirconium;Recycling;Random variables;Delays;Zinc} }

50. K. S. K. Arumugam, M. R. Bloch, and L. Wang, “Covert Communication over a Physically Degraded Relay Channel with Non-Colluding Wardens,” in ieee_isit, Vail, CO, Jun. 2018, pp. 766–770.

    We analyze a physically degraded relay channel, in which the transmitter sends a covert message to the legitimate receiver with the help of a relay. Two wardens, who do not collude with each other, monitor communication from the transmitter and the relay, respectively, through two Discrete Memoryless Channels (DMCs) to detect the presence of a covert message. The objective of the transmitter is to deliver the covert message successfully to the receiver without exceeding the covertness threshold of either warden. We identify the optimal asymptotic scaling of message and key bits and the dependence of the covert throughput on the two covertness thresholds.

    @inproceedings{Arumugam2018, author = {Arumugam, Keerthi Suria Kumar and Bloch, Matthieu R and Wang, Ligong}, booktitle = ieee_isit, title = {Covert Communication over a Physically Degraded Relay Channel with Non-Colluding Wardens}, year = {2018}, address = {Vail, CO}, month = jun, pages = {766--770}, doi = {10.1109/ISIT.2018.8437505}, file = {:2018-Arumugam-ISIT.pdf:PDF}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

51. K. S. K. Arumugam and M. R. Bloch, “Covert communication over broadcast channels,” in ieee_itw, Kaohsiung, Taiwan, Nov. 2017, pp. 299–303.

    We analyze a two-receiver binary-input discrete memoryless broadcast channel, in which the transmitter communicates a common message simultaneously to both users and a covert message to only one of them while treating the other as an adversary. This model captures the problem of embedding covert messages in an innocuous codebook and generalizes previous models in which the innocent behavior corresponds to the absence of communication between legitimate users. We identify the exact asymptotic behavior of the number of reliable and covert bits when the rate of the innocuous codebook is close to the channel capacity of the adversary. In particular, our results characterize the dependence of the number of covert bits on the channel parameters and the characteristics of the innocent codebook.

    @inproceedings{Arumugam2017, author = {Arumugam, Keerthi Suria Kumar and Bloch, M. R.}, booktitle = ieee_itw, title = {Covert communication over broadcast channels}, year = {2017}, address = {Kaohsiung, Taiwan}, month = nov, pages = {299--303}, doi = {10.1109/ITW.2017.8278022}, file = {:2017-Arumugam-ITW.pdf:PDF}, groups = {Steganography and covert communications} }

52. M. Tahmasbi, M. R. Bloch, and V. F. Tan, “Error exponents covert communications,” in ieee_itw, Kaohsiung, Taiwan, Nov. 2017, pp. 304–308.

    We define and study the error exponent of covert communications over binary-input Discrete Memoryless Channels (DMCs). Our main result consists of upper and lower bounds for the exponent, which match in a regime that we explicitly characterize. While our proofs follow standard techniques, the vanishing rate regime inherent to covert communications and the low-weight of codewords introduces specific technical challenges. In particular, the lower bound of the error exponent follows from a non-standard constant-composition ensemble instead of an independent and identically distributed (i.i.d.) ensemble, and the upper bound requires a careful treatment that does not appear in the traditional analysis of error exponent.

    @inproceedings{Tahmasbi2017b, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R and Tan, Vincent F}, title = {Error exponents covert communications}, booktitle = ieee_itw, year = {2017}, pages = {304-308}, address = {Kaohsiung, Taiwan}, month = nov, doi = {10.1109/ITW.2017.8278024}, file = {:2017-Tahmasbi-ITW.pdf:PDF}, groups = {Steganography and covert communications} }

53. M. Tahmasbi and M. R. Bloch, “Covert secret key generation,” in Proc. of IEEE Conference on Communications and Network Security, Workshop on Physical-Layer Methods for Wireless Security, Las Vegas, NV, Oct. 2017, pp. 540–544.

    We investigate the possibility of covert and secret key generation over a discrete memoryless channel model with one way public discussion. Protocols are required to conceal not only the key but also whether a protocol is being implemented. For some models, we show that covert secret key generation is possible and characterize the covert secret key capacity in special cases; in particular, the covert secret key capacity is sometimes equal to the covert capacity of the channel, so that secrecy comes �for free.� Our main contribution is the analysis of a protocol that exploits the likelihood encoder to circumvent source coding with side information and privacy amplification.

    @inproceedings{Tahmasbi2017c, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, title = {Covert secret key generation}, booktitle = {Proc. of IEEE Conference on Communications and Network Security, Workshop on Physical-Layer Methods for Wireless Security}, year = {2017}, pages = {540-544}, address = {Las Vegas, NV}, month = oct, doi = {10.1109/CNS.2017.8228681}, groups = {Steganography and covert communications, Secret key agreement}, keywords = {Communication networks;Communication system security;Conferences;Privacy;Protocols;Security;Throughput} }

54. E. Shipilova, J.-L. Boelle, M. Bloch, M. Barret, and J.-L. Collette, “Matrioshka orthogonal matching pursuit for blended seismic source separation,” in Proc. of SEG International Exposition and Annual Meeting, Houston, TX, Sep. 2017.

    @inproceedings{Shipilova2017Matrioshka, author = {Shipilova, Ekaterina and Boelle, Jean-Luc and Bloch, Matthieu and Barret, Michel and Collette, Jean-Luc}, booktitle = {Proc. of SEG International Exposition and Annual Meeting}, title = {Matrioshka orthogonal matching pursuit for blended seismic source separation}, year = {2017}, address = {Houston, TX}, month = sep }

55. H. Zivari-Fard, M. Bloch, and A. Nosratinia, “Two-Transmitter Two-Receiver Channel with Confidential Messages,” in Proc. of Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2017.

    We study the two-transmitter two-receiver channel with confidential messages channel under a secrecy constraint, exploring the effect of a single eavesdropper on the secure communication rate. A general achievable secrecy rate region and an outer bound are derived for the degraded version of this channel. An example is provided in which the inner and outer bound meet. For the general non-degraded channel, another outer bound is derived and a special case is highlighted in which the inner and outer bound meet. Our inner bound recovers the known inner bounds for the multiple-access wiretap channel, broadcast channel with confidential messages, and the compound MAC channel.

    @inproceedings{Zivari-Fard2017, author = {Zivari-Fard, Hassan and Bloch, Matthieu and Nosratinia, Aria}, title = {Two-Transmitter Two-Receiver Channel with Confidential Messages}, booktitle = {Proc. of Allerton Conference on Communication, Control, and Computing}, year = {2017}, address = {Monticello, IL}, month = sep, doi = {10.1109/ALLERTON.2017.8262725}, groups = {Wiretap channels}, howpublished = {accepted to \emph{Allerton Conference on Communication Control and Computing}} }

56. M. Tahmasbi, M. R. Bloch, and A. Yener, “Learning Adversary’s Actions for Secret Communication,” in ieee_isit, Aachen, Germany, Jun. 2017, pp. 2713–2717.

    We analyze the problem of secure communication over a wiretap channel with an active adversary, in which the legitimate transmitter has the opportunity to sense and learn the adversary’s actions. Specifically, the adversary has the ability to switch between two channels and to observe the corresponding output at every channel use; the encoder, however, has causal access to observations impacted by adversary’s actions. We develop a joint learning/transmission scheme in which the legitimate users learn and adapt to the adversary’s actions. For some channel models, we show that the achievable rates, which we define precisely, are arbitrarily close to those obtained with hindsight, had the transmitter known the actions ahead of time. This suggests that there is much to exploit and gain in physical-layer security by monitoring the environment.

    @inproceedings{Tahmasbi2017a, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R and Yener, Aylin}, title = {Learning Adversary's Actions for Secret Communication}, booktitle = ieee_isit, year = {2017}, pages = {2713--2717}, address = {Aachen, Germany}, month = jun, doi = {10.1109/ISIT.2017.8007021}, file = {:2017-Tahmasbi-ISIT.pdf:PDF}, groups = {Adversarial models}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

57. M. R. Bloch and S. Guha, “Optimal Covert Communications using Pulse-Position Modulation,” in ieee_isit, Aachen, Germany, Jun. 2017, pp. 2835–2839.

    This paper shows the optimality of Pulse-Position Modulation (PPM) for covert communications over discrete-memoryless channels. Specifically, the concatenation of a random m-ary outer code of length O(m) and an inner code consisting of PPM of order m achieves the information-theoretic limits of covert communications. This suggests alternative code constructions for covert communications, in which the sparsity of the PPM symbols ensures covertness and an appropriate choice of the blocklength results in the square root law.

    @inproceedings{Bloch2017, author = {Bloch, Matthieu R and Guha, Saikat}, title = {Optimal Covert Communications using Pulse-Position Modulation}, booktitle = ieee_isit, year = {2017}, pages = {2835--2839}, address = {Aachen, Germany}, month = jun, doi = {10.1109/ISIT.2017.8007045}, file = {:2017-Bloch-ISIT.pdf:PDF}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

58. G. Cervia, L. Luzzi, M. L. Treust, and M. R. Bloch, “Strong Coordination of Signals and Actions over Noisy Channels,” in ieee_isit, Aachen, Germany, Jun. 2017, pp. 2845–2849.

    We develop a random binning scheme for strong coordination in a network of two nodes separated by a noisy channel, in which the input and output signals have to be coordinated with the source and its reconstruction. In the case of non-causal encoding and decoding, we propose a joint source-channel coding scheme and develop inner and outer bounds for the strong coordination region. While the set of achievable target distributions is the same as for empirical coordination, we characterize the rate of common randomness required for strong coordination.

    @inproceedings{Cervia2017, author = {Cervia, Giulia and Luzzi, Laura and Treust, Ma\"el Le and Bloch, Matthieu R}, title = {Strong Coordination of Signals and Actions over Noisy Channels}, booktitle = ieee_isit, year = {2017}, pages = {2845--2849}, address = {Aachen, Germany}, month = jun, doi = {10.1109/ISIT.2017.8007047}, groups = {Coordination of networks}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

59. E. Shipilova, J.-L. Boelle, M. Barret, M. Bloch, and J.-L. Collette, “Separation of impulsive blended seismic sources using Orthogonal Matching Pursuit,” in 79th Annual International Conference and Exhibition EAGE, Paris, France, Jun. 2017.

    @inproceedings{Shipilova2017a, author = {Shipilova, Ekaterina and Boelle, Jean-Luc and Barret, Michel and Bloch, Matthieu and Collette, Jean-Luc}, title = {Separation of impulsive blended seismic sources using Orthogonal Matching Pursuit}, booktitle = {79th Annual International Conference and Exhibition EAGE}, year = {2017}, address = {Paris, France}, month = jun, doi = {10.3997/2214-4609.201700875} }

60. I. A. Kadampot and M. R. Bloch, “Coordination with Clustered Common Randomness in a Three-Terminal Line Network,” in ieee_isit, Aachen, Germany, Jun. 2017, pp. 1828–1832.

