Conclusion to Understanding Message Security

Although message security was once considered a specialized requirement, the increasing importance of Internet e-mail and the lack of security in SMTP e-mail increase the need for message security. Message security provides digital signatures and message encryption, which make messages more secure. Digital signatures provide authentication and nonrepudiation, as well as data integrity. Message encryption provides confidentiality and data integrity. Understanding message security requires understanding these concepts and their services.

Public key cryptography provides supporting concepts and mechanisms, to make message security possible. Digital certificates and PKI, which are key elements of the S/MIME standard, make public key cryptography possible.

With an understanding of these elements, you have an understanding of S/MIME. Because S/MIME is an Internet standard, this understanding can be applied to any implementation of S/MIME.

The following sections show how to implement and support S/MIME-based message security in Exchange Server 2003.