Differential cryptanalysis of Substitution Permutation network

Differential cryptanalysis observes the effect of differences of input pairs of a cipher on the differences of its resultant output pairs. The difference of two cipher text is expressed as function of their corresponding plain text difference. In this paper we have focused on differential attack on a basic Substitution-Permutation network. Substitution-Permutation Network is the easiest way to achieve diffusion and confusion property of a cipher, in this Substitution-Permutation network plain texts and keys are provided with many alternate rounds of permutation and substitution. The attack on SPN network is done with the help of differential characteristics established among various rounds of S-boxes. At the end we discussed our implementation result and its accuracy.