Simulation-Based Concurrent Non-malleable Commitments and Decommitments

Abstract. In this paper we consider commitment schemes that are secure against concurrent man-in-the-middle (cMiM) attacks. Under such attacks, two possible notions of security for commitment schemes have been proposed in the literature: concurrent non-malleability with respect to commitment and concurrent non-malleability with respect to decommitment (i.e., opening). After the original notion of non-malleability introduced by [Dolev, Dwork and Naor STOC 91] that is based on the independence of the committed messages, a new and stronger simulation-based notion of non-malleability has been proposed with respect to openings or with respect to commitment [1,2,3,4] by requiring that for any man-in-the-middle adversary there is a stand-alone adversary that succeeds with the same probability. When commitment schemes are used as sub-protocols (which is often the case) the simulation-based notion is much more powerful and simplifies the task of proving the security of the larger protocols. The...

• Type: Conference
• Year: 2009
• Where: TCC
• Authors: Rafail Ostrovsky, Giuseppe Persiano, Ivan Visconti
• Keywords: Commitment Schemes, Cryptography, Simulation-based Definitions, Stronger Simulation-based Notion, TCC 2009