Who are you? Secure identities in single hop ad hoc networks

Sybil attacks occur when malicious users create multiple fake identities to gain an advantage over honest users. Wireless ad hoc networks are particularly vulnerable to these attacks because the participants are not known in advance, and they use an open and shared communication medium. In this paper, we develop algorithms that can effectively thwart sybil attacks in single hop multi-channel wireless ad hoc networks using radio resource testing strategies. We present and analyze new anti-sybil algorithms for establishing trusted identities, specifically, that guarantee, with high probability, that each honest device accepts a set of trusted and unforgeable identities that include all other honest devices and a bounded number of fake (sybil) identities. The proposed algorithms provide trade-offs between time complexity and sybil bounds. We also note that these algorithms solve, as subroutines, two problems of independent interest in this anonymous wireless setting: Byzantine consensus and network size estimation.