Improved Chaotic Mapping And Its Application In File Encryption Systems

The rapid development of modern electronic information and Internet technology makes people’s work and life more convenient,which brings concerns about the information security.Hence,the security of internet information has become the focus of everyone’s attention.Protecting the important files of computer network users has become a new challenge with the high popularity of the Internet.The sensitivity of the initial value,pseudo-randomness,and reproducibility characteristics of chaos are similar to those of cryptography.Designing a new type of passwords based on the chaotic system has become a new method for information encryption.The security of the chaotic information encryption is closely related to the pseudo-randomness of the chaotic system and the encryption algorithm.Therefore,designing a chaotic system with excellent performances and improvement encryption algorithms are of great significance to improve the security of the chaotic encryption system.Based on the chaos theory,the thesis improved the performance of chaotic systems and applied it to the encryption of the system file.The main innovative work is as follows:1.Based on the Logistic chaos mapping and Sine chaos mapping,two improved chaos systems are proposed.The chaotic characteristics of the proposed systems are studied in detail,including the Lyapunov exponent,histogram,bifurcation diagram,and random characteristics.The analysis shows that the improved chaotic systems have a significant improvement in the range of chaotic parameters,mapping interval and randomness.Also,the initial values and parameters of the improved chaotic systems are extended from a finite range to an infinite range.The region where chaos occurs can be set by the user.The above advantages determine that these two proposed systems are very suitable for chaotic information encryption.2.Based on the improved chaotic systems,two file encryption algorithms are proposed.One is the strength encryption algorithm focusing on the security,which is suitable for small files encryption.Based on this algorithm,an image encryption system is designed using the improved Sine chaos system as a serial generator.The key sensitivity and information entropy of the encrypted image show that the proposed algorithm has a good security.The other algorithm is the fast encryption algorithm focusing on the encryption speed,which is suitable for large files encryption.The algorithm is verified using an improved Logistic chaos system.The results show that the proposed algorithm has a higher encryption speed compared to other algorithms.3.Combined with the above two encryption algorithms,a file encryption system is designed using the Swing package to encrypt and protect computer files.The system mainly includes two parts: user login and file encryption or decryption.The user login part uses the database to encrypt the user information.The file encryption and decryption part uses the proposed encryption algorithms.The user can choose the appropriate encryption algorithms according to their own needs.The main feature of this algorithm is to combine the user name and user key,which enhances the security.