Archive for the 'Cryptography' Category

August 28, 2015
Proof-of-Possession Key Semantics for JWTs spec addressing remaining comments

OAuth logoProof-of-Possession Key Semantics for JWTs draft -04 addresses the remaining working group comments received – both a few leftover WGLC comments and comments received during IETF 93 in Prague. The changes were:

  • Allowed the use of “jwk” for symmetric keys when the JWT is encrypted.
  • Added the “jku” (JWK Set URL) member.
  • Added privacy considerations.
  • Reordered sections so that the “cnf” (confirmation) claim is defined before it is used.
  • Noted that applications can define new claim names, in addition to “cnf”, to represent additional proof-of-possession keys, using the same representation as “cnf”.
  • Applied wording clarifications suggested by Nat Sakimura.

The updated specification is available at:

An HTML formatted version is also available at:

August 9, 2015
JWS Unencoded Payload Option specification

IETF logoThe former JWS Signing Input Options specification has been renamed to JWS Unencoded Payload Option to reflect that there is now only one JWS Signing Input option defined in the spec – the “b64″:false option. The “sph” option was removed by popular demand. I also added a section on unencoded payload content restrictions and an example using the JWS JSON Serialization.

The specification is available at:

An HTML formatted version is also available at:

July 23, 2015
JWS Signing Input Options initial working group draft

IETF logoThe initial working group version of JWS Signing Input Options has been posted. It contains no normative changes from draft-jones-jose-jws-signing-input-options-00.

Let the working group discussions begin! I particularly call your attention to Martin Thomson’s review at http://www.ietf.org/mail-archive/web/jose/current/msg05158.html, Nat Sakimura’s review at http://www.ietf.org/mail-archive/web/jose/current/msg05189.html, and Matias Woloski’s review at http://www.ietf.org/mail-archive/web/jose/current/msg05191.html to start things off.

The specification is available at:

An HTML formatted version is also available at:

July 13, 2015
JWK Thumbprint -08 approved by IESG

IETF logoThe IESG has approved JWK Thumbprint draft -08, meaning that it will now progress to the RFC Editor. Draft -08 added IANA instructions in response to an IESG comment by Barry Leiba.

The specification is available at:

An HTML formatted version is also available at:

July 7, 2015
JWK Thumbprint -07 draft addressing Gen-ART review comment

IETF logoJWK Thumbprint draft -07 has been published, addressing a Gen-ART review comment by Joel Halpern. Beyond updating the acknowledgements, the only change was replacing this sentence:

“Only if multiple parties will be reproducing the JWK Thumbprint calculation for some reason, will parties other than the original producer of the JWK Thumbprint need to know which hash function was used.”

with these two:

“However, in some cases, multiple parties will be reproducing the JWK Thumbprint calculation and comparing the results. In these cases, the parties will need to know which hash function was used and use the same one.”

The specification is available at:

An HTML formatted version is also available at:

July 7, 2015
Proof-of-Possession Key Semantics for JWTs spec addressing WGLC comments

OAuth logoThe editors have published draft-ietf-oauth-proof-of-possession-03, which addresses the working group last call comments received. Thanks to all of you who provided feedback. The changes were:

  • Separated the jwk and jwe confirmation members; the former represents a public key as a JWK and the latter represents a symmetric key as a JWE encrypted JWK.
  • Changed the title to indicate that a proof-of-possession key is being communicated.
  • Updated language that formerly assumed that the issuer was an OAuth 2.0 authorization server.
  • Described ways that applications can choose to identify the presenter, including use of the iss, sub, and azp claims.
  • Harmonized the registry language with that used in JWT [RFC 7519].
  • Addressed other issues identified during working group last call.
  • Referenced the JWT and JOSE RFCs.

