A Certificateless Proxy Ring Signature Scheme with Provable Security

Proxy ring signature allows proxy signer to sign messages on behalf of the original signer while providing anonymity. Certificateless public key cryptography was first introduced by Al-Riyami and Paterson in Asiacrypt 2003. In certificateless cryptography, it does not require the use of certificates to guarantee the authenticity of users’ public keys. Meanwhile, certificateless cryptography does not have the key escrow problem, which seems to be inherent in the Identity-based cryptography. In this paper, we introduce the notion of proxy ring signature into certificateless public key cryptography and propose a concrete certificateless proxy ring signature scheme. The security models of certificateless proxy ring signature are also formalized. The security of the proposed scheme can be proved to be equivalent to the computational DiffieHellman problem in the random oracle with a tight reduction.