Securely Available Credentials (sacred)

Last Modified: 2005-06-27


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Description of Working Group:

The credentials used in a public key infrastructure (PKI) typically
consist of a public/private key pair, a corresponding certificate
or certificate chain and some trust or root certification authority
information. They are usually stored on a desktop or laptop system
as part of an application specific store. Currently, support for
credential export/import is uneven and end users need to get too
involved with the mechanics of creating and maintaining their PKI

Application specific stores also mean that users cannot easily use the
same credential in multiple applications or on multiple devices. In
effect, today, credentials aren't portable. PKIs that use hardware
tokens (e.g., smart cards, PCMCIA cards) do allow for portability of
user's credentials, however, most systems do not use hardware tokens,
but would benefit if similar portability features were available.
Ideally, users would be able to use a common set of credentials with
their desktop and laptop PCs, PDAs, cell phones, and other
Internet-ready devices. Even where hardware tokens are used, there may
also be substantial benefit derived from using credential portability
protocols in support of management functions such as, for example,
installation, token recovery (e.g. locked PIN), or token replacement.

There are at least two possible solutions for providing credential
portability.  The first involves the use of a "credential server".
Credentials are uploaded to the server by one device (e.g., a desktop
computer); they can be stored there and downloaded when needed by the
same or a different device (e.g., a mobile phone, PDA, or laptop

A second solution involves the "direct" transfer of credentials from
one device to another (e.g., from a mobile phone to a PDA).  Although
there may be servers involved in the transfer, in security terms the
transfer is direct - that is, there is no "credential server" that
an active part in securing the exchanges.

While it might be possible that a single protocol can be developed for
both types of solution, two different protocols may be needed: one for
interacting with a "credential server"; and the other to facilitate the
"direct" transfer of credentials.

Security is at a premium for this working group; only authorized
clients should be allowed to download credentials; credentials must be
protected against eavesdropping and active attacks; attackers
must not be able to successfully replace an entity's credentials at a
credential server; etc. In general, the security provided by such
systems will be less than is provided in systems using hardware
tokens, as the hardware tokens tend to be more resistant to improper
inspection and modification.  However, in many environments,
the security offered will be sufficient.

Availability is also at a premium. Credentials must be available
to many different types of client with different characteristics in
terms of processing power, storage and network connectivity.

The working group will produce:

1) An informational document(s) describing and identifying the detailed
  requirements for any protocol in this area, along with an
  architectural view of any such protocol.

2) A standards-track document(s) describing the details of the adopted
  or developed protocol.

The WG will specifically take into account the requirements of the
IPSRA WG, and the protocols selected by this WG should provide a
solution for a subset of those requirements.

Goals and Milestones:

Done    Submit first draft of Requirements document
Done    Submit first draft of Frameworks document
Done    Submit second draft of Requirements document
Done    Submit second draft of Frameworks document
Done    Submit first draft of Protocol document (incl. PDU syntax)
Done    Requirements document to Informational RFC
Done    Submit second draft of Protocol document
Done    Framework doc ready for WG last call
Done    Protocol doc ready for WG last call
Done    Frameworks document to Informational RFC
Done    Protocol document to Proposed Standard

No Current Internet-Drafts

Request For Comments:

Securely Available Credentials - Requirements (RFC 3157) (46169 bytes)
Securely Available Credentials - Credential Server Framework (RFC 3760) (49910 bytes)
Securely Available Credentials Protocol (RFC 3767) (49552 bytes)