Internet DRAFT - draft-smith-abfab-usability-ui-considerations
draft-smith-abfab-usability-ui-considerations
w
ABFAB R. Smith
Internet-Draft Cardiff University
Intended status: Informational September 25, 2013
Expires: March 29, 2014
Application Bridging for Federated Access Beyond web (ABFAB) Usability
and User Interface Considerations
draft-smith-abfab-usability-ui-considerations-04
Abstract
The use of ABFAB-based technologies requires that each user's device
is configured with the user's identities that they wish to use in
ABFAB transactions. This will require something on that device,
either built into the operating system or a standalone utility, that
will manage the user's identities and identity to service mappings.
Anyone designing that "something" will face the same set of
challenges. This document aims to document these challenges with the
aim of producing well-thought out UIs with some degree of
consistency.
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 http://datatracker.ietf.org/drafts/current/.
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 March 29, 2014.
Copyright Notice
Copyright (c) 2013 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
Smith Expires March 29, 2014 [Page 1]
Internet-Draft ABFAB UI Considerations September 2013
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.
Smith Expires March 29, 2014 [Page 2]
Internet-Draft ABFAB UI Considerations September 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Context . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Considerations around Terminology . . . . . . . . . . . . . . 6
5.1. Identity . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Services . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.3. Identity to Service Mapping . . . . . . . . . . . . . . . 6
6. Considerations around Management of Identities . . . . . . . . 7
6.1. Information associated with each Identity . . . . . . . . 7
6.2. Adding/Association of an Identity . . . . . . . . . . . . 8
6.2.1. Manual Addition . . . . . . . . . . . . . . . . . . . 8
6.2.2. Manually Triggered Automated Addition . . . . . . . . 9
6.2.3. Fully Automated Addition . . . . . . . . . . . . . . . 10
6.3. Modifying Identity Information . . . . . . . . . . . . . . 10
6.3.1. Manual Modification . . . . . . . . . . . . . . . . . 10
6.3.2. Automated Modification . . . . . . . . . . . . . . . . 11
6.4. Verifying an identity . . . . . . . . . . . . . . . . . . 11
6.5. Removing an Identity . . . . . . . . . . . . . . . . . . . 11
6.5.1. Manual Removal . . . . . . . . . . . . . . . . . . . . 11
6.5.2. Automated Removal . . . . . . . . . . . . . . . . . . 11
7. Considerations around Management of Service to Identity
Mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Listing Services and Identities . . . . . . . . . . . . . 12
7.2. Showing the Identity currently in use . . . . . . . . . . 12
7.3. Associating a Service with an Identity . . . . . . . . . . 12
7.3.1. User-driven Manual Association . . . . . . . . . . . . 12
7.3.2. Automated Rules-based Association . . . . . . . . . . 13
7.4. Disassociating a Service with an Identity . . . . . . . . 13
8. Handling of Errors . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Identity Association/Verification Errors . . . . . . . . . 14
8.2. Service Errors . . . . . . . . . . . . . . . . . . . . . . 14
8.3. Other Errors. . . . . . . . . . . . . . . . . . . . . . . 14
9. Handling of Successes . . . . . . . . . . . . . . . . . . . . 14
9.1. Reporting Authentication Success on First Use of
Identity . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.2. Reporting Authentication Success . . . . . . . . . . . . . 14
10. Other Considerations . . . . . . . . . . . . . . . . . . . . . 14
10.1. Import/Export of Credentials . . . . . . . . . . . . . . . 14
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
13. Security Considerations . . . . . . . . . . . . . . . . . . . 15
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
15. Normative References . . . . . . . . . . . . . . . . . . . . . 15
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 15
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 16
Smith Expires March 29, 2014 [Page 3]
Internet-Draft ABFAB UI Considerations September 2013
1. Introduction
The use of ABFAB-based technologies requires that a user's device is
configured with their identities that they wish to use in ABFAB
transactions. Achieving this will require something on that device,
either built into the operating system or a standalone utility, that
will manage the user's identities and identity to service mappings.
