  Traditional Byzantine consensus does not work in P2P network due to Sybil
attack while the most prevalent Sybil-proof consensus at present still can't
resist adversary with dominant compute power. This paper proposed opinion
dynamics based consensus for P2P network with trust relationships, consisting
of the sky framework and the sky model. With the sky framework, opinion
dynamics can be applied in P2P network for consensus which is Sybil-proof
through trust relationships and emerges from local interactions of each node
with its direct contacts without topology, global information or even sample of
the network involved. The sky model has better performance of convergence than
existing models including MR, voter and Sznajd, and its lower bound of fault
tolerance performance is also analyzed and proved. Simulations show that our
approach can tolerant failures by at least 13% random nodes or 2% top
influential nodes while over 96% correct nodes still make correct decision
within 70 seconds on the SNAP Wikipedia who-votes-on-whom network for initial
configuration of convergence>0.5 with reasonable latencies. Comparing to
compute power based consensus, our approach can resist any faulty or malicious
nodes by unfollowing them. To the best of our knowledge, it's the first work to
bring opinion dynamics to P2P network for consensus.
