Cryptology ePrint Archive: Report 2017/165

SymSum: Symmetric-Sum Distinguishers Against Round Reduced SHA3

Dhiman Saha and Sukhendu Kuila and Dipanwita Roy Chowdhury

Abstract: In this work we show the existence of special sets of inputs for which the sum of the images under SHA3 exhibits a symmetric property. We develop an analytical framework which accounts for the existence of these sets. The framework constitutes identification of a generic property of iterated SPN based functions pertaining to the round-constant addition and combining it with the notion of $m-$fold vectorial derivatives for differentiation over specially selected subspaces. Based on this we propose a new distinguisher called SymSum for the SHA3 family which penetrates up to 9 rounds and outperforms the ZeroSum distinguisher by a factor of four. Interestingly, the current work is the first analysis of SHA3/Keccak that relies on round-constants but is independent of their Hamming-weights.

Category / Keywords: distinguisher, Keccak, SHA3, hash functions, cryptanalysis, zero-sums, self-symmetry, vectorial derivatives

Original Publication (in the same form): IACR-TOSC-2017

Date: received 20 Feb 2017, last revised 24 Feb 2017

Contact author: saha dhiman at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20170224:075001 (All versions of this report)

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