Public Evidence from Secret Ballots

Elections seem simple---aren't they just counting? But they have a unique, challenging combination of security and privacy requirements. The stakes are high; the context is adversarial; the electorate needs to be convinced that the results are correct; and the secrecy of the ballot must be ensured. And they have practical constraints: time is of the essence, and voting systems need to be affordable and maintainable, and usable by voters, election officials, and pollworkers. It is thus not surprising that voting is a rich research area spanning theory, applied cryptography, practical systems analysis, usable security, and statistics. Election integrity involves two key concepts: convincing evidence that outcomes are correct and privacy, which amounts to convincing assurance that there is no evidence about how any given person voted. These are obviously in tension. We examine how current systems walk this tightrope.Comment: To appear in E-Vote-Id '1

Coding against delayed adversaries

In this work we consider the communication of information in the presence of a delayed adversarial jammer. In the setting under study, a sender wishes to communicate a message to a receiver by transmitting a codeword x = ( x(1), ..., x(n)) over a communication channel. The adversarial jammer can view the transmitted symbols xi one at a time, but must base its action ( when changing xi) on x(j) for j 0 present a single letter characterization of the achievable communication rate in the presence of such adversaries