Certificateless undeniable signature scheme

The concept of certificateless public key cryptography (CL-PKC) was introduced by Al-Riyami and Paterson. Such a cryptosystem does not suffer from the key escrow problem while avoiding the onerous management of certificates. In this paper, we present the first certificateless undeniable signature scheme. We consider two different types of adversaries and formalize the security notions for certificateless undeniable signature. And we prove that in the random oracle model, our scheme is secure in the sense of existential unforgeability under the Bilinear Diffie-Hellman assumption and is secure in the sense of invisibility under the Decisional Bilinear Diffie-Hellman assumption.