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A "Paradoxical" Identity-Based Signature Scheme Resulting from Zero-Knowledge (Guillou, Quisquater 1988)

Last modified: 2026-10-27

DOI: 10.1007/0-387-34799-2_16 · URL: https://doi.org/10.1007/0-387-34799-2_16

Summary

Presents the Guillou–Quisquater (GQ) identification protocol and its signature via Fiat–Shamir (CRYPTO '88, published 1990): a proof of knowledge of an RSA e-th root, giving an identity-based scheme with a single round and small memory, suited to smart cards. GQ is one of the classical sigma protocols alongside Schnorr, and illustrates the step from zero-knowledge identification to signatures.

Related resources

• Efficient Signature Generation by Smart Cards (Schnorr 1991) (paper, 1991)
• How to Prove Yourself: Practical Solutions to Identification and Signature Problems (Fiat-Shamir) (paper, 1986)
• On Sigma Protocols (Damgård) (paper, 2004)
• The Knowledge Complexity of Interactive Proof Systems (GMR85) (paper, 1985)
• Unifying Zero-Knowledge Proofs of Knowledge (Maurer 2009) (paper, 2009)