Provably Secure Generic Construction of Certificate Based Signature from Certificateless Signature in Standard Model

Similar to certificateless cryptography, certificate-based cryptography is another novel public key setting which combines the merits of traditional public key cryptography (PKC) and identity-based cryptography (IBC). Both certificateless cryptography and certificate based cryptography do not have the key escrow problem in identity-based cryptography, and greatly reduce the overhead of certificate management in traditional PKC. Public key encryption and digital signature are two main issues in public key cryptography. In this paper, we deal with the generic construction of certificate based signature from certificateless signature. In 2009, Wu et al. proposed the first generic conversion from certificateless signature (CLS) to certificate based signature (CBS). However, Wu et al.’s method has to involve a cryptographic hash function which is assumed to be a random oracle for security proof. This paper proposes another intuitive, simple and provably secure generic conversion from CLS to CBS. A new security model for CLS is formalized and then it is proved that this generic conversion is secure in the stand model, only if the underlying CLS scheme is secure in our new security model. As Email addresses: [email protected] (Wei Gao), [email protected] (Guilin Wang), [email protected] (Kefei Chen), [email protected] (Xueli Wang ) This work is completed when the first author visited University of Wollongong (20112012) Preprint submitted to **** February 27, 2012 an example, based on this new generic method, we construct a new provably secure certificate based signature scheme.