Paper 2012/104 Original: eprint.iacr.org/2012/104 ↗

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

Abstract

Both certificateless cryptography (CLC) and certificate-based cryptography (CBC) are two novel public key paradigms which combine the merits of traditional public key cryptography (PKC) and identity-based cryptography (IBC). They succeed in avoiding the key escrow problem in IBC and reducing the public key management overhead in traditional PKC. This paper deals with the generic construction of certificate based signature (CBS) from certificateless signature (CLS). Wu et al. proposed the first generic conversion from CLS to CBS provably secure in the random oracle model. This paper proposes an intuitive, simple and provably secure generic conversion from CLS to CBS. The security for this conversion is proved in the standard model. To develope the security proof of this conversion, we put forth one novel security model which introduces a previously neglected notrivial attack and better captures the CLS security notion. Following this generic conversion, a provably secure CLS scheme is constructed as an example.