<!DOCTYPE html>
<html lang="en" class="Internet-Draft">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>OpenID Connect Key Binding 1.0 - draft 00</title>
<meta content="Dick Hardt" name="author">
<meta content="Ethan Heilman" name="author">
<meta content="
OpenID Key Binding specifies how to bind a public key to an OpenID Connect ID Token using mechanisms defined in RFC 9449, OAuth 2.0 Demonstrating Proof of Possession (DPoP).
" name="description">
<meta content="xml2rfc 3.30.1" name="generator">
<meta content="security" name="keyword">
<meta content="openid" name="keyword">
<meta content="lifecycle" name="keyword">
<meta name="ietf.draft">
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xml2rfc 3.30.1
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<link href="openid-connect-key-binding-1_0.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">/*
NOTE: Changes at the bottom of this file overrides some earlier settings.
Once the style has stabilized and has been adopted as an official RFC style,
this can be consolidated so that style settings occur only in one place, but
for now the contents of this file consists first of the initial CSS work as
provided to the RFC Formatter (xml2rfc) work, followed by itemized and
commented changes found necessary during the development of the v3
formatters.
*/
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/* This is commented out here, as the string-set: doesn't
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/* Changes introduced to fix issues found during implementation */
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address .non-ascii {
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/* With it being possible to set tables with alignment
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/* Avoid reference text that sits in a block with very wide left margin,
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/* Limit the width of the author address vcard, so names in right-to-left
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/* For address alignment dependent on LTR or RTL scripts */
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/* Provide table alignment support. We can't use the alignX classes above
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table.left {
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caption a[href] {
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@media print {
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/* avoid overwriting the top border line with the ToC header */
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/* Tweak the bcp14 keyword presentation */
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h4 {
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/* Float artwork pilcrow to the right */
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margin-top: 0.15em;
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}
/* Make pilcrows on dd visible */
@media screen {
dd:hover > a.pilcrow {
visibility: visible;
}
}
/* Make the placement of figcaption match that of a table's caption
by removing the figure's added bottom margin */
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/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
possibly even requiring a new line */
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a.pilcrow {
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}
/* Styling for the external metadata */
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/* Styling for title RFC Number */
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padding: 1em 0 0 0;
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/* Make .olPercent look the same as <ol><li> */
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min-height: initial;
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/* Give aside some styling to set it apart */
aside {
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margin: 1em 0 1em 2em;
padding: 0.2em 2em;
}
aside > dl,
aside > ol,
aside > ul,
aside > table,
aside > p {
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/* Additional page break settings */
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}
/* Font size adjustments for print */
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</head>
<body class="xml2rfc">
<table class="ears">
<thead><tr>
<td class="left"></td>
<td class="center">openid-connect-key-binding</td>
<td class="right">September 2025</td>
</tr></thead>