    To achieve strong coordination in a network, nodes benefit from access to a source of common randomness. Most studies pertaining to strong coordination assume the existence of a source of common randomness accessible to all nodes in the network. This assumption, however, is not practical in a decentralized network. We analyze the problem of strong coordination in a three-terminal line network with common randomness available only at the first two nodes and assume that the actions of the first node are specified by an external agent. We use coding schemes developed for channel resolvability codes to characterize the strong coordination capacity region when the intermediate node is operating in a functional mode. A comparison of our coordination capacity region with a case in which all nodes have access to a common randomness shows that we have to increase the communication rate between the second and the third nodes to achieve the same coordination distribution.

    @inproceedings{Kadampot2017, author = {Kadampot, Ishaque Ashar and Bloch, Matthieu R}, title = {Coordination with Clustered Common Randomness in a Three-Terminal Line Network}, booktitle = ieee_isit, year = {2017}, pages = {1828--1832}, address = {Aachen, Germany}, month = jun, doi = {10.1109/ISIT.2017.8006845}, groups = {Coordination of networks}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}} }

61. G. Frèche, M. R. Bloch, and M. Barret, “Polar codes for covert communications over asynchronous Discrete Memoryless Channels,” in Proc. of 51st Annual Conference on Information Sciences and Systems, Baltimore, MD, Mar. 2017, pp. 1–1.

    We develop a covert communication scheme for binary-input asynchronous Discrete Memoryless Channels based on binary polar codes, in which legitimate parties exploit uncertainty created by both the channel noise and the time of transmission. The proposed code jointly ensures reliable communication for a legitimate receiver and low probability of detection with respect to an adversary, both observing noisy versions of the codewords. Binary polar codes are used to shape the weight distribution of codewords and ensure that the average weight decays as the block length grows. The performance of the proposed code is limited by the speed of polarization, which in turns controls the decay of the average codeword weight with the block length. Although the proposed construction falls short of achieving the performance of random codes, it inherits the low-complexity properties of polar codes.

    @inproceedings{Freche2017a, author = {Fr\`eche, Guillaume and Bloch, Matthieu R. and Barret, Michel}, booktitle = {Proc. of 51st Annual Conference on Information Sciences and Systems}, title = {Polar codes for covert communications over asynchronous Discrete Memoryless Channels}, year = {2017}, address = {Baltimore, MD}, month = mar, pages = {1-1}, creationdate = {2017-08-30T00:00:00}, doi = {10.1109/CISS.2017.7926132}, groups = {Steganography and covert communications, Polar codes}, keywords = {Memoryless systems;Noise measurement;Receivers;Reliability;Shape;Uncertainty}, owner = {mattbloch} }

62. K. S. K. Arumugam, I. A. Kadampot, M. Tahmasbi, S. Shah, M. Bloch, and S. Pokutta, “Modulation recognition using side information and hybrid learning,” in Proc. IEEE Int. Symp. Dynamic Spectrum Access Networks (DySPAN), Piscataway, NJ, Mar. 2017, pp. 1–2.

    Recent applications of machine learning to modulation recognition have demonstrated the potential of deep learning to achieve state-of-the-art performance. We propose to further extend this approach by using flexible time-space decompositions that are more in line with the actual learning task, as well as integrate side-information, such as higher order moments, directly into the training process. Our promising preliminary results suggest that there are many more benefits to be reaped from such approaches.

    @inproceedings{Arumugam2017a, author = {Arumugam, Keerthi Suria Kumar and Kadampot, I. A. and Tahmasbi, M. and Shah, S. and Bloch, M. and Pokutta, S.}, booktitle = {Proc. IEEE Int. Symp. Dynamic Spectrum Access Networks (DySPAN)}, title = {Modulation recognition using side information and hybrid learning}, year = {2017}, address = {Piscataway, NJ}, month = mar, pages = {1--2}, doi = {10.1109/DySPAN.2017.7920750}, file = {:2017-Arumugam-Dyspan.pdf:PDF}, groups = {Steganography and covert communications}, keywords = {learning (artificial intelligence), modulation, telecommunication computing, deep learning, flexible time-space decompositions, higher order moments, machine learning, modulation recognition, side information, Cognitive radio, Convolution, Dynamic spectrum access, Machine learning, Modulation, Network architecture, Signal to noise ratio} }

63. G. Cervia, L. Luzzi, M. R. Bloch, and M. L. Treust, “Polar coding for empirical coordination of signals and actions over noisy channels,” in ieee_itw, Cambridge, United Kingdom, Sep. 2016, pp. 81–85.

    We develop a polar coding scheme for empirical coordination in a two-node network with a noisy link in which the input and output signals have to be coordinated with the source and the reconstruction. In the case of non-causal encoding and decoding, we show that polar codes achieve the best known inner bound for the empirical coordination region, provided that a vanishing rate of common randomness is available. This scheme provides a constructive alternative to random binning and coding proofs.

    @inproceedings{Cervia2016, author = {Cervia, G. and Luzzi, L. and Bloch, M. R. and Treust, M. Le}, booktitle = ieee_itw, title = {Polar coding for empirical coordination of signals and actions over noisy channels}, year = {2016}, address = {Cambridge, United Kingdom}, month = sep, pages = {81-85}, creationdate = {2016-03-20T00:00:00}, doi = {10.1109/ITW.2016.7606800}, groups = {Coordination of networks}, keywords = {Conferences;Decoding;Electronic mail;Encoding;Noise measurement}, owner = {mattbloch} }

64. M. Tahmasbi and M. R. Bloch, “Second Order Asymptotics for Degraded Wiretap Channels: How Good Are Existing Codes?,” in 54th Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2016, pp. 830–837.

    We develop three new results regarding the second-order asymptotics of secure communication over wiretap channels. We first establish the optimal second-order asymptotics for a class of degraded wiretap channels without feedback under an effective secrecy criterion. We then derive the optimal second-order asymptotics for degraded wiretap channels with feedback. We finally develop a new converse bound for channel resolvability with non-capacity achieving distributions, which we use to develop useful converse bounds for asymmetric degraded wiretap channels. Our results are illustrated with several numerical examples, and suggest that known coding techniques already achieve their best performance.

    @inproceedings{Tahmasbi2016a, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, booktitle = {54th Annual Allerton Conference on Communication, Control, and Computing}, title = {Second Order Asymptotics for Degraded Wiretap Channels: How Good Are Existing Codes?}, year = {2016}, address = {Monticello, IL}, month = sep, pages = {830-837}, doi = {10.1109/ALLERTON.2016.7852319}, groups = {Wiretap channels}, keywords = {encoding;telecommunication security;asymmetric degraded wiretap channels;channel resolvability;converse bound;effective secrecy criterion;existing codes;known coding techniques;optimal second-order asymptotics;secure communication;Decoding;Encoding;Measurement;Monte Carlo methods;Receivers;Reliability;Transmitters} }

65. K. S. K. Arumugam and M. R. Bloch, “Keyless asynchronous covert communication,” in ieee_itw, Cambridge, United Kingdom, Sep. 2016, pp. 191–195.

    We consider a scenario in which Alice asynchronously communicates with Bob over a Discrete Memoryless Channel (DMC) while escaping detection from an adversary who observes their communication through another DMC. Specifically, Alice transmits codewords of length n and chooses the transmission epoch T uniformly at random among N available time epochs, where N >> n. This deliberate symbol level-asynchronism forces the adversary to monitor a window of size N much larger than the codeword length n, and results in an increased covert throughput compared to the scenario without asynchronism. Our result generalizes a previous work in which asynchronism was introduced at the codeword level, i.e., having Alice choose a transmission window among non-overlapping windows of length n.

    @inproceedings{Arumugam2016a, author = {Arumugam, Keerthi Suria Kumar and Bloch, M. R.}, booktitle = ieee_itw, title = {Keyless asynchronous covert communication}, year = {2016}, address = {Cambridge, United Kingdom}, month = sep, pages = {191-195}, creationdate = {2016-03-20T00:00:00}, doi = {10.1109/ITW.2016.7606822}, file = {:2016-Arumugam-ITW-Keyless Asynchronous Covert Communication.pdf:PDF}, groups = {Steganography and covert communications}, keywords = {Conferences;Monitoring}, owner = {mattbloch} }

66. R. A. Chou, M. R. Bloch, and A. Yener, “Universal covertness for Discrete Memoryless Sources,” in 54th Annual Allerton Conference on Communication, Control, and Computing (Allerton), Monticello, IL, Aug. 2016, pp. 516–523.

    Consider a sequence S of length n emitted by a Discrete Memoryless Source (DMS) with unknown distribution p. We wish to construct a lossless source code that maps S to a sequence S’ of minimal length m such that S’ approximates in terms of Kullback-Leibler divergence a sequence emitted by another DMS with known distribution q. Our main result is the existence of a coding scheme that performs such a task with an asymptotically optimal compression rate, i.e., such that the limit of m/n is H(p)/H(q) as n goes to infinity. Our coding scheme overcomes the challenges created by the lack of knowledge about p by relying on a sufficiently fine estimation of H(p), followed by an appropriately designed type-based compression that jointly performs source resolvability and universal lossless source coding. Our result recovers several previous results that either assume p uniform, or q uniform, or p known. The price paid for these generalizations is the use of common randomness with vanishing rate. We further determine that the length of the latter roughly scales as the square root of n, by an analysis of second order asymptotics and error exponents.

    @inproceedings{Chou2016, author = {Chou, R\'emi A. and Bloch, Matthieu R. and Yener, Aylin}, booktitle = {54th Annual Allerton Conference on Communication, Control, and Computing (Allerton)}, title = {Universal covertness for Discrete Memoryless Sources}, year = {2016}, address = {Monticello, IL}, month = aug, pages = {516-523}, creationdate = {2016-01-26T00:00:00}, doi = {10.1109/ALLERTON.2016.7852275}, groups = {Steganography and covert communications}, keywords = {source coding;DMS;discrete memoryless source;error exponent analysis;second order asymptotic analysis;source resolvability;universal covertness;universal lossless source coding;Decoding;Entropy;Estimation;Random variables;Reliability;Source coding}, owner = {mattbloch} }

67. B. N. Vellambi, J. Kliewer, and M. R. Bloch, “Lossy Compression with Near-uniform Encoder Outputs,” in ieee_isit, Barcelona, Spain, Jul. 2016, pp. 530–534.

    It is well known that lossless compression of a discrete memoryless source with near-uniform encoder output is possible at a rate above its entropy if and only if the encoder and decoder share a common random seed. This work focuses on deriving conditions for near-uniform encoder output(s) in the Wyner-Ziv and the distributed lossy compression problems. We show that in the Wyner-Ziv problem, near-uniform encoder output and operation close to the WZ-rate limit is simultaneously possible, whereas in the distributed lossy compression problem, jointly near-uniform outputs is achievable in the interior of the distributed lossy compression rate region if the sources share non-trivial G�cs-K�rner common information.

    @inproceedings{Vellambi2016, author = {Vellambi, Badri N. and Kliewer, J\"org and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Lossy Compression with Near-uniform Encoder Outputs}, year = {2016}, address = {Barcelona, Spain}, month = jul, pages = {530-534}, creationdate = {2016-01-26T00:00:00}, doi = {10.1109/ISIT.2016.7541355}, groups = {Randomness processing}, keywords = {Decoding;Distortion;Electronic mail;Encoding;Monte Carlo methods;Receivers}, owner = {mattbloch} }

68. M. Tahmasbi and M. R. Bloch, “Second-Order Asymptotics of Covert Communications over Noisy Channels,” in ieee_isit, Barcelona, Spain, Jul. 2016, pp. 2224–2228.

