File: rfc9201.html

package info (click to toggle)
doc-rfc 20230121-1
links: PTS, VCS
area: non-free
in suites: bookworm, forky, sid, trixie
size: 1,609,944 kB
file content (2052 lines) | stat: -rw-r--r-- 76,406 bytes
<!DOCTYPE html>
<html lang="en" class="RFC">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>RFC 9201: Additional OAuth Parameters for Authentication and Authorization for Constrained Environments (ACE)</title>
<meta content="Ludwig Seitz" name="author">
<meta content="
       This specification defines new parameters and encodings for the OAuth
      2.0 token and introspection endpoints when used with the framework for
      Authentication and Authorization for Constrained Environments (ACE).
      These are used to express the proof-of-possession (PoP) key the client
      wishes to use, the PoP key that the authorization server
      has selected, and the PoP key the resource server uses to authenticate
      to the client. 
    " name="description">
<meta content="xml2rfc 3.14.2" name="generator">
<meta content="CoAP" name="keyword">
<meta content="OAuth 2.0" name="keyword">
<meta content="Access Control" name="keyword">
<meta content="Authorization" name="keyword">
<meta content="Internet of Things" name="keyword">
<meta content="9201" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.14.2
    Python 3.9.13
    appdirs 1.4.4
    ConfigArgParse 1.5.3
    google-i18n-address 2.5.1
    html5lib 1.1
    intervaltree 3.1.0
    Jinja2 3.1.2
    kitchen 1.2.6
    lxml 4.9.0
    MarkupSafe 2.1.1
    pycountry 22.3.5
    PyYAML 6.0
    requests 2.28.0
    setuptools 44.1.1
    six 1.16.0
    weasyprint 56.1
-->
<link href="rfc9201.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 necssary during the development of the v3
  formatters.

*/

/* fonts */
@import url('https://fonts.googleapis.com/css?family=Noto+Sans'); /* Sans-serif */
@import url('https://fonts.googleapis.com/css?family=Noto+Serif'); /* Serif (print) */
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono'); /* Monospace */

@viewport {
  zoom: 1.0;
  width: extend-to-zoom;
}
@-ms-viewport {
  width: extend-to-zoom;
  zoom: 1.0;
}
/* general and mobile first */
html {
}
body {
  max-width: 90%;
  margin: 1.5em auto;
  color: #222;
  background-color: #fff;
  font-size: 14px;
  font-family: 'Noto Sans', Arial, Helvetica, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
  display: none;
}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
  margin: 1em 0 0.5em;
  font-weight: bold;
  line-height: 1.3;
}
#title {
  clear: both;
  border-bottom: 1px solid #ddd;
  margin: 0 0 0.5em 0;
  padding: 1em 0 0.5em;
}
.author {
  padding-bottom: 4px;
}
h1 {
  font-size: 26px;
  margin: 1em 0;
}
h2 {
  font-size: 22px;
  margin-top: -20px;  /* provide offset for in-page anchors */
  padding-top: 33px;
}
h3 {
  font-size: 18px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h4 {
  font-size: 16px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h5, h6 {
  font-size: 14px;
}
#n-copyright-notice {
  border-bottom: 1px solid #ddd;
  padding-bottom: 1em;
  margin-bottom: 1em;
}
/* general structure */
p {
  padding: 0;
  margin: 0 0 1em 0;
  text-align: left;
}
div, span {
  position: relative;
}
div {
  margin: 0;
}
.alignRight.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignRight.art-text pre {
  padding: 0;
}
.alignRight {
  margin: 1em 0;
}
.alignRight > *:first-child {
  border: none;
  margin: 0;
  float: right;
  clear: both;
}
.alignRight > *:nth-child(2) {
  clear: both;
  display: block;
  border: none;
}
svg {
  display: block;
}
.alignCenter.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignCenter.art-text pre {
  padding: 0;
}
.alignCenter {
  margin: 1em 0;
}
.alignCenter > *:first-child {
  display: table;
  border: none;
  margin: 0 auto;
}

/* lists */
ol, ul {
  padding: 0;
  margin: 0 0 1em 2em;
}
ol ol, ul ul, ol ul, ul ol {
  margin-left: 1em;
}
li {
  margin: 0 0 0.25em 0;
}
.ulCompact li {
  margin: 0;
}
ul.empty, .ulEmpty {
  list-style-type: none;
}
ul.empty li, .ulEmpty li {
  margin-top: 0.5em;
}
ul.ulBare, li.ulBare {
  margin-left: 0em !important;
}
ul.compact, .ulCompact,
ol.compact, .olCompact {
  line-height: 100%;
  margin: 0 0 0 2em;
}

/* definition lists */
dl {
}
dl > dt {
  float: left;
  margin-right: 1em;
}
/* 
dl.nohang > dt {
  float: none;
}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
  margin-bottom: 0em;
}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0em;
}

/* links */
a {
  text-decoration: none;
}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
}
figcaption a[href],
a[href].selfRef {
  color: #222;
}
/* XXX probably not this:
a.selfRef:hover {
  background-color: transparent;
  cursor: default;
} */

/* Figures */
tt, code, pre, code {
  background-color: #f9f9f9;
  font-family: 'Roboto Mono', monospace;
}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
  max-width: 100%;
}
figure {
  margin: 0;
}
figure blockquote {
  margin: 0.8em 0.4em 0.4em;
}
figcaption {
  font-style: italic;
  margin: 0 0 1em 0;
}
@media screen {
  pre {
    overflow-x: auto;
    max-width: 100%;
    max-width: calc(100% - 22px);
  }
}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 1.2em 2em;
}
blockquote {
  background-color: #f9f9f9;
  color: #111; /* Arlen: WCAG 2019 */
  border: 1px solid #ddd;
  border-radius: 3px;
  margin: 1em 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}

