Signature schemes secure against hard-to-invert leakage

  • Authors:
  • Sebastian Faust;Carmit Hazay;Jesper Buus Nielsen;Peter Sebastian Nordholt;Angela Zottarel

  • Affiliations:
  • Aarhus University, Denmark;Computer Engineering Department, Bar-Ilan University, Israel;Aarhus University, Denmark;Aarhus University, Denmark;Aarhus University, Denmark

  • Venue:
  • ASIACRYPT'12 Proceedings of the 18th international conference on The Theory and Application of Cryptology and Information Security
  • Year:
  • 2012

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Abstract

In the auxiliary input model an adversary is allowed to see a computationally hard-to-invert function of the secret key. The auxiliary input model weakens the bounded leakage assumption commonly made in leakage resilient cryptography as the hard-to-invert function may information-theoretically reveal the entire secret key. In this work, we propose the first constructions of digital signature schemes that are secure in the auxiliary input model. Our main contribution is a digital signature scheme that is secure against chosen message attacks when given an exponentially hard-to-invert function of the secret key. As a second contribution, we construct a signature scheme that achieves security for random messages assuming that the adversary is given a polynomial-time hard to invert function. Here, polynomial-hardness is required even when given the entire public-key --- so called weak auxiliary input security. We show that such signature schemes readily give us auxiliary input secure identification schemes.