Research On Lightweight Chaotic Block Cipher For Railway Balise

As operators of high-speed rail systems increasingly rely on automation and wireless communication technology, it’s important to transfer information securely to avoid traffic accident and protect the personal safety of million passengers. Balise is a key equipment of railway train control system, information exchange between the query, it’s necessary to use cryptographic techniques to ensure the safety and reliability of the information. However, due to the balise need to do real-time encoding, the cipher algorithm not only should ensure balise message’s security but also should have a higher operating efficiency. To alleviate the problem of insufficient cryptographic techniques study for the railway balise, combined with the integer chaotic system, this thesis mainly researchers on the design, analysis of lightweight chaotic dynamic S-box and lightweight chaotic block cipher. The following aspects are mainly included:The block cipher’s design, analysis and the basic theory of chaos are summarized. Firstly, the architecture of the block cipher, several common structures and the safety analysis theory are introduced. Then, the chaos and cryptography-related features are illustrated, several chaotic maps are listed.Based on integer inverse tent map and integer logistic map, combined with linear feedback shift registers, this thesis proposes a improved mixed integer chaotic system. By using methods including disturbance and mix to improve the performance of integer chaos, the autocorrelation properties of integer chaos sequence is good. Then, presents a dynamic S-box algorithm based on the improved mixed integer chaotic system and establishes a model to evaluate the running time upper bound of the algorithm. Theoretical analysis and simulation results show that the dynamic S-box algorithm have higher operating efficiency, and the S-boxes generated by the algorithm have good cryptographic properties.Then, this thesis proposes a lightweight chaotic block cipher LCBC based on generalized Feistel structure, in which the components are mostly constructed by using integer chaotic map. On the basis of the proposed dynamic S-box algorithm, a 4X 4 dynamic S-box algorithm is designed. Based on integer Lorenz map, presents a chaos simulated annealing algorithm and obtains four optimal S-boxes from the 4x 4 dynamic S-box algorithm through intelligent way. Extends the integer cat map to the four-dimensional to construct the diffusion function HCT, according to the number of brunch, HCT has good diffusion properties. Safety and performance analysis shows that the algorithm not only be able to resist differential attacks and linear attacks, has good confusion and diffusion properties, but also have higher operating efficiency and occupy small storage space, it is suitable for balise.When applied to the balise message encoding, LCBC can work with the exit balise message encoding. By analyzing the encryption and decryption of balise message’s effect, change of their histogram and the work efficiency, the results show that encrypted balise messages like random signals, the message information is sufficiently hidden, and the efficiency of encryption and decryption is more high. Therefore, LCBC can satisfy the requirements of real-time encoding of balise, and effectively improve the security strength of the balise message.Finally, the work of the thesis is comprehensively summarized, and the future research work is prospected.