Security Test On Key Components Of Block Ciphers And Research On Practical Securty Against Differential Cryptanalysis And Linear Cryptanalysis

Block ciphers play a significant role in modern cryptography, and has rather wide application in information security, so to study the security of block ciphers is of great realistic significance.Under this background, this dissertation will study the evaluation methods and testing technology for block cipher security, including two aspects: testing technology for key components of block cipher security and evaluation methods and implementation technologies for block ciphers against differential cryptanalysis and linear cryptanalysis, several principal achievements have been obtained as follows:⑴Practical security for block ciphers against differential cryptanalysis and linear cryptanalysis are an important measure to evaluate the security of block ciphers against differential cryptanalysis and linear cryptanalysis, we focus on practical security against differential cryptanalysis and linear cryptanalysis for block ciphers that key is XORed with data. When the round function has the general form, a new method for the minimal numbers of linear active round functions based on the concatenation rules of linear cryptanalysis is proposed , we also draw a conclusion that minimal numbers of differential active round functions and the minimal numbers of linear active round functions are not always the same for a class of Generalized Feistel Ciphers based on chaotic maps which was evaluated wrongly. when the round function using the basic SP network, we put a algorithm of the minimal numbers of differential active round function extended to the minimal numbers of differential active S-box, and compute he minimal numbers of differential active S-box within six rounds for Camellia.⑵In this paper, we study safety testing indexes of the block cipher three key components: S-box, P permutation and the key schedule algorithm, and design general safety testing methods, at the same time improve the efficiency of existing test tools. In the functional testing with the existing tools, we not only programming realize the computation of S-box's more comprehensive criterions, and programming realize the computation of the P permutation and the key schedule algorithm's safety testing indexes; with traditional testing methods, tests in Algebraic number, non-linear-order and non-linearity are a more effective use of the algorithms.