Based on perfect concurrent signature,a novel fair exchange protocol was presented.In this protocol anyone can't identify who has signed which signature when two parties have exchanged their two ambiguous signatures and rela-tive data items.Not until the initial signer publishes a secret information,are the two signatures bound to respective signer concurrently.After that,the other party sends the key of decrypting goods,and thus the two parties can fairly get each other's data items without the trusted third party (TTP),which avoids the possibility of two parties' collusion and the bottleneck of the TTP involvement.Through analysis,this protocol well ensures some significant properties of fair ex-change,such as fairness,non-repudiation and abuse-free etc.What's more,it only needs four messages between two par-ties and it is very simple and highly efficient.
