DRAFT
The Service Provider Assurance policy requirements can be expressed in several use cases. Below is a list of the tested cases requested by SPs intending to request qualifiers in 2012.
UC0: SP Requires Silver
The SP requires InCommon Silver LOA.
The SP includes http://id.incommon.org/assurance/silver in the SAML RequestedAuthnContext element. It accepts assertions that contain http://id.incommon.org/assurance/silver in the AuthnContext from IdPs with http://id.incommon.org/assurance/silver in InCommon metadata.
Commentary:
As usual, the SP should intelligently handle errors. In particular, the SP should be prepared to handle the case that not all users at a particular IdP may be eligible for Silver LOA (for example, users not vetted at Silver), so even if the IdP is tagged with http://id.incommon.org/assurance/silver in InCommon metadata, authentication for some users may result in an "AuthnFailed" response.
As an optimization, the SP may avoid issuing requests to IdPs that are not accredited at Silver, since these requests would always be rejected later anyway. The SP may locally block ("short-circuit") requests of this type. The SP may provide a local discovery interface that lists only IdPs with http://id.incommon.org/assurance/silver in InCommon metadata to constrain users to only choose Silver accredited IdPs.
Examples:
- NSC Meteor Access for Financial AId
UC1: SP Requires Bronze
The SP requires InCommon Bronze LOA (or higher).
The SP includes http://id.incommon.org/assurance/silver and http://id.incommon.org/assurance/bronze in the SAML RequestedAuthnContext element. It accepts either:
- Assertions that contain http://id.incommon.org/assurance/silver in the AuthnContext from IdPs with http://id.incommon.org/assurance/silver in InCommon metadata, or
- Assertions that contain http://id.incommon.org/assurance/bronze in the AuthnContext from IdPs with http://id.incommon.org/assurance/bronze in InCommon metadata
Commentary:
As usual, the SP should intelligently handle errors. In particular, the SP should be prepared to handle the case that not all users at a particular IdP may be eligible for Silver or Bronze (for example, users not vetted at the Silver or passwords too weak for Bronze), so even if the IdP is tagged with http://id.incommon.org/assurance/silver or http://id.incommon.org/assurance/bronze in InCommon metadata, authentication for some users may result in an "AuthnFailed" response.
Examples:
- The InCommon Federation Manager (FM)
- The InCommon Certificate Manager (CM)
The FM and the CM recognize Bronze password credentials as the first factor of a two-factor authentication. The InCommon Operations Identity Provider is authoritative for the second "what you have" factor.
UC2: SP Prefers Silver
The SP must operate in a world where not all IdPs can yet provide Silver assertions, and Silver-capable IdPs can't provide Silver assertions for all users/circumstances. In cases where lower LOA assertions are used, the SP restricts access/functionality and/or implements other compensating controls. The SP wants to get Silver assertions whenever possible. The SP can determine which IdPs are Silver-capable from metadata.
SP includes http://id.incommon.org/assurance/silver in the SAML RequestedAuthnContext element. If the IdP returns an assertion containing http://id.incommon.org/assurance/silver in the AuthnContext, the SP checks that the IdP has http://id.incommon.org/assurance/silver in its InCommon metadata, and if the check passes, the SP considers the authentication to be at the Silver level. Alternatively, if the IdP returns an "AuthnFailed" response, possibly indicating the particular user is not Silver qualified, the SP makes a new request without a RequestedAuthnContext element, for a lower LOA authentication. Ideally the user will not be prompted to authenticate a second time for this second request by the SP, i.e., the IdP has set a cookie in the user's browser.
As an optimization, the SP may choose to look in InCommon metadata and not include a SAML RequestedAuthnContext element in requests to IdPs that are not Silver accredited.
Examples:
- CILogon