The updated specification is available at:

An HTML formatted version is also available at:

June 24, 2015
JWK Thumbprint -06 addressing SecDir review comments

IETF logoA new JWK Thumbprint draft has been posted addressing the IETF Security Directorate (SecDir) comments from Adam Montville. The changes clarify aspects of the selection and dissemination of the hash algorithm choice and update the instructions to the Designated Experts when registering JWK members and values.

The specification is available at:

An HTML formatted version is also available at:

May 27, 2015
JWS Signing Input Options Specification

IETF logoThere’s been interest being able to not base64url-encode the JWS Payload under some circumstances by a number of people. I’ve occasionally thought about ways to accomplish this, and prompted again by discussions with Phillip Hallam-Baker, Martin Thomson, Jim Schaad, and others at IETF 92 in Dallas, recollections of conversations with Matt Miller and Richard Barnes on the topic, and with Anders Rundgren on the JOSE mailing list, I decided to write down a concrete proposal while there’s still a JOSE working group to possibly consider taking it forward. The abstract of the spec is:

JSON Web Signature (JWS) represents the payload of a JWS as a base64url encoded value and uses this value in the JWS Signature computation. While this enables arbitrary payloads to be integrity protected, some have described use cases in which the base64url encoding is unnecessary and/or an impediment to adoption, especially when the payload is large and/or detached. This specification defines a means of accommodating these use cases by defining an option to change the JWS Signing Input computation to not base64url-encode the payload.

Also, JWS includes a representation of the JWS Protected Header and a period (‘.’) character in the JWS Signature computation. While this cryptographically binds the protected Header Parameters to the integrity protected payload, some of have described use cases in which this binding is unnecessary and/or an impediment to adoption, especially when the payload is large and/or detached. This specification defines a means of accommodating these use cases by defining an option to change the JWS Signing Input computation to not include a representation of the JWS Protected Header and a period (‘.’) character in the JWS Signing Input.

These options are intended to broaden the set of use cases for which the use of JWS is a good fit.

The specification is available at:

An HTML formatted version is also available at:

May 27, 2015
Tightened Key Managed JWS Spec

IETF logoThe -01 version of draft-jones-jose-key-managed-json-web-signature tightened the semantics by prohibiting use of “dir” as the “alg” header parameter value so a second equivalent representation for content integrity-protected with a MAC with no key management isn’t introduced. (A normal JWS will do just fine in this case.) Thanks to Jim Schaad for pointing this out. This version also adds acknowledgements and references the now-final JOSE RFCs.

This specification is available at:

An HTML formatted version is also available at:

May 27, 2015
JWK Thumbprint -05 draft addressing issues raised in Kathleen Moriarty’s AD review

IETF logoThis JWK Thumbprint draft addresses issues raised in Kathleen Moriarty’s AD review of the -04 draft. This resulted in several useful clarifications. This version also references the now-final JOSE RFCs.

The specification is available at:

An HTML formatted version is also available at:

May 19, 2015
The OAuth Assertions specs are now RFCs!

OAuth logoThe OAuth Assertions specifications are now standards – IETF RFCs. They are:

  • RFC 7521: Assertion Framework for OAuth 2.0 Client Authentication and Authorization Grants
  • RFC 7522: Security Assertion Markup Language (SAML) 2.0 Profile for OAuth 2.0 Client Authentication and Authorization Grants
  • RFC 7523: JSON Web Token (JWT) Profile for OAuth 2.0 Client Authentication and Authorization Grants

This completes the nearly 5 year journey to create standards for using security tokens as OAuth 2.0 authorization grants and for OAuth 2.0 client authentication. Like the JWT and JOSE specs that are now also RFCs, these specifications have been in widespread use for a number of years, enabling claims-based use of OAuth 2.0. My personal thanks to Brian Campbell and Chuck Mortimore for getting the ball rolling on this and seeing it through to completion, to Yaron Goland for helping us generalize what started as a SAML-only authorization-grant-only spec to a framework also supporting client authentication and JWTs, and to the OAuth working group members, chairs, area directors, and IETF members who contributed to these useful specifications.

