Internet Engineering Task Force (IETF) R. Smith, Ed.
Request for Comments: 7832 Jisc
Category: Informational May 2016
ISSN: 2070-1721
Application Bridging for Federated Access Beyond Web (ABFAB) Use Cases
Abstract
Federated identity is typically associated with web-based services at
present, but there is growing interest in its application in non-web-
based contexts. The goal of this memo is to document a selection of
the wide variety of these contexts whose user experience could be
improved through the use of technologies based on the Application
Bridging for Federated Access Beyond web (ABFAB) architecture and
specifications.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7832.
Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction ....................................................2
2. Context of Use Cases ............................................3
3. Use Cases .......................................................3
3.1. Cloud Services .............................................3
3.1.1. Cloud-Based Application Services ....................4
3.1.2. Cloud-Based Infrastructure Services .................5
3.2. High-Performance Computing .................................6
3.3. Grid Infrastructure ........................................6
3.4. Databases and Directories ..................................7
3.5. Media Streaming ............................................8
3.6. Printing ...................................................9
3.7. Accessing Applications from Devices on a Telecoms
Infrastructure .............................................9
3.8. Enhanced Security Services for S/MIME .....................10
3.9. Smart Objects .............................................11
4. Security Considerations ........................................11
5. References .....................................................12
5.1. Normative References ......................................12
5.2. Informative References ....................................12
Acknowledgments ...................................................13
Contributors ......................................................13
Author's Address ..................................................13
1. Introduction
Federated identity facilitates the controlled sharing of information
about people (a.k.a. "principals"), commonly across organizational
boundaries. This avoids redundant registration of principals who
operate in and across multiple domains, both reducing the
administrative overhead for the organizations involved and improving
the usability of systems 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 organizations 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 (e.g., the Security Assertion
Markup Language (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 ABFAB
architecture [RFC7831] and specifications could be used.
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2. Context of Use Cases
The use cases described in this document are a result of work led by
Jisc, the operator of the United Kingdom's education and research
network, responding to requirements from its community. These use
cases have also been augmented by various inputs from the IETF
community.
The ABFAB architecture and specifications enables authentication and
authorization to occur across organizational boundaries. For many
applications, principals need not have pre-instantiated accounts that
their federated identity maps to before their first visit to that
application; the application can perform this process on the fly. In
cases where such accounts are required for particular applications,
the pre-provisioning process is out of scope; the ABFAB technology
assumes that any such requirements have already been fulfilled.
Standards-based work of note that would assist with this
pre-provisioning of accounts includes the standards and
specifications produced by the IETF SCIM working group.
3. Use Cases
This section describes some of the various potential 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 technologies attempt to solve the use cases and how
this could be improved upon by ABFAB implementations.
3.1. Cloud Services
Cloud computing is emerging as a common way of provisioning
infrastructure services in an on-demand manner. These services are
typically offered as one of three models:
o General infrastructure services such as computing power, networks,
storage, and utilities ("Infrastructure as a Service", or IaaS);
o Software stacks or platforms such as database servers, web
servers, and application runtime environments ("Platform as a
Service", or PaaS);
o Common application software such as email, shared storage,
business applications such as Customer Relationship Management
(CRM), or scientific applications ("Software as a Service",
or SaaS).
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In many cases, the provisioned cloud infrastructures and applications
need to be integrated with existing infrastructure of the
organization, and it is of course desirable if this could be achieved
in a way that allows business or scientific workflows to act across
infrastructure -- both across the cloud and in the local
infrastructure -- in as seamless a manner as possible.
There are two main areas where federated access fits in cloud
computing:
o Using federation to help mediate access to cloud-based application
services (e.g., cloud-provided email or CRM systems);
o Using federation to help mediate access to the management of
cloud-based infrastructure services.
