A Provably Secure Ring Signature Scheme in Certificateless Cryptography
This work addresses security and efficiency issues in anonymous group signatures for cryptography applications, though it is incremental as it builds on existing certificateless cryptography frameworks.
The authors tackled the problem of designing a secure ring signature scheme in certificateless cryptography, proposing a concrete scheme that is provably secure in the random oracle model under the Computational Diffie-Hellman assumption, while also formalizing security models and demonstrating vulnerabilities in a generic construction.
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 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 propose a concrete certificateless ring signature scheme. The security models of certificateless ring signature are also formalized. Our new scheme is provably secure in the random oracle model, with the assumption that the Computational Diffie-Hellman problem is hard. In addition, we also show that a generic construction of certificateless ring signature is insecure against the key replacement attack defined in our security models.