May 19, 2015
JWT and JOSE are now RFCs!

IETF logoThe JSON Web Token (JWT) and JSON Object Signing and Encryption (JOSE) specifications are now standards – IETF RFCs. They are:

This completes a 4.5 year journey to create a simple JSON-based security token format and underlying JSON-based cryptographic standards. The goal was always to “keep simple things simple” – making it easy to build and deploy implementations solving commonly-occurring problems using whatever modern development tools implementers chose. We took an engineering approach – including features we believed would be commonly used and intentionally leaving out more esoteric features, to keep the implementation footprint small. I’m happy to report that the working groups and the resulting standards stayed true to this vision, with the already widespread adoption and an industry award being testaments to this accomplishment.

The origin of these specifications was the realization in the fall of 2010 that a number of us had created similar JSON-based security token formats. Seemed like it was time for a standard! I did a survey of the choices made by the different specs and made a convergence proposal based on the survey. The result was draft-jones-json-web-token-00. Meanwhile, Eric Rescorla and Joe Hildebrand had independently created another JSON-based signature and encryption proposal. We joined forces at IETF 81, incorporating parts of both specs, with the result being the -00 versions of the JOSE working group specs.

Lots of people deserve thanks for their contributions. Nat Sakimura, John Bradley, Yaron Goland, Dirk Balfanz, John Panzer, Paul Tarjan, Luke Shepard, Eric Rescorla, and Joe Hildebrand created the precursors to these RFCs. (Many of them also stayed involved throughout the process.) Richard Barnes, Matt Miller, James Manger, and Jim Schaad all provided detailed input throughout the process that greatly improved the result. Brian Campbell, Axel Nennker, Emmanuel Raviart, Edmund Jay, and Vladimir Dzhuvinov all created early implementations and fed their experiences back into the spec designs. Sean Turner, Stephen Farrell, and Kathleen Moriarty all did detailed reviews that added ideas and improved the specs. Matt Miller also created the accompanying JOSE Cookbook – RFC 7520. Chuck Mortimore, Brian Campbell, and I created the related OAuth assertions specs, which are now also RFCs. Karen O’Donoghue stepped in at key points to keep us moving forward. Of course, many other JOSE and OAuth working group and IETF members also made important contributions. Finally, I want to thank Tony Nadalin and others at Microsoft for believing in the vision for these specs and consistently supporting my work on them.

I’ll close by remarking that I’ve been told that the sign of a successful technology is that it ends up being used in ways that the inventors never imagined. That’s certainly already true here. I can’t wait to see all the ways that people will continue to use JWTs and JOSE to build useful, secure applications!

March 9, 2015
OAuth Proof-of-Possession draft -02 closing open issues

OAuth logoAn updated OAuth Proof-of-Possession draft has been posted that address the open issues identified in the previous draft. Changes were:

  • Defined the terms Issuer, Presenter, and Recipient and updated their usage within the document.
  • Added a description of a use case using an asymmetric proof-of-possession key to the introduction.
  • Added the “kid” (key ID) confirmation method.

Thanks to Hannes Tschofenig for writing text to address the open issues.

This specification is available at:

An HTML formatted version is also available at:

March 3, 2015
JWK Thumbprint -04 draft incorporating feedback during second WGLC

IETF logoThe latest JWK Thumbprint draft addresses review comments on the -03 draft by Jim Schaad, which resulted in several clarifications and some corrections to the case of RFC 2119 keywords.

The specification is available at:

An HTML formatted version is also available at:

March 3, 2015
Key Managed JSON Web Signature (KMJWS) specification

IETF logoI took a little time today and wrote a short draft specifying a JWS-like object that uses key management for the MAC key used to integrity protect the payload. We had considered doing this in JOSE issue #2 but didn’t do so at the time because of lack of demand. However, I wanted to get this down now to demonstrate that it is easy to do and specify a way to do it, should demand develop in the future – possibly after the JOSE working group has been closed. See http://tools.ietf.org/html/draft-jones-jose-key-managed-json-web-signature-00 or http://self-issued.info/docs/draft-jones-jose-key-managed-json-web-signature-00.html.