Anyone designing that "something" will face the same set of
challenges. This document aims to document these challenges with the
aim of producing well-thought out UIs with some degree of
consistency.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Terminology
Various items of terminology used in the document are heavily
overloaded and thus could mean a variety of different things to
different people. In an attempt to minimise this problem, this
section gives a brief description of the main items of terminology
used in order to aid with a consistent understanding of this
document.
o NAI: Network Access Identifier - a standard way of identifying a
user. See [RFC4282].
o Identity: In this context, an identity is a credential given to a
user by a particular organisation with which they have an
association. A user MAY have multiple identities. The identity
will consist of an NAI, alongside other information that supports
authentication.
o Service: The thing that the user is attempting to authenticate to
via ABFAB technology. See [TODO: Link to ABFAB-Use-Cases] for
example use cases of what these services could be.
o Identity Selector: The mechanism by which the GSS-API acquires the
identity to use with a particular service. An Identity Selector
typically would allow the user to configure a set of identities
along with service to identity mappings.
o Trust anchor: An authoritative source of verification of a
particular service, used to allow authentication of a server using
X.509 [TODO: link]. Typically a commercial CA to allow
Smith Expires March 29, 2014 [Page 4]
Internet-Draft ABFAB UI Considerations September 2013
authentication via chain of trust, or a preconfigured non-
commercial certificate.
4. Context
When using the ABFAB architecture to perform federated authentication
to some service, when a user attempts to authenticate to an ABFAB
secured application they will need to provide identity information
that they wish to authenticate to that particular service with. This
will happen through a process of the application calling the GSS-API,
which will in turn gather the users credentials through whatever
mechanism it has been configured to do so. We will call this
mechanism the "identity selector" in this document, though note that
this is not a recommendation on terminology for the mechanism!
The simplest way to achieve the desired effect would be a mechanism
that simply takes the credentials from the currently logged in user
(e.g. the Windows Domain Credentials) and uses those for all services
that request authenticate through ABFAB. This approach gives
ultimate simplicity in terms of UI - i.e. it wouldn't have one - but
the least flexibility. If there is ever to be a requirement for a
user to use a different set of credentials for a service, then
something more complex will be needed.
Where there is a requirement for multiple credentials to be
supported, there are of course two methods that could be employed to
configure identities and associated information:
o They could be configured manually by a user in a configuration
file that could be edited by hand or some such simple mechanism,
and read by the GSS-API mechanism. While this could work very
well functionally, in practice only a small subset of users would
be happy with - and able to - configure their identities in such a
manner.
o They could be configured through some interactive mechanism. For
ease of use this should have a simple UI, although a headless mode
may need to be supported for those not using a GUI.
When designing an identity selector with a UI (or indeed, with a
headless mode), any implementer will share a common set of usability
considerations inherent to the context. This document aims to
explore these considerations, and provide advice and guidance on
addressing them where possible.
Smith Expires March 29, 2014 [Page 5]
Internet-Draft ABFAB UI Considerations September 2013
5. Considerations around Terminology
Anyone designing an identity selector will have to grapple with
choosing terminology that the average user has some chance of
understanding. This terminology can split into a few main functional
areas, as discussed next.
5.1. Identity
The first area where terminology is needed is around the identity/
identities of the user. Users are typically used to seeing a variety
of terms for aspects of their identity in the federated sense, and an
even larger variety in the wider internet sense. For example, in the
federated sense some of these terms include "username", "login",
"network account", "institutional account", "home organisation
account", "credentials", and a myriad of other such terms. However,
NAI - the technically correct name for their identity in an ABFAB
sense - is highly unlikely to be one of these terms that users are
used to seeing.
Implementers of an identity selector will need to carefully consider
their intended audience for both their level of technical capability
and the existing terminology that they may have been exposed to.
Beyond terminology, careful thought needs to be given to the paradigm
to use when presenting identity to users, as identities and services
are abstract concepts that some users may not find is easily
understandable. Implementers may wish to keep such abstract
concepts, or may wish to examine attempts to map to real world
paradigms, e.g. the idea of using "Identity Cards" that are held in
the user's "Wallet", as used by Microsoft Cardspace.
5.2. Services
Terminology around services is likely to be less of a problem than
identity, but it will actually depend on what the service is. For
example, each service could be simply described as "server",
"system", etc. But for simplicity just the word "service" will
probably suffice.
5.3. Identity to Service Mapping
Depending on your perspective either each identity may be mapped to
multiple services, or each service has multiple identities mapped to
it. Thus any UI could present either perspective, or both.
Smith Expires March 29, 2014 [Page 6]
Internet-Draft ABFAB UI Considerations September 2013
6. Considerations around Management of Identities
One of the core features of an identity selector is the management of
a user's identities. This section first looks at what information
associated with an identity will need to managed, and then looks in
detail at various usability considerations of this area.
