SSL, S-HTTP and S/MIME

Often users ask about the differences between the various security and encryption
protocols, and how to use them. While this isn’t an encryption document, it is a good
idea to explain briefly what each protocol is, and where to find more information.

• SSL: - SSL, or Secure Sockets Layer, is an encryption method developed by
Netscape to provide security over the Internet. It supports several different
encryption protocols, and provides client and server authentication. SSL operates
at the transport layer, creates a secure encrypted channel of data, and thus can
seamlessly encrypt data of many types. This is most commonly seen when going
to a secure site to view a secure online document with Communicator, and serves
as the basis for secure communications with Communicator, as well as many
other Netscape Communications data encryption. More information can be
found at http://www.consensus.com/security/ssl-talk-faq.html. Information
on Netscape’s other security implementations, and a good starting point for
these protocols is available at http://home.netscape.com/info/security-doc.html.
It’s also worth noting that the SSL protocol can be used to pass
many other common protocols, "wrapping" them for security. See
http://www.quiltaholic.com/rickk/sslwrap/
• S-HTTP: - S-HTTP is another protocol that provides security services across the
Internet. It was designed to provide confidentiality, authentication, integrity, and
non-repudiability [cannot be mistaken for someone else] while supporting multiple
key-management mechanisms and cryptographic algorithms via option negotiation
between the parties involved in each transaction. S-HTTP is limited to the
specific software that is implementing it, and encrypts each message individually.
[ From RSA Cryptography FAQ, page 138]
• S/MIME: - S/MIME, or Secure Multipurpose Internet Mail Extension, is an encryption
standard used to encrypt electronic mail and other types of messages
on the Internet. It is an open standard developed by RSA, so it is likely we will
see it on Linux one day soon. More information on S/MIME can be found at
http://home.netscape.com/assist/security/smime/overview.html.