/* tables */
table {
  width: 100%;
  margin: 0 0 1em;
  border-collapse: collapse;
  border: 1px solid #eee;
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.5em 0.75em;
}
th {
  text-align: left;
  background-color: #e9e9e9;
}
tr:nth-child(2n+1) > td {
  background-color: #f5f5f5;
}
table caption {
  font-style: italic;
  margin: 0;
  padding: 0;
  text-align: left;
}
table p {
  /* XXX to avoid bottom margin on table row signifiers. If paragraphs should
     be allowed within tables more generally, it would be far better to select on a class. */
  margin: 0;
}

/* pilcrow */
a.pilcrow {
  color: #666; /* Arlen: AHDJ 2019 */
  text-decoration: none;
  visibility: hidden;
  user-select: none;
  -ms-user-select: none;
  -o-user-select:none;
  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
@media screen {
  aside:hover > a.pilcrow,
  p:hover > a.pilcrow,
  blockquote:hover > a.pilcrow,
  div:hover > a.pilcrow,
  li:hover > a.pilcrow,
  pre:hover > a.pilcrow {
    visibility: visible;
  }
  a.pilcrow:hover {
    background-color: transparent;
  }
}

/* misc */
hr {
  border: 0;
  border-top: 1px solid #eee;
}
.bcp14 {
  font-variant: small-caps;
}

.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
  width: 3em;
  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
/* Fix PDF info block run off issue */
@media print {
  #identifiers dd {
    float: none;
  }
}
#identifiers .authors .author {
  display: inline-block;
  margin-right: 1.5em;
}
#identifiers .authors .org {
  font-style: italic;
}

/* The prepared/rendered info at the very bottom of the page */
.docInfo {
  color: #666; /* Arlen: WCAG 2019 */
  font-size: 0.9em;
  font-style: italic;
  margin-top: 2em;
}
.docInfo .prepared {
  float: left;
}
.docInfo .prepared {
  float: right;
}

/* table of contents */
#toc  {
  padding: 0.75em 0 2em 0;
  margin-bottom: 1em;
}
nav.toc ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
nav.toc li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
/* references */
.references dt {
  text-align: right;
  font-weight: bold;
  min-width: 7em;
}
.references dd {
  margin-left: 8em;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

.references .ascii {
  margin-bottom: 0.25em;
}

/* index */
.index ul {
  margin: 0 0 0 1em;
  padding: 0;
  list-style: none;
}
.index ul ul {
  margin: 0;
}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
  margin: 0.5em 0 1em;
}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
    -moz-column-count: 2;
    -moz-column-gap: 20px;
  }
  .index ul ul {
    -moz-column-count: 1;
    -moz-column-gap: 0;
  }
}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}

address.vcard .nameRole {
  font-weight: 700;
  margin-left: 0;
}
address.vcard .label {
  font-family: "Noto Sans",Arial,Helvetica,sans-serif;
  margin: 0.5em 0;
}
address.vcard .type {
  display: none;
}
.alternative-contact {
  margin: 1.5em 0 1em;
}
hr.addr {
  border-top: 1px dashed;
  margin: 0;
  color: #ddd;
  max-width: calc(100% - 16px);
}

/* temporary notes */
.rfcEditorRemove::before {
  position: absolute;
  top: 0.2em;
  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
  background-color: #ffd; /* Arlen: WCAG 2019 */
}
.rfcEditorRemove {
  position: relative;
  padding-top: 1.8em;
  background-color: #ffd; /* Arlen: WCAG 2019 */
  border-radius: 3px;
}
.cref {
  background-color: #ffd; /* Arlen: WCAG 2019 */
  padding: 2px 4px;
}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 1023px) {
  body {
    padding-top: 2em;
  }
  #title {
    padding: 1em 0;
  }
  h1 {
    font-size: 24px;
  }
  h2 {
    font-size: 20px;
    margin-top: -18px;  /* provide offset for in-page anchors */
    padding-top: 38px;
  }
  #identifiers dd {
    max-width: 60%;
  }
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    background-color: inherit;
    border-bottom: 1px solid #ccc;
  }
  #toc h2 {
    margin: -1px 0 0 0;
    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
    font-size: 1.1em;
    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
    position: relative;
    width: 1em;
    height: 1px;
    left: -164px;
    margin: 6px 0 0 0;
    background: white none repeat scroll 0 0;
    box-shadow: 0 4px 0 0 white, 0 8px 0 0 white;
    content: "";
  }
  #toc nav {
    display: none;
    padding: 0.5em 1em 1em;
    overflow: auto;
    height: calc(100vh - 48px);
    border-left: 1px solid #ddd;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
  body {
    max-width: 724px;
    margin: 42px auto;
    padding-left: 1.5em;
    padding-right: 29em;
  }
  #toc {
    position: fixed;
    top: 42px;
    right: 42px;
    width: 25%;
    margin: 0;
    padding: 0 1em;
    z-index: 1;
  }
  #toc h2 {
    border-top: none;
    border-bottom: 1px solid #ddd;
    font-size: 1em;
    font-weight: normal;
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 0;
    overflow: auto;
  }
  img { /* future proofing */
    max-width: 100%;
    height: auto;
  }
}

/* pagination */
@media print {
  body {

    width: 100%;
  }
  p {
    orphans: 3;
    widows: 3;
  }
  #n-copyright-notice {
    border-bottom: none;
  }
  #toc, #n-introduction {
    page-break-before: always;
  }
  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
    page-break-inside: avoid;
  }
  figure {
    overflow: scroll;
  }
  pre.breakable {
    break-inside: auto;
  }
  h1, h2, h3, h4, h5, h6 {
    page-break-after: avoid;
  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
  }
  table {
    border: 1px solid #ddd;
  }
  td {
    border-top: 1px solid #ddd;
  }
}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
  string-set: ears-top-left content();
}