    We consider the problem of covert communication over noisy binary input Discrete Memoryless Channels (DMCs). Covertness is measured with respect to an adversary in terms of the divergence between the channel output distribution induced with and without communication. We characterize the exact second order asymptotics of the number of bits that can be reliably transmitted with a probability of error less than epsilon and a divergence less than delta. The main technical contribution of this paper is a detailed analysis of how to expurgate a random code while maintaining its channel resolvability properties.

    @inproceedings{Tahmasbi2016, author = {Tahmasbi, Mehrdad and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Second-Order Asymptotics of Covert Communications over Noisy Channels}, year = {2016}, address = {Barcelona, Spain}, month = jul, pages = {2224-2228}, creationdate = {2016-01-26T00:00:00}, doi = {10.1109/ISIT.2016.7541694}, groups = {Steganography and covert communications}, keywords = {Encoding;Monte Carlo methods;Noise measurement;Random variables;Reliability;Zinc}, owner = {mattbloch} }

69. K. S. K. Arumugam and M. R. Bloch, “Keyless Covert Communication over Multiple-Access Channels,” in ieee_isit, Barcelona, Spain, Jul. 2016, pp. 2229–2233.

    We consider a scenario in which two legitimate transmitters attempt to communicate with a legitimate receiver over a discrete memoryless Multiple-Access Channel (MAC), while escaping detection from an adversary who observes their communication through another discrete memoryless MAC. If the MAC to the legitimate receiver is "better" than the one to the adversary, in a sense that we make precise, then the legitimate users can reliably communicate on the order of sqrtn bits per n channel uses with arbitrarily Low Probability of Detection (LPD) without using a secret key. We also identify the pre-constants of the scaling, which leads to a characterization of the covert capacity region.

    @inproceedings{Arumugam2016, author = {Arumugam, Keerthi Suria Kumar and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Keyless Covert Communication over Multiple-Access Channels}, year = {2016}, address = {Barcelona, Spain}, month = jul, pages = {2229-2233}, creationdate = {2016-01-26T00:00:00}, doi = {10.1109/ISIT.2016.7541695}, file = {:2016-Arumugam-ISIT.pdf:PDF}, groups = {Steganography and covert communications}, keywords = {Channel models;Encoding;Random variables;Receivers;Reliability;Transmitters}, owner = {mattbloch} }

70. M. Le Treust and M. R. Bloch, “Empirical Coordination, State Masking and State Amplification: Core of the Decoder’s Knowledge,” in ieee_isit, Barcelona, Spain, Jul. 2016, pp. 895–899.

    We revisit the problem of state masking and state amplification for state-dependent channel with causal state information at the encoder from the point of view of empirical coordination. Empirical coordination, which requires all sequences of symbols to be jointly typical for a target joint probability distribution, provides a unified perspective to simultaneously study state masking, state amplification, and capacity-distortion trade-off. Our main result is a characterization of the set of achievable rates, information leakages and joint distributions. We also discuss several specializations and extensions of the result, including the cases of zero message rate, without empirical coordination, strictly causal encoding, two-sided state information and noisy channel feedback. We introduce the notion of "core of the decoder’s knowledge," to capture what the decoder can infer about all the signals involved in the model.

    @inproceedings{LeTreust2016, author = {{Le Treust}, Mael and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Empirical Coordination, State Masking and State Amplification: Core of the Decoder's Knowledge}, year = {2016}, address = {Barcelona, Spain}, month = jul, pages = {895-899}, creationdate = {2016-01-26T00:00:00}, doi = {10.1109/ISIT.2016.7541428}, groups = {Coordination of networks}, keywords = {Channel coding;Decoding;Distortion;Probability distribution;Random variables;Causal Encoding;Empirical Coordination;Information Leakage;Noisy Channel Feedback;Shannon Theory;State Amplification;State Masking;State-Dependent Channel}, owner = {mattbloch} }

71. B. N. Vellambi, J. Kliewer, and M. R. Bloch, “Strong coordination over a line when actions are Markovian,” in Proc. of Annual Conference on Information Science and Systems, Princeton, NJ, Mar. 2016, pp. 412–417.

    We analyze the problem of strong coordination over a multi-hop line network when the actions to be generated by the nodes satisfy a Markov chain that is matched to the network topology. We devise and prove the optimality of two schemes that cover the portions of the capacity region corresponding to unlimited or no common randomness shared by all nodes.

    @inproceedings{Vellambi2015b, author = {Vellambi, B. N. and Kliewer, J. and Bloch, M. R.}, booktitle = {Proc. of Annual Conference on Information Science and Systems}, title = {Strong coordination over a line when actions are Markovian}, year = {2016}, address = {Princeton, NJ}, month = mar, pages = {412-417}, creationdate = {2015-12-15T00:00:00}, doi = {10.1109/CISS.2016.7460538}, groups = {Coordination of networks}, keywords = {Markov processes;random processes;telecommunication network topology;telecommunication transmission lines;Markov chain;capacity region;multihop line network;network topology;no common randomness;strong coordination problem;unlimited randomness;Strong coordination;channel resolvability;channel synthesis;line network}, owner = {mattbloch} }

72. R. A. Chou and M. R. Bloch, “Using deterministic decisions for low-entropy bits in the encoding and decoding of polar codes,” in Proc. of 53rd Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2015, pp. 1380–1385.

    We show how to replace some of the randomized decisions in the encoding and decoding of polar codes by deterministic decisions. Specifically, we prove that random decisions on low-entropy bits may be replaced by an argmax decision without any loss of performance. We illustrate the usefulness of this result in the case of polar coding for the Wyner-Ziv problem and for channel coding.

    @inproceedings{Chou2015a, author = {Chou, R\'emi A. and Bloch, M. R.}, booktitle = {Proc. of 53rd Annual Allerton Conference on Communication, Control, and Computing}, title = {Using deterministic decisions for low-entropy bits in the encoding and decoding of polar codes}, year = {2015}, address = {Monticello, IL}, month = sep, pages = {1380-1385}, creationdate = {2015-07-07T00:00:00}, doi = {10.1109/ALLERTON.2015.7447169}, file = {:2015-Chou-Allerton-Using_deterministic_decisions_for_low-entropy_bits_in_the_encoding_and_decoding_of_polar_codes.pdf:PDF}, groups = {Polar codes}, keywords = {channel coding;Wyner-Ziv problem;argmax decision;channel coding;deterministic decisions;low-entropy bits;polar codes;Channel coding;Computers;Couplings;Decoding;Distortion;Source coding}, owner = {mattbloch} }

73. B. N. Vellambi, J. Kliewer, and M. Bloch, “Strong Coordination over Multi-hop Line Networks,” in ieee_itw, Jeju, Korea, Jul. 2015, pp. 192–196.

    We analyze the problem of strong coordination over a multi-hop line network where the node initiating the coordination is a terminal network node. We provide a characterization of the capacity region when the initiating node possesses unlimited local randomness and intermediate nodes operate under a functional regime. In this regime, next-hop messages are created only using common randomness and previous-hop incoming messages, i.e., local randomness at intermediate nodes is only used for generating actions.

    @inproceedings{Vellambi2015a, author = {Vellambi, Badri N. and Kliewer, Joerg and Bloch, Matthieu}, booktitle = ieee_itw, title = {Strong Coordination over Multi-hop Line Networks}, year = {2015}, address = {Jeju, Korea}, month = jul, pages = {192-196}, creationdate = {2015-05-25T00:00:00}, doi = {10.1109/ITWF.2015.7360761}, groups = {Coordination of networks}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, keywords = {radio networks;capacity region;hop incoming messages;intermediate nodes;multihop line networks;next-hop messages;terminal network node;Conferences;Electronic mail;Information theory;Random variables;Relays;Spread spectrum communication;Yttrium}, owner = {mattbloch} }

74. M. R. Bloch, “A Channel Resolvability Perspective on Stealth Communications,” in ieee_isit, Hong Kong, Jun. 2015, pp. 2535–2539.

    We analyze the problem of stealth communication and low probability of detection from the perspective of channel resolvability. We show that stealth communication over discrete memoryless channels and additive white Gaussian noise channels is possible without secret key as soon as the legitimate receiver’s channel is "better" than the warden’s channel, which generalizes previously known results to a much larger class of channels. The underlying technical problem that we solve is how to develop concentration inequalities for "low weight" sequences; the crux of our approach is to define modified "typical sets" that are amenable to concentration inequalities.

    @inproceedings{Bloch2015, author = {Bloch, Matthieu R}, booktitle = ieee_isit, title = {A Channel Resolvability Perspective on Stealth Communications}, year = {2015}, address = {Hong Kong}, month = jun, pages = {2535--2539}, creationdate = {2015-01-27T00:00:00}, doi = {10.1109/ISIT.2015.7282913}, groups = {Steganography and covert communications}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, keywords = {AWGN channels;Memoryless systems;Noise measurement;Random variables;Reliability theory}, owner = {mattbloch} }

75. R. A. Chou, M. R. Bloch, and J. Kliewer, “Polar Coding for Empirical and Strong Coordination via Distribution Approximation,” in ieee_isit, Hong Kong, Jun. 2015, pp. 1512–1516.

    We design low-complexity polar codes for empirical and strong coordination in two-node network. Our constructions hinge on the observation that polar codes may be used to approximate distribution; which we leverage to prove that nested polar codes achieve the capacity region of empirical coordination and strong coordination.

    @inproceedings{Chou2015, author = {Chou, R\'emi A. and Bloch, Matthieu R and Kliewer, Joerg}, booktitle = ieee_isit, title = {Polar Coding for Empirical and Strong Coordination via Distribution Approximation}, year = {2015}, address = {Hong Kong}, month = jun, pages = {1512--1516}, creationdate = {2015-01-27T00:00:00}, doi = {10.1109/ISIT.2015.7282708}, groups = {Polar codes, Coordination of networks}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, keywords = {Approximation methods;Convergence;Decoding;Encoding;Joints;Probability distribution;Random variables}, owner = {mattbloch} }

76. B. N. Vellambi, M. R. Bloch, R. A. Chou, and J. Kliewer, “Lossless and Lossy Source Compression with Near-Uniform Outputs: Is Common Randomness Always Required?,” in ieee_isit, Hong Kong, Jun. 2015, pp. 2171–2175.

    It is known that a sub-linear rate of source-independent random seed (common randomness) can enable the construction of lossless compression codes whose output is nearly uniform under the variational distance (Chou-Bloch-ISIT’13). This work uses finite-blocklength techniques to present an alternate proof that for near-uniform lossless compression, the seed length has to grow strictly larger than n, where n represents the blocklength of the lossless compression code. In the lossy setting, we show the surprising result that a seed is not required to make the encoder output nearly uniform.

