Brief announcement: improving social-network-based sybil-resilient node admission control

We present Gatekeeper, a decentralized protocol that performs Sybil-resilient node admission control based on a social network. Gatekeeper can admit most honest nodes while limiting the number of Sybils admitted per attack edge to <i>O</i>(log <i>k</i>), where <i>k</i> is the number of attack edges. Our result improves over SybilLimit [3] by a factor of log <i>n</i> in the face of <i>O</i>(1) attack edges. Even when the number of attack edges reaches <i>O</i>(<i>n</i>/ log <i>n</i>), Gatekeeper only admits <i>O</i>(log <i>n</i>) Sybils per attack edge, similar to that achieved by SybilLimit.