.ears thead .center {
  string-set: ears-top-center content();
}

.ears thead .right {
  string-set: ears-top-right content();
}

.ears tfoot .left {
  string-set: ears-bottom-left content();
}

.ears tfoot .center {
  string-set: ears-bottom-center content();
}

.ears tfoot .right {
  string-set: ears-bottom-right content();
}
*/

@page :first {
  padding-top: 0;
  @top-left {
    content: normal;
    border: none;
  }
  @top-center {
    content: normal;
    border: none;
  }
  @top-right {
    content: normal;
    border: none;
  }
}

@page {
  size: A4;
  margin-bottom: 45mm;
  padding-top: 20px;
  /* The follwing is commented out here, but set appropriately by in code, as
     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-left {
    content: string(ears-top-left);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-center {
    content: string(ears-top-center);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-right {
    content: string(ears-top-right);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @bottom-left {
    content: string(ears-bottom-left);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-center {
    content: string(ears-bottom-center);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-right {
      content: '[Page ' counter(page) ']';
      vertical-align: top;
      border-top: solid 1px #ccc;
  }
  */

}

/* Changes introduced to fix issues found during implementation */
/* Make sure links are clickable even if overlapped by following H* */
a {
  z-index: 2;
}
/* Separate body from document info even without intervening H1 */
section {
  clear: both;
}


/* Top align author divs, to avoid names without organization dropping level with org names */
.author {
  vertical-align: top;
}

/* Leave room in document info to show Internet-Draft on one line */
#identifiers dt {
  width: 8em;
}

/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
  margin-left: 1em;
}

/* Give floating toc a background color (needed when it's a div inside section */
#toc {
  background-color: white;
}

/* Make the collapsed ToC header render white on gray also when it's a link */
@media screen and (max-width: 1023px) {
  #toc h2 a,
  #toc h2 a:link,
  #toc h2 a:focus,
  #toc h2 a:hover,
  #toc a.toplink,
  #toc a.toplink:hover {
    color: white;
    background-color: #444;
    text-decoration: none;
  }
}

/* Give the bottom of the ToC some whitespace */
@media screen and (min-width: 1024px) {
  #toc {
    padding: 0 0 1em 1em;
  }
}

/* Style section numbers with more space between number and title */
.section-number {
  padding-right: 0.5em;
}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
  font-size: 95%;
}

/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
.art-text pre {
  line-height: 1.12;
}


/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin-right: 0.5em;
}

/* Fix the dl styling to match the RFC 7992 attributes */
dl > dt,
dl.dlParallel > dt {
  float: left;
  margin-right: 1em;
}
dl.dlNewline > dt {
  float: none;
}

/* Provide styling for table cell text alignment */
table td.text-left,
table th.text-left {
  text-align: left;
}
table td.text-center,
table th.text-center {
  text-align: center;
}
table td.text-right,
table th.text-right {
  text-align: right;
}

/* Make the alternative author contact informatio look less like just another
   author, and group it closer with the primary author contact information */
.alternative-contact {
  margin: 0.5em 0 0.25em 0;
}
address .non-ascii {
  margin: 0 0 0 2em;
}

/* With it being possible to set tables with alignment
  left, center, and right, { width: 100%; } does not make sense */
table {
  width: auto;
}

/* Avoid reference text that sits in a block with very wide left margin,
   because of a long floating dt label.*/
.references dd {
  overflow: visible;
}

/* Control caption placement */
caption {
  caption-side: bottom;
}

/* Limit the width of the author address vcard, so names in right-to-left
   script don't end up on the other side of the page. */

address.vcard {
  max-width: 30em;
  margin-right: auto;
}

/* For address alignment dependent on LTR or RTL scripts */
address div.left {
  text-align: left;
}
address div.right {
  text-align: right;
}

/* Provide table alignment support.  We can't use the alignX classes above
   since they do unwanted things with caption and other styling. */
table.right {
 margin-left: auto;
 margin-right: 0;
}
table.center {
 margin-left: auto;
 margin-right: auto;
}
table.left {
 margin-left: 0;
 margin-right: auto;
}

/* Give the table caption label the same styling as the figcaption */
caption a[href] {
  color: #222;
}

@media print {
  .toplink {
    display: none;
  }

  /* avoid overwriting the top border line with the ToC header */
  #toc {
    padding-top: 1px;
  }

  /* Avoid page breaks inside dl and author address entries */
  .vcard {
    page-break-inside: avoid;
  }

