Algebraic cryptanalysis of 58-round SHA-1

  • Authors:
  • Makoto Sugita;Mitsuru Kawazoe;Ludovic Perret;Hideki Imai

  • Affiliations:
  • IT Security Center, Information-technology Promotion Agency, Japan, Tokyo, Japan;Faculty of Liberal Arts and Sciences, Osaka Prefecture University, Osaka, Japan;SPIRAL/SALSA, Site Passy-Kennedy, LIP6, Paris 6 University, Paris France;National Institute of Advanced Industrial Science and Technology, Tokyo, Japan and Department of Electrical, Electronic and Communication Engineering, Faculty of Science and Engineering, Chuo Univ ...

  • Venue:
  • FSE'07 Proceedings of the 14th international conference on Fast Software Encryption
  • Year:
  • 2007

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Abstract

In 2004, a new attack against SHA-1 has been proposed by a team leaded by Wang [15]. The aim of this article1 is to sophisticate and improve Wang's attack by using algebraic techniques. We introduce new notions, namely semi-neutral bit and adjuster and propose then an improved message modification technique based on algebraic techniques. In the case of the 58-round SHA-1, the experimental complexity of our improved attack is 231 SHA-1 computations, whereas Wang's method needs 234 SHA-1 computations. We have found many new collisions for the 58-round SHA-1. We also study the complexity of our attack for the full SHA-1.