Cryptology ePrint Archive: Report 2018/111

MRHS Solver Based on Linear Algebra and Exhaustive Search

Håvard Raddum and Pavol Zajac

Abstract: We show how to build a binary matrix from the MRHS representation of a symmetric-key cipher. The matrix contains the cipher represented as an equation system and can be used to assess a cipher's resistance against algebraic attacks. We give an algorithm for solving the system and compute its complexity. The complexity is normally close to exhaustive search on the variables representing the user-selected key. Finally, we show that for some variants of LowMC, the joined MRHS matrix representation can be used to speed up regular encryption in addition to exhaustive key search.

Category / Keywords: secret-key cryptography / Algebraic cryptanalysis, MRHS, LowMC

Date: received 30 Jan 2018

Contact author: pavol zajac at stuba sk

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Version: 20180130:212536 (All versions of this report)

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