Differential Cryptanalysis Study Of Some Lightweight Block Ciphers

The important basises of information security are cryptographic theory and cryptographic technologies. With the development of the Internet of Things, Lightweight block cipher security has become an important research topic. The development of the Internet also promote the communication industry to progress. Cryptographic algorithms with features of low power consumption and high security can be used in resource-constrained devices. And therefore cryptographers pay more and more attentionon on lightweight block cipher algorithm.Although differential cryptanalysis is proposed primarily analying for DES, but it still can be applied to the similar structures effectively. Differential cryptanalysis is a chosen-plaintext attack, and through analyzing the effect of the differeces in paintext pairs on the differences in the ciphertext it can restore some or all of the key bits. Compared with the exhaustive search attack, differential cryptanalysis is more effective. And it is so far one of the effective ways to attack iteration block cipher. The research on differential characteristics of nonlinear partial is the core of differential cryptanalysis, so the research on differential characteristics of S box should be put focus on.MIBS is a kind of lightweight block cipher with a Feistel structure, and the round function structure of MIBS is SP-type. Its key length is 64 bits or 80 bits. The main feature of MIBS is simple hardware implementation and low power consumption. Through in-depth study of the theory of differential cryptanalysis and based on the concrete structure of MIBS, a novel searching algorithm which is an optimization on the basis of the Mitsuru Matsui algorithm is proposed in this paper. By using the optimized search algorithm, the biggest differential characteristic of high round MIBS could be got in a short time.As an improved variant of DES, DESL is also a kind of lightweight block cipher. Combined with the design rules of s-box in DESL, the differential distribution table of a concrete s-box is obtained using computer. Through a deep research on the differential features of the s-box,a round characters search algorithm of DESL is designed, and several typical round characters and corresponding probability are also obtained.