    @inproceedings{Vellambi2015, author = {Vellambi, Badri N. and Bloch, Matthieu R. and Chou, R\'emi A. and Kliewer, Joerg}, booktitle = ieee_isit, title = {Lossless and Lossy Source Compression with Near-Uniform Outputs: Is Common Randomness Always Required?}, year = {2015}, address = {Hong Kong}, month = jun, pages = {2171--2175}, creationdate = {2015-01-27T00:00:00}, doi = {10.1109/ISIT.2015.7282840}, groups = {Randomness processing}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, keywords = {Decoding;Distortion;Encoding;Manganese;Random variables;Tin;Finite-blocklength techniques;Lossless coding;Rate-distortion;Source coding}, owner = {mattbloch} }

77. R. A. Chou and M. R. Bloch, “Polar Coding for the Broadcast Channel with Confidential Messages,” in ieee_itw, Jerusalem, Israel, Apr. 2015, pp. 1–5.

    We develop a low-complexity and secrecy capacity achieving polar coding scheme for the discrete memoryless wiretap channel. Our scheme extends previous work by using a nearly optimal amount of uniform randomness in the stochastic encoder, and avoiding assumptions regarding the symmetry or degraded nature of the channels. The price paid for these extensions is that the encoder and decoder are required to share a secret seed of negligible size. We also highlight a close conceptual connection between the proposed polar coding scheme and a random binning proof of the secrecy capacity.

    @inproceedings{Chou2014e, author = {Chou, R\'emi A. and Bloch, Matthieu R}, booktitle = ieee_itw, title = {Polar Coding for the Broadcast Channel with Confidential Messages}, year = {2015}, address = {Jerusalem, Israel}, month = apr, pages = {1-5}, creationdate = {2014-11-13T00:00:00}, doi = {10.1109/ITW.2015.7133142}, groups = {Wiretap codes, Polar codes}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, keywords = {broadcast channels;channel capacity;channel coding;decoding;broadcast channel;channel symmetry;confidential messages;decoder;discrete memoryless wiretap channel;polar coding scheme;secrecy capacity;stochastic encoder;Channel coding;Decoding;Entropy;Joints;Parity check codes;Stochastic processes}, owner = {mattbloch} }

78. M. R. Bloch and J. Kliewer, “Strong Coordination over a Three-Terminal Relay Network,” in ieee_itw, Hobart, Tasmania, Nov. 2014, pp. 646–650.

    @inproceedings{Bloch2014a, author = {Bloch, Matthieu R and Kliewer, Joerg}, booktitle = ieee_itw, title = {Strong Coordination over a Three-Terminal Relay Network}, year = {2014}, address = {Hobart, Tasmania}, month = nov, pages = {646--650}, creationdate = {2014-05-12T00:00:00}, doi = {10.1109/ITW.2014.6970911}, groups = {Coordination of networks}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, owner = {mattbloch} }

79. R. A. Chou, M. R. Bloch, and J. Kliewer, “Low-Complexity Channel Resolvability Codes for the Symmetric Multiple-Access Channel,” in ieee_itw, Hobart, Tasmania, Nov. 2014, pp. 466–470.

    @inproceedings{Chou2014, author = {Chou, R\'emi A. and Bloch, Matthieu R and Kliewer, J\"org}, booktitle = ieee_itw, title = {Low-Complexity Channel Resolvability Codes for the Symmetric Multiple-Access Channel}, year = {2014}, address = {Hobart, Tasmania}, month = nov, pages = {466--470}, creationdate = {2014-01-24T00:00:00}, doi = {10.1109/ITW.2014.6970875}, file = {:2014-Chou-ITW.pdf:PDF}, groups = {Randomness processing}, howpublished = {accepted to \emph{IEEE Information Theory Workhop}}, owner = {mattbloch} }

80. R. A. Chou and M. R. Bloch, “Uniform Distributed Source Coding for the Multiple Access Wiretap Channel,” in Proc. of IEEE Conference on Communications and Network Security, San Francisco, CA, Oct. 2014, pp. 127–132.

    @inproceedings{Chou2014c, author = {Chou, R\'emi A. and Bloch, Matthieu R}, booktitle = {Proc. of IEEE Conference on Communications and Network Security}, title = {Uniform Distributed Source Coding for the Multiple Access Wiretap Channel}, year = {2014}, address = {San Francisco, CA}, month = oct, pages = {127--132}, creationdate = {2014-07-07T00:00:00}, doi = {10.1109/CNS.2014.6997477}, groups = {Wiretap channels}, howpublished = {accepted at \emph{IEEE Conference on Communications and Network Security: Wokshop on Physical-layer Methods for Wireless Security} (invited)}, owner = {mattbloch} }

81. V. Y. F. Tan and M. R. Bloch, “Information spectrum approach to strong converse theorems for degraded wiretap channels,” in Proc. of 52nd Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2014, pp. 747–754.

    @inproceedings{Tan2014, author = {Tan, Vincent Y. F. and Bloch, Matthieu R.}, booktitle = {Proc. of 52nd Annual Allerton Conference on Communication, Control, and Computing}, title = {Information spectrum approach to strong converse theorems for degraded wiretap channels}, year = {2014}, address = {Monticello, IL}, month = sep, pages = {747-754}, creationdate = {2014-06-15T00:00:00}, doi = {10.1109/ALLERTON.2014.7028529}, eprint = {1406.6758}, groups = {Wiretap channels}, keywords = {Capacity planning;Error probability;Manganese;Measurement;Random variables;Security;Zinc}, owner = {mattbloch} }

82. N. Li et al., “Ultrafast Random Bit Generation Based on the Chaotic Dynamics of a Semiconductor Laser,” in Proc. of CLEO, San Jose, CA, Jun. 2014, pp. 1–2.

    We achieve physical random bit generation (RBG) that does not exceed the limit set by information theory via extracting 4 bits per sample or keep 55 bits per sample, leading to faster physical-based pseudo RBG.

    @inproceedings{Li2014, author = {Li, Nianqiang and Kim, Byungchil and Chizhevsky, V. N. and Locquet, Alexandre and Bloch, Matthieu and Citrin, David and Pan, Wei}, booktitle = {Proc. of CLEO}, title = {Ultrafast Random Bit Generation Based on the Chaotic Dynamics of a Semiconductor Laser}, year = {2014}, address = {San Jose, CA}, month = jun, pages = {1--2}, doi = {10.1364/CLEO_AT.2014.JTh2A.102}, groups = {Physical random number generation}, journal = {{CLEO}: 2014}, keywords = {Chaos; Semiconductor lasers; Instabilities and chaos} }

83. J. J. Boutros, V. Dedeoglu, and M. R. Bloch, “The Anti-Diversity Concept for Secure Communication on a Two-Link Compound Channel,” in Proc. of International Zurich Seminar on Communications, Zurich, Switzerland, Feb. 2014.

    @inproceedings{Boutros2013, author = {Boutros, Joseph J. and Dedeoglu, Volkan and Bloch, Matthieu R.}, booktitle = {Proc. of International Zurich Seminar on Communications}, title = {The Anti-Diversity Concept for Secure Communication on a Two-Link Compound Channel}, year = {2014}, address = {Zurich, Switzerland}, month = feb, creationdate = {2013-10-24T00:00:00}, doi = {10.3929/ethz-a-010095293}, groups = {Wiretap codes}, howpublished = {accepted to \emph{2014 International Zurich Seminar}}, owner = {mattbloch} }

84. R. A. Chou and M. R. Bloch, “Secret-Key Generation with Arbitrarily Varying Eavesdropper’s Channel,” in Proc. of Global Conference on Signal and Information Processing, Austin, TX, Sep. 2013, pp. 277–280.

    @inproceedings{Chou2013c, author = {Chou, R\'emi A. and Bloch, Matthieu R}, booktitle = {Proc. of Global Conference on Signal and Information Processing}, title = {Secret-Key Generation with Arbitrarily Varying Eavesdropper's Channel}, year = {2013}, address = {Austin, TX}, month = sep, pages = {277--280}, creationdate = {2013-10-21T00:00:00}, doi = {10.1109/GlobalSIP.2013.6736869}, groups = {Secret key agreement}, owner = {mattbloch} }

85. R. A. Chou and M. R. Bloch, “Data compression with nearly uniform ouput,” in ieee_isit, Istanbul, Turkey, Jul. 2013, pp. 1979–1983.

    For any lossless fixed-length compression scheme operating at the optimal coding rate, it is known that the encoder output is not uniform in variational distance, which yet might be desirable in some security schemes. In the case of independent and identically distributed (i.i.d.) sources, uniformity in divergence might be achieved if a uniformly distributed sequence, called seed, of length dn negligible compared to the message length n, is shared between the encoder and the decoder. We show that the optimal scaling of dn that jointly ensures an optimal coding rate and a uniform encoder output in divergence, is roughly on the order of sqrt(n). We also develop a near optimal achievability scheme using invertible extractors.

    @inproceedings{Chou2013, author = {Chou, R\'emi A. and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Data compression with nearly uniform ouput}, year = {2013}, address = {Istanbul, Turkey}, month = jul, pages = {1979-1983}, doi = {10.1109/ISIT.2013.6620572}, file = {:Users/mattbloch/Documents/Publications/2013-Chou-ISIT.pdf:PDF}, groups = {Randomness processing}, issn = {2157-8095} }

86. C. Ling, L. Luzzi, and M. R. Bloch, “Secret key generation from Gaussian sources using lattice hashing,” in ieee_isit, Istanbul, Turkey, Jul. 2013, pp. 2621–2625.

    @inproceedings{Lin2013, author = {Ling, Cong and Luzzi, Laura and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {Secret key generation from Gaussian sources using lattice hashing}, year = {2013}, address = {Istanbul, Turkey}, month = jul, pages = {2621-2625}, creationdate = {2013-01-21T00:00:00}, doi = {10.1109/ISIT.2013.6620701}, eprint = {1306.5299}, file = {:2010-Ling-ISIT.pdf:PDF}, groups = {Secret key agreement}, issn = {2157-8095}, keywords = {Encoding;Error probability;Lattices;Quantization (signal);Vectors;Zinc}, owner = {mattbloch}, quality = {1} }

87. M. R. Bloch and J. Kliewer, “Strong coordination over a line network,” in ieee_isit, Istanbul, Turkey, Jul. 2013, pp. 2319–2323.

    @inproceedings{Bloch2013a, author = {Bloch, Matthieu R. and Kliewer, Joerg}, booktitle = ieee_isit, title = {Strong coordination over a line network}, year = {2013}, address = {Istanbul, Turkey}, month = jul, pages = {2319-2323}, creationdate = {2013-01-21T00:00:00}, doi = {10.1109/ISIT.2013.6620640}, eprint = {1305.5992}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, issn = {2157-8095}, owner = {mattbloch}, quality = {1} }

88. A. J. Pierrot, R. A. Chou, and M. R. Bloch, “Experimental Aspects of Secret-Key Generation in Indoor Wireless Environments,” in Proc. of Signal IEEE 4th Workshop on Signal Processing Advances in Wireless Communications, Apr. 2013.

    This paper proposes a proof-of-principle design of a secret key generation system along with the desirable secrecy analysis to guarantee information-theoretic security. We conduct physical experiments on programmable radios in an indoor environment to analyze the statistical characteristics of the induced source that we employ to generate secret keys. We also provide a generic security analysis of the system, and we give an estimate of the achievable secret key rates for a target information leakage in the finite block-length regime.

