Certificateless Concurrent Signature Scheme

Certificateless public key cryptography was introduced to remove the use of certificate to ensure the authentication of the user´s public key in the traditional certificate-based public key cryptography and overcome he key escrow problem in the identity-based public key cryptography. Concurrent signatures were introduced as an alternative approach to solving the problem of fair exchange of signatures. Combining the concept of certificateless cryptography with the concept of concurrent signature, in this paper, we present a notion of certificateless concurrent signature with a formal security model and propose a provably secure scheme assuming the hardness of computational Diffie-Hellman Problem.