<tfoot><tr>
<td class="left">Hardt & Heilman</td>
<td class="center">Standards Track</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-workgroup">Workgroup:</dt>
<dd class="workgroup">OpenID Connect</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2025-09-08" class="published">8 September 2025</time>
</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
<div class="author-name">D. Hardt</div>
<div class="org">Hellō</div>
</div>
<div class="author">
<div class="author-name">E. Heilman</div>
<div class="org">Cloudflare</div>
</div>
</dd>
</dl>
</div>
<h1 id="title">OpenID Connect Key Binding 1.0 - draft 00</h1>
<section id="section-abstract">
<h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">OpenID Key Binding specifies how to bind a public key to an OpenID Connect ID Token using mechanisms defined in RFC 9449, OAuth 2.0 Demonstrating Proof of Possession (DPoP).<a href="#section-abstract-1" class="pilcrow">¶</a></p>
</section>
<div id="toc">
<section id="section-toc.1">
<a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
</h2>
<nav class="toc"><ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1">
<p id="section-toc.1-1.1.1"><a href="#section-1" class="auto internal xref">1</a>. <a href="#name-introduction" class="internal xref">Introduction</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.1">
<p id="section-toc.1-1.1.2.1.1" class="keepWithNext"><a href="#section-1.1" class="auto internal xref">1.1</a>. <a href="#name-requirements-notation-and-c" class="internal xref">Requirements Notation and Conventions</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.2">
<p id="section-toc.1-1.1.2.2.1" class="keepWithNext"><a href="#section-1.2" class="auto internal xref">1.2</a>. <a href="#name-terminology" class="internal xref">Terminology</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.3">
<p id="section-toc.1-1.1.2.3.1" class="keepWithNext"><a href="#section-1.3" class="auto internal xref">1.3</a>. <a href="#name-protocol-profile-overview" class="internal xref">Protocol Profile Overview</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.4">
<p id="section-toc.1-1.1.2.4.1"><a href="#section-1.4" class="auto internal xref">1.4</a>. <a href="#name-openid-connect-metadata" class="internal xref">OpenID Connect Metadata</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.5">
<p id="section-toc.1-1.1.2.5.1"><a href="#section-1.5" class="auto internal xref">1.5</a>. <a href="#name-authentication-request-auth" class="internal xref">Authentication Request - Authorization Code Flow</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.6">
<p id="section-toc.1-1.1.2.6.1"><a href="#section-1.6" class="auto internal xref">1.6</a>. <a href="#name-authentication-request-devi" class="internal xref">Authentication Request - Device Authorization Flow</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.7">
<p id="section-toc.1-1.1.2.7.1"><a href="#section-1.7" class="auto internal xref">1.7</a>. <a href="#name-authentication-response" class="internal xref">Authentication Response</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.8">
<p id="section-toc.1-1.1.2.8.1"><a href="#section-1.8" class="auto internal xref">1.8</a>. <a href="#name-token-request" class="internal xref">Token Request</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1.2.9">
<p id="section-toc.1-1.1.2.9.1"><a href="#section-1.9" class="auto internal xref">1.9</a>. <a href="#name-token-response" class="internal xref">Token Response</a></p>
</li>
</ul>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.2">
<p id="section-toc.1-1.2.1"><a href="#section-2" class="auto internal xref">2</a>. <a href="#name-privacy-considerations" class="internal xref">Privacy Considerations</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3">
<p id="section-toc.1-1.3.1"><a href="#section-3" class="auto internal xref">3</a>. <a href="#name-security-considerations" class="internal xref">Security Considerations</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4">
<p id="section-toc.1-1.4.1"><a href="#section-4" class="auto internal xref">4</a>. <a href="#name-iana-considerations" class="internal xref">IANA Considerations</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5">
<p id="section-toc.1-1.5.1"><a href="#section-5" class="auto internal xref">5</a>. <a href="#name-references" class="internal xref">References</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5.2.1">