}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* 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 */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
   margin-bottom: 0;
}
.alignLeft,
.alignCenter,
.alignRight {
  margin: 1em 0 0 0;
}
/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
   possibly even requiring a new line */
@media print {
  a.pilcrow {
    display: none;
  }
}
/* Styling for the external metadata */
div#external-metadata {
  background-color: #eee;
  padding: 0.5em;
  margin-bottom: 0.5em;
  display: none;
}
div#internal-metadata {
  padding: 0.5em;                       /* to match the external-metadata padding */
}
/* Styling for title RFC Number */
h1#rfcnum {
  clear: both;
  margin: 0 0 -1em;
  padding: 1em 0 0 0;
}
/* Make .olPercent look the same as <ol><li> */
dl.olPercent > dd {
  margin-bottom: 0.25em;
  min-height: initial;
}
/* Give aside some styling to set it apart */
aside {
  border-left: 1px solid #ddd;
  margin: 1em 0 1em 2em;
  padding: 0.2em 2em;
}
aside > dl,
aside > ol,
aside > ul,
aside > table,
aside > p {
  margin-bottom: 0.5em;
}
/* Additional page break settings */
@media print {
  figcaption, table caption {
    page-break-before: avoid;
  }
}
/* Font size adjustments for print */
@media print {
  body  { font-size: 10pt;      line-height: normal; max-width: 96%; }
  h1    { font-size: 1.72em;    padding-top: 1.5em; } /* 1*1.2*1.2*1.2 */
  h2    { font-size: 1.44em;    padding-top: 1.5em; } /* 1*1.2*1.2 */
  h3    { font-size: 1.2em;     padding-top: 1.5em; } /* 1*1.2 */
  h4    { font-size: 1em;       padding-top: 1.5em; }
  h5, h6 { font-size: 1em;      margin: initial; padding: 0.5em 0 0.3em; }
}
/* Sourcecode margin in print, when there's no pilcrow */
@media print {
  .artwork,
  .sourcecode {
    margin-bottom: 1em;
  }
}
/* Avoid narrow tables forcing too narrow table captions, which may render badly */
table {
  min-width: 20em;
}
/* ol type a */
ol.type-a { list-style-type: lower-alpha; }
ol.type-A { list-style-type: upper-alpha; }
ol.type-i { list-style-type: lower-roman; }
ol.type-I { list-style-type: lower-roman; }
/* Apply the print table and row borders in general, on request from the RPC,
and increase the contrast between border and odd row background sligthtly */
table {
  border: 1px solid #ddd;
}
td {
  border-top: 1px solid #ddd;
}
tr {
  break-inside: avoid;
}
tr:nth-child(2n+1) > td {
  background-color: #f8f8f8;
}
/* Use style rules to govern display of the TOC. */
@media screen and (max-width: 1023px) {
  #toc nav { display: none; }
  #toc.active nav { display: block; }
}
/* Add support for keepWithNext */
.keepWithNext {
  break-after: avoid-page;
  break-after: avoid-page;
}
/* Add support for keepWithPrevious */
.keepWithPrevious {
  break-before: avoid-page;
}
/* Change the approach to avoiding breaks inside artwork etc. */
figure, pre, table, .artwork, .sourcecode  {
  break-before: auto;
  break-after: auto;
}
/* Avoid breaks between <dt> and <dd> */
dl {
  break-before: auto;
  break-inside: auto;
}
dt {
  break-before: auto;
  break-after: avoid-page;
}
dd {
  break-before: avoid-page;
  break-after: auto;
  orphans: 3;
  widows: 3
}
span.break, dd.break {
  margin-bottom: 0;
  min-height: 0;
  break-before: auto;
  break-inside: auto;
  break-after: auto;
}
/* Undo break-before ToC */
@media print {
  #toc {
    break-before: auto;
  }
}
/* Text in compact lists should not get extra bottim margin space,
   since that would makes the list not compact */
ul.compact p, .ulCompact p,
ol.compact p, .olCompact p {
 margin: 0;
}
/* But the list as a whole needs the extra space at the end */
section ul.compact,
section .ulCompact,
section ol.compact,
section .olCompact {
  margin-bottom: 1em;                    /* same as p not within ul.compact etc. */
}
/* The tt and code background above interferes with for instance table cell
   backgrounds.  Changed to something a bit more selective. */
tt, code {
  background-color: transparent;
}
p tt, p code, li tt, li code {
  background-color: #f8f8f8;
}
/* Tweak the pre margin -- 0px doesn't come out well */
pre {
   margin-top: 0.5px;
}
/* Tweak the comact list text */
ul.compact, .ulCompact,
ol.compact, .olCompact,
dl.compact, .dlCompact {
  line-height: normal;
}
/* Don't add top margin for nested lists */
li > ul, li > ol, li > dl,
dd > ul, dd > ol, dd > dl,
dl > dd > dl {
  margin-top: initial;
}
/* Elements that should not be rendered on the same line as a <dt> */
/* This should match the element list in writer.text.TextWriter.render_dl() */
dd > div.artwork:first-child,
dd > aside:first-child,
dd > figure:first-child,
dd > ol:first-child,
dd > div:first-child > pre.sourcecode,
dd > table:first-child,
dd > ul:first-child {
  clear: left;
}
/* fix for weird browser behaviour when <dd/> is empty */
dt+dd:empty::before{
  content: "\00a0";
}
/* Make paragraph spacing inside <li> smaller than in body text, to fit better within the list */
li > p {
  margin-bottom: 0.5em
}
/* Don't let p margin spill out from inside list items */
li > p:last-of-type {
  margin-bottom: 0;
}
</style>
<link href="rfc-local.css" rel="stylesheet" type="text/css">
<link href="https://dx.doi.org/10.17487/rfc9201" rel="alternate">
  <link href="urn:issn:2070-1721" rel="alternate">
  <link href="https://datatracker.ietf.org/doc/draft-ietf-ace-oauth-params-16" rel="prev">
  </head>
<body>
<script src="https://www.rfc-editor.org/js/metadata.min.js"></script>
<table class="ears">
<thead><tr>
<td class="left">RFC 9201</td>
<td class="center">OAuth Parameters for ACE</td>
<td class="right">August 2022</td>
</tr></thead>
<tfoot><tr>
<td class="left">Seitz</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-stream">Stream:</dt>
<dd class="stream">Internet Engineering Task Force (IETF)</dd>
<dt class="label-rfc">RFC:</dt>
<dd class="rfc"><a href="https://www.rfc-editor.org/rfc/rfc9201" class="eref">9201</a></dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2022-08" class="published">August 2022</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Author:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">L. Seitz</div>
<div class="org">Combitech</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9201</h1>
