Analysis and improvement of lindell's UC-secure commitment schemes

  • Authors:
  • Olivier Blazy;Céline Chevalier;David Pointcheval;Damien Vergnaud

  • Affiliations:
  • Ruhr-Universität Bochum, Germany;Université Panthéon-Assas, Paris, France;ENS, Paris, France;ENS, Paris, France

  • Venue:
  • ACNS'13 Proceedings of the 11th international conference on Applied Cryptography and Network Security
  • Year:
  • 2013

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Abstract

In 2011, Lindell proposed an efficient commitment scheme, with a non-interactive opening algorithm, in the Universal Composability (UC) framework. He recently acknowledged a bug in its security analysis for the adaptive case. We analyze the proof of the original paper and propose a simple patch of the scheme. More interestingly, we then modify it and present a more efficient commitment scheme secure in the UC framework, with the same level of security as Lindell's protocol: adaptive corruptions, with erasures. The security is proven in the standard model (with a Common Reference String) under the classical Decisional Diffie-Hellman assumption. Our proposal is the most efficient UC-secure commitment proposed to date (in terms of computational workload and communication complexity).