This spec reuses key management functionality already present in the JWE spec and MAC functionality already present in the JWS spec. The result is essentially a JWS with an Encrypted Key value added, and a new “mac” Header Parameter value representing the MAC algorithm used. (Like JWE, the key management algorithm is carried in the “alg” Header Parameter value.)

I also wrote this now as possible input into our thinking on options for creating a CBOR JOSE mapping. If there are CBOR use cases needing managed MAC keys, this could help us reason about ways to structure the solution.

Yes, the spec name and abbreviation are far from catchy. Better naming ideas would be great.

Feedback welcomed.

February 26, 2015
JWK Thumbprint -03 draft incorporating additional feedback

IETF logoA new JWK Thumbprint draft has been posted that addresses additional review comments by James Manger and Jim Schaad. Changes included adding a discussion on the relationship of JWK Thumbprints to digests of X.509 values. No normative changes resulted.

The specification is available at:

An HTML formatted version is also available at:

February 19, 2015
JWK Thumbprint -02 draft incorporating WGLC feedback

IETF logoNat Sakimura and I have updated the JSON Web Key (JWK) Thumbprint draft to incorporate feedback receiving during JOSE working group last call. Changes were:

  • No longer register the new JSON Web Signature (JWS) and JSON Web Encryption (JWE) Header Parameters and the new JSON Web Key (JWK) member name jkt (JWK SHA-256 Thumbprint) for holding these values.
  • Added security considerations about the measures needed to ensure that a unique JWK Thumbprint value is produced for a key.
  • Added text saying that a base64url encoded JWK Thumbprint value could be used as a kid (key ID) value.
  • Broke a sentence up that used to be way too long.

The specification is available at:

An HTML formatted version is also available at:

January 22, 2015
JWK Thumbprint -01 draft incorporating feedback from Jim Schaad

IETF logoThe JSON Web Key (JWK) Thumbprint draft has been updated to incorporate feedback received from Jim Schaad, including defining the JWK Thumbprint computation in a manner that allows different hash functions to be used over time. The specification is available at:

An HTML formatted version is also available at:

January 16, 2015
The JWT, JOSE, and OAuth Assertions drafts have all been sent to the RFC Editor

IETF logoAll of these 9 drafts have now been approved and sent to the RFC Editor:

  1. draft-ietf-jose-json-web-signature
  2. draft-ietf-jose-json-web-encryption
  3. draft-ietf-jose-json-web-key
  4. draft-ietf-jose-json-web-algorithms
  5. draft-ietf-oauth-json-web-token
  6. draft-ietf-jose-cookbook
  7. draft-ietf-oauth-assertions
  8. draft-ietf-oauth-saml2-bearer
  9. draft-ietf-oauth-jwt-bearer

That means that their content is now completely stable and they’ll soon become Internet standards – RFCs. Thanks for all of your contributions in creating, reviewing, and most importantly, using these specifications. Special thanks go to the other spec editors Nat Sakimura, John Bradley, Joe Hildebrand, Brian Campbell, Chuck Mortimore, Matt Miller, and Yaron Goland.

January 16, 2015
Final pre-RFC JOSE drafts

IETF logoNew versions of the JSON Web Signature (JWS) and JSON Web Key (JWK) drafts have been submitted that address a few more IESG comments that were identified by our area director Kathleen Moriarty during her final review of the documents. Thanks to Richard Barnes for working on wording to address his comment on security considerations for binding attributes to JWKs. See the Document History sections for descriptions of the edits, none of which resulted in data structure changes.

The plan is for these documents to be forwarded to the RFC editor. The other related documents have already been approved.

The specifications are available at:

HTML formatted versions are available at:

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