A Provably Secure Certificateless Proxy Signature Scheme

Proxy signature, a variant of digital signature, is in the limelight in recent years for secure communication. For instance, when a manager is occupied with business matters, or travelling on business, he has to delegate an agent to deal with his day-today office concerns. Therefore, a proxy signature scheme is necessary in this scenario. Although identity-based proxy signature schemes have been proposed in many studies, certificateless public key cryptography (CL-PKC), first proposed by Al-Riyami and Paterson, has been widely used to avoid the key escrow problem in identity-based public key cryptography. In this paper, we combine the concepts of certificateless cryptography and proxy signature to propose a certificateless proxy signature scheme from bilinear pairings, and we also present its security model. This scheme is provably secure and existentially unforgeable under the chosen message attack in the random oracle model.