April 3, 2019
OAuth 2.0 Demonstration of Proof-of-Possession at the Application Layer

OAuth logoI’m excited that a new, simpler approach for application-level proof of possession of OAuth access tokens and refresh tokens is being developed by members of the IETF OAuth working group. The effort is led by Daniel Fett, who had previously done formal analysis of the OAuth protocol. I wanted to bring it to your attention now to solicit your early feedback. This approach was designed in discussions at the Fourth OAuth Security Workshop and is captured in a new individual draft specification for Demonstration of Proof-of-Possession (DPoP) intended for the OAuth working group. The abstract of the new specification is:

This document describes a mechanism for sender-constraining OAuth 2.0 tokens via a proof-of-possession mechanism on the application level. This mechanism allows to detect replay attacks with access and refresh tokens.

The specification is still an early draft and undergoing active development, but I believe the approach shows a lot of promise and is likely to be adopted by the OAuth working group soon. It works by creating a proof-of-possession signature over an access token or refresh token that would otherwise be a bearer token. And there’s already one implementation that I’m aware of – by Filip Skokan of Auth0. Let us know what you think of this new work!

The specification is available at:

An HTML-formatted version is also available at:

March 27, 2019
Working group adoption of “COSE and JOSE Registrations for WebAuthn Algorithms”

IETF logoI’m pleased to report that the IETF COSE Working Group has adopted the specification “COSE and JOSE Registrations for WebAuthn Algorithms”. An abstract of what it does is:

This specification defines how to use several algorithms with COSE [RFC8152] that are used by implementations of the W3C Web Authentication (WebAuthn) [WebAuthn] and FIDO2 Client to Authenticator Protocol (CTAP) [CTAP] specifications. These algorithms are to be registered in the IANA “COSE Algorithms” registry [IANA.COSE.Algorithms] and also in the IANA “JSON Web Signature and Encryption Algorithms” registry [IANA.JOSE.Algorithms], when not already registered there.

The algorithms registered are RSASSA-PKCS1-v1_5 with four different hash functions and signing with the secp256k1 curve. Note that there was consensus in the working group meeting not to work on registrations for the Elliptic Curve Direct Anonymous Attestation (ECDAA) algorithms “ED256” and “ED512”, both because of issues that have been raised with them and because they are not in widespread use.

The -01 version will address the review comments received on the mailing list from Jim Schaad and John Mattsson.

The specification is available at:

An HTML-formatted version is also available at:

March 12, 2019
Security Event Token (SET) delivery specifications updated in preparation for IETF 104

IETF logoThe two Security Event Token (SET) delivery specifications have been updated to address working group feedback received, in preparation for discussions at IETF 104 in Prague. The Push Delivery spec went through working group last call (WGLC). It has been updated to incorporate the WGLC comments. Changes made are summarized in the spec change log, the contents of which were also posted to the working group mailing list. Thanks to Annabelle Backman for the edits to the Push Delivery spec.

It’s worth noting that the Push Delivery spec and the Security Event Token (SET) are now being used in early Risk and Incident Sharing and Coordination (RISC) deployments, including between Google and Adobe. See the article about these deployments by Mat Honan of BuzzFeed.

Changes to the Poll Delivery spec are also summarized in that spec’s change log, which contains:

  • Removed vestigial language remaining from when the push and poll delivery methods were defined in a common specification.
  • Replaced remaining uses of the terms Event Transmitter and Event Recipient with the correct terms SET Transmitter and SET Recipient.
  • Removed uses of the unnecessary term “Event Stream”.
  • Removed dependencies between the semantics of maxEvents and returnImmediately.
  • Said that PII in SETs is to be encrypted with TLS, JWE, or both.
  • Corrected grammar and spelling errors.

The specifications are available at:

HTML-formatted versions are also available at:

March 11, 2019
OAuth Device Flow spec renamed to “OAuth 2.0 Device Authorization Grant”

OAuth logoResponding to feedback from multiple parties that the title “OAuth 2.0 Device Flow for Browserless and Input Constrained Devices” was too much of a mouthful, the title of the specification has been simplified to “OAuth 2.0 Device Authorization Grant”. Likewise, we received feedback that “Device flow” was an insider term that caused more confusion than clarity, so its use has been removed from the specification. Finally, last minute feedback was received that client authorization and error handling were not explicitly spelled out. The specification now says that these occur in the same manner as in OAuth 2.0 [RFC 6749].

Many thanks to William Denniss for performing these edits! Hopefully this will be the draft that is sent to the RFC Editor.

The specification is available at:

An HTML-formatted version is also available at:

March 11, 2019
Additional COSE algorithms used by W3C Web Authentication (WebAuthn)

IETF logoThe new COSE working group charter includes this deliverable:

4. Define the algorithms needed for W3C Web Authentication for COSE using draft-jones-webauthn-cose-algorithms and draft-jones-webauthn-secp256k1 as a starting point (Informational).

