Research And Implementation Of Information Security Based S/MIME Protocol

Email is one of the most popular but the unsafe applications on Internet. Nowadays, the demand of communication with email is increasing quickly, and more and more secret information has been sent through the unsafe Internet Medium such as email. Traditionally, based MIME, email is transmitted in form of original text. The sender can easily forge his name. Therefore, email is confronted with such unsafe factor as leaking, dropping, tempering, disavowing, etc. Cryptography is the key to solve these information security problems.The S/MIME protocol is an international standard based on data security technology of RSA. It can ensure the security of email in the process of transmission. By extending MIME , a popular form of email, and processing the email data with data security algorithms, S/MIME protocol provides the security services including integrity ,confidentiality and undeniablity .This paper has developed a client system to ensure security of email. This system has combined the S/MIME protocol, SMTP protocol and POP3 protocol and realized triple-DES ,RSA and SHA-1 algorithms to process the MIME body . It can encrypt, sign, send, receive, decrypt, and verify email. This system can be a special client system for secure email, also can be a component of other application software.In this system, Triple-DES algorithm uses key having 112 bits, SHA-1 algorithm produces 160 bits number, and RSA algorithm uses keys having over 1024 bits. These algorithms have enough intensity against strong attack. So they can ensure the email security.