Separating Random Oracle Proofs from Complexity Theoretic Proofs: The Non-committing Encryption Case

  • Authors:
  • Jesper Buus Nielsen

  • Affiliations:
  • -

  • Venue:
  • CRYPTO '02 Proceedings of the 22nd Annual International Cryptology Conference on Advances in Cryptology
  • Year:
  • 2002

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Abstract

We show that there exists a natural protocol problem which has a simple solution in the random-oracle (RO) model and which has no solution in the complexity-theoretic (CT) model, namely the problem of constructing a non-interactive communication protocol secure against adaptive adversaries a.k.a. non-interactive non-committing encryption. This separation between the models is due to the so-called programability of the random oracle. We show this by providing a formulation of the RO model in which the oracle is not programmable, and showing that in this model, there does not exist non-interactive non-committing encryption.