RFC 3851 (rfc3851) - Page 2 of 36
Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3
Alternative Format: Original Text Document
RFC 3851 S/MIME 3.1 Message Specification July 2004
3.1. Preparing the MIME Entity for Signing, Enveloping
or Compressing . . . . . . . . . . . . . . . . . . . . . 14
3.2. The application/pkcs7-mime Type. . . . . . . . . . . . . 19
3.3. Creating an Enveloped-only Message . . . . . . . . . . . 21
3.4. Creating a Signed-only Message . . . . . . . . . . . . . 22
3.5. Creating an Compressed-only Message. . . . . . . . . . . 26
3.6. Multiple Operations. . . . . . . . . . . . . . . . . . . 27
3.7. Creating a Certificate Management Messagetoc . . . . . . 27
3.8. Registration Requests. . . . . . . . . . . . . . . . . . 28
3.9. Identifying an S/MIME Message. . . . . . . . . . . . . . 28
4. Certificate Processing . . . . . . . . . . . . . . . . . . . . 29
4.1. Key Pair Generation. . . . . . . . . . . . . . . . . . . 29
5. Security Considerations. . . . . . . . . . . . . . . . . . . . 29
A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . . . . 31
B. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
B.1. Normative References . . . . . . . . . . . . . . . . . . 32
B.2. Informative References . . . . . . . . . . . . . . . . . 34
C. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35
D. Editor's Address . . . . . . . . . . . . . . . . . . . . . . . 35
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 36
1. Introduction
S/MIME (Secure/Multipurpose Internet Mail Extensions) provides a
consistent way to send and receive secure MIME data. Based on the
popular Internet MIME standard, S/MIME provides the following
cryptographic security services for electronic messaging
applications: authentication, message integrity and non-repudiation
of origin (using digital signatures), and data confidentiality (using
encryption).
S/MIME can be used by traditional mail user agents (MUAs) to add
cryptographic security services to mail that is sent, and to
interpret cryptographic security services in mail that is received.
However, S/MIME is not restricted to mail; it 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.
Further, S/MIME can be used in automated message transfer agents that
use cryptographic security services that do not require any human
intervention, such as the signing of software-generated documents and
the encryption of FAX messages sent over the Internet.
Ramsdell Standards Track