Certificate-Based Perfect Concurrent Signatures

Concurrent signature was introduced as an alternative approach to solving the problem of fair exchange of signatures. It allows two entities to produce two signatures in such a way that, the signer of each signature is ambiguous from a third party´s point of view until the release of a secret, known as the keystone. Once the keystone is released, both signatures become binding to their respective signers concurrently. Certificate-based public key cryptography was introduced to remove the use of certificate to ensure the authentication of the user´s public key in the traditional public key cryptography and to overcome the key escrow problem in the identity-based public key cryptography. Combining the concept of concurrent signature with the concept of certificate-based cryptography, in this paper, we propose a certificate-based perfect concurrent signature scheme assuming the hardness of Computational Diffie-Hellman Problem.