Paper 2010/355

Near-Collisions on the Reduced-Round Compression Functions of Skein and BLAKE

Bozhan Su, Wenling Wu, Shuang Wu, and Le Dong


The SHA-3 competition organized by NIST aims to find a new hash standard as a replacement of SHA-2. Till now, 14 submissions have been selected as the second round candidates, including Skein and BLAKE, both of which have components based on modular addition, rotation and bitwise XOR (ARX). In this paper, we propose improved near-collision attacks on the reduced-round compression functions of Skein and a variant of BLAKE. The attacks are based on linear differentials of the modular additions. The computational complexity of near-collision attacks on a 4-round compression function of BLAKE-32, 4-round and 5-round compression functions of BLAKE-64 are 2^{21}, 2^{16} and 2^{216} respectively, and the attacks on a 24-round compression functions of Skein-256, Skein-512 and Skein-1024 have a complexity of 2^{60}, 2^{230} and 2^{395} respectively.

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Published elsewhere. Unknown where it was published
Hash functionNear-collisionSHA-3 candidatesSkeinBLAKE
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subozhan @ is iscas ac cn
2010-06-24: last of 2 revisions
2010-06-18: received
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      author = {Bozhan Su and Wenling Wu and Shuang Wu and Le Dong},
      title = {Near-Collisions on the Reduced-Round Compression Functions of Skein and BLAKE},
      howpublished = {Cryptology ePrint Archive, Paper 2010/355},
      year = {2010},
      note = {\url{}},
      url = {}
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