A New Method for Impossible Differential Cryptanalysis of 7-Round AES-192

Abstract

Impossible differential cryptanalysis is an analysis method by constructing impossible differential path, eliminating the keys satisfying this path, and finally recovering the secret keys. This paper has utilized a new property of MixColumns Transformation, constructed a new 4-round impossible differential path, added 1-round and 3-round possible differential path before and behind this path respectively, and constructed a new 7-round impossible differential path. This path has been utilized to analyze 64-bit initial keys of 7-round AES-192, and this analysis method requires 271 pairs of selected plaintexts, about 272 memory cells and about 2135 encryption and decryption computation.