Research And Application Of Block Cipher Algorithm

Along with the progress and development of science and technology,the development of information security is particularly important.How to protect the information more safely and how to provide a reliable guarantee for all kinds of data,which make the research and application of cryptographic algorithms gradually attracted people's attention.Block cipher is one of the widely used cryptographic systems with higher security.AES cipher is a new generation block cipher algorithm proposed by American Department of commerce.S box,as a component of confusion in AES algorithm,is an important factor affecting the attack resistance of the algorithm.The traditional method of screening affine pair makes the S box constructed has the phenomenon of iterative short period and does not fully meet the strict avalanche criterion,which brings greatly challenges to the security of AES algorithm.The requirement of AES algorithm in implementation is the thing that runs faster,has high security and guarantees the lowest cost.The specific work done in this paper is as follows:Firstly,this paper introduces the research background,significance and the development history of block cipher.On count of the research status quo and the main problems of block cipher algorithm,we analyzed and compared the proposed solution and summarized the representative knowledge about AES code,and elaborated the specific steps of the implementation procedures.Secondly,according to the structure of the traditional AES algorithm in S screening box of affine problem,an improved algorithm based on the average distance of the strict avalanche criterion and construction time: using different on different affine strict avalanche criterion with distance is proposed,the algebraic properties respectively make analysis;when calculating the strict avalanche criterion distance is the least S the average time box structure,and the average constructiontime difference,this paper set the minimum threshold,then randomly selected to construct affine S box;compared with the traditional algorithm and other algorithms,analyze and summarize the advantages and disadvantages of the algorithm.In addition,the paper improved the implementation of AES algorithm by merging the row shift and Column mixed transformation in order to the execution time.It also proved the independence between the various steps of the decryption process of the round function,and unified the encryption and decryption process of round function steps,thereby reducing the cost of the software and hardware of AES algorithm.The improved cipher standard will improve the algebraic properties of S box to some extent,and improve the ability of AES cipher to resist attack and the efficiency of execution.Finally,in order to verify the feasibility of the proposed algorithm,a cryptographic system is designed and implemented,which can be used to encrypt and decrypt the text information in classical and modern cryptography.This paper respectively described the cryptographic algorithms of the application cryptographic system in this paper from the three aspects of design principle,algorithm description and system implementation.