Cryptology ePrint Archive: Report 2013/618

Security Amplification against Meet-in-the-Middle Attacks Using Whitening

Pierre-Alain Fouque and Pierre Karpman

Abstract: In this paper we introduce a model for studying meet-in-the-middle attacks on block ciphers, and a simple block cipher construction provably resistant to such attacks in this model. A side-result of this is a proper formalization for an unproven alternative to DESX proposed by Kilian and Rogaway; this construction can now be shown to be sound in our model. Meet-in-the-middle attacks exploit weaknesses in key schedule algorithms, and building constructions resistant to such attacks is an important issue for improving the security of block ciphers. Our construction is generic so that it can be used on top of any block cipher, and it does not require to increase the key-length. We use an exposure resilient function (or ERF) as a building block and we propose a concrete and efficient instantiation strategy based on compression functions.

Category / Keywords: secret-key cryptography / Block cipher, meet-in-the-middle attack, provable security, exposure resilient function.

Original Publication (with major differences): Accepted at IMA CC 2013

Date: received 26 Sep 2013, last revised 26 Sep 2013

Contact author: pierre karpman at gmail com

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Version: 20130927:124400 (All versions of this report)

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