<p id="section-toc.1-1.5.2.1.1"><a href="#section-5.1" class="auto internal xref">5.1</a>. <a href="#name-normative-references" class="internal xref">Normative References</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5.2.2">
<p id="section-toc.1-1.5.2.2.1"><a href="#section-5.2" class="auto internal xref">5.2</a>. <a href="#name-informative-references" class="internal xref">Informative References</a></p>
</li>
</ul>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6">
<p id="section-toc.1-1.6.1"><a href="#appendix-A" class="auto internal xref">Appendix A</a>. <a href="#name-acknowledgements" class="internal xref">Acknowledgements</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.7">
<p id="section-toc.1-1.7.1"><a href="#appendix-B" class="auto internal xref">Appendix B</a>. <a href="#name-notices" class="internal xref">Notices</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.8">
<p id="section-toc.1-1.8.1"><a href="#appendix-C" class="auto internal xref">Appendix C</a>. <a href="#name-document-history" class="internal xref">Document History</a></p>
</li>
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.9">
<p id="section-toc.1-1.9.1"><a href="#appendix-D" class="auto internal xref"></a><a href="#name-authors-addresses" class="internal xref">Authors' Addresses</a></p>
</li>
</ul>
</nav>
</section>
</div>
<div id="introduction">
<section id="section-1">
<h2 id="name-introduction">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
</h2>
<p id="section-1-1">OpenID Connect is a protocol that enables a Relying Party (RP) to delegate authentication and obtain identity claims to an OpenID Connect Provider (OP).<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">When authenticating with OpenID Connect, RP provides a nonce in its authentication request. The ID Token signed and returned by the OP contains the nonce and claims about the user. When verifying the ID Token, the RP confirms it contains the nonce, binding the session that made the request to the response.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">When an RP wants to prove to another system that it has authenticated a user, it may present the ID Token as a bearer token. However, bearer tokens are vulnerable to theft and replay attacks - if an attacker intercepts the ID Token, they can impersonate the authenticated user to downstream systems that accept a ID Token as a bearer token.<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">By binding a cryptographic key to the ID Token, the RP can prove to downstream systems not only that a user has been authenticated, but that the RP itself was the original recipient of that authentication. This transforms the ID Token from a vulnerable bearer token into a proof-of-possession token that provides stronger security guarantees.<a href="#section-1-4" class="pilcrow">¶</a></p>
<p id="section-1-5">This specification profiles OpenID Connect 1.0, RFC8628 - OAuth 2.0 Device Authorization Grant, and RFC9449 - OAuth 2.0 Demonstrating Proof of Possession (DPoP) to enable cryptographically bound ID Tokens that resist theft and replay attacks while maintaining compatibility with existing OpenID Connect infrastructure.<a href="#section-1-5" class="pilcrow">¶</a></p>
<div id="requirements-notation-and-conventions">
<section id="section-1.1">
<h3 id="name-requirements-notation-and-c">
<a href="#section-1.1" class="section-number selfRef">1.1. </a><a href="#name-requirements-notation-and-c" class="section-name selfRef">Requirements Notation and Conventions</a>
</h3>
<p id="section-1.1-1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in {{RFC2119}}.<a href="#section-1.1-1" class="pilcrow">¶</a></p>
<p id="section-1.1-2">In the .txt version of this specification,
values are quoted to indicate that they are to be taken literally.
When using these values in protocol messages,
the quotes MUST NOT be used as part of the value.
In the HTML version of this specification,
values to be taken literally are indicated by
the use of <em>this fixed-width font</em>.<a href="#section-1.1-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="terminology">
<section id="section-1.2">
<h3 id="name-terminology">
<a href="#section-1.2" class="section-number selfRef">1.2. </a><a href="#name-terminology" class="section-name selfRef">Terminology</a>
</h3>
<p id="section-1.2-1">This specification uses the following terms:<a href="#section-1.2-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-1.2-2.1">
