Cryptanalysis of Dynamic SHA(2)

  • Jean-Philippe Aumasson
  • Orr Dunkelman
  • Sebastiaan Indesteege
  • Bart Preneel
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5867)

Abstract

In this paper, we analyze the hash functions Dynamic SHA and Dynamic SHA2, which have been selected as first round candidates in the NIST hash function competition. These hash functions rely heavily on data-dependent rotations, similar to certain block ciphers, e.g., RC5. Our analysis suggests that in the case of hash functions, where the attacker has more control over the rotations, this approach is less favorable than in block ciphers. We present practical, or close to practical, collision attacks on both Dynamic SHA and Dynamic SHA2. Moreover, we present a preimage attack on Dynamic SHA that is faster than exhaustive search.

Keywords

Dynamic SHA Dynamic SHA2 SHA-3 candidate hash function collision attack 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Jean-Philippe Aumasson
    • 1
  • Orr Dunkelman
    • 2
  • Sebastiaan Indesteege
    • 3
    • 4
  • Bart Preneel
    • 3
    • 4
  1. 1.FHNWWindischSwitzerland
  2. 2.École Normale SupérieureINRIA, CNRSParisFrance
  3. 3.Department of Electrical Engineering ESAT/COSICKatholieke Universiteit LeuvenBelgium
  4. 4.Interdisciplinary Institute for BroadBand Technology (IBBT)Belgium

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