New ID-Based Signatures without Trusted PKG

Abstract

In this paper, from bilinear pairings, we propose two ID-based signatures without trusted PKG, which solve the key escrow problem. In the schemes, the PKG is prevented forging a legal user's signature for its traceability. Under random oracle model, our schemes are both proved secure against existential forgery on adoptively chosen message and ID attack, assuming the Computational Diffie-Hellman Problem (CDHP) in Diffie-Hellman group is intractable. By comparison, our schemes have higher efficiency than the existing schemes.