<p id="section-1.2-2.1.1"><strong>OP</strong>: The OpenID Provider as defined in {{OpenID.Core}}.<a href="#section-1.2-2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-1.2-2.2">
<p id="section-1.2-2.2.1"><strong>RP</strong>: The Relying Party as defined in {{OpenID.Core}}.<a href="#section-1.2-2.2.1" class="pilcrow">¶</a></p>
</li>
</ul>
<p id="section-1.2-3">The parameters <strong>dpop_jkt</strong> and <strong>DPoP</strong> as defined in {{RFC9449}}<a href="#section-1.2-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="protocol-profile-overview">
<section id="section-1.3">
<h3 id="name-protocol-profile-overview">
<a href="#section-1.3" class="section-number selfRef">1.3. </a><a href="#name-protocol-profile-overview" class="section-name selfRef">Protocol Profile Overview</a>
</h3>
<p id="section-1.3-1">This specification profiles how to bind a public key to an ID Token by:<a href="#section-1.3-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-1.3-2">
<li id="section-1.3-2.1">
<p id="section-1.3-2.1.1">adding the <code>bound_key</code> scope and <code>dpop_jkt</code> parameter to the OpenID Connect Authentication Request<a href="#section-1.3-2.1.1" class="pilcrow">¶</a></p>
</li>
<li id="section-1.3-2.2">
<p id="section-1.3-2.2.1">receiving the authorization <code>code</code> as usual in the Authentication Response<a href="#section-1.3-2.2.1" class="pilcrow">¶</a></p>
</li>
<li id="section-1.3-2.3">
<p id="section-1.3-2.3.1">adding the <code>DPoP</code> header that includes the hash of the <code>code</code>, <code>c_hash</code>, as a claim in the Token Request to the OP <code>token_endpoint</code><a href="#section-1.3-2.3.1" class="pilcrow">¶</a></p>
</li>
<li id="section-1.3-2.4">
<p id="section-1.3-2.4.1">adding the <code>cnf</code> claim containing the public key to the returned ID Token<a href="#section-1.3-2.4.1" class="pilcrow">¶</a></p>
</li>
</ol>
<div class="alignLeft art-text artwork" id="section-1.3-3">
<pre>+------+ +------+
| |-- Authentication Request --->| |
| RP | (1) bound_key & dpop_jkt | OP |
| | | |
| |<-- Authentication Response --| |
| | (2) authorization code | |
| | | |
| |-- Token Request ------------>| |
| | (3) DPoP header w/ c_hash | |
| | | |
| |<-- Token Response -----------| |
| | (4) cnf claim containing | |
| | the public key in ID Token | |
+------+ +------+
</pre><a href="#section-1.3-3" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="openid-connect-metadata">
<section id="section-1.4">
<h3 id="name-openid-connect-metadata">
<a href="#section-1.4" class="section-number selfRef">1.4. </a><a href="#name-openid-connect-metadata" class="section-name selfRef">OpenID Connect Metadata</a>
</h3>
<p id="section-1.4-1">The OP's OpenID Connect Metadata Document ({{OpenID.Discovery}})SHOULD include":<a href="#section-1.4-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-1.4-2.1">
<p id="section-1.4-2.1.1">the <code>bound_key</code> scope in the <code>supported_scopes</code><a href="#section-1.4-2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-1.4-2.2">
<p id="section-1.4-2.2.1">the <code>dpop_signing_alg_values_supported</code> property containing a list of supported algorithms as defined in IANA.JOSE.ALGS<a href="#section-1.4-2.2.1" class="pilcrow">¶</a></p>
</li>
</ul>
</section>
</div>
<div id="authentication-request-authorization-code-flow">
<section id="section-1.5">
<h3 id="name-authentication-request-auth">
<a href="#section-1.5" class="section-number selfRef">1.5. </a><a href="#name-authentication-request-auth" class="section-name selfRef">Authentication Request - Authorization Code Flow</a>
</h3>
<p id="section-1.5-1">If the RP is running on a device that supports a web browser, it makes an authorization request per {{OpenID.Core}} 3.1. In addition to the <code>scope</code> parameter containing <code>openid</code>, and the <code>response_type</code> having the value <code>code</code>, the <code>scope</code> parameter MUST also include <code>bound_key</code>, and the request MUST include the <code>dpop_jkt</code> parameter having the value of the JWK Thumbprint {{RFC7638}} of the proof-of-possession public key using the SHA-256 hash function, as defined in {{RFC9449}} section 10.<a href="#section-1.5-1" class="pilcrow">¶</a></p>
<p id="section-1.5-2">Following is a non-normative example of an authentication request using the authorization code flow:<a href="#section-1.5-2" class="pilcrow">¶</a></p>
<div class="lang-text sourcecode" id="section-1.5-3">
<pre>GET /authorize?
