Design And Analysis In A Kind Of Chaotic Block Cipher Algorithm Based On Feistel Structure

Chaos system has many excellent properties, such as pseudo-random property,mixing, sensitive to initial condition, complex mapping parameters; these properties areconsistent with the requirements of cryptography: generate pseudo-random signal,confusion and diffusion, difficult to predict the key. Therefore, chaotic cryptographywhich is generated by combining chaos theory and cryptography gradually developedinto an important branch of cryptography. It has become a research hotspot ofcryptography to construct cryptographic algorithm by taking use of the excellentproperties of chaotic systems.The author has seriously studied the chaos theory and block cipher system,conducted an in-depth exploration and research of chaos block cipher. Based on thelearning and analysis of the chaos block cipher which existing home and abroad, a newchaotic block cipher algorithm is proposed which encrypts 128bits plaintext to 128bits cipher text.The S-box in round function is generated by Logistic chaos map, and its nonlinearity and differentialuniformity is improved by scrambling of the Baker map. Meanwhile, 128bits initial key is put intoCubic map to generate the key of algorithm. The encryption process is based on a new extendedFeistel structure, including initial confusion, round function, displacement operation, 8 roundstransform. The algorithm is designed and implemented by hardware description languageVerilogHDL,its encryption and decryption processes are simulated by Modelsim, and implementedin the FPGA development board. Simulation results show that the algorithm has good safetyperformance, very sensitive S-box, large key space, good performance in confusion and diffusion.