Hi,

 

The reason I write this mail is that some of us CAS users in Sweden has
found that different application needs different assurance levels regarding
the authentication handler and the user identity. For example a personalized
page may just need an simple self asserted identity, a student portal need
an proofed identity with a username and password login and a web page where
examiner report the students results may need a onetime password (OTP) or
certificate login. What we can see there is a good “industry standard” for
level of assurance in the combination of OMB M-04-04
(http://www.whitehouse.gov/omb/memoranda/fy04/m04-04.pdf) and NIST SP800-63
(http://csrc.nist.gov/publications/nistpubs/800-63/SP800-63V1_0_2.pdf). To
go the technical way to say that we demand OTP for login or
username/password for login due to the fact that the login technique changes
via time and is a question for the CAS server not the application server. So
what we want to do is to make CAS level of assurance aware and we want to
hear what the rest of the CAS community has to say about this idea. And if
it’s feasibly to include in CAS.

 

To use multiple CAS installations to accommodate this functionality is not a
very good solution due to that than you need to install, configure and
support multiple CAS installations. Furthermore the application deployers
must think more than once when they configure which CAS server that should
be used for the application.

 

The solution is to add an optional parameter demandLoA to the /login
credential requestor to demand a lowest combined level of assurance for the
authentication. The combined level of assurance in this scenario is the
lowest level of assurance of the areas registration and identity proofing,
credential management and tokens used for proving identity. The other two
areas in NIST level of assurance must be seen in the light of CAS itself. If
the optional parameter is not available in the /login URI then a predefined
level of assurance should be used.

 

To evaluate the registration and identity proofing level of assurance CAS
need to know about under what level of assurance a specific user got his
electronic identity. This can be done for example via the LDAP attribute
defined in FAME-PERMIS Definition of the LoA Attribute
(http://www.fame-permis.org/loa.html) or predefined for all users in the
configuration for CAS.

 

To set the level of assurance for credential management I think it should be
sufficient to predefine it in the configuration per identity provider that
is used in the CAS installation.

 

What authentication handler, or handlers, that is valid for each level of
assurance should be defined in the configuration of CAS.

 

The login page must be configured to handle multiple authentication handlers
and present a choice of authentication handler where the combined level of
assurance is equal or higher than the demanded level of assurance.

 

 

Pål Axelsson, Uppsala universitet, for SWAMI* CAS Special Interest Group

*Swedish Alliance for Middleware Infrastructure, SWAMI, is the organization
for middleware cooperation in the Swedish higher education community.
(http://www.swami.se)

 

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