response_type=code
&dpop_jkt=1f2e6338febe335e2cbaa7c7154c3cbdcfd8650f95c5fe7206bb6360e37f4b5a
&scope=openid%20profile%20email%20bound_key
&client_id=s6BhdRkqt3
&state=af0ifjsldkj
&nonce=2a50f9ea812f9bb4c8f7
&redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb HTTP/1.1
Host: server.example.com
</pre><a href="#section-1.5-3" class="pilcrow">¶</a>
</div>
<p id="section-1.5-4">If the OP does not support the <code>bound_key</code> scope, it SHOULD ignore it per {{OpenID.Core}} 3.1.2.1.<a href="#section-1.5-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authentication-request-device-authorization-flow">
<section id="section-1.6">
<h3 id="name-authentication-request-devi">
<a href="#section-1.6" class="section-number selfRef">1.6. </a><a href="#name-authentication-request-devi" class="section-name selfRef">Authentication Request - Device Authorization Flow</a>
</h3>
<p id="section-1.6-1">If the RP is running on a device that does not support a web browser, it makes an authorization request per {{RFC8628}} 3.1. In the request, the <code>scope</code> parameter MUST contain both <code>openid</code> and <code>bound_key</code>. The request MUST include the <code>dpop_jkt</code> parameter having the value of the JWK Thumbprint {{RFC7638}} of the proof-of-possession public key using the SHA-256 hash function, as defined in {{RFC9449}} section 10.<a href="#section-1.6-1" class="pilcrow">¶</a></p>
<p id="section-1.6-2">Following is a non-normative example of an authentication request using the device authorization flow:<a href="#section-1.6-2" class="pilcrow">¶</a></p>
<div class="lang-text sourcecode" id="section-1.6-3">
<pre>TBD
</pre><a href="#section-1.6-3" class="pilcrow">¶</a>
</div>
<p id="section-1.6-4">If the OP does not support the <code>bound_key</code> scope, it SHOULD ignore it per {{OpenID.Core}} 3.1.2.1.<a href="#section-1.6-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authentication-response">
<section id="section-1.7">
<h3 id="name-authentication-response">
<a href="#section-1.7" class="section-number selfRef">1.7. </a><a href="#name-authentication-response" class="section-name selfRef">Authentication Response</a>
</h3>
<p id="section-1.7-1">If the key provided was not previously bound to the client, the OP SHOULD inform a user and obtain consent that a key binding will be done.<a href="#section-1.7-1" class="pilcrow">¶</a></p>
<p id="section-1.7-2">On successful authentication of, and consent from the user, the OP returns an authorization <code>code</code>.<a href="#section-1.7-2" class="pilcrow">¶</a></p>
<p id="section-1.7-3">Following is a non-normative example of a response:<a href="#section-1.7-3" class="pilcrow">¶</a></p>
<div class="lang-text sourcecode" id="section-1.7-4">
<pre>TBD
</pre><a href="#section-1.7-4" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="token-request">
<section id="section-1.8">
<h3 id="name-token-request">
<a href="#section-1.8" class="section-number selfRef">1.8. </a><a href="#name-token-request" class="section-name selfRef">Token Request</a>
</h3>
<p id="section-1.8-1">To obtain the ID Token, the RP:<a href="#section-1.8-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-1.8-2">
<li id="section-1.8-2.1">
<p id="section-1.8-2.1.1">generates a <code>c_hash</code> by computing a SHA256 hash of the authorization <code>code</code><a href="#section-1.8-2.1.1" class="pilcrow">¶</a></p>
</li>
<li id="section-1.8-2.2">
<p id="section-1.8-2.2.1">converts the hash to BASE64URL<a href="#section-1.8-2.2.1" class="pilcrow">¶</a></p>
</li>
<li id="section-1.8-2.3">
<p id="section-1.8-2.3.1">generates a <code>DPoP</code> header, including the <code>c_hash</code> claim in the <code>DPoP</code> header JWT. This binds the authorization code to the token request.<a href="#section-1.8-2.3.1" class="pilcrow">¶</a></p>
