An Improvement Of SMS4Algorithm Based On Dynamic Ideas

SMS4algorithm released by National Business Cryptography ManagementOffice in Jan,2006is the first Business Cryptography algorithm of China for wirelessLAN products. As a cornerstone of public information security, this algorithm shouldhave high quantity in security. But results came out by relevant researches show therestill many security blemishes of the algorithm.The main creative works of this thesis are as follows:1. Presents An improvement of SMS4algorithm based on dynamic ideas.Ameliorated the key expansion algorithm and the round function of SMS4. In the Keyexpansion algorithm,4fixed parameters FK are modified to4parameters which arerandomly selected from16parameters, and32fixed parameters CK are modified to32parameters which are randomly selected from256parameters Dynamic.selectwheel function from two functions.We implement the original and ameliorated SMS4Algorithm and analyzed these two algorithms in factures of ciphertext security andefficiency. The result implied that the ameliorated algorithm has significantlyimproved ciphertext security in only slight time cost. The time to encrypt a given textis about2μs more than the original algorithm.2. Implement the ameliorated algorithm in Xilinx Virtex-II Pro XC2VP30FPGA.The main modules include random number generator, S box, CK box, FK boxreplacement, key expansion, the round function, etc. The random number generator isrealized utilizing the own characteristics of FPGA. Its basic principle is to use an oddnumber of inverters to compose an oscillator as the noise source of the randomnumber generator. S Box, CK boxes and FK boxes permutation implemented by ROMmethods, which reduces resource consumption. The experiments show that theencryption and decryption result is correct and the ameliorated SMS4algorithm isconvenient to implement in hardware environment.