Block Cipher Design And Analysis

In this paper we propose a criterion of how to select DES like structure cipher's S-Boxes and P permutation, based on linear and differential iterative characteristic and make a conclusion that: for the order of S-Boxes we should make it's two round characteristic to be minimum; for the P permutation should make it's more than three round characteristic smaller than two round characteristic. According our criterion we get a variation of DES, it can immune against differential and linear attack. Compare with other variations of DES our design hold the original structure of S-box and make it's strength better.Rijndael was selected as the AES. The best-known attack against Rijndael still is the one presented by the designers called Square attack. Square attack is s a chosen plaintext attack. In this paper we present a new kind of attack called Inverse Square attack, which is a kind of chosen cipher text attack and better than Square attack. We also show that if only inverse the moving direction of ShiftRow or moving direction of RotByte transformation of key schedule, the complexity of our attack will be 28-factor bellow than the Square attack.According to study the design principal and analysis of data encrypt standard DES and the advanced data encrypt standard Rijndael, we design a new kind of block cipher called RD, which use Feistel cipher structure for its framework and applied the S-Box of Rijndael. And we give the description of the cipher's security against linear cryptanalysis, differential cryptanalysis and square attack.