</li>
</ol>
<p id="section-1.8-3">Non-normative example:<a href="#section-1.8-3" class="pilcrow">¶</a></p>
<div class="lang-text sourcecode" id="section-1.8-4">
<pre>POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
DPoP: eyJhbGciOiJFUzI1NiJ9.eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkV\
TMjU2IiwiandrIjp7ImNydiI6IlAtMjU2Iiwia3R5IjoiRUMiLCJ4IjoibWptR\
m1MZm9wVmkwZXRfYTZmZFhUTnJqYVUwR1dlZFN0Y3NfRzU4OEkyMCIsInkiOiJ\
sMFZwRXlSYzdTdUpfdHFhd2NaQ2VLLXVUOEVPVnF4N3NqTHJGeUJTUllZIn0sI\
m5vbmNlIjoiU3BseGxPQmVaUVFZYllTNld4U2JJQSJ9.cp8uN3kHAMS9fhGH7T\
vTSKwH5oNJzAeMhIrgD_HQHGhgt_N1xQHdHiMkn7AMj3UDkwoNOW4Qqak
grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
&redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
</pre><a href="#section-1.8-4" class="pilcrow">¶</a>
</div>
<p id="section-1.8-5">If a DPoP header is included in the token request to the OP, and the <code>dpop_jkt</code> parameter was not included in the authentication request, the OP MUST NOT include the <code>cnf</code> claim in the ID Token.<a href="#section-1.8-5" class="pilcrow">¶</a></p>
<blockquote id="section-1.8-6">
<p id="section-1.8-6.1">This prevents an existing deployment using DPoP for access token from having them included in ID Tokens accidentally.<a href="#section-1.8-6.1" class="pilcrow">¶</a></p>
</blockquote>
<p id="section-1.8-7">The OP MUST:
- perform all verification steps as described in {{RFC9449}} section 5.
- calculate the <code>c_hash</code> from the authorization <code>code</code> just as the RP id.
- confirm the <code>c_hash</code> in the DPoP JWT matches its calculated <code>c_hash</code><a href="#section-1.8-7" class="pilcrow">¶</a></p>
</section>
</div>
<div id="token-response">
<section id="section-1.9">
<h3 id="name-token-response">
<a href="#section-1.9" class="section-number selfRef">1.9. </a><a href="#name-token-response" class="section-name selfRef">Token Response</a>
</h3>
<p id="section-1.9-1">If the token request was successful, the OP MUST return an ID Token containing the <code>cnf</code> claim as defined in {{RFC7800}} set to the jwk of the user's public key and with <code>typ</code> set to <code>id_token+cnf</code> in the ID Token's protected header.<a href="#section-1.9-1" class="pilcrow">¶</a></p>
<p id="section-1.9-2">Non-normative example of the ID Token payload:<a href="#section-1.9-2" class="pilcrow">¶</a></p>
<div class="lang-json sourcecode" id="section-1.9-3">
<pre>{
"iss": "https://server.example.com",
"sub": "24400320",
"aud": "s6BhdRkqt3",
"nonce": "n-0S6_WzA2Mj",
"exp": 1311281970,
"iat": 1311280970,
"cnf":
{
"jwk": {
"alg":"ES256",
"crv": "P-256",
"kty": "EC",
"x": "mjmFmLfopVi0et_a6fdXTNrjaU0GWedStcs_G588I20",
"y": "l0VpEyRc7SuJ_tqawcZCeK-uT8EOVqx7sjLrFyBSRYY"
}
}
}
</pre><a href="#section-1.9-3" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="privacy-considerations">
<section id="section-2">
<h2 id="name-privacy-considerations">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-privacy-considerations" class="section-name selfRef">Privacy Considerations</a>
</h2>
<p id="section-2-1"><em>To be completed.</em><a href="#section-2-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="security-considerations">
<section id="section-3">
<h2 id="name-security-considerations">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
</h2>