    @inproceedings{Pierrot2013a, author = {Pierrot, Alexandre J. and Chou, R\'emi A. and Bloch, Matthieu R.}, booktitle = {Proc. of Signal IEEE 4th Workshop on Signal Processing Advances in Wireless Communications}, title = {Experimental Aspects of Secret-Key Generation in Indoor Wireless Environments}, year = {2013}, month = apr, creationdate = {2013-02-13T00:00:00}, doi = {10.1109/SPAWC.2013.6612134}, file = {:../Publications/2013-Pierrot-SPAWC.pdf:PDF}, groups = {Experimental systems}, howpublished = {accepted to \emph{IEEE Workshop on Signal Processing Advances in Wireless Communications}}, owner = {mattbloch} }

89. R. A. Chou, M. R. Bloch, and E. Abbe, “Polar Coding for Secret-Key Generation,” in ieee_itw, Sevilla, Spain, Apr. 2013, pp. 1–5.

    Practical implementations of secret-key generation are often based on sequential strategies, which handle reliability and secrecy in two successive steps, called reconciliation and privacy amplification. In this paper, we propose an alternative scheme based on polar coding that jointly deals with reliability and secrecy. We study a binary degraded symmetric discrete memoryless source model with uniform marginals, and assume one-way rate-limited public communication between two legitimate users. Specifically, we propose secret-key capacity-achieving polar coding schemes, in which users rely on pre-shared secret seed of negligible rate. For the model studied, we thus provide the first example of low-complexity secret-key capacity-achieving scheme that handles vector quantization, for rate-limited public communication. Furthermore, we provide examples for which no seed is required.

    @inproceedings{Chou2013a, author = {Chou, R\'emi A. and Bloch, Matthieu R. and Abbe, Emmanuel}, booktitle = ieee_itw, title = {Polar Coding for Secret-Key Generation}, year = {2013}, address = {Sevilla, Spain}, month = apr, pages = {1-5}, creationdate = {2013-03-07T00:00:00}, doi = {10.1109/ITW.2013.6691225}, eprint = {1305.4746}, groups = {Secret key agreement, Polar codes}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, owner = {mattbloch} }

90. A. J. Pierrot and M. R. Bloch, “Joint Channel Intrinsic Randomness and Channel Resolvability,” in ieee_itw, Sevilla, Spain, Apr. 2013, pp. 1–5.

    This paper investigates the separation of channel intrinsic randomness and channel resolvability. We derive joint exponents, which are compared to the tandem exponents obtained with a separate approach. We prove at once, in a simple manner, achievability results for channel intrinsic randomness, random number generation, and channel resolvability. We also provide converse results in different special settings.

    @inproceedings{Pierrot2013b, author = {Pierrot, Alexandre J. and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {Joint Channel Intrinsic Randomness and Channel Resolvability}, year = {2013}, address = {Sevilla, Spain}, month = apr, pages = {1-5}, creationdate = {2013-04-17T00:00:00}, doi = {10.1109/ITW.2013.6691334}, file = {:2013-Pierrot-ITW.pdf:PDF}, howpublished = {accepted to \emph{IEEE Information Theory Workshop}}, owner = {mbloch} }

91. F. Renna et al., “Low-power secret key agreement over OFDM,” in Proc. of the 2nd ACM workshop on Hot topics on wireless network security and privacy, Budapest, Hungary, Apr. 2013, pp. 43–48.

    Information-theoretic secret-key agreement is perhaps the most practically feasible mechanism that provides unconditional security at the physical layer to date. In this paper, we consider the problem of secret-key agreement by sharing randomness at low power over an orthogonal frequency division multiplexing (OFDM) link, in the presence of an eavesdropper. The low power assumption greatly simplifies the design of the randomness sharing scheme, even in a fading channel scenario. We assess the performance of the proposed system in terms of secrecy key rate and show that a practical approach to key sharing is obtained by using low-density parity check (LDPC) codes for information reconciliation. Numerical results confirm the merits of the proposed approach as a feasible and practical solution. Moreover, the outage formulation allows to implement secret-key agreement even when only statistical knowledge of the eavesdropper channel is available.

    @inproceedings{Renna2013, author = {Renna, Francesco and Laurenti, Nicola and Tomasin, Stefano and Baldi, Marco and Maturo, Nicola and Bianchi, Marco and Chiaraluce, Franco and Bloch, Matthieu}, booktitle = {Proc. of the 2nd ACM workshop on Hot topics on wireless network security and privacy}, title = {Low-power secret key agreement over {OFDM}}, year = {2013}, address = {Budapest, Hungary}, month = apr, pages = {43--48}, creationdate = {2013-01-25T00:00:00}, doi = {10.1145/2463183.2463194}, file = {:2013-Renna-HotWiSec.pdf:PDF}, groups = {Secret key agreement}, howpublished = {accepted to the \emph{Second ACM Workshop on Hot Topics on Wireless Network Security and Privacy}}, owner = {mattbloch}, quality = {1} }

92. M. R. Bloch, L. Luzzi, and J. Kliewer, “Strong Coordination with Polar Codes,” in Proc. of 50th Allerton Conference on Communication, Control, and Computing, Monticello, IL, Oct. 2012, pp. 565–571.

    In this paper, we design explicit codes for strong coordination in two-node networks. Specifically, we consider a two-node network in which the action imposed by nature is binary and uniform, and the action to coordinate is obtained via a symmetric discrete memoryless channel. By observing that polar codes are useful for channel resolvability over binary symmetric channels, we prove that nested polar codes achieve a subset of the strong coordination capacity region, and therefore provide a constructive and low complexity solution for strong coordination.

    @inproceedings{Bloch2012a, author = {Bloch, Matthieu R. and Luzzi, Laura and Kliewer, Joerg}, booktitle = {Proc. of 50th Allerton Conference on Communication, Control, and Computing}, title = {{S}trong Coordination with Polar Codes}, year = {2012}, address = {Monticello, IL}, month = oct, pages = {565-571}, arxiv = {1210.2159}, creationdate = {2012-07-15T00:00:00}, doi = {10.1109/Allerton.2012.6483268}, file = {:2012-Bloch-Allerton.pdf:PDF}, groups = {Coordination of networks, Polar codes}, howpublished = {accepted to \emph{50th Allerton Conference on Communication, Control, and Computing}}, owner = {mattbloch} }

93. A. J. Pierrot and M. R. Bloch, “LDPC-based coded cooperative jamming codes,” in ieee_itw, Lausanne, Switzerland, Sep. 2012, pp. 462–466.

    We present a practical coded cooperative jamming scheme for the problem of secure communications over the two-way wiretap channel. We design low-density parity-check (LDPC) based codes whose codewords interfere at the eavesdropper’s terminal, thus providing secrecy. We show that our scheme can guarantee low information leakage rate, and we assess its precise performance for classical and spatially coupled LDPC codes.

    @inproceedings{Pierrot2012, author = {Pierrot, Alexandre J. and Bloch, Matthieu R.}, booktitle = ieee_itw, title = {{LDPC}-based coded cooperative jamming codes}, year = {2012}, address = {Lausanne, Switzerland}, month = sep, pages = {462--466}, creationdate = {2012-03-14T00:00:00}, doi = {10.1109/ITW.2012.6404716}, file = {:2012-Pierrot-ITW.pdf:PDF}, groups = {Wiretap codes}, howpublished = {accepted at \emph{IEEE Information Theory Workshop}}, owner = {mattbloch} }

94. M. R. Bloch and J. Kliewer, “On secure communication with constrained randomization,” in ieee_isit, Cambridge, MA, Jul. 2012, pp. 1172–1176.

    In this paper, we investigate how constraints on the randomization in the encoding process affect the secrecy rates achievable over wiretap channels. In particular, we characterize the secrecy capacity with a rate-limited local source of randomness and a less capable eavesdropper’s channel, which shows that limited rate incurs a secrecy rate penalty but does not preclude secrecy. We also show that secure communication is possible when randomizing with a non-uniform source of randomness, which suggests the possibility of designing robust coding schemes.

    @inproceedings{Bloch2012, author = {Bloch, Matthieu R. and Kliewer, Joerg}, booktitle = ieee_isit, title = {On secure communication with constrained randomization}, year = {2012}, address = {Cambridge, MA}, month = jul, pages = {1172--1176}, creationdate = {2012-08-30T00:00:00}, doi = {10.1109/ISIT.2012.6283039}, file = {:2012-Bloch-ISIT.pdf:PDF}, groups = {Wiretap channels}, owner = {mattbloch} }

95. R. A. Chou and M. R. Bloch, “One-way rate-limited sequential key-distillation,” in ieee_isit, Cambridge, MA, Jul. 2012, pp. 1777–1781.

    We study the problem of key-distillation for a source model, with a one-way and rate-limited public communication between two legitimate users. Although, the secret-key capacity is already known, we provide an alternative achievability scheme, that directly translates into practical designs. We consider a sequential key-distillation strategy, which consists of a reconciliation phase followed by a privacy amplification phase performed with extractors. We determine the reconciliation capacity and show that, for a degraded source, such a sequential strategy leads to an optimal key-distillation strategy that achieves the secret-key capacity. We illustrate our results in the case of a binary source model.

    @inproceedings{Chou2012, author = {Chou, R\'emi A. and Bloch, Matthieu R.}, booktitle = ieee_isit, title = {One-way rate-limited sequential key-distillation}, year = {2012}, address = {Cambridge, MA}, month = jul, pages = {1777--1781}, creationdate = {2012-08-30T00:00:00}, doi = {10.1109/ISIT.2012.6283584}, file = {:2012-Chou-ISIT.pdf:PDF}, groups = {Secret key agreement}, owner = {mattbloch} }

96. M. R. Bloch, “Achieving Secrecy: capacity vs. Resolvability,” in ieee_isit, Saint Petersburg, Russia, Aug. 2011, pp. 632–636.

    @inproceedings{Bloch2011a, author = {Bloch, Matthieu R.}, booktitle = ieee_isit, title = {{A}chieving Secrecy: capacity vs. Resolvability}, year = {2011}, address = {Saint Petersburg, Russia}, month = aug, pages = {632--636}, creationdate = {2011-02-22T00:00:00}, doi = {10.1109/ISIT.2011.6034207}, file = {:2011-Bloch-ISIT.pdf:PDF}, groups = {Wiretap channels}, howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}, owner = {mattbloch} }

97. F. Renna, M. Bloch, and N. Laurenti, “Semi-Blind Key-Agreement over MIMO Fading Channels,” in Proc. of IEEE International Conference on Communications, Kyoto, Japan, Jun. 2011, pp. 1–6.

