Cryptanalysis of a Provably Secure Certificateless Short Signature Scheme

Abstract

Certificateless public key cryptography, introduced by Al-Riyami and Paterson, simplifies the complex certificate management in PKI-based public key cryptography and solves the key escrow problem of identity-based cryptography. Huang et al. in 2007 showed security models of certificateless signature to simulate possible adversaries according to their attack abilities. Recently, Choi et al. proposed a certificateless short signature scheme. They claimed their scheme to be the only certificateless short signature scheme achieving the strongest security level presented by Huang et al.. They also give their security proofs to support their claim. However, we find that their scheme is not as secure as the authors claimed. In this paper, we give comments on the paper of Choi et al. including the cryptanalysis of their scheme and the weakness of the security proof. © 2013 Springer-Verlag Berlin Heidelberg.