Cryptology ePrint Archive: Report 2009/531

Super-Sbox Cryptanalysis: Improved Attacks for AES-like permutations

Henri Gilbert and Thomas Peyrin

Abstract: In this paper, we improve the recent rebound and start-from-the-middle attacks on AES-like permutations. Our new cryptanalysis technique uses the fact that one can view two rounds of such permutations as a layer of big Sboxes preceded and followed by simple affine transformations. The big Sboxes encountered in this alternative representation are named Super-Sboxes. We apply this method to two second-round SHA-3 candidates Grostl and ECHO, and obtain improvements over the previous cryptanalysis results for these two schemes. Moreover, we improve the best distinguisher for the AES block cipher in the known-key setting, reaching 8 rounds for the 128-bit version.

Category / Keywords: secret-key cryptography / hash function, cryptanalysis, AES, Grostl, ECHO

Date: received 2 Nov 2009, last revised 9 Nov 2009

Contact author: thomas peyrin at ingenico com

Available format(s): PDF | BibTeX Citation

Version: 20091110:005308 (All versions of this report)

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