    We analyze the fundamental limits of secret-<span class=’snippet’>key</span> <span class=’snippet’>agreement</span> <span class=’snippet’>over</span> <span class=’snippet’>MIMO</span> quasi-static <span class=’snippet’>fading</span> <span class=’snippet’>channels</span>. In the low-power and high-power regimes, we establish closed-form expressions for secret-<span class=’snippet’>key</span> capacity. In the low-power regime, we show that the optimal signaling strategy is independent of the eavesdropper’s <span class=’snippet’>fading</span> realization. The low-power secret-<span class=’snippet’>key</span> capacity is achieved by transmitting along the direction corresponding to the maximal eigenvalue of the legitimate <span class=’snippet’>channel</span>. By combining this signaling strategy with reconciliation and privacy amplification, one obtains a <span class=’snippet’>semi</span>-<span class=’snippet’>blind</span> <span class=’snippet’>key</span>-distillation strategy in which the knowledge of the eavesdropper’s <span class=’snippet’>fading</span> is required for privacy amplification alone.

    @inproceedings{Renna2011, author = {Renna, Francesco and Bloch, Matthieu and Laurenti, Nicola}, booktitle = {Proc. of IEEE International Conference on Communications}, title = {{S}emi-Blind Key-Agreement over {MIMO} Fading Channels}, year = {2011}, address = {Kyoto, Japan}, month = jun, pages = {1--6}, creationdate = {2011-08-17T00:00:00}, doi = {10.1109/icc.2011.5963438}, file = {:2011-Renna-ICC.pdf:PDF}, groups = {Secret key agreement}, owner = {mattbloch} }

98. L. Luzzi and M. R. Bloch, “Capacity-based random codes cannot achieve strong secrecy over symmetric wiretap channels,” in Proc. of the 5th International ICST Conference on Performance Evaluation Methodologies and Tools, Cachan, France, May 2011, pp. 641–647.

    @inproceedings{Luzzi2011, author = {Luzzi, Laura and Bloch, Matthieu R.}, booktitle = {Proc. of the 5th International ICST Conference on Performance Evaluation Methodologies and Tools}, title = {{C}apacity-based random codes cannot achieve strong secrecy over symmetric wiretap channels}, year = {2011}, address = {Cachan, France}, month = may, note = {(invited)}, pages = {641--647}, creationdate = {2011-04-16T00:00:00}, groups = {Wiretap channels}, howpublished = {accepted at \emph{SecureNets 2011}}, owner = {mattbloch} }

99. F. Renna, M. Bloch, and N. Laurenti, “Semi-Blind Key-Agreement over MIMO Quasi-Static Channels,” in Proc. of 2011 NEWCOM/COST Joint Workshop, Paris, France, Mar. 2011, pp. 1–6.

    @inproceedings{Renna2011a, author = {Renna, Francesco and Bloch, Matthieu and Laurenti, Nicola}, booktitle = {Proc. of 2011 NEWCOM/COST Joint Workshop}, title = {{S}emi-Blind Key-Agreement over {MIMO} Quasi-Static Channels}, year = {2011}, address = {Paris, France}, month = mar, pages = {1--6}, creationdate = {2011-01-17T00:00:00}, groups = {Secret key agreement}, howpublished = {accepted to \emph{NEWCOM++ / COST 2100 Joint workshop}}, owner = {mattbloch} }

100. A. T. Suresh, A. Subramanian, A. Thangaraj, M. Bloch, and S. McLaughlin, “Strong Secrecy for Erasure Wiretap Channels,” in ieee_itw, Dublin, Ireland, Sep. 2010.

     @inproceedings{Suresh2010, author = {Suresh, Ananda T. and Subramanian, Arunkumar and Thangaraj, Andrew and Bloch, Matthieu and McLaughlin, Steven}, booktitle = ieee_itw, title = {{S}trong Secrecy for Erasure Wiretap Channels}, year = {2010}, address = {Dublin, Ireland}, month = sep, citeseerurl = {1004.5540}, creationdate = {2010-03-30T00:00:00}, doi = {10.1109/CIG.2010.5592770}, groups = {Wiretap codes}, howpublished = {accepted at the IEEE Information Theory Workshop, Dublin}, owner = {matthieu} }

101. A. Subramanian, A. T. Suresh, A. Thangaraj, M. Bloch, and S. McLaughlin, “Strong and Weak Secrecy in Wiretap Channels,” in Proc. of 6th International Symposium on Turbo Codes and Iterative Information Processing, Brest, France, Sep. 2010, pp. 30–34.

     In the wiretap channel model, symbols transmitted through a main channel to a legitimate receiver are observed by an eavesdropper across a wiretapper’s channel. The goal of coding for wiretap channels is to facilitate error-free decoding across the main channel, while ensuring zero information transfer across the wiretapper’s channel. Strong secrecy requires the total information transfer to the eavesdropper to tend to zero, while weak secrecy requires the per-symbol information transfer to go to zero. In this paper, we will consider coding methods for binary wiretap channels with a noiseless main channel and a BEC or a BSC wiretapper’s channel. We will provide conditions and codes that achieve strong and weak secrecy for the BEC case. For the BSC case, we will discuss some existing coding methods and develop additional criteria for secrecy.

     @inproceedings{Subramanian2010, author = {Subramanian, Arunkumar and Suresh, Ananda T. and Thangaraj, Andrew and Bloch, Matthieu and McLaughlin, Steven}, booktitle = {Proc. of 6th International Symposium on Turbo Codes and Iterative Information Processing}, title = {{S}trong and Weak Secrecy in Wiretap Channels}, year = {2010}, address = {Brest, France}, month = sep, note = {(invited)}, pages = {30 - 34}, creationdate = {2010-07-11T00:00:00}, doi = {10.1109/ISTC.2010.5613867}, groups = {Wiretap codes}, howpublished = {accepted at 6th International Symposium on Turbo Codes and Iterative Information Processing}, owner = {matthieu} }

102. M. Bloch, “Channel Intrinsic Randomness,” in ieee_isit, Austin, TX, Jun. 2010, pp. 2607–2611.

     @inproceedings{Bloch2010b, author = {Bloch, Matthieu}, booktitle = ieee_isit, title = {{C}hannel Intrinsic Randomness}, year = {2010}, address = {Austin, TX}, month = jun, pages = {2607--2611}, creationdate = {2009-12-30T00:00:00}, doi = {10.1109/ISIT.2010.5513744}, groups = {Randomness processing}, howpublished = {accepted at IEEE International Symposium on Information Theory 2010}, owner = {matthieu} }

103. J. P. Vilela, M. Bloch, J. Barros, and S. W. McLaughlin, “Friendly Jamming for Wireless Secrecy,” in Proc. of IEEE International Conference on Communications, Cape Town, South Africa, May 2010, pp. 1550–3607.

     @inproceedings{Vilela2010, author = {Vilela, Joao Paulo and Bloch, Matthieu and Barros, Joao and McLaughlin, Steven W.}, booktitle = {Proc. of IEEE International Conference on Communications}, title = {{F}riendly Jamming for Wireless Secrecy}, year = {2010}, address = {Cape Town, South Africa}, month = may, pages = {1550-3607}, creationdate = {2008-12-19T00:00:00}, doi = {10.1109/ICC.2010.5502606}, groups = {Wiretap channels}, howpublished = {To appear in proceeding of IEEE International Conference on Communications}, owner = {matthieu} }

104. M. Rodrigues, A. Somekh-Baruch, and M. Bloch, “On Gaussian Wiretap Channels with Arbitrary Inputs,” in Proc. of European Wireless, Lucca, Italy, Apr. 2010, pp. 774–781.

     This paper investigates the secrecy capacity of the Gaussian wiretap channel with M-PAM inputs, by capitalizing on the relationship between mutual information and minimum mean squared error (MMSE). In particular, we establish optimality conditions for both the M-PAM input power and the M-PAM input distribution, which we specialize to the asymptotic low-power and high-power regimes. By using the properties of the MMSE to establish sufficient conditions for the uniqueness of the solution of some of the underlying non-convex optimization problems, we also propose efficient algorithms to compute the optimal solutions. Interestingly, we show that with M-PAM inputs it is sub-optimal to use all the available power for some range of parameters - this is in sharp contrast to standard Gaussian channels. We also extend the results to the parallel Gaussian wiretap channel with M-PAM inputs. We put forth a mercury-waterfilling interpretation of the optimal power allocation procedure for parallel Gaussian wiretap channels which generalizes the conventional mercury-waterfilling interpretation for parallel Gaussian channels, with the mercury level amending the base level to account for both the non-Gaussianess of the input and the secrecy constraint.

     @inproceedings{Rodrigues2010, author = {Rodrigues, Miguel and Somekh-Baruch, Anelia and Bloch, Matthieu}, booktitle = {Proc. of European Wireless}, title = {{O}n {G}aussian Wiretap Channels with Arbitrary Inputs}, year = {2010}, address = {Lucca, Italy}, month = apr, pages = {774--781}, creationdate = {2009-11-10T00:00:00}, doi = {10.1109/EW.2010.5483475}, file = {:2010-Rodrigues-EW.pdf:PDF}, groups = {Wiretap channels}, howpublished = {accepted at European Wireless 2010}, keywords = {Gaussian wiretap channels;M-PAM inputs;minimum mean squared error;mutual information;mean square error methods;radio networks;telecommunication channels;}, owner = {matthieu} }

105. E. MolavianJazi, M. Bloch, and J. N. Laneman, “Arbitrary Jamming Can Preclude Secure Communications,” in Proc. 47th Annual Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2009, pp. 1069–1075.

     @inproceedings{MolavianJazi2009, author = {MolavianJazi, Ebrahim and Bloch, Matthieu and Laneman, J. Nicholas}, booktitle = {Proc. 47th Annual Allerton Conference on Communication, Control, and Computing}, title = {{A}rbitrary Jamming Can Preclude Secure Communications}, year = {2009}, address = {Monticello, IL}, month = sep, pages = {1069--1075}, creationdate = {2009-07-09T00:00:00}, doi = {10.1109/ALLERTON.2009.5394876}, file = {:2009-MolavianJazi-Allerton-Arbitrary Jamming Can Preclude Secure Communication.pdf:PDF}, groups = {Adversarial models}, howpublished = {accepted at 47th Allerton Conference on Communications, Control, and Computing}, owner = {matthieu} }

106. M. Bloch, “Channel Scrambling for Secrecy,” in ieee_isit, Seoul, Korea, Jul. 2009, pp. 2452–2456.

     @inproceedings{Bloch2009a, author = {Bloch, Matthieu}, booktitle = ieee_isit, title = {{C}hannel Scrambling for Secrecy}, year = {2009}, address = {Seoul, Korea}, month = jul, pages = {2452--2456}, creationdate = {2008-12-19T00:00:00}, doi = {10.1109/ISIT.2009.5206058}, file = {:2009-Bloch-ISIT.pdf:PDF;:/Users/mbloch/Downloads/2009-Bloch-ISIT-Channel Scrambling for Secrecy.pdf:PDF}, groups = {Wiretap channels}, howpublished = {accepted at the 2009 IEEE International Symposium on Information Theory}, owner = {matthieu} }

107. B. P. Dunn, M. Bloch, and J. N. Laneman, “Secure bits through queues,” in ieee_itw, Volos, Greece, Jun. 2009, pp. 37–41.

