Abstract:

 In order to solve the problems of security and efficiency in three-party contract singing protocols, an efficient abuse-free three-party contract singing protocol was proposed by using the notion of Verifiable Encryption of Chameleon Signatures (VECS). Theoretical analysis show that the protocol enjoys the properties of completeness, fairness, abusefreeness, accountability, invisibility of the third party and the distinguishing property of everlasting secrecy about the contract against the third party. Besides, the proposed protocol decreases the interaction round and number of the message among the parties, and thus is more efficient than the existing protocols.

Key words:  fair exchange;contract signing;chameleon signatures;verifiable encryption