A Certificateless Proxy Ring Signature Scheme

The concept of ring signature was first introduced by Rivest et al.in Asiacrypt 2001.In a ring signature,instead of revealing the actual identity of the message signer, the signer specifies a set of possible signers.The verifier can be convinced that the signature was indeed generated by one of the ring members;however,he is unable to tell which member actually produced the signature.The certificateless public key cryptography was introduced by Al-Riyami et al.in 2003.CL-PKC alleviates the key escrow problem as we have in ID-PKC,at the same time,reduces the cost and simplies the use of the technology when compared with certificate-based public key cryptography.Zhang et al.proposed a proxy ring signature scheme in 2003.It has advantages of proxy signature and ring signature.It is very useful when proxy signer need to sign message on behalf of the original entity while providing anonymity.Based on the merit of certificateless public key cryptography,in this paper,we propose a certificateless proxy ring signature scheme by a certificateless ring signature scheme and a short signature scheme.The result shows that the certificateless proxy ring signature scheme not only solves all the problems of certificate management and key escrow,but also satisfies all the required charac- teristics(for example, verifia- bility,unconditional anonymity,unforgeability,undeniability or distinguishability) of proxy ring signature.