<h1 id="title">Additional OAuth Parameters for Authentication and Authorization for Constrained Environments (ACE)</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This specification defines new parameters and encodings for the OAuth
      2.0 token and introspection endpoints when used with the framework for
      Authentication and Authorization for Constrained Environments (ACE).
      These are used to express the proof-of-possession (PoP) key the client
      wishes to use, the PoP key that the authorization server
      has selected, and the PoP key the resource server uses to authenticate
      to the client.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This is an Internet Standards Track document.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            <span><a href="https://www.rfc-editor.org/info/rfc9201">https://www.rfc-editor.org/info/rfc9201</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2022 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Revised BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Revised BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<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" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1" class="keepWithNext"><a href="#section-2" class="xref">2</a>.  <a href="#name-terminology" class="xref">Terminology</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="xref">3</a>.  <a href="#name-parameters-for-the-token-en" class="xref">Parameters for the Token Endpoint</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3.2.1">
                <p id="section-toc.1-1.3.2.1.1" class="keepWithNext"><a href="#section-3.1" class="xref">3.1</a>.  <a href="#name-client-to-as-request" class="xref">Client-to-AS Request</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3.2.2">
                <p id="section-toc.1-1.3.2.2.1"><a href="#section-3.2" class="xref">3.2</a>.  <a href="#name-as-to-client-response" class="xref">AS-to-Client Response</a></p>
</li>
            </ul>
</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="xref">4</a>.  <a href="#name-parameters-for-the-introspe" class="xref">Parameters for the Introspection Endpoint</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="xref">5</a>.  <a href="#name-confirmation-method-paramet" class="xref">Confirmation Method Parameters</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-cbor-mappings" class="xref">CBOR Mappings</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="#section-7" class="xref">7</a>.  <a href="#name-requirements-when-using-asy" class="xref">Requirements When Using Asymmetric Keys</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="#section-8" class="xref">8</a>.  <a href="#name-security-considerations" class="xref">Security Considerations</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="#section-9" class="xref">9</a>.  <a href="#name-privacy-considerations" class="xref">Privacy Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-10" class="xref">10</a>. <a href="#name-iana-considerations" class="xref">IANA Considerations</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10.2.1">
                <p id="section-toc.1-1.10.2.1.1"><a href="#section-10.1" class="xref">10.1</a>.  <a href="#name-oauth-parameter-registratio" class="xref">OAuth Parameter Registration</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10.2.2">
                <p id="section-toc.1-1.10.2.2.1"><a href="#section-10.2" class="xref">10.2</a>.  <a href="#name-oauth-parameters-cbor-mappi" class="xref">OAuth Parameters CBOR Mappings Registration</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10.2.3">
                <p id="section-toc.1-1.10.2.3.1"><a href="#section-10.3" class="xref">10.3</a>.  <a href="#name-oauth-token-introspection-r" class="xref">OAuth Token Introspection Response CBOR Mappings Registration</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#section-11" class="xref">11</a>. <a href="#name-references" class="xref">References</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.11.2.1">
                <p id="section-toc.1-1.11.2.1.1"><a href="#section-11.1" class="xref">11.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.11.2.2">
                <p id="section-toc.1-1.11.2.2.1"><a href="#section-11.2" class="xref">11.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.12">
            <p id="section-toc.1-1.12.1"><a href="#appendix-A" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.13">
            <p id="section-toc.1-1.13.1"><a href="#appendix-B" class="xref"></a><a href="#name-authors-address" class="xref">Author's Address</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="intro">
<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">The Authentication and Authorization for Constrained Environments (ACE)
  specification <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span> requires some new
  parameters for interactions with the OAuth 2.0 <span>[<a href="#RFC6749" class="xref">RFC6749</a>]</span> token
  and introspection endpoints, as well as some new claims to be used in access
  tokens.  These parameters and claims can also be used in other contexts
  and have therefore been put into a dedicated document to
  facilitate their use in a manner independent of
  <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">Note that although all examples are shown in Concise Binary Object
  Representation (CBOR) <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>, JSON
  <span>[<a href="#RFC8259" class="xref">RFC8259</a>]</span> <span class="bcp14">MAY</span> be used as an alternative for HTTP-based
  communications, as specified in <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>.<a href="#section-1-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="terminology">
<section id="section-2">
      <h2 id="name-terminology">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-terminology" class="section-name selfRef">Terminology</a>
      </h2>
<p id="section-2-1">The key words "<span class="bcp14">MUST</span>", "<span class="bcp14">MUST NOT</span>", "<span class="bcp14">REQUIRED</span>", "<span class="bcp14">SHALL</span>", "<span class="bcp14">SHALL NOT</span>", "<span class="bcp14">SHOULD</span>", "<span class="bcp14">SHOULD NOT</span>", "<span class="bcp14">RECOMMENDED</span>", "<span class="bcp14">NOT RECOMMENDED</span>", "<span class="bcp14">MAY</span>", and
