Encryption Algorithm Based On Two Design And Implementation Of The Encryption And Decryption System

The development of Internet and progress of the informatization are becoming faster and faster, so the situation of information security is becoming severer and severer. Communication with encryption is the kernel problem of the information security. Good cryptosystem will be useful for solving the information security problem.Cryptosystem can be divided into private-key encryption and public-key encryption. RSA is publicly known as the most mature public-key encryption. It can not only be used to encrypt, but also used in digital signature and identity authentication. And AES is the representative of public-key encryption. As the DES method is not qualified to the application now, American selected Rijndael algorithm as the new encryption standard in 2000. Rijndael has a good performance, efficiency, security and be flexible. Now, AES has been widely used in different kinds of information change and network security. So, the analyze and research of RSA and AES is very important to our country.The main work of the thesis is listed as follows:(1) firstly, some knowledge and basic theories about cryptography are introduced and the developing state of the cryptography is illustrated. Then, the RSA and AES algorithm is introduced thoroughly, such as the basic theories of the two cryptosystem, the flows of the algorithms and some shortages. And then, the design thinking of the algorithms are is analyzed in detail.(2) the security of the RSA and the choices of its parameters are discussed. And then the add, sub, multi and divide operations which are used in the RSA algorithm are analyzed and implemented. And the C pseudocodes are also given in the thesis. Next, AES algorithm is deeply analyzed and researched, including every step in this algorithm. And the C pseudocodes of each step are also given in the thesis. Besides, some frequently-used algorithms are introduced, such as the big integer's four basic arithmetic, modular arithmetic and the power operation, and so on.(3) the Visual C++ develop environment and MFC are introduced. And then the encryption and decryption system's graphical interface is implemented and the functions C pseudocodes are given. At last, a summary is given.