Optimum modulo 2/sup m/ multidimensional transform diffusion in block ciphers
James L. Massey · 2003
Linear transform structures as "diffusers" for iterative block ciphers of the substitution/linear-transformation type with symbols in Z2m, the ring of integers modulo 2m were considered. In such a cipher, encryption was accomplished by passing the plaintext input through a succession of "rounds". In each round, the round input was the first passed through a key-controlled substitution, which for each value of the round key relaizes a permutation on the space of plaintexts, and then passed through an unkeyed invertible linear transformation to yield the round output.