Paper 2009/382

Linearization Framework for Collision Attacks: Application to CubeHash and MD6

Eric Brier, Shahram Khazaei, Willi Meier, and Thomas Peyrin

Abstract

In this paper, an improved differential cryptanalysis framework for finding collisions in hash functions is provided. Its principle is based on linearization of compression functions in order to find low weight differential characteristics as initiated by Chabaud and Joux. This is formalized and refined however in several ways: for the problem of finding a conforming message pair whose differential trail follows a linear trail, a condition function is introduced so that finding a collision is equivalent to finding a preimage of the zero vector under the condition function. Then, the dependency table concept shows how much influence every input bit of the condition function has on each output bit. Careful analysis of the dependency table reveals degrees of freedom that can be exploited in accelerated preimage reconstruction under the condition function. These concepts are applied to an in-depth collision analysis of reduced-round versions of the two SHA-3 candidates CubeHash and MD6, and are demonstrated to give by far the best currently known collision attacks on these SHA-3 candidates.

Metadata
Available format(s)
PDF
Publication info
Published elsewhere. The short version appears in the proceeding of ASIACYPT 2009.
Keywords
Hash functionscollisionsdifferential attackSHA-3CubeHash and MD6
Contact author(s)
shahram khazaei @ gmail com
History
2009-09-03: last of 4 revisions
2009-08-10: received
See all versions
Short URL
https://ia.cr/2009/382
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2009/382,
      author = {Eric Brier and Shahram Khazaei and Willi Meier and Thomas Peyrin},
      title = {Linearization Framework for Collision Attacks: Application to {CubeHash} and {MD6}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2009/382},
      year = {2009},
      url = {https://eprint.iacr.org/2009/382}
}
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