<p id="section-3-1">Proof of possession authentication provides a greater level of security than bearer token authentication. To authenticate with a bearer token, the authentication secret must be sent over the internet to the authenticating party. This presents a risk that the authentication secret be stolen is transit or stolen at the server endpoint and replayed. With proof of possession, the authentication secret, i.e. the private key, never needs to leave the client. This reduces the chance of exposure and allows the client to use additional security mechanisms to protect the private key such as HSMs (Hardware Security Modules) or web browser based SSMs (Software Security Modules).<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">Public key bound ID Tokens provide a higher level security than bearer ID Tokens by using proof of possession rather than bearer authentication. For this reason public key bound ID Tokens MUST NOT be accepted as a form of bearer token authentication. If bearer token authentication is desired, bearer ID Tokens should be used instead.<a href="#section-3-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="iana-considerations">
<section id="section-4">
<h2 id="name-iana-considerations">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
</h2>
<p id="section-4-1">Media Type Registry
The following entry should be added to the "Media Types" registry for the new JWT type:
Type name: application
Subtype name: dpop+id_token<a href="#section-4-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="references">
<section id="section-5">
<h2 id="name-references">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-references" class="section-name selfRef">References</a>
</h2>
<div id="normative-references">
<section id="section-5.1">
<h3 id="name-normative-references">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
</h3>
<ul class="normal">
<li class="normal" id="section-5.1-1.1">
<p id="section-5.1-1.1.1"><strong>[RFC2119]</strong> Bradner, S. “Key words for use in RFCs to Indicate Requirement Levels,” <em>RFC 2119</em>, March 1997.<a href="#section-5.1-1.1.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.1-1.1.2.1">
<p id="section-5.1-1.1.2.1.1"><strong>[RFC7549]</strong> W. Mills, P. Saint-Andre, T. Hardie, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” RFC 7549, May 2015. Available at <a href="https://datatracker.ietf.org/doc/html/rfc7549">https://datatracker.ietf.org/doc/html/rfc7549</a>.<a href="#section-5.1-1.1.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.1-1.1.2.2">
<p id="section-5.1-1.1.2.2.1"><strong>[RFC7638]</strong> M. Jones, “JSON Web Key (JWK) Thumbprint,” RFC 7638, September 2015. Available at <a href="https://datatracker.ietf.org/doc/html/rfc7638">https://datatracker.ietf.org/doc/html/rfc7638</a>.<a href="#section-5.1-1.1.2.2.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.1-1.1.2.3">
<p id="section-5.1-1.1.2.3.1"><strong>[RFC7800]</strong> M. Jones, J. Bradley, N. Sakimura, “Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs),” RFC 7800, April 2016. Available at <a href="https://datatracker.ietf.org/doc/html/rfc7800">https://datatracker.ietf.org/doc/html/rfc7800</a>.<a href="#section-5.1-1.1.2.3.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.1-1.1.2.4">
<p id="section-5.1-1.1.2.4.1"><strong>[RFC8628]</strong> W. Denniss, J. Bradley, “OAuth 2.0 Device Authorization Grant,” RFC 8628, June 2019. Available at <a href="https://datatracker.ietf.org/doc/html/rfc8628">https://datatracker.ietf.org/doc/html/rfc8628</a>.<a href="#section-5.1-1.1.2.4.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.1-1.1.2.5">
<p id="section-5.1-1.1.2.5.1"><strong>[RFC9449]</strong> D. Fett, B. Campbell, J. Bradley, “OAuth 2.0 Demonstrating Proof-of-Possession at the Application Layer (DPoP),” RFC 9449, July 2023. Available at <a href="https://datatracker.ietf.org/doc/html/rfc9449">https://datatracker.ietf.org/doc/html/rfc9449</a>.<a href="#section-5.1-1.1.2.5.1" class="pilcrow">¶</a></p>
