Revisiting lower and upper bounds for selective decommitments

  • Authors:

  • Rafail Ostrovsky;Vanishree Rao;Alessandra Scafuro;Ivan Visconti

  • Affiliations:

  • Department of Computer Science, UCLA and Department of Mathematics, UCLA;Department of Computer Science, UCLA;Dipartimento di Informatica, University of Salerno, Italy;Dipartimento di Informatica, University of Salerno, Italy

  • Venue:
  • TCC'13 Proceedings of the 10th theory of cryptography conference on Theory of Cryptography
  • Year:
  • 2013

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Abstract

In [6,7], Dwork et al. posed the fundamental question of existence of commitment schemes that are secure against selective opening attacks (SOA, for short). In [2] Bellare, Hofheinz, and Yilek, and Hofheinz in [13] answered it affirmatively by presenting a scheme which is based solely on the non-black-box use of a one-way permutation needing a super-constant number of rounds. This result however opened other challenging questions about achieving a better round complexity and obtaining fully black-box schemes using underlying primitives and code of the adversary in a black-box manner. Recently, in TCC 2011, Xiao ([23]) investigated on how to achieve (nearly) optimal SOA-secure commitment schemes where optimality is in the sense of both the round complexity and the black-box use of cryptographic primitives. The work of Xiao focuses on a simulation-based security notion of SOA. Moreover, the various results in [23] focus only on either parallel or concurrent SOA. In this work we first point out various issues in the claims of [23] that actually re-open several of the questions left open in [2,13]. Then, we provide new lower bounds and concrete constructions that produce a very different state-of-the-art compared to the one claimed in [23].