RFC 2692 (rfc2692) - Page 2 of 14

SPKI Requirements

RFC 2692                   SPKI Requirements              September 1999


Charter of the SPKI working group

   Many Internet protocols and applications which use the Internet
   employ public key technology for security purposes and require a
   public key infrastructure to manage public keys.

   The task of the working group will be to develop Internet standards
   for an IETF sponsored public key certificate format, associated
   signature and other formats, and key acquisition protocols.  The key
   certificate format and associated protocols are to be simple to
   understand, implement, and use. For purposes of the working group,
   the resulting formats and protocols are to be known as the Simple
   Public Key Infrastructure, or SPKI.

   The SPKI is intended to provide mechanisms to support security in a
   wide range of Internet applications, including IPSEC protocols,
   encrypted electronic mail and WWW documents, payment protocols, and
   any other application which will require the use of public key
   certificates and the ability to access them. It is intended that the
   Simple Public Key Infrastructure will support a range of trust
   models.

Background

   The term certificate traces back to the MIT bachelor's thesis of
   Loren M. Kohnfelder [KOHN].  Kohnfelder, in turn, was responding to a
   suggestion by Diffie and Hellman in their seminal paper [DH].  Diffie
   and Hellman noted that with public key cryptography, one no longer
   needs a secure channel over which to transmit secret keys between
   communicants.  Instead, they suggested, one can publish a modified
   telephone book -- one with public keys in place of telephone numbers.
   One could then look up his or her desired communication partner in
   the directory, find that person's public key and open a secure
   channel to that person.  Kohnfelder took that suggestion and noted
   that an on-line service has the disadvantage of being a performance
   bottleneck.  To replace it, he proposed creation of digitally signed
   directory entries which he called certificates.  In the time since
   1978, the term certificate has frequently been assumed to mean a
   binding between name and key.

   The SPKI team directly addressed the issue of  bindings and
   realized that such certificates are of extremely limited use for
   trust management.  A keyholder's name is one attribute of the
   keyholder, but as can be seen in the list of needs in this document,
   a person's name is rarely of security interest.  A user of a
   certificate needs to know whether a given keyholder has been granted
   some specific authorization.




Ellison                       Experimental