Design And Application Of Secure Multi-party Fair Exchange Protocol

The rapid development of Internet has created a lot of application scenarios for multi-party computation.The fair exchange protocol is an application protocol of secure multi-party computation.It has been widely applied in various fields.However,fair exchange protocol has many shortcomings and problems with the increasing demands for data security and privacy protection.These will affect the development and application.The issues of anonymity,fairness and dependence on the third party are concerned in the secure multi-party fair exchange protocol.Identity whether anonymous will directly affect participants' privacy.The degree of dependence on the third party is related to the efficiency of protocol and sensitive information of participants.At the same time,the existence of the third party may cause some cryptographic attacks.To solve the above problem,this paper has done the following work.Firstly,participants participate in protocol with real identity,which can reveal identity information or other sensitive information.Attackers can make use of these information to do illegal things.Meanwhile,a trusted third party is used to ensure fairness.It will bring potential threat to privacy.In view of the above problems,an anonymous fair exchange protocol with semi-trusted third party is proposed.It is a protection of privacy information by participating in the protocol anonymously.Based on the idea of forcing participants to be honest,an implemention scheme is provided.The efficiency of encrypting and decrypting data by RSA and AES algorithm is much higher than that of RSA algorithm.Secondly,the existing multi-party certified Email protocol has fewer participants and functions.Basing on this situation,this paper proposes a new multi-party certified Email protocol for line topology based on signcryption scheme for signature and message authentication.The efficiency of the protocol has been improved.We verify whether the hash value of received information from the second round of decryption is the same as that of the first round of information,so as to avoid the lack of confirmation of information.In addition,the protocol has time authentication.The freshness of messages can be verified by comparing the time of transmission and receipt.At last,the security and efficiency of the improved protocol are analyzed.Thirdly,the third party may bring some potential security problems.To solve this problem,the no center multiparty fair exchange protocol is proposed based on bitcoin.The fairness is achieved by paying the deposit,and the anonymity of participants depends on the anonymity of bitcoin system.In addition,there is an ideal function in the protocol.The participants did not receive information or received the wrong information,they could send information to the ideal function to ensure their own interests.