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Application Bridging for Federated Access Beyond web (ABFAB) Use Cases

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This is an older version of an Internet-Draft that was ultimately published as RFC 7832.
Author Rhys Smith
Last updated 2012-02-21 (Latest revision 2011-07-05)
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ABFAB                                                      R. Smith, Ed.
Internet-Draft                                        Cardiff University
Intended status: Informational                         February 21, 2012
Expires: August 24, 2012

 Application Bridging for Federated Access Beyond web (ABFAB) Use Cases


   Federated authentication has so far been typically associated with
   Web-based services, but there is growing interest in the application
   of federated authentication for non-Web services.  The goal of this
   document is to document a selection of the wide variety of contexts
   whose user experience could be improved through the use of
   technologies based on the ABFAB architecture and specifications.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 24, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Context of Use Cases . . . . . . . . . . . . . . . . . . . . .  3
   4.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     4.1.  Cloud Services . . . . . . . . . . . . . . . . . . . . . .  4
     4.2.  High Performance Computing . . . . . . . . . . . . . . . .  5
     4.3.  Grid Infrastructure  . . . . . . . . . . . . . . . . . . .  5
     4.4.  Databases and Directories  . . . . . . . . . . . . . . . .  6
     4.5.  Media Streaming  . . . . . . . . . . . . . . . . . . . . .  7
     4.6.  Printing . . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.7.  Accessing Applications from Devices on a Telecoms
           Infrastructure . . . . . . . . . . . . . . . . . . . . . .  8
     4.8.  Trust Router . . . . . . . . . . . . . . . . . . . . . . .  9
     4.9.  PLASMA . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     4.10. SIP  . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   5.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . .  9
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 11
   Appendix B.  Open Issues . . . . . . . . . . . . . . . . . . . . . 12

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1.  Introduction

   Federated identity facilitates the controlled sharing of information
   about people (a.k.a. 'principals'), commonly across organisational
   boundaries.  This avoids redundant registration of principals who
   operate in and across multiple domains; both reducing administrative
   overhead for the organisations involved and improving usability for
   the principal.  Simultaneously, it can also help address privacy-
   related concerns, along with the regulatory and statutory
   requirements of some jurisdictions.

   The information that is passed between organisations may include
   authentication state and identity information that can be used for
   many purposes, including making access management decisions.  A
   number of mechanisms support the transmission of this information for
   Web-based scenarios in particular (for example SAML
   [OASIS.saml-profiles-2.0-os]), but there is significant interest in
   the more general application of federated identity to include non-Web
   use cases.  This document enumerates some of these use-cases,
   describing how technologies based on the the ABFAB architecture
   [I-D.lear-abfab-arch] and specifications could be used.

2.  Terminology


   o  Cloud:

   o  Federated Identity:

   o  Principal:

3.  Context of Use Cases

   The use cases described in the present document are a result of work
   led by JANET(UK), the operator of the United Kingdom's education and
   research network, responding to requirements from that particular

   In the interest of promoting the development of technology of broad
   applicability, the present authors welcome use cases and requirements
   from other sectors and communities.

4.  Use Cases

   This section describes a variety of use cases where technologies
   based on the ABFAB architecture and specifications could help improve
   the user experience; each includes a brief description of how current

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   technologies attempt to solve the use cases and how this could
   improved upon.

4.1.  Cloud Services

   Many organisations are seeking to deliver services to their users
   through the use of providers based in the 'cloud'.  This is typically
   motivated by a desire to avoid management and operation of commodity
   services which, through economies of scale and so-forth, can often be
   delivered more efficiently by such providers.

   Many providers already provide web-based access using conventional
   federated authentication mechanisms; for example, outsourced email
   provision where federated access is enabled using 'web-mail'
   applications where access is mediated through the use of SAML
   [OASIS.saml-profiles-2.0-os].  This use of federated authentication
   enables organisations that consume cloud services to more efficiently
   orchestrate the delivery of these services to their users.

   Frequently, however, users will prefer to use desktop applications
   that do not use web (i.e.  HTTP [RFC2616] based) protocols.  For
   example, a desktop email client may use a variety of non-web
   protocols including SMTP [RFC2821], IMAP [RFC2060] and POP [RFC1939].
   Some cloud providers support access to their services using non-web
   protocols, however, the authentication mechanisms used by these
   protocols will typically require that the provider has access to the
   user's credentials - i.e. non federated.  Consequently, the provider
   will require that users' credentials are regularly synchronised from
   the user organisation to the provider, with the obvious overhead this
   imparts on the organisation along with the obvious implications for
   security and privacy; or else be provisioned directly by the provider
   to the user.

