Network Working Group                                           J. Linn
Request for Comments: 1511                        Geer Zolot Associates
                                                         September 1993

               Common Authentication Technology Overview

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is


   The IETF's Common Authentication Technology (CAT) working group has
   pursued, and continues to pursue, several interrelated activities,
   involving definition of service interfaces as well as protocols.  As
   a goal, it has sought to separate security implementation tasks from
   integration of security data elements into caller protocols, enabling
   those tasks to be partitioned and performed separately by
   implementors with different areas of expertise.  This strategy is
   intended to provide leverage for the IETF community's security-
   oriented resources (by allowing a single security implementation to
   be integrated with, and used by, multiple caller protocols), and to
   allow protocol implementors to focus on the functions that their
   protocols are designed to provide rather than on characteristics of
   particular security mechanisms (by defining an abstract service which
   multiple mechanisms can realize).

   The CAT WG has worked towards agreement on a common service
   interface, (the Generic Security Service Application Program
   Interface, or GSS-API), allowing callers to invoke security
   functions, and also towards agreement on a common security token
   format incorporating means to identify the mechanism type in
   conjunction with which security data elements should be interpreted.
   The GSS-API, comprising a mechanism-independent model for security
   integration, provides authentication services (peer entity
   authentication) to a variety of protocol callers in a manner which
   insulates those callers from the specifics of underlying security
   mechanisms.  With certain underlying mechanisms, per-message
   protection facilities (data origin authentication, data integrity,
   and data confidentiality) can also be provided. This work is
   represented in a pair of RFCs: RFC-1508 (GSS-API) and RFC-1509
   (concrete bindings realizing the GSS-API for the C language).

J. Linn                                                         [Page 1]

RFC 1511                      CAT Overview                September 1993

   Concurrently, the CAT WG has worked on agreements on underlying
   security technologies, and their associated protocols, implementing
   the GSS-API model.  Definitions of two candidate mechanisms are
   currently available as Internet specifications; development of
   additional mechanisms is anticipated.  RFC-1510, a standards-track
   specification, documents the Kerberos Version 5 technology, based on
   secret-key cryptography and contributed by the Massachusetts
   Institute of Technology.  RFC-1507, an experimental specification,
   documents the Distributed Authentication Services technology, based
   on X.509 public-key technology and contributed by Digital Equipment


   [1]  Kaufman, C., "Distributed Authentication Security Service", RFC
        1507, Digital Equipment Corporation, September 1993.

   [2]  Linn, J., "Generic Security Service Application Program
        Interface", RFC 1508, Geer Zolot Associates, September 1993.

   [3]  Wray, J., "Generic Security Service API : C-bindings", RFC 1509,
        Digital Equipment Corporation, September 1993.

   [4]  Kohl, J., and C. Neuman, "The Kerberos Network Authentication
        Service (V5)", Digital Equipment Corporation, USC/Information
        Sciences Institute, September 1993.

Security Considerations

   Security issues are discussed throughout the references.

Author's Address

   John Linn
   Geer Zolot Associates
   One Main St.
   Cambridge, MA  02142  USA

   Phone: +1 617.374.3700

J. Linn                                                         [Page 2]