The Fiat–Shamir Transform for Group and Ring Signature Schemes
The Fiat-Shamir (FS) transform is a popular tool to produce particularly efficient digital signature schemes out of identification protocols. It is known that the resulting signature scheme is secure (in the random oracle model) if and only if the identification protocol is secure against passive impersonators. A similar results holds for constructing ID-based signature schemes out of ID-based identification protocols.
The transformation had also been applied to identification protocols with additional privacy properties. So, via the FS transform, ad-hoc group identification schemes yield ring signatures and identity escrow schemes yield group signature schemes. Unfortunately, results akin to those above are not known to hold for these latter settings and the security of the resulting schemes needs to be proved from scratch, or worse, it is often simply assumed.
In this paper we provide the missing foundations for the use of the FS transform in these more complex settings. We start with defining a formal security model for identity escrow schemes (a concept proposed earlier but never rigorously formalized). Our main result constists of necessary and sufficient conditions for an identity escrow scheme to yield (via the FS transform) a secure group signature schemes. In addition, using the similarity between group and ring signature schemes we give analogous results for the latter primitive.
- The Fiat–Shamir Transform for Group and Ring Signature Schemes
- Book Title
- Security and Cryptography for Networks
- Book Subtitle
- 7th International Conference, SCN 2010, Amalfi, Italy, September 13-15, 2010. Proceedings
- pp 363-380
- Print ISBN
- Online ISBN
- Series Title
- Lecture Notes in Computer Science
- Series Volume
- Series ISSN
- Springer Berlin Heidelberg
- Copyright Holder
- Springer-Verlag Berlin Heidelberg
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- Editor Affiliations
- 16. AT&T Labs Research
- 17. Dipartimento di Informatica ed Applicazioni, Università di Salerno
- Author Affiliations
- 18. Dept. Computer Science, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol, BS8 1UB, United Kingdom
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