One Formalized Approach to Truncated Differential Cryptanalysis of Block Ciphers

Abstract We propose a formalized approach to truncated differential cryptanalysis based on ternary masks that separately account for unchanged, obligatorily changed, and unknown bits in differences. We introduce a security parameter for S-boxes and encryption mappings, which bounds the probability of truncated differentials from below, and examine its basic algebraic properties. Our approach enables the adaptation of existing techniques used in classical differential attacks to truncated differential cryptanalysis, allowing us to extract more information from the encryption process and evaluate the complexity of truncated differential attacks.