Privacy Enhanced Mail

standard for electronic mail on the Internet which ensures privacy

Privacy Enhanced Mail (PEM), is an early IETF proposal for securing email using public key cryptography. Although PEM became an IETF proposed standard it was never widely deployed or used. One reason for the lack of deployment was that the PEM protocol depended on prior deployment of a hierarchical public key infrastructure (PKI) with a single root. Deployment of such a PKI proved impossible as the operational cost and legal liability of the root and 'policy' CAs became understood. In addition to being an obstacle to deployment the single rooted hierarchy was rejected by some commentators as an unacceptable imposition of central authority. This led Phil Zimmermann to propose the Web of Trust as the PKI infrastructure for PGP.
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Privacy Enhanced Mail, standard for electronic mail on the Internet which ensures privacy

(PEM) Internet electronic mail which provides confidentiality, authentication and message integrity using various encryption methods.
See also Pretty Good Privacy.