3.1.1. Cloud-Based Application Services
Many organizations 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 that, 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 "webmail"
applications where access is mediated through the use of SAML
[OASIS.saml-profiles-2.0-os]. This use of federated authentication
enables organizations that consume cloud services to more efficiently
orchestrate the delivery of these services to their users and also
enables single sign-on to the services for these users.
Frequently, however, users will prefer to use desktop applications
that do not use web (i.e., based on HTTP) protocols. For example, a
desktop email client may use a variety of non-web protocols,
including SMTP [RFC5321], IMAP [RFC3501], and the Post Office
Protocol (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 synchronized from the user organization to the provider,
with the obvious overhead this imparts on the organization along with
the obvious implications for security and privacy, or else be
provisioned directly by the provider to the user.
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The latter approach of directly provisioning accounts may be
acceptable in the case where an organization has relationships with
only a small number of providers, but this approach may become
untenable if an organization obtains services from many providers.
Consequently, any organization 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 utilize 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.
3.1.2. Cloud-Based Infrastructure Services
Typical IaaS or PaaS cloud use cases deal with provisioning on-demand
cloud-based infrastructure services that may include infrastructure
components such as computing and storage resources, network
infrastructure, and other utilities. Cloud-based virtualized
applications should ideally operate in the same way as regular
non-virtualized applications whilst allowing management of the
virtual computing resources (scaling, migration, reconfiguration)
without changing the management applications.
In many cases, moving applications or platforms to the cloud may
require their redesigning/refactoring to support dynamic deployment
and configuration, including their security services, and
authentication and authorization services. These will typically
today be extensively based on manual setup and configuration of such
components and features as trusted certificates and trust anchors,
authorities and trusted services (both their location and
certificates), attribute namespaces, and policies.
ABFAB could help in this context as a way of moving from the model of
manually configured authentication and authorization towards a more
easily managed system involving federated trust and identity, and
ABFAB will be applicable for a wide range of existing features (e.g.,
connecting to a newly provisioned Virtual Machine through
ABFAB-enabled Secure Shell (SSH) [RFC4251] instead of having to
manually manage an administrative login to that machine).
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3.2. High-Performance Computing
High-Performance Computing (HPC) is a discipline that uses
supercomputers and computer clusters to solve complex computation
problems; it is most commonly associated with scientific research or
computational science.
Access to HPC resources, often mediated through technologies such as
SSH, 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
organizations. The HPC community would like to utilize 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 the following additional requirements:
o Improve business continuity: In the event of operational issues at
an HPC system at one organization (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 organizations;
o Establish "HPC as a service": Many organizations 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 many of the protocols and technologies currently
in use by HPC providers, such as SSH.
3.3. Grid Infrastructure
Grids are large-scale distributed infrastructures, consisting of many
loosely coupled, independently managed, and geographically
distributed resources managed by organizationally independent
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providers. Users of grids utilize these resources using grid
middleware that allows them to submit and control computing jobs,
manipulate datasets, communicate with other users, etc. These users
are organized into Virtual Organizations (VOs); each VO represents a
group of people working collaboratively on a common project. VOs
facilitate both the management of their users and the meditation of
agreements between their users and resource providers.
Authentication and authorization within most grids are 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 authorization
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
reasons.
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 SSH daemons.
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. Authorization within the grid would still be performed
using VO membership as asserted by the user's Identity Provider (IdP)
through the federated transport.
3.4. Databases and Directories
Databases (e.g., MySQL, PostgreSQL, Oracle) and directory
technologies (e.g., OpenLDAP (http://www.openldap.org/), Microsoft
Active Directory, Novell eDirectory) are very commonly used within
many organizations for a variety of purposes. Such purposes can
include core administrative functions, such as hosting identity
information for its users, as well as business functions (e.g.,
student records systems at educational organizations).
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Access to such database and directory systems is usually provided for
internal users only; however, users external to the organizations
sometimes require access to these systems directly -- for example,
external examiners in educational organizations requiring access to
student records systems, members of cross-organizational project
teams who store information in a particular organization's systems,
and external auditors.
