Multi-Party Concurrent Signature Scheme Based on Designated Verifiers

Abstract

Fair exchange signature is of importance in the field of the open-network-based security applications. A new multi-party concurrent signature (MPCS) scheme based on designated verifiers is introduced, which features fairness and unforgeability based on the hardness of the Computational Diffie-Hellman (CDH) assumption in the random oracle model. In this scheme, each signer has the right to choose randomly his/her own individual keystone and retrieve all other individual keystones by the Extraction algorithm. If all signers release their own individual keystones, all signatures can be bound. There is not a decisive signer or a more power signer in selecting and releasing keystones. Therefore, the situation of keystones switched by dishonest signers can be effectively avoided and the fairness of the MPCS scheme is also apparently improved. Our MPCS scheme is proved to be secure and can counteract the adaptive chosen message attack.