Understanding Message Security

Although message security features have been available in Microsoft® Exchange since the first version, these features have typically been used only by customers with specialized security requirements and specialized security staff. Only security specialists and those with cryptography backgrounds needed to understand e-mail message security concepts. Most discussions about these concepts have been by security experts and cryptographers, for security experts and cryptographers. Others who are not security specialists had few resources available, and little need for those resources.

However, as message security grows in popularity and acceptance, administrators need to understand these principles and concepts. This understanding is especially important because of the increased support for Secure/Multipurpose Internet Mail Extensions (S/MIME) in Microsoft Exchange Server 2003.

This section presents an introduction to S/MIME and its related concepts. No background in security is needed. This introduction explains general S/MIME concepts, so that you can then apply these concepts specifically to Exchange. This is not a comprehensive tutorial in S/MIME and cryptography, but if you complete this chapter, you can then read more advanced sources of information, with an understanding of the basic principles. If you are already knowledgeable about S/MIME and its related topics, you may want to omit this chapter or read it as a refresher.

This section starts with basic information about S/MIME message security: digital signatures and message encryption. The chapter then provides additional information about support and capabilities for digital signatures and message encryption. At the end of this section, you should understand:

• Digital signatures

• Message encryption

• Public key cryptography

• Digital certificates