Chapter 10

Electronic Mail Security: PGP, S/MIME

Pretty Good Privacy (PGP) was invented by Philip Zimmermann who released version 1.0 in 1991. Subsequent versions 2.6.x and 5.x (or 3.0) of PGP have been implemented by an all-volunteer collaboration under the design guidance of Zimmermann. PGP is widely used in the individual and commercial versions that run on a variety of platforms throughout the computer community. PGP uses a combination of symmetric secret-key and asymmetric public-key encryption to provide security services for electronic mail and data files. It also provides data integrity services for messages and data files by using digital signature, encryption, compression (zip), and radix-64 conversion (ASCII Armor). With the explosively growing reliance on e-mail and file storage, authentication and confidentiality services have become increasing demands.

MIME is an extension to the RFC 2822 framework which defines a format for text messages being sent using e-mail. MIME is actually intended to address some of the problems and limitations of the use of SMTP. Secure/Multipurpose Internet Mail Extension (S/MIME) is a security enhancement to the MIME Internet e-mail format standard, based on technology from RSA Data Security.

Although both PGP and S/MIME are on an IETF standards track, it appears likely that PGP will remain the choice for personnel e-mail security for many users, while S/MIME will emerge as the industry standard for commercial and organizational use. Two ...

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