Research And Implementation Of Secure Email System Based On AES Algorithm

E-mail is widely used in Internet because of its convenience and rapidity.It has also become one of the main tools for people to communicate and communicate in daily life.However,the openness of Internet has reduced the security of e-mail transmission on Internet,and e-mail is vulnerable to attacks by third parties.E-mail uses SMTP protocol during the transmission process,and because there is no encryption service in the mail transfer protocol,an attacker can get content of the mail during the transmission.Because it is difficult to ensure the security of transmission network,in order to ensure the confidentiality of the content of e-mail and prevent information leakage,it is necessary to provide encryption service for e-mail.This paper designs a secure E-mail software which can be used in the open wireless network environment on windows system.The software can effectively transmit e-mail encrypted,realize the integration of e-mail encryption and e-mail sending and receiving,and ensure the security of e-mail content at the same time of sending e-mail.This paper applies cryptography to e-mail system,uses a more efficient AES algorithm to encrypt the content of mail,optimizes the mixed transformation of column and inverse column,and uses matrix instead of the mixed matrix of column bytes and reverse column bytes of original algorithm,so that computing and decryption operations are equal.The computing resources can reduce the delay of decryption process,and solve the problem that decryption operation is longer than encryption operation time.It has a lot of advantages of high security coefficient and rapid encryption and decryption.The CBC encryption mode is selected for the iteration of block cipher algorithm,and the XOR operation is carried out between the clear text group and the former cipher packet,and then encryption is carried out to avoid the same cipher deciphering,which greatly improves the security of e-mail transmission in the network.This paper uses the integrated development environment of Visual Studio.NET and the programming language of C# to design an application suitable for running on the PC machine.It analyzes the principle of e-mail transmission and related protocols,and gives the design process of each module through system architecture of the module,encryption and decryption module through secure e-mail and receiving module.Finally,a detailed system functional test is carried out.