Research And Design Of Block Cipher Algorithms

In cryptography, block cipher is a hotspot and it has been widely used in data encryption, message authentication, authentication and key management. With the enactment of DES, block cipher become one of the two basic research of cryptography. People had a thorough research in design and analysis of block cipher in AES and NESSIE plans. In SHA-3 plan, more than a half hash functions borrowed ideas from block cipher, this will promote a further development of block cipher. By studying the existing block cipher, a common block cipher and a lightweight block cipher were designed.Among the four standard block ciper selected by NESSIE in 2003, SHACAL-2 has the longest block length and key size, which is application to the security of general network and information system. We modified it in key expansion function and the iterative function to accelerate the diffusion and confusion of it. Dependence test shows improved algorithm advance by 1 round to meet avalanche effect. Differential attack presents the time complexity in the 18 steps of this algorithm improves from O(214) to O(227). The efficiency was also advanced.RC6 was selected in AES and NESSIE plan. Recently because of its own characteristics, RC6 is also used in digital image, cloud. It fully satisfies the effect with 6-round. In order to accelerate the avalanche effect, two letters were swapped in round function of RC6. χ2 test and differential analysis show safety is improved. As only 2 letters changed, the efficiency of modified algorithm is equivalent roughly to RC6.AES is the Advanced Data Encryption Standard and it is always a hotspot in cryptography. A block cipher based on Feistel structure named FWTS was designed by studying the AES algorithm in this paper. FWTS algorithm is Feistel structure, which is application to the security of general network and information system. Dependence test and impossible differential analysis with 6-round show that FWTS meets modern safety requirements for block cipher. The efficiency tests show that FWTS algorithm has a higher efficiency compared to AES.A lightweight block cipher named SFP was designed by studying PRESENT algorithm. SFP algorithm is Feistel structure. Dependence test, linear analysis, differential analysis and key schedule attack show that SFP satisfies the security requirements of the lightweight block cipher algorithm, and it also meets the needs of resource-constrained environment as its hardware implementation requires only 1355 GE. The SFP software efficiency is about twice as PRESENT.