"<span class="bcp14">OPTIONAL</span>" in this document are to be interpreted as described in BCP 14 <span>[<a href="#RFC2119" class="xref">RFC2119</a>]</span> <span>[<a href="#RFC8174" class="xref">RFC8174</a>]</span> when, and only when, they appear in all capitals, as shown here.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">Readers are assumed to be familiar with the terminology from <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>, especially the terminology
  for entities in the architecture such as client (C), resource server (RS),
  and authorization server (AS).<a href="#section-2-2" class="pilcrow">¶</a></p>
<p id="section-2-3">Terminology from <span>[<a href="#RFC8152" class="xref">RFC8152</a>]</span> is used in the examples,
  especially COSE_Key, which is defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8152#section-7" class="relref">Section 7</a> of [<a href="#RFC8152" class="xref">RFC8152</a>]</span>.<a href="#section-2-3" class="pilcrow">¶</a></p>
<p id="section-2-4">Note that the term "endpoint" is used here following its OAuth 2.0
      <span>[<a href="#RFC6749" class="xref">RFC6749</a>]</span> definition, which is to denote resources
      such as token and introspection at the AS and authz-info at the RS.  The Constrained
      Application Protocol (CoAP) <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span> definition,
      which is "[a]n entity participating in the CoAP protocol", is not used in this
      specification.<a href="#section-2-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="tokenEndpoint">
<section id="section-3">
      <h2 id="name-parameters-for-the-token-en">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-parameters-for-the-token-en" class="section-name selfRef">Parameters for the Token Endpoint</a>
      </h2>
<p id="section-3-1">This section defines additional parameters for the interactions with
  the token endpoint in the ACE framework <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>.<a href="#section-3-1" class="pilcrow">¶</a></p>
<div id="tokenRequest">
<section id="section-3.1">
        <h3 id="name-client-to-as-request">
<a href="#section-3.1" class="section-number selfRef">3.1. </a><a href="#name-client-to-as-request" class="section-name selfRef">Client-to-AS Request</a>
        </h3>
<p id="section-3.1-1">This section defines the <code>req_cnf</code> parameter allowing clients to
   request a specific PoP key in an access token from a token
   endpoint in the ACE framework <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>:<a href="#section-3.1-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlNewline" id="section-3.1-2">
          <dt id="section-3.1-2.1">req_cnf</dt>
          <dd style="margin-left: 1.5em" id="section-3.1-2.2">
            <span class="bcp14">OPTIONAL</span>.  This field contains information about the key the
 client would like to bind to the access token for proof of possession.
 It is <span class="bcp14">RECOMMENDED</span> that an AS rejects a request containing a symmetric
 key value in the <code>req_cnf</code> field (kty=Symmetric), since the AS is
 expected to be able to generate better symmetric keys than a
 constrained client. (Note: this does not apply to key identifiers
 referencing a symmetric key.) The AS <span class="bcp14">MUST</span> verify that the client
 really is in possession of the corresponding key.  Profiles of
 <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span> using this specification
 <span class="bcp14">MUST</span>
 define the PoP method used by the AS if they allow
 clients to use this request parameter.  Values of this parameter follow
 the syntax and semantics of the <code>cnf</code> claim either from
 <span><a href="https://www.rfc-editor.org/rfc/rfc8747#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC8747" class="xref">RFC8747</a>]</span> for CBOR-based
 interactions or from
 <span><a href="https://www.rfc-editor.org/rfc/rfc7800#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC7800" class="xref">RFC7800</a>]</span> for JSON-based
   interactions.<a href="#section-3.1-2.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-3.1-3"><a href="#fig_symmATreq" class="xref">Figure 1</a> shows a request for an access
 token using the <code>req_cnf</code> parameter to request a specific public key as a
 PoP key.  The content is displayed in CBOR diagnostic
 notation with line breaks for better readability.<a href="#section-3.1-3" class="pilcrow">¶</a></p>
<span id="name-example-request-for-an-acce"></span><div id="fig_symmATreq">
<figure id="figure-1">
          <div id="section-3.1-4.1">
<pre class="lang-cbor-diag sourcecode">
Header: POST (Code=0.02)
Uri-Host: "as.example.com"
Uri-Path: "token"
Content-Format: application/ace+cbor
Payload:
{
   / req_cnf / 4 : {
     / COSE_Key / 1 : {
     / kty /  1 : 2 /EC2/,
     / kid /  2 : h'11',
     / crv / -1 : 1 /P-256/,
     / x /   -2 : h'BAC5B11CAD8F99F9C72B05CF4B9E26D24
                  4DC189F745228255A219A86D6A09EFF',
     / y /   -3 : h'20138BF82DC1B6D562BE0FA54AB7804A3
                  A64B6D72CCFED6B6FB6ED28BBFC117E'
      }
   }
 }
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-example-request-for-an-acce" class="selfRef">Example Request for an Access Token Bound to an Asymmetric Key</a>
          </figcaption></figure>
</div>
</section>
</div>
<div id="tokenResponse">
<section id="section-3.2">
        <h3 id="name-as-to-client-response">
<a href="#section-3.2" class="section-number selfRef">3.2. </a><a href="#name-as-to-client-response" class="section-name selfRef">AS-to-Client Response</a>
        </h3>
<p id="section-3.2-1">This section defines the following additional parameters for
    an AS response to a request to the token endpoint:<a href="#section-3.2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlNewline" id="section-3.2-2">
          <dt id="section-3.2-2.1">cnf</dt>
          <dd style="margin-left: 1.5em" id="section-3.2-2.2">
            <span class="bcp14">REQUIRED</span> if the token type is "pop" and a symmetric key is used.
 <span class="bcp14">MAY</span> be present for asymmetric PoP keys.  This field
 contains the PoP key that the AS selected for the
 token.  Values of this parameter follow the syntax and semantics of the