6.1. Information associated with each Identity
There is firstly a minimal set of information that MUST be stored
about each identity to allow ABFAB authentication to take place:
o NAI: The user's Network Access Identifier (see [RFC4282]) for this
particular credentials. For example, "joe@example.com".
o Password: The password associated with this particular NAI.
o Trust anchor: For the identity selector to be able to verify that
the server it is going to talk to and attempt to authenticate
against is the server that it is expecting, and that it is not
being spoofed in some way. This is likely to be an X.509
certificate [TODO X509 ref], or a tuple of (trusted root
certificate, servername in Subject or subjectAltName).
Next up is a small set of information that SHOULD be stored about
each identity to allow the user to effectively select a particular
identity:
o Friendly name for identity: To allow the user to differentiate
between the set of identities represented in the Identity
Selector. This should be editable by the user. The only
restriction on this name is that it MUST be unique within that
particular user's set of identities. For example: "My
University", "Google Account", "Work Login", etc.
o Friendly icon for identity: To allow the user to differentiate
between the set of identities they have they should be able to set
an icon for that particular identity.
Finally, there is a set of optional information that MAY be stored
about each identity that represent useful information for the user to
have. Note that this list is not intended to be exhaustive; any
implementer is free to add any more items to their identity selector
that make sense in their implementation.
o Password changing URL: The URL the user should visit should they
need to change their password for this particular identity. For
example, "http://www.example.com/passwordreset".
Smith Expires March 29, 2014 [Page 7]
Internet-Draft ABFAB UI Considerations September 2013
o Helpdesk URL: The URL the user should visit to get contact details
for the helpdesk of the organisation that issued this particular
identity for when the user encounters issues and needs help. For
example, https://www.exmaple.com/helpdesk.
6.2. Adding/Association of an Identity
Users will have one or more identities given to them by organisations
that they have a relationship with. One of the core tasks of an
identity selector will be to learn about these identities in order to
use them when it comes to authenticating to services on behalf of the
user. Adding these identities could be done in one of three ways:
manual addition, automated addition that is manually triggered, or
automated addition that is automatically triggered. Each of these
are discussed in more detail next.
Note that the term "association" or "addition" of an identity is used
rather than "provisioning" of an identity, because while we actually
are provisioning identities into the UI, provisioning is an
overloaded term in the identity and access management space and could
easily be confused with identity provisioning in the sense of the
creation of the identity by the home organisation's identity
management procedures.
6.2.1. Manual Addition
Allowing users to manually add an identity is technically the easiest
method to get this information, but it is a method that has the
greatest usability drawbacks. Most of the information required is
relatively technical and finding some way of explaining what each
field is to an non-technical audience is challenging (to say the
least). This especially is the case for trust anchor information.
Thus this method should be considered as a power-user option only, or
as a fall-back should the other methods not be applicable.
When this method is used, careful consideration should be given to
the UI presented to the user. The UI will have to ask for all of the
information detailed in Section 6.1.
There are two points at which a user could manually add an identity:
o Asynchronously: the user could be allowed to, at any time, trigger
a workflow of manually adding an identity. This represents the
most flexible way of adding an identity since a user can perform
this at any time. It does, however, have inherent issues when it
comes to verifying the newly added identity - see Section 6.4.
Smith Expires March 29, 2014 [Page 8]
Internet-Draft ABFAB UI Considerations September 2013
o Just In Time: when connecting to a service which has no mapping to
an existing identity, the user could be given an option to add a
new one, as well as associating with an existing one. This
presents a better user experience when it comes to verifying the
newly added identity (see Section 6.4), however, represents a less
direct method of adding an identity. Users who have not yet added
the appropriate identity to their identity selector may find it
difficult to understand that they must try to access a particular
service in order to add an identity.
Of course, implementers could support both styles of identity
addition to gain the benefits of both and give flexibility to the
user.
One item worthy of discussion here is the area of verification of
trust anchors. An Identity Selector SHOULD try to ensure that manual
addition of an identity and checking of the relevant trust anchors is
done as securely as possible, whereby users have to enter and confirm
all trust anchor information, or be required to explicitly agree to
an insecure configuration if this is not done properly.
6.2.2. Manually Triggered Automated Addition
One way to bypass the need for manual addition of a user's identity -
and all of the usability issues inherent with that approach - is to
provide some sort of manually triggered, but automated, provisioning
process.
One approach to accomplishing this, for example, could be for an
organisation to have a section on their website where their users
could visit, enter the user part of their NAI, and be given piece of
provisioning data that contains much or all of the relevant identity
information for importing into the identity selector.
It is reasonable to assume that any such provisioning service is
likely to be organisation specific, so that the Issuing Organisation
and realm part of the NAI will be constant, as would be the trust
anchor information. The user part of their NAI will have been input
on the web service. The password could be provided as a part of the
provisioning file or the identity selector could prompt the user to
enter it.
