Practical hidden identity-based signature scheme from bilinear pairings

Hidden identity-based signatures (abbreviated as Hidden-IBS) can be seen as a variant of the traditional notion of group signatures. Compared with group signature schemes, Hidden-IBS is more attractive in the application of identity-management systems and anonymous credential systems. In Financial Cryptography 2007, Kiayias and Zhou firstly proposed the Hidden-IBS from bilinear pairings. Unfortunately, the Kiayias-Zhou scheme fails to fulfill exculpability and CCA2-anonymity, which are vital properties for group signature scheme and Hidden-IBS. This paper presents a revised scheme by incorporating the techniques of unlinkable randomizable signatures and the Σ-compiler of Furukawa et al. The new scheme enhances security of the Kiayias-Zhou scheme and preserves a desirable property of the original scheme, i.e., concurrent join. Moreover, another essential improvement in the revised scheme is efficiency. Concretely, the processes of signature generation and verification are more efficient than those of the Kiayias-Zhou scheme, and the resulted signature is only half of the latter one´s.