Assurance

["Herrington, Karen" <>]

The MFA Interoperability Profile Working Group discussed this issue in its call last week, and we'd like some more input from all of you.  Here’s a summary of that discussion, followed by some questions for you.

 

Summary of Last Week’s Discussion

There is a cost to creating entity categories.  While it is relatively easy to define them (what the group has to do), there is also a cost to InCommon to modify its documentation and Federation Manager software.  Further, assuming this becomes an international profile, all federations will bear that cost.  Finally, this startup cost may be dwarfed by the ongoing effort on the part of IdP and SP operators, who must understand an increasing number of entity categories and react as appropriate.

 

So, we need to ensure that new entity categories bring value.  These use cases have been identified for the use of an MFA entity category for IdPs:

 

1. Enable an SP to filter its discovery interface based on whether an IdP supports MFA.
2. Reduce the number of authentication requests an SP must issue to an IdP for certain types of error handling when MFA is desired, but other forms of authentication are acceptable.
3. Provide a formal mechanism for an institution to declare its compliance with the MFA profile (or perhaps a future stronger MFA profile).
4. Provide a workaround for SPs to avoid IdPs that do not behave as expected within the SAML spec.  For example, they respond incorrectly to requests for specific authentication contexts (or they do not respond at all), or they crash.

 

The group had not previously discussed the discovery issue, but recognizes its importance; it’s likely the most significant reason for defining an entity category.  The group had earlier decided that the potential additional authentication requests didn’t warrant an entity category, and that formal declaration of compliance was not necessary.  The fourth issue of IdP behavior is broader than just the profiles defined by this group, and so out of scope, but it was recognized that definition of an MFA entity category would address that issue in this narrow instance.

 

Questions for You

1. If we define an MFA entity category, what should its criteria be?  The group discussed the following:

1. What does it mean for an IdP to “support MFA?”  Is it the ability to issue assertions in compliance with the MFA profile for at least one member of its community?  Something else?
2. Should the ability to issue assertions in compliance with the Base Level profile also be included so that SPs that prefer MFA but will accept anything else can do that with a single authentication request?  This would imply that the ability to assert Base Level be required of all members of the IdP’s community.
1. Would a formal institutional declaration of compliance with the MFA profile cause you to trust its MFA assertions more?  Could that declaration be as simple as a box in the Federation Manager that would be checked by the site administrator, or should further documentation be required?

 

Thanks for your input,

Karen Herrington

Chair, MFA Interoperability Profile Working Group