Substitution-Permutation networks: sPn Definition A substitution-permutation(SP) network is a product cipher composed of a number of stages each involving substitutions and permutations Substitution Ts: 0, 1)>10, 1] Permutation Tp:{1,…,m}{1,…!m The plaintext has Im bits: X=X1l..IX where: XG=(X (-+1 The spn has Nrrounds, in which we perform on x m substitutions Ts followed by one permutation Tp, to get the ciphertext y.Substitution-Permutation Networks: SPN • Substitution pS : {0,1}l → {0,1}l • Permutation pP : {1, …,lm} → {1, …,lm} The plaintext has lm bits: x = x(1)|| . . . ||x(m) where: x(i)= (x(i-1)l+1 , . . . , xil ) The SPN has Nr rounds, in which we perform on x m substitutions pS followed by one permutation pP , to get the ciphertext y. Definition A substitution-permutation (SP) network is a product cipher composed of a number of stages each involving substitutions and permutations