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. Therefore, the security of the schemes obtained this way does not clearly follow from that of the base identification p...

• Type: Journal
• Year: 2010
• Where: SCN
• Authors: Ming-Feng Lee, Nigel P. Smart, Bogdan Warinschi
• Keywords: Communications, Identity Escrow, Identification Protocol, SCN 2010, Signature