12.2 SMIME Overview

12.2 S/MIME Overview

The S/MIME standard offers a consistent way to send and receive secure MIME data. S/MIME provides the following cryptographic security services for electronic messaging applications: authentication; message integrity and nonrepudiation of origin, using digital signatures; and privacy and data security, using encryption.

S/MIME can be used by traditional mail clients to add cryptographic services to mail that is sent and to interpret cryptographic services in mail that is received. However, S/MIME is not restricted to mail but can be used with any transport mechanism that transports MIME data, such as HTTP. As such, S/MIME takes advantage of the object-based features of MIME and allows secure messages to be exchanged in mixed-transport systems.

Many of the difficulties early implementers faced with the S/MIME standard were caused by incomplete specifications. The S/MIME specifications, through several long iterations, have not been verified to be implementable and interoperable by many vendors . RSA has also created S/MIME compliance tests, along with an S/MIME seal that states that an implementation has passed S/MIME compliance testing.