substitutionpermutation
Substitution-permutation refers to a design framework for symmetric key block ciphers in which the cipher state is repeatedly transformed by alternating nonlinear substitution steps with linear permutation steps. The aim is to achieve confusion and diffusion so that the relationship between plaintext, ciphertext, and key becomes complex and difficult to exploit.
In an SPN, rounds typically begin with a key addition (often an XOR with a round key),
Notable SPN-based ciphers include the Advanced Encryption Standard (AES), which uses SubBytes, ShiftRows, and MixColumns as
The SPN framework contrasts with Feistel networks; SPNs generally offer straightforward parallelization of rounds and can