 <code>cnf</code> claim either from <span><a href="https://www.rfc-editor.org/rfc/rfc8747#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC8747" class="xref">RFC8747</a>]</span>
 for
 CBOR-based interactions or from <span><a href="https://www.rfc-editor.org/rfc/rfc7800#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC7800" class="xref">RFC7800</a>]</span>
 for JSON-based interactions.  See <a href="#paramCnf" class="xref">Section 5</a> for
 additional discussion of the usage of this parameter.<a href="#section-3.2-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-3.2-2.3">rs_cnf</dt>
          <dd style="margin-left: 1.5em" id="section-3.2-2.4">
            <span class="bcp14">OPTIONAL</span> if the token type is "pop" and asymmetric keys are used.
 <span class="bcp14">MUST NOT</span> be present otherwise. This field contains information about
 the public key used by the RS to authenticate.  If this parameter is
 absent, either the RS does not use a public key or the AS knows that
 the RS can authenticate itself to the client without additional
 information.  Values of this parameter follow the syntax and semantics
 of the <code>cnf</code> claim either from
 <span><a href="https://www.rfc-editor.org/rfc/rfc8747#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC8747" class="xref">RFC8747</a>]</span> for CBOR-based
 interactions or from
 <span><a href="https://www.rfc-editor.org/rfc/rfc7800#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC7800" class="xref">RFC7800</a>]</span> for JSON-based
 interactions.  See
 <a href="#paramCnf" class="xref">Section 5</a> for additional discussion of the usage
 of this parameter.<a href="#section-3.2-2.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-3.2-3"><a href="#fig_symmATres" class="xref">Figure 2</a> shows an AS response containing
 a token and a <code>cnf</code> parameter with a symmetric PoP key.<a href="#section-3.2-3" class="pilcrow">¶</a></p>
<span id="name-example-as-response-with-an"></span><div id="fig_symmATres">
<figure id="figure-2">
          <div id="section-3.2-4.1">
<pre class="lang-cbor-diag sourcecode">
Header: Created (Code=2.01)
Content-Format: application/ace+cbor
Payload:
{
  / access_token / 1 : h'4A5015DF686428/...
   (remainder of CWT omitted for brevity;
   CWT contains COSE_Key in the "cnf" claim)/',
  / cnf / 8 : {
   / COSE_Key / 1 : {
      / kty / 1 : 4 / Symmetric /,
      / kid / 2 : h'DFD1AA97',
      / k /  -1 : h'849B5786457C1491BE3A76DCEA6C427108'
    }
  }
}
</pre>
</div>
<figcaption><a href="#figure-2" class="selfRef">Figure 2</a>:
<a href="#name-example-as-response-with-an" class="selfRef">Example AS Response with an Access Token Bound to a Symmetric Key</a>
          </figcaption></figure>
</div>
<p id="section-3.2-5"><a href="#fig_asymmATres" class="xref">Figure 3</a> shows an AS response containing
 a token bound to a previously requested asymmetric PoP key (not
 shown) and an <code>rs_cnf</code> parameter containing the public key of the RS.<a href="#section-3.2-5" class="pilcrow">¶</a></p>
<span id="name-example-as-response-includi"></span><div id="fig_asymmATres">
<figure id="figure-3">
          <div id="section-3.2-6.1">
<pre class="lang-cbor-diag sourcecode">
Header: Created (Code=2.01)
Content-Format: application/ace+cbor
Payload:
{
  / access_token / 1 : h'D08343A1010AA1054D2A45DF6FBC5A5A/...
   (remainder of CWT omitted for brevity)/',
  / rs_cnf / 41 : {
    / COSE_Key / 1 : {
     / kty /  1 : 2 /EC2/,
     / kid /  2 : h'12',
     / crv / -1 : 1 /P-256/,
      / x /  -2 : h'BCEE7EAAC162F91E6F330F5771211E220
                  B8B546C96589B0AC4AD0FD24C77E1F1',
      / y /  -3 : h'C647B38C55EFBBC4E62E651720F002D5D
                  75B2E0C02CD1326E662BCA222B90416'
    }
  }
}
</pre>
</div>
<figcaption><a href="#figure-3" class="selfRef">Figure 3</a>:
<a href="#name-example-as-response-includi" class="selfRef">Example AS Response Including the RS's Public Key</a>
          </figcaption></figure>
</div>
</section>
</div>
</section>
</div>
<div id="introsp">
<section id="section-4">
      <h2 id="name-parameters-for-the-introspe">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-parameters-for-the-introspe" class="section-name selfRef">Parameters for the Introspection Endpoint</a>
      </h2>
<p id="section-4-1">This section defines the use of CBOR instead of JSON for the <code>cnf</code>
      introspection response parameter specified in <span><a href="https://www.rfc-editor.org/rfc/rfc8705#section-9.4" class="relref">Section 9.4</a> of [<a href="#RFC8705" class="xref">RFC8705</a>]</span>.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">If CBOR is used instead of JSON in an interaction with the introspection
      endpoint, the AS <span class="bcp14">MUST</span> use the parameter mapping specified in <a href="#fig_cborParameters" class="xref">Table 1</a> and the value must follow the syntax
      of <code>cnf</code> claim values from <span><a href="https://www.rfc-editor.org/rfc/rfc8747#section-3.1" class="relref">Section 3.1</a> of [<a href="#RFC8747" class="xref">RFC8747</a>]</span>.<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3"><a href="#fig_introRes" class="xref">Figure 4</a> shows an AS response to an introspection
  request including the <code>cnf</code> parameter to indicate the PoP key bound to the token.<a href="#section-4-3" class="pilcrow">¶</a></p>
<span id="name-example-introspection-respo"></span><div id="fig_introRes">
<figure id="figure-4">
        <div id="section-4-4.1">
<pre class="lang-cbor-diag sourcecode">
Header: Created (Code=2.01)
Content-Format: application/ace+cbor
Payload:
{
  / active / 10 : true,
  / scope / 9 : "read",
  / aud / 3 : "tempSensor4711",
  / cnf / 8 : {
    / COSE_Key / 1 : {
      / kty /  1 : 2 /EC2/,
      / kid /  2 : h'11',
      / crv / -1 : 1 /P-256/,
      / x /   -2 : h'BAC5B11CAD8F99F9C72B05CF4B9E26D24
                   4DC189F745228255A219A86D6A09EFF',
      / y /   -3 : h'20138BF82DC1B6D562BE0FA54AB7804A3
                   A64B6D72CCFED6B6FB6ED28BBFC117E'
    }
  }
}
</pre>
</div>
<figcaption><a href="#figure-4" class="selfRef">Figure 4</a>:
<a href="#name-example-introspection-respo" class="selfRef">Example Introspection Response</a>
        </figcaption></figure>
</div>
</section>
</div>
<div id="paramCnf">
<section id="section-5">
