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

Somitra Kumar Sanadhya; Palash Sarkar

Paper 2008/272

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

Somitra Kumar Sanadhya and Palash Sarkar

Abstract

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.

Metadata

Available format(s): PDF PS
Publication info: Published elsewhere. Accepted at ASIACCS 2009.
Keywords: SHA-2 hash family non-randomness hash function design.
Contact author(s): somitra_r @ isical ac in
History: 2010-02-11: last of 2 revisions; 2008-06-18: received; See all versions
Short URL: https://ia.cr/2008/272
License: CC BY

BibTeX

@misc{cryptoeprint:2008/272,
      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{https://eprint.iacr.org/2008/272}},
      url = {https://eprint.iacr.org/2008/272}
}