Anti-sybil Attack Algorithm Based On Social Network Trust Weight

Since the emergence of Napster, P2P technology has been subject to attention. Up to date, it has been developed to the third generation which takes BT as the representative of the hybrid network, and critically inherits the advantages of older products, creating a new generation of trend. Because of P2P distribute system's openness and anonymity, it isvulnerable to all kinds of attacks, especially Sybil attack, a malicious user creates multiple fake users who do not actually exist, then attacker trick ordinary users into interacting with the fake users in order to achieve improved reputation, additional resources, tampering with data transmission, and even control the entire network. Many attacks based on Sybil attack to lauch attack or use it as auxiliary means. Based on the social network's concept of trust between people, this paper add trust weight to Sybil Guard's original random router method, more truly reflect the actual state of transactions between nodes, based on transactions on the adaptive weights reduce probability of the node having transaction with fake users, forcing the attacker to pay a much higher price, thereby increasing system robustness.This paper firstly introduces the basic concepts of P2P networks and related background, descrides Sybil attack's characteristic, analyzes and compares the Sybil attack general defense method.Secondly, this paper analyzes the characteristics of social networks and the development process. According to ?Six Degrees of Separation', the formation of a single random routing network of traditional P2P network and social network integration, stressing the P2P network trust relationship between adjacent nodes, and thus limit of transactions.Finally, this paper presents a social network based on the weight of trust; each adjacent node has trust impedance between the nodes, the longer the path, the greater the impedance. At the same time, taking into account the multiple pathways of trust, the introduction of a series-parallel resistor circuit calculation method, a comprehensive calculation of the trust impedance, in order to determine whether the transaction. And after each transaction from the transaction node itself transactions to be assessed, adaptive weighting trust, deepen trust level of node, network trust relationship between nodes have dynamic balance and reduce the Sybil attack probability.