ARIA密码算法的不可能差分归一化分析

Unified Impossible Differential Cryptanalysis of ARIA

Unified Impossible Differential (UID) cryptanalysis is a systematic method for finding impossible differentials for block ciphers. Regarding to the problem of automatically retrieving the impossible differential characteristics of block ciphers, with the use of particular intermediate difference state expression, UID gets the same or better results compared with other present cryptanalysis results. ARIA is a Korean block cipher expecting that there are no impossible differentials on four or more rounds. Based on a property of the Diffusion Layer (DL) of ARIA, a specific selection is used before conflict searching to optimize. UID is applied to ARIA, and 6 721 impossible differential chains are found. The length of those chains is four rounds, the same as existing results, but more varied in form. Moreover, ARIA is a Substitution-Permutation Network (SPN), not a Feistel structure or generalized Feistel structure as UID was applied to before.