An Efficient Digital Signature Scheme

Cryptographic techniques, such as encipherment, igital signatures, key management and secret sharing schemes, are important building blocks in the implementation of all security services. In situations where there is not complete trust between sender and receiver, something more than authentication is needed. The most attractive solution to this problem is the digital signature. In 2003, Al-Riyami and Paterson proposed the certificateless public key cryptography which is intermediate between traditional certificate public key cryptography and Identity based public key cryptography. In this paper, we propose a new certificateless signature scheme from bilinear pairings. The proposed scheme is much more efficient than those previous certificateless signature schemes. In the signing phase, no bilinear pairing operations are needed, and in the verifying phase, only two bilinear pairing operations are needed. All this contributes to the efficiency of the proposed scheme. The proposed scheme is unforgeable under the hardness assumptions of the q-strong Diffie-Hellman problem and the computational Diffie-Hellman problem.