RFC 1114 (rfc1114) - Page 2 of 25

Privacy enhancement for Internet electronic mail: Part II - certificate-based key management

RFC 1114              Mail Privacy: Key Management           August 1989


   3.4.1.7  Certificate Signature                                     20
   3.4.2  Validation Conventions                                      20
   3.4.3  Relation with X.509 Certificate Specification               22
   NOTES                                                              24

1.  Executive Summary

   This is one of a series of RFCs defining privacy enhancement
   mechanisms for electronic mail transferred using Internet mail
   protocols.  RFC-1113 (the successor to RFC 1040) prescribes protocol
   extensions and processing procedures for RFC-822 mail messages, given
   that suitable cryptographic keys are held by originators and
   recipients as a necessary precondition.  RFC-1115 specifies
   algorithms for use in processing privacy-enhanced messages, as called
   for in RFC-1113.  This RFC defines a supporting key management
   architecture and infrastructure, based on public-key certificate
   techniques, to provide keying information to message originators and
   recipients.  A subsequent RFC, the fourth in this series, will
   provide detailed specifications, paper and electronic application
   forms, etc. for the key management infrastructure described herein.

   The key management architecture described in this RFC is compatible
   with the authentication framework described in X.509.  The major
   contributions of this RFC lie not in the specification of computer
   communication protocols or algorithms but rather in procedures and
   conventions for the key management infrastructure.  This RFC
   incorporates numerous conventions to facilitate near term
   implementation.  Some of these conventions may be superceded in time
   as the motivations for them no longer apply, e.g., when X.500 or
   similar directory servers become well established.

   The RSA cryptographic algorithm, covered in the U.S. by patents
   administered through RSA Data Security, Inc. (hereafter abbreviated
   RSADSI) has been selected for use in this key management system.
   This algorithm has been selected because it provides all the
   necessary algorithmic facilities, is "time tested" and is relatively
   efficient to implement in either software or hardware.  It is also
   the primary algorithm identified (at this time) for use in
   international standards where an asymmetric encryption algorithm is
   required.  Protocol facilities (e.g., algorithm identifiers) exist to
   permit use of other asymmetric algorithms if, in the future, it
   becomes appropriate to employ a different algorithm for key
   management.  However, the infrastructure described herein is specific
   to use of the RSA algorithm in many respects and thus might be
   different if the underlying algorithm were to change.

   Current plans call for RSADSI to act in concert with subscriber
   organizations as a "certifying authority" in a fashion described



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