   The latter approach of directly provisioning accounts may be
   acceptable in the case where an organisation has relationships with
   only a small number of providers, but may become untenable if an
   organisation obtains services from many providers.  Consequently any
   organisation with a requirement to use non-web protocols would prefer
   to make use of the credentials that they have already provisioned
   their users with, and to utilise federated authentication with non-
   web protocols to obtain access to cloud-based providers.

   ABFAB could help in this context as its specifications would enable
   federated authentication for a variety of non-web protocols, thus
   gaining the benefits of federated authentication without any of the
   drawbacks that are currently experienced.

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4.2.  High Performance Computing

   High-performance computing (HPC) is a discipline that uses
   supercomputers and computer clusters to solve complex computation
   problems; it most commonly associated with scientific research or
   computational science.

   Access to HPC resources, often mediated through technologies such as
   secure shell [RFC4251], is typically managed through the use of user
   digital certificates [RFC5280] or through manually provisioned
   credentials and accounts.  This requires HPC operators to issue
   certificates or accounts to users using a registration process that
   often duplicates identity management processes that already exist
   within most user organisations.  The HPC community would like to
   utilise federated identity to perform both the user registration and
   authentication functions required to use HPC resources, and so reduce
   costs by avoiding this duplication of effort.

   The HPC community also have following additional requirements:

   o  Improved Business Continuity: In the event of operational issues
      at an HPC system at one organisation (for example, a power
      failure), users and jobs could be transparently moved to other HPC
      systems without the overhead of having to manage user credentials
      for multiple organisations;

   o  Establish HPC-as-a-service: Many organisations who have invested
      in HPC systems want to make their systems easily available to
      external customers.  Federated authentication facilitates this by
      enabling these customers to use their existing identity
      management, user credentialing and support processes;

   o  Improve the user experience: Authentication to HPC systems is
      normally performed using user digital certificates, which some
      users find difficult to use.  Federated authentication can provide
      a better user experience by allowing the use of other types of
      credentials, without requiring technical modifications to the HPC
      system to support these.

   ABFAB could help in this context as it could enable federated
   authentication for the many of the protocols and technologies
   currently in use by HPC providers, such as secure shell.

4.3.  Grid Infrastructure

   Grids are large-scale distributed infrastructures, consisting of many
   loosely coupled, independently managed, and geographically
   distributed resources managed by organisationally independent

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   providers.  Users of grids utilise these resources using grid
   middleware that allows them to submit and control computing jobs,
   manipulate datasets, communicate with other users, etc.  These users
   are organised into Virtual Organisations (VOs); each VO represents a
   group of people working collaboratively on a common project.  VOs
   facilitate both the management of its users and the meditation of
   agreements between its users and resource providers.

   Authentication and authorisation within most grids is performed using
   a Public Key Infrastructure, requiring each user to have an X.509
   public-key certificate [RFC5280].  Authentication is performed
   through ownership of a particular certificate, while authorisation
   decisions are made based on the user's identity (derived from their
   X.509 certificate), membership of a particular VO, or additional
   information assigned to a user by a VO.  While efficient and
   scalable, this approach has been found wanting in terms of usability
   - many users find certificates difficult to manage, for various

   One approach to ameliorating this issue, adopted to some extent by
   some grid communities already, is to abstract away direct access to
   certificates from users, instead using alternative authentication
   mechanisms and then converting the credential provided by these into
   standard grid certificates.  Some implementations of this idea use
   existing federated authentication techniques.  However, current
   implementations of this approach suffer from a number of problems,
   not the least of which is the inability to use the federated
   credentials used to authenticate to a credential-conversion portal to
   also directly authenticate to non-web resources such as secure shell

   The ability to use federated authentication directly through ABFAB,
   without the use of a credential conversion service, would allow users
   to authenticate to a grid and its associated services, allowing them
   to directly launch and control computing jobs, all without having to
   manage, or even see, an X.509 public-key certificate at any point in
   the process.  Authorisation within the grid would still be performed
   using VO membership asserted issued by the user's identity provider
   through the federated transport.

4.4.  Databases and Directories

   Databases (e.g.  MySQL, PostgreSQL, Oracle, etc.) and directory
   technologies (e.g.  OpenLDAP, Microsoft Active Directory, Novell
   eDirectory, etc.) are very commonly used within many organsiations
   for a variety of purposes.  This can include core administrative
   functions, such as hosting identity information for its users, as
   well as business functions (e.g. student records systems at

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   educational organisations).

