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 O(log k), where k is the number of attack edges. Our result improves over SybilLimit [3] by a factor of log n in the face of O(1) attack edges. Even when the number of attack edges reaches O(n/log n), Gatekeeper only admits O(log n) Sybils per attack edge, similar to that achieved by SybilLimit.