Evaluation of the Security of RC6 against the χ^2-Attack

概要

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Knudsen and Meier applied the χ^2-attack to RC6. The χ^2-attack recovers a key by using high correlations measured by χ^2-value. Up to the present, the success probability of any χ^2-attack has not been evaluated theoretically without using experimental results. In this paper, we discuss the success probability of χ^2-attack and give the theorem that evaluates the success probability without using any experimental result, for the first time. We make sure the accuracy of our theorem by demonstrating it on both 4-round RC6 without post-whitening and 4-round RC6-8. We also evaluate the security of RC6 theoretically and show that a variant of the χ^2-attack is faster than an exhaustive key search for the 192-bit-key and 256-bit-key RC6 with up to 16 rounds. As a result, we succeed in answering such an open question that a variant of the χ^2-attack can be used to attack RC6 with 16 or more rounds.
社団法人電子情報通信学会の論文
2007-01-01