   Access to such database and directory systems is usually provided for
   internal users only, however, users external to the organisations
   sometimes require access to these systems directly: for example,
   external examiners in educational organisations requiring access to
   student records systems, members of cross-organisational project
   teams who store information in a particular organisation's systems,
   external auditors, etc.

   Credentials for users both internal or external to the organisation
   that allow access these databases and directories are usually
   provisioned manually within an organisation, either using Identity
   Management technologies or through more manual processes.  For the
   internal users, this situation is fine - this is one of the mainstays
   of Identity Management.  However, for external users who require
   access, this represents more of a problem for organisational
   processes.  The organisation either has to add these external users
   to its internal Identity Management systems, or else provision these
   credentials directly within the database/directory systems and
   continue to manage them, including appropriate access controls
   associated with each credential, for the lifetime of that credential.

   Federated authentication to databases or directories, via ABFAB
   technologies, would improve upon this situation as it would remove
   the need to provision and de-provision credentials to access these
   systems.  Organisations may still wish to manually manage access
   control of federated identities; however, even this could be provided
   through federated means, if the trust relationship between
   organisations was strong enough for the organisation providing the
   service to rely upon it for this purpose.

4.5.  Media Streaming

   Media streaming services (audio or audio/video) are often provided
   publicly to anonymous users, but authentication is important for a
   protected subset of streams where rights management and access
   control must be applied.

   Streams can be delivered via protocols such as RTSP [RFC3226] / RTP
   [RFC3550] which already include authentication, or can be published
   in an encrypted form with keys only being distributed to trusted
   users.  Federated authentication is applicable to both of these

   Alternative mechanisms to managing access exist; for example, an
   approach where a unique stream URI is minted for each user.  However,
   this relies on preserving the secrecy of the stream URI, and also

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   requires a communication channel between the web page used for
   authentication and the streaming service itself.  Federated
   authentication would be a better fit for this kind of access control.
   Thus, AFAB technologies that allow federated authentication directly
   within (inherently non-web) media streaming protocols would represent
   an enhancement to this area.

4.6.  Printing

   A visitor from one organisation to the premises of another often
   requires the use of print services.  Their home organisation may of
   course offer printing, but the output could be a long way away so the
   home service is not useful.  The user will typically want to print
   from within a desktop or mobile application.

   Where this service is currently offered it would usually be achieved
   through the use of 'open' printers (i.e. printers that allow
   anonymous print requests), where printer availability is advertised
   through the use of Bonjour or other similar protocols.  If the
   organisation requires authenticated print requests (usually for
   accounting purposes), the the visitor would usually have to be given
   credentials that allow this, often supplemented with pay-as-you-go
   style payment systems.

   Adding federated authentication to IPP [RFC3229] (and other relevant
   protocols) would enable this kind of remote printing service without
   the administrative overhead of credentialing these visitors (who, of
   course, may well one time visitors to the organisation).  This would
   be immediately applicable to higher education, where this use case is
   increasingly important thanks to the success of federated network
   authentication systems such as eduroam but could also be used in
   other contexts such as commercial print kiosks, or in large,
   heterogeneous organisations.

4.7.  Accessing Applications from Devices on a Telecoms Infrastructure

   Telecom operators typically have the following properties:

   o  A large collection of registered users, many of whom may have
      identities registered to a fairly high level of assurance (often
      for payment purposes).  However, not all users will have this
      property - for example, non-contract customers on mobile telecoms
      infrastructures in countries with low levels of identity
      registration requirements.

   o  An existing network infrastructure capable of authenticating a
      device (e.g. a cellphone or an ADSL router), and by inference, its

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   o  A large collection of applications (both web-based and non web-
      based) that its users wish to access using their device.  These
      applications could be hosted by the telecoms operator directly, or
      could be any application or system on the internet - for example,
      network messaging services, VoIP, email, etc.

   At present, authentication to these applications will be typically
   configured manually by the user on the device (or on a different
   device connected to that device) but inputting their (usually pre-
   provisioned out-of-band) credentials for that application - one per

   The use of ABFAB technologies in this case, via a mechanism dubbed
   "federated cross-layer access" (see [I-D.wei-abfab-fcla]) would
   enhance the user experience of using these applications through
   devices greatly.  Federated cross-layer access would make use of the
   initial mutual authentication between device and network to enable
   subsequent authentication and authorisation to happen in a seamless
   manner for the user of that device authenticating to applications.