I have written draft-jones-cose-additional-algorithms, which combines these starting points into a single draft, which registers these algorithms in the IANA COSE registries. When not already registered, this draft also registers these algorithms for use with JOSE in the IANA JOSE registries. I believe that this draft is ready for working group adoption to satisfy this deliverable.

The specification is available at:

An HTML-formatted version is also available at:

March 9, 2019
FIDO2 Client to Authenticator Protocol (CTAP) standard published

FIDO logoI’m thrilled to report that the FIDO2 Client to Authenticator Protocol (CTAP) is now a published FIDO Alliance standard! Together with the now-standard Web Authentication (WebAuthn) specification, this completes standardization of the APIs and protocols needed to enable password-less logins on the Web, on PCs, and on and mobile devices. This is a huge step forward for online security, privacy, and convenience!

The FIDO2 CTAP standard is available in HTML and PDF versions at these locations:

March 4, 2019
The W3C Web Authentication (WebAuthn) specification is now a standard!

W3C logoI’m thrilled to report that the Web Authentication (WebAuthn) specification is now a W3C standard! See the W3C press release describing this major advance in Web security and convenience, which enables logging in without passwords. Alex Simons, Microsoft Vice President of Identity Program Management is quoted in the release, saying:

“Our work with W3C and FIDO Alliance, and contributions to FIDO2 standards have been a critical piece of Microsoft’s commitment to a world without passwords, which started in 2015. Today, Windows 10 with Microsoft Edge fully supports the WebAuthn standard and millions of users can log in to their Microsoft account without using a password.”

The release also describes commitments to the standard by Google, Mozilla, and Apple, among others. Thanks to all who worked on the standard and who built implementations as we developed the standard – ensuring that that the standard can be used for a broad set of use cases, including password-less sign-in with platform authenticators, mobile devices, and security keys.

February 21, 2019
Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) spec fixing nits

IETF logoThe Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) specification has been updated to address issues identified by Roman Danyliw while writing his shepherd review. Thanks to Samuel Erdtman for fixing an incorrect example.

The specification is available at:

An HTML-formatted version is also available at:

January 17, 2019
W3C Web Authentication (WebAuthn) advances to Proposed Recommendation (PR)

W3C logoThe World Wide Web Consortium (W3C) has published a Proposed Recommendation (PR) for the Web Authentication (WebAuthn) specification, bringing WebAuthn one step closer to becoming a completed standard. The Proposed Recommendation is at https://www.w3.org/TR/2019/PR-webauthn-20190117/.

The PR contains only clarifications and editorial improvements to the second Candidate Recommendation (CR), with no substantial changes. The next step will be to publish a Recommendation – a W3C standard – based on the Proposed Recommendation.

December 3, 2018
OpenID Connect Federation Specification

OpenID logoThe OpenID Connect Federation 1.0 specification is being developed to enable large-scale federations to be deployed using OpenID Connect. It enables trust among federation participants to be established through signed statements made by federation operators about federation participants.

The design of this specification builds upon the experiences gained in operating large-scale SAML 2.0 federations, and indeed, is authored by people having practical experience with these federations. The primary authors are Roland Hedberg and Andreas Åkre Solberg, with additional contributions by Samuel Gulliksson, John Bradley, and myself, as well as members of the OpenID Connect working group, which is the home of the specification.

A key innovation that differentiates OpenID Connect federations from most SAML 2.0 federations is that OpenID Connect federation employs heirarchal metadata, where participants directly publish statements about themselves, versus the aggregated metadata approach used by many SAML 2.0 federations, where the federation operator publishes a single file concatenating all the metadata for all the federation participants.

The specification was just updated so that the latest version can be discussed at a SURFnet OpenID Connect “Wisdom of the Crowd” session today.

The latest version of specification is available at:

This URL always points to the latest published version:

Please review and/or implement this important specification and send your feedback to the OpenID Connect working group!

November 9, 2018
Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) spec adding Key ID considerations

IETF logoKey ID confirmation method considerations suggested by Jim Schaad have been added to the Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) specification. Per discussions in the working group meeting in Bangkok, it’s now time for the shepherd review.

The specification is available at:

An HTML-formatted version is also available at:

November 8, 2018
JWT BCP updates addressing Area Director review comments

OAuth logoThe JSON Web Token (JWT) Best Current Practices (BCP) specification has been updated to address the review comments from Security Area Director (AD) Eric Rescorla. Thanks to Eric for the review and to Yaron Sheffer for working on the responses with me.

Note that IETF publication has already been requested. The next step is for the shepherd review to be submitted and responded to.

