Internal differential collision attacks on the reduced-round GrØstl-0 hash function

  • Authors:
  • Kota Ideguchi;Elmar Tischhauser;Bart Preneel

  • Affiliations:
  • Systems Development Laboratory, Hitachi, LTD, Yokohama, Japan;ESAT-COSIC and IBBT, Katholieke Universiteit Leuven, Heverlee, Belgium 3001 and Fund for Scientific Research, Flanders, Belgium;ESAT-COSIC and IBBT, Katholieke Universiteit Leuven, Heverlee, Belgium 3001

  • Venue:
  • Designs, Codes and Cryptography
  • Year:
  • 2014

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Abstract

We analyze the GrØstl-0 hash function, that is the version of GrØstl submitted to the SHA-3 competition. This paper extends Peyrin's internal differential strategy, that uses differential paths between the permutations P and Q of GrØstl-0 to construct distinguishers of the compression function. This results in collision attacks and semi-free-start collision attacks on the GrØstl-0 hash function and compression function with reduced rounds. Specifically, we show collision attacks on the GrØstl-0-256 hash function reduced to 5 and 6 out of 10 rounds with time complexities 248 and 2112 and on the GrØstl-0-512 hash function reduced to 6 out of 14 rounds with time complexity 2183. Furthermore, we demonstrate semi-free-start collision attacks on the GrØstl-0-256 compression function reduced to 8 rounds and the GrØstl-0-512 compression function reduced to 9 rounds. Finally, we show improved distinguishers for the GrØstl-0-256 permutations with reduced rounds.