Credentials for users either internal or external to the organization
that allow access to these databases and directories are usually
provisioned manually within an organization, 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 organizational
processes. The organization has to either (1) add these external
users to its internal identity management systems or (2) 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. Organizations 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
organizations was strong enough for the organization providing the
service to rely upon it for this purpose.
3.5. 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 that already include
authentication, such as the Real Time Streaming Protocol (RTSP)
[RFC2326] or RTP [RFC3550], or can be published in an encrypted form
with keys only being distributed to trusted users. Federated
authentication is applicable to both of these cases.
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
requires a communication channel between the web page used for
authentication and the streaming service itself. Federated
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authentication would be a better fit for this kind of access control.
Thus, ABFAB technologies that allow federated authentication directly
within (inherently non-web) media streaming protocols would represent
an enhancement to this area.
3.6. Printing
A visitor from one organization to the premises of another often
requires the use of print services. Their home organization 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
organization requires authenticated print requests (usually for
accounting purposes), 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 the Internet Printing Protocol
(IPP) [RFC2911] (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 be one-time
visitors to the organization). 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 (https://www.eduroam.org), but could also be used in
other contexts such as commercial print kiosks, or in large
heterogeneous organizations.
3.7. 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 Asymmetric Digital Subscriber Line
(ADSL) router) and, by inference, its owner.
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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 devices.
These applications could be hosted by the telecom operator
directly, or they could be any application or system on the
internet -- for example, network messaging services, VoIP,
or email.
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) by inputting their (usually
pre-provisioned out of band) credentials for that application -- one
per application.
The use of ABFAB technologies in this case, via a mechanism dubbed
"federated cross-layer access" (see [FCLA]) would greatly enhance the
user experience of using these applications through devices.
Federated cross-layer access would make use of the initial mutual
authentication between device and network, to allow subsequent
authentication and authorization to happen in a seamless manner for
the user of that device authenticating to applications.
3.8. Enhanced Security Services for S/MIME
There are many situations where organizations want to protect
information with robust access control, either for implementation of
intellectual property right protections, for enforcement of
contractual confidentiality agreements, or because of legal
regulations. The Enhanced Security Services (ESS) for S/MIME defines
an access control mechanism that is enforced by the recipient's
client after decryption of the message (see [MSG-AC-REQ]). The data
model used makes use of Policy Decision Points (PDPs), which make the
policy decisions; Policy Enforcement Points (PEPs), which make
decision requests to the PDP; and Policy Information Points (PIPs),
which issue attributes about subjects. The decisions themselves are
based on the policies and on the subject attributes.
The use of ABFAB technologies in this case would enable both the
front-end and back-end attribute exchange required to provide subject
attributes. When the PEP contacts the PDP, it would initiate an
ABFAB authentication in order to authenticate to the PDP and allow it
to obtain these required subject attributes. Once authenticated, the
PDP would return a token to the subject PEP that could then be used
for subsequent authentications to the PDP.
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3.9. Smart Objects
Many smart device deployments involve multiple organizations that do
not directly share security infrastructure. For example, in smart
power deployments, devices (e.g., appliances) and infrastructure
(e.g., electric car chargers) will wish to connect to an energy
management system. The energy management system is provided by a
utility company in some deployments. The utility company may wish to
grant access only to authorized devices; for example, a consortium of
utility companies and device manufacturers may certify devices to
connect to power networks.
In another example, consumer devices may be used to access cloud
services. For example, a camera could be bound to a photo processing
site. Authentication and authorization for uploading pictures or
ordering prints are required. Sensors could be used to provide data
to services run by organizations other than the sensor manufacturer.
Authorization and authentication can become very tricky when sensors
have no user interface. Cellular devices may want to access services
provided by a third party, regardless of whether the cellular network
or Wi-Fi is used. This becomes difficult when authorization and
billing are coordinated by the cellular provider.
