Security Analysis Of Feistel-Based Lightweight Block Cipher

With the development of e-commerce and e-government, it becomes important to ensure that information is secure in the open network. Modern cryptography(including encryption, digital signature, etc.) serves as an effective tool in solving problems of information security. It plays the role of a core technology in relevant fields. Block cipher is widely applied in encryption of data and message authentication because of its high efficiency and easy standardization. The research of block cipher not only perfects its own growth of the theory and practical applications, but also is used for reference to other cryptosystems.Research on block cipher incorporates design, cryptanalysis, working mode, evaluation of ciphers and so on. Design and analysis of block cipher contradict each other while mutually unit at the same time. Cryptanalysis will contribute new methods to the design of ciphers. The security analysis methods of block cipher mainly consist of differential cryptanalysis and linear cryptanalysis, and more variants of them like impossible differential cryptanalysis, multidimensional linear cryptanalysis are developed and improved.Lightweight block cipher is the specific type of block cipher that is suitable for extremely constrained environment, and its high practical implications arouse a lot of attention from cryptologists. Compared with the traditional block cipher, this lightweight block cipher is simpler and the lengths of both block and key are shorter, while the same attack methods still apply. In addition, as the main structure of block ciphers, Feistel covers a wide range of application and its design or security analysis has always been the emphasis of study in cryptography. Due to the nature of similarity in encryption and decryption operations, Feistel structure is commonly adopted in the design of lightweight block cipher as well. Thus, security analysis of Feistel-based lightweight block cipher is of great theoretic and practical significance.The main works of this paper are as follows:Firstly, we summarize and introduce the basic theory of block ciphers, including design principles, analysis methods and structure comparisons. We mainly focus on the differential cryptanalysis, linear cryptanalysis and the link between them. We present relevant concepts of the lightweight block cipher in this section as well.Secondly, we describe a representative cipher of SP-based lightweight block cipher ——m Crypton. After we present the principle of related-key boomerang attack(belongs to differential cryptanalysis) in detail, we utilize this technique to attack 7 rounds of m Crypton-96 with a time complexity of 28.62 encryptions and a data complexity of 142. The success rate is 0.96.Thirdly, a preventative cipher of the Feistel-based lightweight block cipher ——Piccolo is introduced. We explain how multidimensional zero-correlation linear cryptanalysis(belongs to linear cryptanalysis) works. Then we take advantage of this technique to attack 9 rounds of Piccolo-80, which achieves a computational complexity of 55.832.