4.8.  Trust Router


4.9.  PLASMA


4.10.  SIP


5.  Contributors

   The following individuals made important contributions to the text of
   this document: Tim Bannister (Manchester University), Simon Cooper
   (Janet), Josh Howlett (Janet), and Mark Tysom (Janet).

6.  Acknowledgements

   These use-cases have been deve3loped and documented using significant
   input from Jens Jensen (STFC Rutherford Appleton Laboratory), Daniel
   Kouril (CESNET), Michal Prochazka (CESNET), Ian Stewart (University
   of Edinburgh), Stephen Booth (Edinburgh Parallel Computing Centre),
   Eefje van der Harst (SURFnet), Joost van Dijk (SURFnet), Robin
   Breathe (Oxford Brookes University), and Yinxing Wei (ZTE

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7.  Security Considerations


8.  IANA Considerations

   This document does not require actions by IANA.

9.  References

9.1.  Normative References

   [I-D.lear-abfab-arch]         Howlett, J., Hartman, S., Tschofenig,
                                 H., and E. Lear, "Application Bridging
                                 for Federated Access Beyond Web (ABFAB)
                                 Architecture", draft-lear-abfab-arch-02
                                 (work in progress), March 2011.

9.2.  Informative References

   [RFC1939]                     Myers, J. and M. Rose, "Post Office
                                 Protocol - Version 3", STD 53,
                                 RFC 1939, May 1996.

   [RFC2060]                     Crispin, M., "Internet Message Access
                                 Protocol - Version 4rev1", RFC 2060,
                                 December 1996.

   [RFC2616]                     Fielding, R., Gettys, J., Mogul, J.,
                                 Frystyk, H., Masinter, L., Leach, P.,
                                 and T. Berners-Lee, "Hypertext Transfer
                                 Protocol -- HTTP/1.1", RFC 2616,
                                 June 1999.

   [RFC2821]                     Klensin, J., "Simple Mail Transfer
                                 Protocol", RFC 2821, April 2001.

   [RFC3226]                     Gudmundsson, O., "DNSSEC and IPv6 A6
                                 aware server/resolver message size
                                 requirements", RFC 3226, December 2001.

   [RFC3229]                     Mogul, J., Krishnamurthy, B., Douglis,
                                 F., Feldmann, A., Goland, Y., van Hoff,
                                 A., and D. Hellerstein, "Delta encoding
                                 in HTTP", RFC 3229, January 2002.

   [RFC3550]                     Schulzrinne, H., Casner, S., Frederick,
                                 R., and V. Jacobson, "RTP: A Transport

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                                 Protocol for Real-Time Applications",
                                 STD 64, RFC 3550, July 2003.

   [RFC4251]                     Ylonen, T. and C. Lonvick, "The Secure
                                 Shell (SSH) Protocol Architecture",
                                 RFC 4251, January 2006.

   [RFC5280]                     Cooper, D., Santesson, S., Farrell, S.,
                                 Boeyen, S., Housley, R., and W. Polk,
                                 "Internet X.509 Public Key
                                 Infrastructure Certificate and
                                 Certificate Revocation List (CRL)
                                 Profile", RFC 5280, May 2008.

   [OASIS.saml-profiles-2.0-os]  Hughes, J., Cantor, S., Hodges, J.,
                                 Hirsch, F., Mishra, P., Philpott, R.,
                                 and E. Maler, "Profiles for the OASIS
                                 Security Assertion Markup Language
                                 (SAML) V2.0", OASIS
                                 Standard OASIS.saml-profiles-2.0-os,
                                 March 2005.

   [I-D.wei-abfab-fcla]          Wei, Y., "Federated Cross-Layer
                                 Access", draft-wei-abfab-fcla-01 (work
                                 in progress), October 2011.

Appendix A.  Change Log

   Note to RFC Editor: if this document does not obsolete an existing
   RFC, please remove this appendix before publication as an RFC.

   Draft -01 to draft -02

   1.  Added Telecoms Operator Cross Layer use case.

   2.  Minor changes in wording through the draft.

   Draft -00 to draft -01

   1.  Added Databases and Directories use case.

   2.  Added Media Streaming use case.

   3.  Added printing use case.

   4.  Added remote working use case.

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   5.  Minor changes in wording through the draft.

   6.  Added references to the various protocols mentioned.

Appendix B.  Open Issues

   Note to RFC Editor: please remove this appendix before publication as
   an RFC.

Author's Address

   Dr. Rhys Smith (editor)
   Cardiff University
   39-41 Park Place
   Cardiff  CF10 3BB
   United Kingdom

   Phone: +44 29 2087 0126

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