This is of relevance: Haifeng Yu, Michael Kaminsky, Phillip B. Gibbons, and Abraham Flaxman, "SybilGuard: Defending Against Sybil Attacks via Social Networks."

This is of relevance: Haifeng Yu, Michael Kaminsky, Phillip B. Gibbons, and Abraham Flaxman, "SybilGuard: Defending Against Sybil Attacks via Social Networks." Proceedings of ACM SIGCOMM Conference , September 2006 http://www.cs.cmu.edu/~yhf/sybilguard-sigcomm06.pdf http://www.cs.cmu.edu/~yhf/sybilguard-sigcomm06.pdf In effect, this paper provides a way of "scaling" a trusted social network and minimizing the influence of sock-puppet accounts.