Distinguisher for Substitution-Permutation Network

This paper provides a detailed overview of differential cryptanalysis, with particular emphasis on its application to Substitution-Permutation Networks (SPNs). Differential cryptanalysis is a powerful attack that exploits patterns in the differences between plaintext pairs and the corresponding ciphertext pairs to reveal information about the secret key. The paper outlines the fundamental concepts of SPN structure, including the role of substitution and permutation layers, and demonstrates how differential characteristics can be leveraged to trace the propagation of differences through the cipher. By analysing the effect of these differences over multiple rounds, it becomes possible to weaken the cipher’s security and reduce the search space for potential key candidates.