On the security of certificateless threshold ring signature without random oracles
Threshold ring signature is a special extension of the ring signature, where several signers may be required to cooperatively sign messages for sharing the responsibility and authority, while the actual signers are unconditionally anonymous to signature verifier. Certificateless PKC can eliminate the complex management of certificate in public key infrastructure and solve the inherent key escrow problem in ID-based PKC. At present, most of existing threshold ring signatures are proposed in the random oracle, however, they sometimes are proven to be insecure when the hash functions are instantiated. In this paper, we propose a certificateless threshold ring signature scheme with concrete implementation without random oracles and we prove it to be secure under the computational Diffie-Hellman difficult problem.