Research On The Design And Analysis Of Block Cipher Algorithm

With the development of the design and analysis of cryptologic algorithm, the fusion and reference between the ideas of design of cryptologic algorithm has become an inevitable tendency. Since the design of S box has become mature and perfect already in the block cryptologic algorithm with the structure of SP network, the design and analysis of P permutation has become a hot spot recently. As a part of round function, P permutation has played a vital role in the security of the cipher algorithm, and the branch number which is the vital evaluated index for performance has played a more important role. Therefore, it is of great significance to design a transformation whose diffusion is as excellent as possible in the design and analysis of the cryptologic algorithm.The works of this paper are as follows. Firstly, the design principles of the block ciphers is introduced, the main cryptoanalysis methods are proposed, and two typical block ciphers such as CLEFIA and Camellia are introduced briefly. Secondly, we research the impossible differential cryptanalysis of Camellia deeply and take a successful attack13round the CLEFIA-128without whiting for the first time. Thirdly, we design a Mixing Transformation (MT) with confusion, diffusion and a good branch number by combining Addition, Rotation and XOR (ARX). What’s more, we design a LD block cipher algorithm of Feistel Structure whose unit transformed by byte, and elaborate its design principle and components. Finally, statistics and analysis on the selection of MT is completed especially for the numbers of rotation. At the same time, all the MT are given which have meet the excellent branch number. The proof that Linear Transformation (LT) in LD algorithm, which reach upper bound of branch numbers and satisfy involutory property, is given. We also analyze the security of LD algorithm, and contrast the execution speed of the algorithm with AES algorithm.