Research On Improved Method And Security Of Key Extension For DES Algorithm

With the development of computer network technology,security problems in the network emerge one after another.In the process of storing and transmitting user data,the security problems such as user information leakage and tampering may occur at any time.Therefore,providing users with secure and reliable confidential communication is an urgent problem to be solved in the development of computer networks.In recent years,the state has invested more and more in information security.The National Natural Science Foundation,863,963 and other major research projects have adopted cryptography as the main target of information security.Encryption technology has attracted the attention of experts and scholars.The DES algorithm(data encryption standard)is a modified version of the LUCIFER algorithm submitted by IBM in 1975 by NBS.It is a block cipher.The confidentiality of the DES algorithm mainly depends on the confidentiality of the key.The algorithm itself is public.Although the DES algorithm is simple in principle,operability,and fast,its short key length results in low security and it is difficult to resist exhaustive search attacks.Some government agencies or large organizations can use a dedicated machine to complete the crack in a few hours.In 2000 IBM replaced it with the AES algorithm.Since the DES algorithm represents a popular algorithm,it still has great research value.This article is from this point of view,mainly introduces the structural characteristics of DES algorithm and the detailed steps of encryption and compares the encryption effect of AES algorithm and RSA algorithm,compares DES algorithm with AES algorithm vertically,and makes symmetric encryption technology and asymmetric encryption technology horizontal.Comparative Study.After a deep understanding of the characteristics of the DES algorithm,it is concluded how to choose the optimal encryption method.Then,based on the shortcomings of the DES algorithm,four unique improvements are proposed:"mode improvement" makes the ciphertext encrypted by the same ciphertext different;"N-DES multiple iterations" increases the number of iterations of the DES algorithm,"3-DES The improved and independent subkeys use the 3-DES structure to change the use sequence of the subkeys,and the keys are not related to each other;the "change subkey order" uses the vector hybrid hash table method to scramble the order of use of the keys.Finally,OPENSSL and related encryption and decryption software are used to simulate the process of DES algorithm,AES algorithm,RSA algorithm,3-DES algorithm and four algorithms to improve the scheme.Finally,through a series of comparative experiments,the running speed,ciphertext change position and avalanche of the algorithm are observed,effect.Experiments show that the four improved methods have significantly improved speed,avalanche effect,safety and so on.