Relationships among Differential, Truncated Differential, Impossible Differential Cryptanalyses against Word-Oriented Block Ciphers like RIJNDAEL, E2.
誠 杉田, Kazukuni Kobara, 一浩 上原, Shuji Kubota, Hideki Imai · 2000
We propose a new method for evaluating the security of block ciphers against differential cryptanalysis and propose new structures for block ciphers. To this end, we define the word-wise Markov (Feistel) cipher and random output-differential (Feistel) cipher and clarify the relations among the differential, the truncated differential and the impossible differential cryptanalyses of the random output-differential (Feistel) cipher. This random output-differential (Feistel) cipher model uses a not too strong assumption because denying this approximation model is equivalenttodenying truncated differential cryptanalysis. Utilizing these relations, weevaluate the truncated differential probability and the maximum average of differential probability of the word-wise Markov (Feistel) ciphers like Rijndael, E2 and the modified version of block cipher E2. This evaluation indicates that all three are provably secure against differential cryptanalysis, and that Rijndael and a modified version of b...