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Consider a source, Alice, broadcasting private messages to multiple receivers through a broadcast erasure channel; users send back to Alice public feedback that she causally uses to decide the coding strategy for her following transmissions. Recently, the multiple unicast capacity region for this problem has been exactly characterized for a number of(More)
We characterize the secret message capacity of a wiretapped erasure channel where causal channel state information of the honest nodes is publicly available. In doing so, we establish an intimate connection between message secrecy and secret key generation for the same channel setup. We propose a linear coding scheme that has polynomial encoding/decoding(More)
We consider a 1-to-K communication scenario, where a source transmits private messages to K receivers through a broadcast erasure channel, and the receivers feedback strictly, causally, and publicly their channel states after each transmission. We explore the achievable rate region when we require that the message to each receiver remains secret-in the(More)
We address the problem of pollution attacks in coding-based distributed storage systems. In a pollution attack, the adversary maliciously alters some of the stored encoded packets, which results in the incorrect decoding of a large part of the original data upon retrieval. We propose algorithms to detect and recover from such attacks. In contrast to(More)
We consider the problem of securing inter-flow network coding with multiple sources. We present a practical homomorphic signature scheme that makes possible to verify network coded packets composed of data originating from different sources. The multi-source signature scheme allows to circumvent the need of a secret key shared by all sources. Our solution(More)
Automatic speechreading systems through their use of visual information to support the acoustic signal have been shown to yield better recognition performance than purely acoustic systems, especially when background noise is present. In this paper an answer is sought to the most important questions of speechreading: Which features can represent visual(More)
We address the problem of pollution attacks in coding based distributed storage systems proposed for wireless sensor networks. In a pollution attack, the adversary maliciously alters some of the stored encoded packets, which results in the incorrect decoding of a large part of the original data upon retrieval. We propose algorithms to detect and recover(More)
We investigate the problem of secure communication in a simple network with three communicating parties, two distributed sources who communicate over orthogonal channels to one destination node. The cooperation between the sources is restricted to a rate limited common random source they both observe. The communication channels are erasure channels with(More)
We present a novel information theoretic approach to make network coding based storage secure against pollution attacks in sensor networks. The approach is based on a new decoding algorithm which makes it possible to find adversarial blocks using one more encoded block than strictly necessary for decoding. Our scheme fits well to the requirements of sensor(More)
We investigate the problem of information theoretically secure communication in a line network with erasure channels and state feedback. We consider a spectrum of cases for the private randomness that intermediate nodes can generate, ranging from having intermediate nodes generate unlimited private randomness, to having intermediate nodes generate no(More)