Cryptology ePrint Archive: Report 2007/135

Efficient ID-based Signature Without Trusted PKG

Jingwei Liu and Rong Sun and Weidong Kou and Xinmei Wang

Abstract: In this paper, we introduce the exact concept of ID-based signature without trusted Private Key Generator (PKG), which solves the key escrow problem through binding two partially public keys with a same identity. In this scheme, PKG is prevented from forging a legal user’s signature because he only generates the partially private key. Using Gap Diffie-Hellman (GDH) groups, we construct an efficient ID-based signature scheme without trusted PKG, which security relies on the hardness of the Computation Diffie-Hellman Problem (CDHP). More precisely, under the random oracle model, our scheme is proved to be secure against existential forgery on adaptively chosen message and ID attack, which is a natural ID-based version of the standard adaptively chosen message attack, assuming CDHP is intractable. Our scheme not only eliminates the inherent key escrow problem but also has a higher efficiency than the existing schemes.

Category / Keywords: public-key cryptography / ID-based Signature, Key Escrow, Gap Diffie-Hellman Group, Bilinear Pairing, Dishonest PKG

Publication Info: has NOT been published elsewhere

Date: received 17 Apr 2007

Contact author: jwliu at mail xidian edu cn

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Version: 20070418:123451 (All versions of this report)

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