Cryptology ePrint Archive: Report 2005/385

Practical Group Signatures without Random Oracles

Giuseppe Ateniese and Jan Camenisch and Susan Hohenberger and Breno de Medeiros

Abstract: We provide a construction for a group signature scheme that is provably secure in a universally composable framework, within the standard model with trusted parameters. Our proposed scheme is fairly simple and its efficiency falls within small factors of the most efficient group signature schemes with provable security in any model (including random oracles). Security of our constructions require new cryptographic assumptions, namely the Strong LRSW, EDH, and Strong SXDH assumptions. Evidence for any assumption we introduce is provided by proving hardness in the generic group model.

Our second contribution is the first definition of security for group signatures based on the simulatability of real protocol executions in an ideal setting that captures the basic properties of unforgeability, anonymity, unlinkability, and exculpability for group signature schemes.

Category / Keywords: Group signatures, random oracles, standard model, group signature security definition, ideal functionality.

Date: received 24 Oct 2005, last revised 24 Aug 2006

Contact author: jca at zurich ibm com

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Version: 20060824:155453 (All versions of this report)

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