P2P环境下的具有隐私保护的信誉协议

Privacy Preserving Reputation Protocol for P2P Environment

信誉协议通过计算系统用户的信誉评价结果的总合得到最后的信誉结果,然后根据该信誉结果做出相应的决策。在现实情况中信誉系统中的用户往往会反馈一个不诚实的信誉值,因为他们担心他们真实的评价结果会遭到对手的报复。提出一个具有隐私保护的信誉协议,该协议能保证某实体得到其他实体诚实公平的信誉评价。在该协议中使用Shamir门限密钥共享为参与者提供共享子密钥,并利用具有同态性质的可验证密钥共享使得交易员和密钥持有者之间能够验证共享子密钥的正确性。协议中持有共享子密钥的参与者是随机选择的。运用语义安全的ElGa-mal密码系统和Cramer Shoup密码系统,共享密钥的持有者可以以隐私保护的方法提交他们的信誉值,并由一个可信的代理计算信誉结果提交给信誉引擎。用户可通过访问信誉引擎获得信誉结果。该协议保证了信誉结果计算过程中的隐私保护性和信誉结果的可靠性。

Reputation protocol is used to compute feedback by summing up the individual reputations of other system users. The feedback is then used to make a decision. It is always the case that the entities in a reputation system will provide dishonest feedback due to fear of exposing their privacy which would lead to retaliatory acts from opponents. In this paper, a privacy preserving reputation protocol enable an entity to acquire fair reputation from other entities. In this protocol Shamir Secret Sharing and Verifiable Secret Sharing with homomorphic property are employed to enable the dealer and secret holders to verify the correctness of the shared secret. Moreover a random selection of the participating secret holders is achieved. And using the shared secret key, the secret reputation feedback is attained by decryption. Fur- ther more, the nice privacy preserving properties of the semantically secure ElGamal and Cramer Shoup Cryptosystem are used to enable the Secret holders to submit their secret reputation feedback in a privacy preserving way and securely access a database of current reputation feedback maintained by a reputation engine.