A Provably Secure Threshold Ring Signature Scheme in Certificateless Cryptography

Ring signature is a kind of group-oriented signature. It allows a member of a group to sign messages on behalf of the group without revealing his/her identity. Certificateless public key cryptography was first introduced by Al-Riyami and Paterson at 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 thresholdring signature into certificateless public key cryptography and propose a concrete certificateless threshold ring signature (CLT-Ring) scheme. The security models of certificateless threshold ring signature are also formalized. The new scheme is provably secure in the random oracle model.