Additionally, the user SHOULD be given the opportunity to:
o Supply or change the default friendly name for that identity - to
allow the user to customise the identifier they use for that
identity;
Smith Expires March 29, 2014 [Page 9]
Internet-Draft ABFAB UI Considerations September 2013
o Indicate whether or not the identity selector should always ask
before using services with this identity - to customise the way in
which the identity selector interacts with the user with this
particular identity;
o Reject the addition of the identity completely - to allow the user
to back out of the association process in an intuitive way.
In this case, trust anchors could be directly provided through the
provisioning mechanism to help establish the trust relationship in a
secure manner.
6.2.3. Fully Automated Addition
Many organisations manage the machines of their users using
enterprise management tools. Such organisations may wish to be able
to automatically add a particular user's identity to the identity
selector on their machine/network account so that the user has to do
nothing.
This represents the best usability for the user - who wouldn't
actually have to do anything. However, it can only work on machines
centrally managed by the organisation.
Additionally, having an identity automatically provided, including
its password, does have some particular usability issues. Users are
used to having to provide their username and password to access
services. When attempting to access services, authenticating to them
completely transparently to the user could represent a source of
confusion. User training within an organisation to explain that
automated provisioning of their identity has been enabled is the only
way to counter this.
6.3. Modifying Identity Information
This process is conceptually fairly similar to adding an identity,
and thus shares many of the usability issues with that process. Some
particular things are discussed here.
6.3.1. Manual Modification
An identity selector may allow a user to manually modify some or all
of the information associated with each identity. The obvious item
that MUST be allowed to be changed by the user is the password
associated with the identity.
Smith Expires March 29, 2014 [Page 10]
Internet-Draft ABFAB UI Considerations September 2013
6.3.2. Automated Modification
To ease usability, organisations may wish to automatically provide
updates to identity information. For example, if the user's password
changes, it could automatically update the password for the identity
in the user's identity selector.
6.4. Verifying an identity
An inherent by-product of the ABFAB architecture is that an identity
cannot be verified during the addition process; it can only be
verified while it is in use with a real service. This represents a
definite usability issue no matter which method of identity addition
is used (see Section 6.2):
o If the user has manually added the identity (see Section 6.2) they
may have gone through the whole manual process with no errors and
so believe the identity has been set up correctly. However, when
they attempt to access a service, they may be given an error
message, thus causing some amount of confusion.
o If the user has had the identity provisioned into their identity
selector, then there is a much greater chance of the identity
information being correct. However, if any of the information is
not correct, then there is the potential for confusion as the user
did not add the information in the first place.
Also, if the identity information is incorrect the user may not know
where the error lies, and the error messages provided by the
mechanism may not be helpful enough to indicate the error and how to
fix it (see Section 8).
6.5. Removing an Identity
This is fairly similar to adding or modifying an identity, and thus
shares many of the usability issues with those processes. Some
particular things are discussed here.
6.5.1. Manual Removal
Allowing the user to manually delete an identity is probably the best
way to achieve the goal. Any UI should allow for this option.
6.5.2. Automated Removal
While automated removal of an identity is a way of achieving the goal
without having to interact with the user, the consequence is that
things may disappear from the user's identity selector without them
Smith Expires March 29, 2014 [Page 11]
Internet-Draft ABFAB UI Considerations September 2013
realising.
7. Considerations around Management of Service to Identity Mappings
A service to identity mapping tell the identity selector which
identity should be used for a particular service. There is
potentially a many-to-many association between identities and
services since a user may wish to use one of their identities for
many services, or more than one identity for a single service (e.g.
if they have multiple roles on that service).
This potentially complex many-to-many association between is not
easily comprehended by the user, and allowing the user to both
manipulate it and control can be challenging. These obstacles are
especially common when errors occur after an association has been
made. In this scenario it is important that an identity can be
disassociated with a service.
7.1. Listing Services and Identities
A service listing should be considered in the identity selector which
is both searchable and editable by the user.
7.2. Showing the Identity currently in use
It would be beneficial if, when using a service, the identity
currently in use could be made visible to the user while he/she is
using a specific service. This allows the user to identify which the
identity is used with a particular service at a particular time (the
user may have more than one identity that they could use with a
particular service) - so that they can then disassociate the pairing.
7.3. Associating a Service with an Identity
There needs to be a way for the user to create the service to
identity association. It is advisable that this link be made only
after the identity in question has authenticated with the service
without any error.