The specification is available at:

An HTML-formatted version is also available at:

November 6, 2018
Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) spec addressing additional WGLC comments

IETF logoThe Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) specification has been updated to addresses a few additional Working Group Last Call (WGLC) comments. All of the (few) changes were about improving the clarity of the exposition. I believe that this completes addressing the WGLC comments.

Thanks to Roman Danyliw for helping to categorize the remaining comments that needed to be addressed.

The specification is available at:

An HTML-formatted version is also available at:

October 23, 2018
OpenID Connect Introduction at October 2018 IIW

OpenID logoI gave the following invited “101” session presentation at the Internet Identity Workshop (IIW) on Tuesday, October 23, 2018:

October 23, 2018
Security Event Token (SET) delivery specifications updated

IETF logoNow that the Security Event Token (SET) specification is RFC 8417, the SecEvent working group is working on defining the SET delivery mechanisms. This week, both the push-based and poll-based SET delivery specs have been updated to simplify their exposition and reduce duplication of text between the drafts. Thanks to Annabelle Backman for doing the bulk of the recent work on the push-based delivery spec. The latest versions of both specs contain these updates:

  • Addressed problems identified in my 18-Jul-18 review message titled “Issues for both the Push and Poll Specs”.
  • Changes to align terminology with RFC 8417, for instance, by using the already defined term SET Recipient rather than SET Receiver.
  • Applied editorial and minor normative corrections.
  • Updated Marius Scurtescu’s contact information.

In addition, the latest version of the poll delivery spec also contains this update:

  • Begun eliminating redundancies between this specification and “Push-Based Security Event Token (SET) Delivery Using HTTP”, referencing, rather that duplicating common normative text.

The specifications are available at:

HTML-formatted versions are also available at:

October 8, 2018
The core Token Binding specs are now RFCs 8471, 8472, and 8473

IETF logoThe IETF Token Binding working group has completed the core Token Binding specifications. These new standards are:

  • RFC 8471: The Token Binding Protocol Version 1.0
  • RFC 8472: Transport Layer Security (TLS) Extension for Token Binding Protocol Negotiation
  • RFC 8473: Token Binding over HTTP

As Alex Simons recently wrote, it’s time for token binding. Especially now that the core specs are done, now’s the time for platforms and applications to deploy Token Binding. This will enable replacing bearer tokens, which can be stolen and reused, with Token Bound tokens, which are useless if stolen. This is a huge security benefit applicable to any tokens used over TLS, including browser cookies, OAuth access tokens and refresh tokens, and OpenID Connect ID Tokens.

Congratulations especially to the editors Andrei Popov, Dirk Balfanz, Jeff Hodges, Magnus Nyström, and Nick Harper and the chairs John Bradley and Leif Johansson for getting this done!

I likewise look forward to timely completion of related Token Binding specifications, which enable use of Token Binding with TLS 1.3, with OAuth 2.0, and with OpenID Connect.

September 29, 2018
Vote to update OpenID IPR Policy document now

A quick reminder that the vote to approve updates to the OpenID IPR Policy document is under way. If you’re an OpenID Foundation member, I encourage you to vote to approve the updates now at https://openid.net/foundation/members/polls/151.

As described in the OpenID Foundation post Proposed Revisions to OpenID IPR Policy Document, the updates enable the use of electronic signatures on contributor agreements instead of requiring on-paper signatures and simplify the descriptions of working group contributors, all without changing the IPR rights of any party.

The foundation needs 30% of the membership to vote in order for the changes to take effect, so please take a moment and vote now. Thanks!

August 29, 2018
The role of standards in accelerating innovation

Use of standards accelerates innovation. Oxymoron? Not at all!

Read Alex Simons’ description of how using robust standards like JWT is accelerating innovation when prototyping decentralized identity systems.

August 21, 2018
It’s Time for Token Binding

IETF logoCheck out Alex Simons’ and Pamela Dingle’s blog post “It’s Time for Token Binding”. Now that the IETF Token Binding specs are essentially done, it’s time to ask those who write TLS software you use to ship Token Binding support soon, if they haven’t already done so.

Token Binding in a nutshell: When an attacker steals a bearer token sent over TLS, he can use it; when an attacker steals a Token Bound token, it’s useless to him.

August 7, 2018
Second W3C Web Authentication (WebAuthn) Candidate Recommendation (CR)

W3C logoW3C has published a second W3C Candidate Recommendation (CR) for the Web Authentication (WebAuthn) specification. The second Candidate Recommendation is at https://www.w3.org/TR/2018/CR-webauthn-20180807/.

This draft contains a few refinements since the first candidate recommendation but no substantial changes. The new CR was needed to fulfill the W3C’s IPR protection requirements. The few changes were based, in part, upon things learned during multiple interop events for WebAuthn implementations. The working group plans to base coming the Proposed Recommendation on this draft.

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