     We investigate the idea of providing information-theoretic security at the network and data link layers by exploiting the timing information resulting from queuing of packets between a source, an intended receiver, and other users in a network. Specifically, we consider the secure transmission of messages by encoding them onto the interarrival timing of packets that enter parallel queues. By leveraging recent results on the secrecy capacity of arbitrary wiretap channels, achievable secrecy rates are obtained. We also show that equivalent secrecy rates can be achieved using a deterministic encoding strategy, which provides an example contrasting the fact that for many memoryless channels a stochastic encoder is required to achieve non-zero secrecy rates.

     @inproceedings{Dunn2009, author = {Dunn, Brian P. and Bloch, Matthieu and Laneman, J. Nicholas}, booktitle = ieee_itw, title = {{S}ecure bits through queues}, year = {2009}, address = {Volos, Greece}, month = jun, pages = {37--41}, creationdate = {2009-07-09T00:00:00}, doi = {10.1109/ITWNIT.2009.5158537}, file = {:2009-Dunn-ITW.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

108. M. Bloch and J. N. Laneman, “Information-Spectrum Methods for Information-Theoretic Security,” in Proc. Information Theory and Applications Workshop, San Diego, CA, Feb. 2009, pp. 23–28.

     @inproceedings{Bloch2009, author = {Bloch, Matthieu and Laneman, J. Nicholas}, booktitle = {Proc. Information Theory and Applications Workshop}, title = {{I}nformation-Spectrum Methods for Information-Theoretic Security}, year = {2009}, address = {San Diego, CA}, month = feb, note = {(invited)}, pages = {23--28}, creationdate = {2008-11-19T00:00:00}, doi = {10.1109/ITA.2009.5044918}, file = {:2009-Bloch-ITA.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

109. M. Bloch and J. N. Laneman, “On the Secrecy Capacity of Arbitrary Wiretap Channels,” in Proceedings of 46th Allerton Conference on Communication, Control, and Computing, Monticello, IL, Sep. 2008, pp. 818–825.

     @inproceedings{Bloch2008e, author = {Bloch, Matthieu and Laneman, J. Nicholas}, booktitle = {Proceedings of 46th Allerton Conference on Communication, Control, and Computing}, title = {{O}n the Secrecy Capacity of Arbitrary Wiretap Channels}, year = {2008}, address = {Monticello, IL}, month = sep, pages = {818--825}, creationdate = {2008-08-04T00:00:00}, doi = {10.1109/ALLERTON.2008.4797642}, file = {:2008-Bloch-Allerton.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

110. J. Barros and M. Bloch, “Strong Secrecy for Wireless Channels,” in Information Theoretic Security, Calgary, Canada, Aug. 2008, pp. 40–53.

     @inproceedings{Barros2008, author = {Barros, Jo{\~a}o and Bloch, Matthieu}, booktitle = {Information Theoretic Security}, title = {{S}trong Secrecy for Wireless Channels}, year = {2008}, address = {Calgary, Canada}, month = aug, note = {(invited)}, pages = {40-53}, publisher = {Springer Berlin / Heidelberg}, series = {Lecture Notes in Computer Science}, creationdate = {2008-06-20T00:00:00}, doi = {10.1007/978-3-540-85093-9_5}, groups = {Wiretap channels, Wireless security}, owner = {matthieu} }

111. M. Bloch and A. Thangaraj, “Confidential Messages to a Cooperative Relay,” in ieee_itw, Porto, Portugal, May 2008, pp. 154–158.

     @inproceedings{Bloch2008b, author = {Bloch, Matthieu and Thangaraj, Andrew}, booktitle = ieee_itw, title = {{C}onfidential Messages to a Cooperative Relay}, year = {2008}, address = {Porto, Portugal}, month = may, pages = {154--158}, creationdate = {2007-12-16T00:00:00}, doi = {10.1109/ITW.2008.4578641}, file = {:2008-Bloch-ITW.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

112. S. Fossier et al., “Quantum Key Distribution over 25 km Using a Fiber Setup Based on Continuous Variables,” in Proc. of CLEO/QELS, San Jose, CA, May 2008, pp. 1–2.

     @inproceedings{Fossier2008, author = {Fossier, Simon and Lodewyck, J. and Diamanti, E. and Bloch, M. and Debuisschert, T. and Tualle-Brouri, R. and Grangier, P.}, booktitle = {Proc. of CLEO/QELS}, title = {{Q}uantum Key Distribution over 25 km Using a Fiber Setup Based on Continuous Variables}, year = {2008}, address = {San Jose, CA}, month = may, pages = {1--2}, comment = {http://www.opticsinfobase.org/abstract.cfm?URI=QELS-2008-QWE2}, creationdate = {2008-04-22T00:00:00}, doi = {10.1109/QELS.2008.4553262}, file = {:2008-Fossier-CLEO.pdf:PDF}, groups = {Quantum information science}, owner = {matthieu} }

113. M. Bloch, R. Narasimha, and S. W. McLaughlin, “Client-Server Architecture Design based on Wiretap Codes,” in Proc of the 2008 International Zurich Seminar on Communications, Zurich, Switzerland, Mar. 2008, pp. 44–47.

     We propose a method to design attack-resistant client-server architectures based on wiretap codes. We show that by appropriately spreading messages across different packets a client-server architecture under active attack can be modeled as a passive wiretap channel. The secrecy capacity of this equivalent wiretap channel is then used as an optimization metric to limit the impact of the attacks.

     @inproceedings{Bloch2008, author = {Bloch, Matthieu and Narasimha, Rajesh and McLaughlin, Steven W.}, booktitle = {Proc of the 2008 International Zurich Seminar on Communications}, title = {{C}lient-Server Architecture Design based on Wiretap Codes}, year = {2008}, address = {Zurich, Switzerland}, month = mar, pages = {44--47}, creationdate = {2007-12-16T00:00:00}, doi = {10.1109/IZS.2008.4497272}, file = {:2008-Bloch-IZS.pdf:PDF}, groups = {Wiretap channels}, owner = {matthieu} }

114. E. Diamanti et al., “Implementation of an all-fiber continuous variables quantum key distribution system,” in International Conference on Quantum Information Processing and Communication, Barcelona, Spain, Oct. 2007.

     @inproceedings{Diamanti2007, author = {Diamanti, Eleni and Fossier, Simon and Lodewyck, J\'erome and Bloch, Matthieu and Garcia-Patron, Raul and Karpov, Evgueni and Debuisschert, Thierry and Cerf, Nicolas J. and Tualle-Brouri, Rosa and McLaughlin, Steven W. and Grangier, Philippe}, booktitle = {International Conference on Quantum Information Processing and Communication}, title = {{I}mplementation of an all-fiber continuous variables quantum key distribution system}, year = {2007}, address = {Barcelona, Spain}, month = oct, creationdate = {2008-01-14T00:00:00}, groups = {Quantum information science}, owner = {matthieu} }

115. M. Bloch, J. Barros, and S. W. McLaughlin, “Practical Information-Theoretic Commitment,” in Proc. 45th Allerton Conference on Communication Control and Computing, Monticello, IL, Sep. 2007, pp. 1035–1039.

     @inproceedings{Bloch2007d, author = {Bloch, Matthieu and Barros, Joao and McLaughlin, Steven W.}, booktitle = {Proc. 45th Allerton Conference on Communication Control and Computing}, title = {{P}ractical Information-Theoretic Commitment}, year = {2007}, address = {Monticello, IL}, month = sep, pages = {1035--1039}, comment = {Cited 1 time 1. A Practical Scheme for String Commitment based on the Gaussian Channel, Frederique Oggier and Kirill Morozo , IEEE Information Theory Workshop, 2008}, creationdate = {2006-11-15T00:00:00}, groups = {Cryptographic primitives}, owner = {Matthieu} }

116. J. Lodewyck et al., “Quantum key distribution device with coherent states,” in Proc. of SPIE Optics East, Boston, MA, USA, Sep. 2007, vol. 6780, pp. 67800Z/1–14.

     @inproceedings{Lodewyck2007b, author = {Lodewyck, J. and Bloch, M. and Garcia-Patron, R. and Fossier, S. and Karpov, E. and Diamanti, E. and Debuisschert, T. and Cerf, N. J. and Tualle-Brouri, R. and McLaughlin, S. W. and Grangier, P.}, booktitle = {Proc. of SPIE Optics East}, title = {{Q}uantum key distribution device with coherent states}, year = {2007}, address = {Boston, MA, USA}, month = sep, note = {(invited)}, pages = {67800Z/1-14}, volume = {6780}, creationdate = {2007-10-01T00:00:00}, doi = {10.1117/12.736855}, file = {:2007-Lodewyck-SPIEeast.pdf:PDF}, groups = {Quantum information science}, owner = {matthieu} }

117. J. Lodewyck et al., “Distribution quantique de clé a 25 km au moyen d’un dispositif fibré utilisant des variables continues,” in 10eme Colloque sur les Lasers et l’Optique Quantique, Grenoble, France, Jul. 2007.

     @inproceedings{Lodewyck2007a, author = {Lodewyck, J\'erome and Bloch, Matthieu and Fossier, Simon and Diamanti, Eleni and Debuisschert, Thierry and Tualle-Brouri, Rosa and Grangier, Philippe}, booktitle = {10eme Colloque sur les Lasers et l'Optique Quantique}, title = {{D}istribution quantique de cl\'e a 25 km au moyen d'un dispositif fibr\'e utilisant des variables continues}, year = {2007}, address = {Grenoble, France}, month = jul, creationdate = {2007-10-01T00:00:00}, doi = {10.1051/anphys:2008033}, file = {:2007-Lodewyck-COLOQ.pdf:PDF}, groups = {Quantum information science}, owner = {matthieu} }

118. S. Kaimalettu, A. Thangaraj, M. Bloch, and S. W. McLaughlin, “Constellation Shaping using LDPC Codes,” in ieee_isit, Nice, France, Jun. 2007, pp. 2366–2370.

     It is well-known that a Gaussian source distribution is required for maximum information transfer across a Gaussian channel. In a coded modulation system an equiprobable symbol constellation loses at most 1.53 dB when compared to a Gaussian source. To bridge this shaping gap, a code can be used to make the source distribution more Gaussian over an expanded constellation that results in lower average transmitted energy. Trellis shaping uses convolutional codes and the Viterbi algorithm for minimizing the transmitted energy. In this work, we propose trellis shaping using low-density parity-check codes as the shaping codes. We show that the 2-state min-sum algorithm over the Tanner graph can be used to efficiently implement the energy minimization. This is a more than 4-fold decrease in complexity over 4-state convolutional code-based trellis shaping. Using one of our simple shaping codes, we have observed a shaping gain of up to 0.65 dB (with CER = 1.26; PAPR = 3.86) (as compared with CER=1.41 and PAPR=3.3 for convolutional-code based trellis shaping with similar shaping gain). This encouraging result indicates that more complex LDPC-based approaches will do even better. We also present simulation results to show that constellation shaping provides similar gains over wireless channels under slow fading conditions.

