Paper 2008/272

A New Hash Family Obtained by Modifying the SHA-2 Family

Somitra Kumar Sanadhya and Palash Sarkar


In this work, we study several properties of the SHA-2 design which have been utilized in recent collision attacks against reduced round SHA-2. Small modifications to the SHA-2 design are suggested to thwart these attacks. The modified round function provides the same resistance to linearization attacks as the original SHA-2 round function, but, provides better resistance to non-linear attacks. Our next contribution is to introduce the general idea of ``multiple feed-forward" for the construction of cryptographic hash functions. This can provide increased resistance to the Chabaud-Joux type ``perturbation-correction'' collision attacks. The idea of feed-forward is taken further by introducing the idea of feed-forward across message blocks leading to resistance against generic multi-collision attacks. The net effect of the suggested changes to the SHA-2 design has insignificant impact on the efficiency of computing the digest.

Note: Rectified an error in the pseudo-code in Fig 1. We thank Jinmin Zhong for bringing this to our attention.

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Published elsewhere. Accepted at ASIACCS 2009.
SHA-2 hash familynon-randomnesshash function design.
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somitra_r @ isical ac in
2010-02-11: last of 2 revisions
2008-06-18: received
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      author = {Somitra Kumar Sanadhya and Palash Sarkar},
      title = {A New Hash Family Obtained by Modifying the {SHA}-2 Family},
      howpublished = {Cryptology ePrint Archive, Paper 2008/272},
      year = {2008},
      note = {\url{}},
      url = {}
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