Biblio

A vast literature on secret sharing protocols now exists based on the folk theorem that the wireless channel between communicating parties Alice and Bob cannot be controlled or predicted by a third party in a fine-grain way. We find that the folk theorem unfortunately does not hold. In particular, we show how an adversary, using a customized full-duplex forwarder, can control the channel seen by Alice and Bob in fine granularity without leaving a trace, while predicting with high probability the secrets generated by any channel reciprocity based secret sharing protocol. An implementation of our proposed secret manipulator, called Channel Spoofer, on a software-defined radio platform empirically verifies Channel Spoofer's effectiveness in breaking several representative state-of-the-art secret sharing protocols. To the best of our knowledge, the proposed Channel Spoofer is the first practical attacker against all extant channel reciprocity based secret sharing protocols.

For a multicast group of n receivers, existing techniques either achieve high throughput at the cost of prohibitively large (e.g., O(n)) feedback overhead, or achieve low feedback overhead but without either optimal or near-optimal throughput guarantees. Simultaneously achieving good throughput guarantees and low feedback overhead has been an open problem and could be the key reason why wireless multicast has not been successfully deployed in practice. In this paper, we develop a novel anonymous-query based rate control, which approaches the optimal throughput with a constant feedback overhead independent of the number of receivers. In addition to our theoretical results, through implementation on a software-defined ratio platform, we show that the anonymous-query based algorithm achieves low-overhead and robustness in practice.