Mike Jones: self-issued

Musings on Digital Identity

Month: August 2008

PPID Compatibility Note for Sites Accepting Self-Issued Information Cards

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On August 27, 2008

In Documentation, Information Cards, Interoperability, Windows CardSpace

Information Card IconRelying Parties often identify subjects using the Private Personal Identifier (PPID) claim and Signing Key values sent by an Information Card. Thus, it is important that the PPID and Signing Key values produced by a card be stable and long-lived.

Unfortunately, the PPIDs and Signing Keys generated by self-issued (a.k.a. personal) Information Cards using the algorithm originally shipped with Windows CardSpace (and documented in ISIP V1.0) for sites using regular certificates were not stable under several important conditions. Therefore, after considering industry feedback on the long-term problems that this continued instability would cause, and in consultation with other Identity Selector authors, a decision was made to change these algorithms in a way that will provide much better long-term stability of these important Subject identifiers for Relying Parties. The new algorithm is documented in the Identity Selector Interoperability Profile (ISIP) V1.5.

This change shipped with the version of Windows CardSpace in the .NET Framework 3.5 Service Pack 1. This service pack will be installed by Windows Update on systems with the .NET Framework 2.0, 3.0, and 3.5 in the coming months. I know that the Bandit and Higgins projects have implemented the new algorithm as well.

Unfortunately, this change means that the PPIDs and Signing Keys for self-issued cards used at existing Relying Parties that employ standard SSL certificates will change after this installation.

What Sites Need to Do

Sites need to ensure that they have tested mechanisms in place to enable their users to re-associate their Information Card with their account when the card’s PPID and Signing Key change. The good news is that these mechanisms are likely already in place in the form of “lost card” handling procedures.

When the card is used after the update, it will appear to be an unrecognized card. Just as sites’ lost card procedures can be used today to associate a new Information Card with their account, these same procedures can be used to re-associate the existing card with the account after these changes.

These lost card procedures will typically involve sending the user a message at the e-mail address of record for the account. This message contains a link that enables them to associate an Information Card with their account. This flow is nearly identical to the “lost password” flows often found on sites. Best practices for lost card handling are documented in the “Enabling Information Card Recovery” section of Patterns for Supporting Information Cards at Web Sites: Personal Cards for Sign up and Signing In.

Additional Steps Sites Could Take

In the short term, sites could also choose to add text to their Information Card login pages warning users that their existing cards will not be recognized as being associated with their accounts after the .NET update, and directing them to use the “lost card” feature of the site to remedy this situation.

EV and no-SSL Sites Not Affected

None of this affects sites using Extended Validation (EV) certificates or sites not using SSL certificates. These algorithms were already stable and have not changed. No action is required in these cases.

Background on the Problem

Because the original PPID and Signing Key algorithms used the entire certificate chain, these values could change under several circumstances:

  • First, as sites renew their certificates, it is common for the certificate chain for the new cert to differ from the old one. This would change the PPID, breaking the user’s self-issued cards at those sites. And of course, the chain always changes if the site changes its certificate provider.
  • Second, because the algorithm for converting the bytes of the chain certificates into characters was not fully specified by ISIP V1.0 for some OIDs, for some kinds of certificates, different Identity Selectors produced different results for the PPID claim, Signing Key, Client Pseudonym PPID, and IP Identifier values.
  • Finally, in ISIP V1.0, the PPID for a site using a non-EV certificate is different than the PPID for a site that uses an EV certificate, even in the case where the non-EV leaf cert content meets the EV issuance criteria. This means that when a site upgraded to using an EV certificate, user’s cards would stop working at that site.

Overview of the Solution

To address these issues, the computation of the PPID and Signing Key for sites using regular certificates has been changed to no longer include information from the certificate chain, but only information from the leaf certificate. This will provide stability both when certificates are renewed and when a certificate is obtained from a new issuer.

Furthermore, the new algorithm generates the same PPID values for sites using EV and non-EV certificates with the same leaf certificate information, while generating different Signing Keys. This will help enable a smooth migration path for sites upgrading from non-EV to EV certificates because the PPID remaining the same can be used as evidence that the same card is being used before and after the certificate upgrade.

More about the specifics of the algorithm change can be found in Section 8.6.1 of ISIP V1.5 and additional guidance and commentary can be found in the corresponding section of the ISIP V1.5 Guide.