There are a few ways this association could happen.
7.3.1. User-driven Manual Association
There are two ways in which manual association of an identity to a
service could happen:
1. The user could manually associate a particular service with a
particular identity using the identity selector before they first
Smith Expires March 29, 2014 [Page 12]
Internet-Draft ABFAB UI Considerations September 2013
attempt to use the service. In order to do so, however, the user
would need to know all the required technical details of that
service beforehand, such as its GSS Acceptor Name.
2. On encountering a service new to the identity selector, the
identity selector could pop up a dialogue box to the user asking
if they would like to use an existing identity for this service
(and might also allow them to create a new identity and use
that).
7.3.2. Automated Rules-based Association
It would be beneficial from a usability perspective to minimise - or
avoid entirely - situations where the user has to pick an identity
for a particular service. This could be accomplished by having rules
to describe services and their mapping to identities. Such a rule
could match, for example, a particular identity for all IMAP servers,
or a particular identity for all services in a given service realm.
These rules could be configured as a part of the automated identity
addition process described in Section 6.2.2 or Section 6.2.3
7.4. Disassociating a Service with an Identity
A user MUST be able to disassociate an identity with a service - that
is, to be able to remove the mapping without having to remove the
identity.
There should also be provision for the automated disassociation of an
identity with a service for appropriate types of authentication
failures.
8. Handling of Errors
All GSS-API calls need to be instantiated from the application. For
this reason when an error occurs the user needs to be sent back to
the application to re-initiate the GSS-API call. This can get
tedious and cause the user to opt out of what they are trying to
accomplish. In addition to this the error messages themselves may
not be useful enough for the user to decipher what has gone wrong.
It is important to try and avoid error cases all together while using
GSS-API as error messages and error handling can really effect
usability. Another solution would be to alter the application to
handle the errors as it is instantiating the GSS-API communication.
TODO: Lots more to discuss here...
Smith Expires March 29, 2014 [Page 13]
Internet-Draft ABFAB UI Considerations September 2013
8.1. Identity Association/Verification Errors
TODO: e.g. wrong password, bad trust anchors, etc. TODO.
8.2. Service Errors
TODO: e.g. identity is correct but no authorisation. TODO.
8.3. Other Errors.
TODO: e.g. network errors. TODO.
9. Handling of Successes
It is of course hoped that the identity selector will have to
occasionally handle successes as well as errors. This section has
some brief discussion about some areas you might want to think about.
9.1. Reporting Authentication Success on First Use of Identity
The first time an identity is used with a service, it would be good
practice to visually indicate in some way that the process has been
successful, in order that the user understands what is happening and
is then prepared for future authentication attempts.
9.2. Reporting Authentication Success
On an on-going basis you may or may not wish to indicate visually to
the user a successful authentication to a service. This relates to
Section 7.2.
10. Other Considerations
This section briefly discusses other considerations that you might
want to think about that don't fit in any of the other categories.
10.1. Import/Export of Credentials
For various reasons, an identity selector implementation might want
to include functionality that allows for the export/import of
identities and service to identity mappings. This could be for
backup purposes, to allow a degree of mobility between identity
selector instances, etc.
If providing this functionality, it would be advisable that the
credential store that is the result of the export should be secure -
encrypted and password protected - given the nature of the
information.
Smith Expires March 29, 2014 [Page 14]
Internet-Draft ABFAB UI Considerations September 2013
11. Contributors
The following individuals made important contributions to the text of
this document: Sam Hartman (Painless Security LLC), and Maria Turk
(Codethink Ltd).
12. Acknowledgements
Jim, Stefan.
13. Security Considerations
TODO
14. IANA Considerations
This document does not require actions by IANA.
15. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
Network Access Identifier", RFC 4282, December 2005.
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 -03 to draft -04
1. Addressing various comments from Jim and Stefan.
Draft -02 to draft -03
1. Bumping version to keep it alive.
Draft -01 to draft -02
1. Completed the major consideration sections, lots of rewording
throughout.
Draft -00 to draft -01
1. None, republishing to refresh the document. Other than adding
this comment...
Smith Expires March 29, 2014 [Page 15]
Internet-Draft ABFAB UI Considerations September 2013
Appendix B. Open Issues
Note to RFC Editor: please remove this appendix before publication as
an RFC.
Author's Address
Dr. Rhys Smith
Cardiff University
39-41 Park Place
Cardiff CF10 3BB
United Kingdom
Phone: +44 29 2087 0126
EMail: smith@cardiff.ac.uk
Smith Expires March 29, 2014 [Page 16]