</li>
</ul>
</li>
<li class="normal" id="section-5.1-1.2">
<p id="section-5.1-1.2.1"><strong>OpenID.Core</strong> – “OpenID Connect Core 1.0 incorporating errata set 2,” available at <a href="https://openid.net/specs/openid-connect-core-1_0.html">https://openid.net/specs/openid-connect-core-1_0.html</a>.<a href="#section-5.1-1.2.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.1-1.3">
<p id="section-5.1-1.3.1"><strong>OpenID.Discovery</strong> – “OpenID Connect Discovery 1.0,” available at <a href="https://openid.net/specs/openid-connect-discovery-1_0.html">https://openid.net/specs/openid-connect-discovery-1_0.html</a>.<a href="#section-5.1-1.3.1" class="pilcrow">¶</a></p>
</li>
</ul>
</section>
</div>
<div id="informative-references">
<section id="section-5.2">
<h3 id="name-informative-references">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
</h3>
<ul class="normal">
<li class="normal" id="section-5.2-1.1">
<p id="section-5.2-1.1.1"><strong>IANA JSON Web Token Claims Registry</strong>, available at <a href="https://www.iana.org/assignments/jwt/jwt.xhtml">https://www.iana.org/assignments/jwt/jwt.xhtml</a>.<a href="#section-5.2-1.1.1" class="pilcrow">¶</a></p>
</li>
<li class="normal" id="section-5.2-1.2">
<p id="section-5.2-1.2.1"><strong>IANA OAuth Parameters</strong>, available at <a href="https://www.iana.org/assignments/oauth-parameters/oauth-parameters.xhtml#client-metadata">https://www.iana.org/assignments/oauth-parameters/oauth-parameters.xhtml#client-metadata</a>.<a href="#section-5.2-1.2.1" class="pilcrow">¶</a></p>
</li>
</ul>
</section>
</div>
</section>
</div>
<div id="acknowledgements">
<section id="appendix-A">
<h2 id="name-acknowledgements">
<a href="#appendix-A" class="section-number selfRef">Appendix A. </a><a href="#name-acknowledgements" class="section-name selfRef">Acknowledgements</a>
</h2>
<p id="appendix-A-1">The authors would like to thank early feedback provided by Filip Skokan, Jacob Ideskog, and Kosuke Koiwai.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="notices">
<section id="appendix-B">
<h2 id="name-notices">
<a href="#appendix-B" class="section-number selfRef">Appendix B. </a><a href="#name-notices" class="section-name selfRef">Notices</a>
</h2>
<p id="appendix-B-1"><em>To be completed if adopted.</em><a href="#appendix-B-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="document-history">
<section id="appendix-C">
<h2 id="name-document-history">
<a href="#appendix-C" class="section-number selfRef">Appendix C. </a><a href="#name-document-history" class="section-name selfRef">Document History</a>
</h2>
<p id="appendix-C-1">[[ To be removed from the final specification ]]<a href="#appendix-C-1" class="pilcrow">¶</a></p>
<p id="appendix-C-2">-00<a href="#appendix-C-2" class="pilcrow">¶</a></p>
<p id="appendix-C-3">initial draft<a href="#appendix-C-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="appendix-D">
<h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
</h2>
<address class="vcard">
<div dir="auto" class="left"><span class="fn nameRole">Dick Hardt</span></div>
<div dir="auto" class="left"><span class="org">Hellō</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:dick.hardt@gmail.com" class="email">dick.hardt@gmail.com</a>
</div>
</address>
<address class="vcard">
<div dir="auto" class="left"><span class="fn nameRole">Ethan Heilman</span></div>
<div dir="auto" class="left"><span class="org">Cloudflare</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ethan.r.heilman@gmail.com" class="email">ethan.r.heilman@gmail.com</a>
</div>
</address>
</section>
</div>
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