WS-Addressing Identity Extension Published

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On August 27, 2008

In Documentation, Information Cards, Interoperability, Specifications, Windows CardSpace

Information Card IconIBM and Microsoft just published the specification “Application Note: Web Services Addressing Endpoint References and Identity” at http://schemas.xmlsoap.org/ws/2006/02/addressingidentity/. This specification is referenced by the Identity Selector Interoperability Profile (ISIP) and is covered by Microsoft’s Open Specification Promise (OSP). This completes the publication and licensing under the OSP of all specifications that Information Cards based upon the ISIP depend upon.

Note: While ISIP 1.5 references the addressing identity extension using a date of July 2008, it was actually published in August. This is an erratum in the ISIP that resulted from the publication of the extension taking longer than anticipated — not a reference to a different document. Both consistently use the URL http://schemas.xmlsoap.org/ws/2006/02/addressingidentity/.

Analysis of the Third OSIS User-Centric Identity Interop

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On August 23, 2008

In Information Cards, Interoperability, OpenID

OSIS logoCongratulations and thanks to Pamela Dingle for publishing a detailed analysis of what that the industry accomplished together during the Third OSIS User-Centric Identity Interop (I3). As Nulli Secundus writes about the paper:

The OSIS I3 Interop was a five-month event in which organizations, individuals, and projects working in the solution spaces of Information Cards and OpenID collaborated to define and demonstrate their ability to transact successfully regardless of differences in hardware or software platform. Participants worked within each solution space to define and test acceptable behaviors for various situations that crop up when loosely coupled solutions communicate with each other via open protocols. Interop participants created results within two different matrices: feature test results which recorded adherence to acceptable behavior when explicitly tested, and cross-solution results which recorded overall interoperability between solutions with complimentary roles. Combined, the participants recorded over 1200 mostly successful results.

As new solutions enter this space and existing solutions add to their feature sets, the OSIS Interop process and results serve as a metric to inform developers what features will contribute to a consistent experience for users and administrators. OSIS Interops have served as a focal point for discussion and feature concentration and a forcing function to solidify the protocols. Overall, much was accomplished but there is still work to be done. By examining participation, contribution to best practices, process and collaboration, discoveries, and obstacles, the Interop process can be refined and improved to give even more value to those involved; by doing so, diversity in product offerings will not result in difficulty for end users.

Many of the learnings and conclusions that Pamela has captured in the paper have informed the Fourth OSIS User-Centric Identity Interop (I4), which is under way and builds on the accomplishments of I3 and the previous interops. Check out the paper and if you have an implementation of Information Card or OpenID software, the time is now to participate in I4!

Identity Selector Interoperability Profile V1.5

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On August 11, 2008

In Documentation, Information Cards, Interoperability, Specifications, Windows CardSpace

Information Card IconI am pleased to announce the publication of the Identity Selector Interoperability Profile V1.5 and companion guides. The ISIP (as it’s come to be called) documents the protocols and data formats used by Windows CardSpace so as to enable others to build compatible Information Card software.

Version 1.0 of these documents corresponded to the.NET Framework 3.0 version of CardSpace. Version 1.5 corresponds to CardSpace as of .NET Framework 3.5 Service Pack 1. Like the previous version, ISIP 1.5 is licensed under Microsoft’s Open Specification Promise.

Significant new content covers:

  • Relying Parties without SSL certificates
  • Use of WS-Trust 1.3 and WS-SecurityPolicy 1.2
  • Relying Party STSs
  • More stable PPID algorithm
  • Specifications for computing ic:IssuerId and ic:IssuerName
  • Token references by Identity Providers via wst:RequestedAttachedReference and wst:RequestedUnattachedReference elements
  • Custom issuer information in cards
  • Custom error messages
  • Clarification that an ic:MasterKey is required for managed cards
  • Plus numerous of clarifications that were found by others building Information Card software — especially during the OSIS interops

The three new document versions are:

Thanks to the literally dozens of you who provided comments on ways to improve the ISIP and companion docs and who reviewed drafts of this material. This version of the docs benefited substantially from your detailed knowledge of and experience with the previous spec gained through implementing interoperable Information Card software.

Finally, I’d like to thank the members of the CardSpace team who diligently documented many of these features on the CardSpace Team Blog in advance of their publication under the ISIP. Your work let the industry gain early experience with implementing these features and was a tremendous resource to me as I was producing these versions of the documents.

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