     @inproceedings{Kaimalettu2007, author = {Kaimalettu, Sunil and Thangaraj, Andrew and Bloch, Matthieu and McLaughlin, Steven W.}, booktitle = ieee_isit, title = {{C}onstellation Shaping using {LDPC} Codes}, year = {2007}, address = {Nice, France}, month = jun, pages = {2366--2370}, creationdate = {2007-04-03T00:00:00}, doi = {10.1109/ISIT.2007.4557573}, file = {:Users/matthieu/Documents/publications/2007-Kaimalettu-ISIT.pdf:PDF;2007-Kaimalettu-ISIT.pdf:2007-Kaimalettu-ISIT.pdf:PDF}, keywords = {LDPC}, owner = {matthieu} }

119. M. Bloch, J. Barros, M. R. D. Rodrigues, and S. W. McLaughlin, “Information Theoretic Security for Wireless Channels - Theory and Practice,” in Proc. 2007 Information Theory and Application Workshop, San Diego, CA, USA, Feb. 2007.

     @inproceedings{Bloch2007c, author = {Bloch, Matthieu and Barros, Jo{\~a}o and Rodrigues, Miguel R. D. and McLaughlin, Steven W.}, booktitle = {Proc. 2007 Information Theory and Application Workshop}, title = {{I}nformation Theoretic Security for Wireless Channels - Theory and Practice}, year = {2007}, address = {San Diego, CA, USA}, month = feb, note = {(invited)}, comment = {Cited 2 times 1. On the Secrecy Capabilities of ITU Channels, Ye, Chunxuan; Reznik, Alex; Sternburg, Gregory; Shah, Yogendra; Vehicular Technology Conference, 2007 2. Secure Nested Codes for Type II Wiretap Channels, Liu, R.; Liand, Y.; Poor, H. V. & Spasojevi\'c, P., 2007 IEEE Information Theory Workshop, 2007 3. Securing Media Hotspots, Biri, A; Ahmad, A; Affifi H, Wireless Telecomunications Symposium, 2008. WTS 2008}, creationdate = {2007-07-17T00:00:00}, groups = {Wireless security}, owner = {Matthieu} }

120. M. Bloch, J. Barros, M. R. D. Rodrigues, and S. W. McLaughlin, “LDPC-based Secure Wireless Communication with Imperfect Knowledge of the Eavesdropper’s Channels,” in ieee_itw, Chengdu, China, Oct. 2006, pp. 155–159.

     @inproceedings{Bloch2006c, author = {Bloch, Matthieu and Barros, Jo{\~a}o and Rodrigues, Miguel R. D. and McLaughlin, Steven W.}, booktitle = ieee_itw, title = {{LDPC}-based Secure Wireless Communication with Imperfect Knowledge of the Eavesdropper's Channels}, year = {2006}, address = {Chengdu, China}, month = oct, pages = {155-159}, creationdate = {2006-11-15T00:00:00}, doi = {10.1109/ITW2.2006.323778}, file = {:Users/matthieu/Documents/publications/2006-Bloch-ITW-China.pdf:PDF;2006-Bloch-ITW(2).pdf:2006-Bloch-ITW(2).pdf:PDF}, groups = {Wireless security}, owner = {Matthieu} }

121. M. Bloch, J. Barros, M. R. D. Rodrigues, and S. W. McLaughlin, “An Opportunistic Physical-Layer Approach to Secure Wireless Communications,” in Proc. 44th Allerton Conference on Communication Control and Computing, Monticello, IL, Sep. 2006, pp. 849–854.

     @inproceedings{Bloch2006b, author = {Bloch, Matthieu and Barros, Jo{\~a}o and Rodrigues, Miguel R. D. and McLaughlin, Steven W.}, booktitle = {Proc. 44th Allerton Conference on Communication Control and Computing}, title = {{A}n Opportunistic Physical-Layer Approach to Secure Wireless Communications}, year = {2006}, address = {Monticello, IL}, month = sep, pages = {849--854}, comment = {Cited 1 time 1. Secure Communication over Fading Channels , Liang, Y.; Poor, H. V. & (Shitz), S. S., 2008 (CHECK IEEE TRANS IT)}, creationdate = {2007-08-10T00:00:00}, file = {2006-Bloch-Allerton.pdf:2006-Bloch-Allerton.pdf:PDF}, groups = {Wireless security}, owner = {matthieu} }

122. S. Donnet, A. Thangaraj, M. Bloch, J. Cussey, J.-M. Merolla, and L. Larger, “Cryptanalysis of Y-00 under Heterodyne Measurement and Fast Correlation Attack,” in Proc. European Conference on Optical Communication, Cannes, France, Sep. 2006, pp. 1–2.

     @inproceedings{Donnet2006a, author = {Donnet, St\'ephane and Thangaraj, Andrew and Bloch, Matthieu and Cussey, Johann and Merolla, Jean-Marc and Larger, Laurent}, booktitle = {Proc. European Conference on Optical Communication}, title = {{C}ryptanalysis of {Y}-00 under Heterodyne Measurement and Fast Correlation Attack}, year = {2006}, address = {Cannes, France}, month = sep, pages = {1--2}, creationdate = {2006-11-15T00:00:00}, doi = {10.1109/ECOC.2006.4801097}, groups = {Quantum information science}, owner = {Matthieu} }

123. M. Bloch, A. Thangaraj, S. W. McLaughlin, and J.-M. Merolla, “LDPC-based Secret Key Agreement over the Gaussian wiretap channel,” in ieee_isit, Seattle, USA, Jul. 2006, pp. 1179–1183.

     This paper investigates a practical secret key agreement protocol over the Gaussian wire-tap channel. The protocol is based on an efficient information reconciliation method which allows two parties having access to correlated continuous random variables to agree on a common bit string.We describe an explicit reconciliation method based on LDPC codes optimized with EXIT charts and density evolution. When used in conjunction with existing privacy amplification techniques our method allows secret key agreement over the Gaussian wire-tap channel close to the secrecy capacity.

     @inproceedings{Bloch2006a, author = {Bloch, Matthieu and Thangaraj, Andrew and McLaughlin, Steven W. and Merolla, Jean-Marc}, booktitle = ieee_isit, title = {{LDPC}-based Secret Key Agreement over the {G}aussian wiretap channel}, year = {2006}, address = {Seattle, USA}, month = jul, pages = {1179-1183}, comment = {Cited 2 times 1. On the Possibility of Key Agreement Using Variable Directional Antenna, Imai, H.; Kobara, K. & Morozov, K., 1st Joint Workshop on Information Security, 2006 2. Secure Nested Codes for Type II Wiretap Channels, Liu, R.; Liand, Y.; Poor, H. V. & Spasojevi\'c, P., 2007 IEEE Information Theory Workshop, 2007}, creationdate = {2006-11-15T00:00:00}, doi = {10.1109/ISIT.2006.261991}, file = {:Users/matthieu/Documents/publications/2006-Bloch-ISIT.pdf:PDF;2006-Bloch-ISIT.pdf:2006-Bloch-ISIT.pdf:PDF}, groups = {Secret key agreement}, keywords = {LDPC, wire-tap channel}, owner = {Matthieu} }

124. M. Bloch, A. Thangaraj, S. W. McLaughlin, and J.-M. Merolla, “LDPC-based Gaussian Key Reconciliation,” in ieee_itw, Punta del Este, Uruguay, Mar. 2006, pp. 116–120.

     We propose a new information reconciliation method which allows two parties sharing continuous random variables to agree on a common bit string. We show that existing coded modulation techniques can be adapted for reconciliation and give an explicit code construction based on LDPC codes in the case of Gaussian variables. Simulations show that our method achieves higher efficiency than previously reported results.

     @inproceedings{Bloch2006, author = {Bloch, Matthieu and Thangaraj, Andrew and McLaughlin, Steven W. and Merolla, {Jean}-{Marc}}, booktitle = ieee_itw, title = {{LDPC}-based {G}aussian Key Reconciliation}, year = {2006}, address = {Punta del Este, Uruguay}, month = mar, note = {arXiv:cs.IT/0509041}, pages = {116-120}, citeseerurl = {cs.IT/0509041}, comment = {Cited 2 times 1. Secrecy Capacity of Wireless Channels, Barros, J. & Rodrigues, M. R. D., IEEE International Symposium on Information Theory, 2006 2. Tight bound on coherent states quantum key distribution with heterodyne detection, Lodewyck, J. & Grangier, P., Physical Review A, 2007, 76, 022332/1-8 Preprint cited 4 times 1. Controlling excess noise in fiber-optics continuous-variable quantum key distribution, Lodewyck, J.; Debuisschert, T.; Tualle-Brouri, R. & Grangier, P., Physical Review A, 2005, 72, 050303/1-4 2. Optimality of Gaussian Attacks in Continuous-Variable Quantum Cryptography, Navascues, M.; Grosshans, F. & Acin, A., Physical Review Letters, 2006, 97, 190502/1-4 3. From quantum cloning to quantum key distribution with continuous variables: a review, Cerf, N. J. & Grangier, P., JOSA B, 2007, 24, 324-334 4. Experimental Implementation of Non-Gaussian Attacks on a Continuous-Variable Quantum-Key-Distribution System, Lodewyck, J.; Debuisschert, T.; Garcia-Patron, R.; Tualle-Brouri, R.; Cerf, N. J. & Grangier, P., Physical Review Letters, 2007, 98, 030503/1-4}, creationdate = {2006-11-15T00:00:00}, doi = {10.1109/ITW.2006.1633793}, file = {:Users/matthieu/Documents/publications/2006-Bloch-ITW-Uruguay.pdf:PDF;2006-Bloch-ITW.pdf:2006-Bloch-ITW.pdf:PDF}, groups = {Reconciliation algorithms, Secret key agreement}, keywords = {LDPC, continuous variables iterative decoding}, owner = {Matthieu} }

125. J. Cussey, M. Bloch, A. Thangaraj, J.-M. Merolla, and S. W. McLaughlin, “Integrated Direct-Modulation Based Quantum Cryptography System,” in Proc. Optical Network and Technologies, Pisa, Italy, Oct. 2004, pp. 390–395.

     @inproceedings{Cussey2004a, author = {Cussey, Johann and Bloch, Matthieu and Thangaraj, Andrew and Merolla, Jean-Marc and McLaughlin, Steven W.}, booktitle = {Proc. Optical Network and Technologies}, title = {{I}ntegrated Direct-Modulation Based Quantum Cryptography System}, year = {2004}, address = {Pisa, Italy}, month = oct, organization = {IFIP}, pages = {390--395}, series = {IFIP International Federation for Information Processing}, creationdate = {2006-12-14T00:00:00}, doi = {10.1007/0-387-23178-1_49}, groups = {Quantum information science}, owner = {Matthieu} }

126. J. Cussey, M. Bloch, A. Thangaraj, J.-M. Merolla, and S. W. McLaughlin, “Direct-Modulation Scheme for Free-Space Quantum Cryptography,” in Proc. European Conference on Optical Communication, Stockholm, Sweden, Sep. 2004.

     @inproceedings{Cussey2004, author = {Cussey, Johann and Bloch, Matthieu and Thangaraj, Andrew and Merolla, Jean-Marc and McLaughlin, Steven W.}, booktitle = {Proc. European Conference on Optical Communication}, title = {{D}irect-Modulation Scheme for Free-Space Quantum Cryptography}, year = {2004}, address = {Stockholm, Sweden}, month = sep, creationdate = {2006-11-15T00:00:00}, groups = {Quantum information science}, owner = {Matthieu} }