The use of ABFAB technologies in this case would provide
authentication between one entity, such as a smart device, and its
IdP. Only two parties are involved in this exchange; this means that
the smart device need not participate in any complicated public-key
infrastructure even if it is authenticating against many cloud
services. Instead, the device can delegate the process of
authenticating the service, and even deciding whether the device
should be permitted to access the service, to the IdP. This has
several advantages. A wide variety of revenue-sharing models are
enabled. Because device authentication is only with a single IdP,
phishing of device credentials can be avoided. Authorization and
decisions about what personal information to release are made by the
IdP. The device owner can use a rich interface such as a website to
configure authorization and privacy policy even if the device has no
user interface. This model works well with pre-provisioning of
device credentials.
4. Security Considerations
This document contains only use cases and defines no protocol
operations for ABFAB. Security considerations for the ABFAB
architecture are documented in [RFC7831], and security considerations
for ABFAB technologies and protocols that are discussed in these use
cases are documented in the corresponding protocol specifications.
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5. References
5.1. Normative References
[RFC7831] Howlett, J., Hartman, S., Tschofenig, H., and J. Schaad,
"Application Bridging for Federated Access Beyond Web
(ABFAB) Architecture", RFC 7831, DOI 10.17487/RFC7831,
May 2016, <http://www.rfc-editor.org/info/rfc7831>.
5.2. Informative References
[FCLA] Wei, Y., Ed., "Federated Cross-Layer Access", Work in
Progress, draft-wei-abfab-fcla-02, March 2012.
[MSG-AC-REQ]
Freeman, T., Schaad, J., and P. Patterson, "Requirements
for Message Access Control", Work in Progress,
draft-freeman-plasma-requirements-11, March 2015.
[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,
<http://docs.oasis-open.org/security/saml/v2.0/
saml-profiles-2.0-os.pdf>.
[RFC1939] Myers, J. and M. Rose, "Post Office Protocol - Version 3",
STD 53, RFC 1939, DOI 10.17487/RFC1939, May 1996,
<http://www.rfc-editor.org/info/rfc1939>.
[RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
Streaming Protocol (RTSP)", RFC 2326,
DOI 10.17487/RFC2326, April 1998,
<http://www.rfc-editor.org/info/rfc2326>.
[RFC2911] Hastings, T., Ed., Herriot, R., deBry, R., Isaacson, S.,
and P. Powell, "Internet Printing Protocol/1.1: Model and
Semantics", RFC 2911, DOI 10.17487/RFC2911,
September 2000, <http://www.rfc-editor.org/info/rfc2911>.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -
VERSION 4rev1", RFC 3501, DOI 10.17487/RFC3501,
March 2003, <http://www.rfc-editor.org/info/rfc3501>.
Smith Informational [Page 12]RFC 7832 ABFAB Use Cases May 2016
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>.
[RFC4251] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Protocol Architecture", RFC 4251, DOI 10.17487/RFC4251,
January 2006, <http://www.rfc-editor.org/info/rfc4251>.
[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, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
DOI 10.17487/RFC5321, October 2008,
<http://www.rfc-editor.org/info/rfc5321>.
Acknowledgments
These use cases have been developed 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), Yinxing Wei (ZTE Corporation),
Trevor Freeman (Microsoft Corporation), Sam Hartman (Painless
Security, LLC), and Yuri Demchenko (University of Amsterdam).
Contributors
The following individuals made important contributions to the text of
this document: Tim Bannister (Manchester University), Simon Cooper
(Jisc), Josh Howlett (Jisc), and Mark Tysom (Jisc).
Author's Address
Dr. Rhys Smith (editor)
Jisc
Lumen House, Library Avenue, Harwell
Oxford OX11 0SG
United Kingdom
Phone: +44 1235 822145
Email: rhys.smith@jisc.ac.uk
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