Analysis method for impossible difference-intermediate encounter attack password

Abstract

The invention discloses an impossible difference-intermediate encounter attack password analysis method, which comprises the following steps of: obtaining an impossible difference partition device of a certain block cipher, respectively expanding forwards and backwards for several rounds according to the difference characteristics of the head and the tail of the impossible difference partition device, and recording corresponding parameters; selecting a plaintext to attack, encrypting to obtain a corresponding ciphertext, and calculating data complexity required by the attack according to corresponding parameters; a key involved in the forward extension part is guessed, partial encryption is performed on the plaintext, pairing is performed by using data after partial encryption, and ciphertext data pairs corresponding to data pairs satisfying forward differential propagation are stored in a hash table; a key related to the backward expansion part is guessed, partial decryption is carried out on the ciphertext, pairing is carried out by using the partially decrypted data, online matching is carried out on a ciphertext pair corresponding to a data pair satisfying backward differential propagation and a ciphertext data pair in a hash table, and a wrong key is eliminated; and carrying out exhaustion search on the remaining candidate keys to find a correct key.

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