      <h2 id="name-confirmation-method-paramet">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-confirmation-method-paramet" class="section-name selfRef">Confirmation Method Parameters</a>
      </h2>
<p id="section-5-1">The confirmation method parameters are used in
  <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span> as follows:<a href="#section-5-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5-2.1">
          <code>req_cnf</code> in the access token request C -&gt; AS, <span class="bcp14">OPTIONAL</span> to
 indicate the  client's raw public key or the key identifier of a previously
 established key between the C and RS that the client wishes to use
 for proof of possession of the access token.<a href="#section-5-2.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-5-2.2">
          <code>cnf</code> in the token response AS -&gt; C, <span class="bcp14">OPTIONAL</span> if using an
 asymmetric key or a key that the client requested via a key identifier
 in the request. <span class="bcp14">REQUIRED</span> if the client didn't specify a <code>req_cnf</code> and
 symmetric keys are used.  Used to indicate the symmetric key generated
 by the AS for proof of possession of the access token.<a href="#section-5-2.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-5-2.3">
          <code>cnf</code> in the introspection response AS -&gt; RS, <span class="bcp14">REQUIRED</span> if the
 access token that was subject to introspection is a PoP
 token, absent otherwise.  Indicates the PoP key bound
 to the access token.<a href="#section-5-2.3" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-5-2.4">
          <code>rs_cnf</code> in the token response AS -&gt; C, <span class="bcp14">OPTIONAL</span> to indicate
 the public key of the RS if it uses one to authenticate itself to the client
 and the binding between the key and RS identity is not established through
 other means.<a href="#section-5-2.4" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-5-3">Note that the COSE_Key structure in a confirmation claim or parameter
      may contain an <code>alg</code> or <code>key_ops</code> parameter.  If such parameters are
      present, a client <span class="bcp14">MUST NOT</span> use a key that is incompatible with
      the profile or PoP algorithm according to those
      parameters. An RS <span class="bcp14">MUST</span> reject a proof of possession using such a key
      with a response code equivalent to the CoAP code 4.00 (Bad Request).<a href="#section-5-3" class="pilcrow">¶</a></p>
<p id="section-5-4">If an access token is issued for an audience that includes several RSs,
  the <code>rs_cnf</code> parameter <span class="bcp14">MUST NOT</span> be used, since the client cannot
  determine for which RS the key applies.  This document recommends to
  specify a different endpoint that the client can use to acquire RS
  authentication keys in such cases.  The specification of such an endpoint
  is out of scope for this document.<a href="#section-5-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="paramsCbor">
<section id="section-6">
      <h2 id="name-cbor-mappings">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-cbor-mappings" class="section-name selfRef">CBOR Mappings</a>
      </h2>
<p id="section-6-1">If CBOR is used, the new parameters and claims defined in this document
  <span class="bcp14">MUST</span> be mapped to CBOR types, as specified in <a href="#fig_cborParameters" class="xref">Table 1</a>, using the given integer abbreviation for the
  map key.<a href="#section-6-1" class="pilcrow">¶</a></p>
<span id="name-cbor-mappings-for-new-param"></span><div id="fig_cborParameters">
<table class="left" id="table-1">
        <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-cbor-mappings-for-new-param" class="selfRef">CBOR Mappings for New Parameters and Claims</a>
        </caption>
<thead>
          <tr>
            <th class="text-left" rowspan="1" colspan="1">Name</th>
            <th class="text-left" rowspan="1" colspan="1">CBOR Key</th>
            <th class="text-left" rowspan="1" colspan="1">Value Type</th>
            <th class="text-left" rowspan="1" colspan="1">Usage</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">req_cnf</td>
            <td class="text-left" rowspan="1" colspan="1">4</td>
            <td class="text-left" rowspan="1" colspan="1">map</td>
            <td class="text-left" rowspan="1" colspan="1">token request</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">cnf</td>
            <td class="text-left" rowspan="1" colspan="1">8</td>
            <td class="text-left" rowspan="1" colspan="1">map</td>
            <td class="text-left" rowspan="1" colspan="1">token response</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">cnf</td>
            <td class="text-left" rowspan="1" colspan="1">8</td>
            <td class="text-left" rowspan="1" colspan="1">map</td>
            <td class="text-left" rowspan="1" colspan="1">introspection response</td>
          </tr>
          <tr>
            <td class="text-left" rowspan="1" colspan="1">rs_cnf</td>
            <td class="text-left" rowspan="1" colspan="1">41</td>
            <td class="text-left" rowspan="1" colspan="1">map</td>
            <td class="text-left" rowspan="1" colspan="1">token response</td>
          </tr>
        </tbody>
      </table>
</div>
</section>
</div>
<div id="asymmReq">
<section id="section-7">
      <h2 id="name-requirements-when-using-asy">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-requirements-when-using-asy" class="section-name selfRef">Requirements When Using Asymmetric Keys</a>
      </h2>
<p id="section-7-1">An RS using asymmetric keys to authenticate to the client <span class="bcp14">MUST NOT</span>
      hold several different asymmetric key pairs applicable to the same
      authentication algorithm.  For example, when using DTLS, the RS <span class="bcp14">MUST NOT</span> hold several asymmetric key pairs applicable to the same cipher suite.
      The reason for this restriction is that the RS has no way of determining
      which key to use before the client's identity is established.  Therefore,
      authentication attempts by the RS could randomly fail based on which key the
      RS selects, unless the algorithm negotiation produces a unique choice of key pair
      for the RS.<a href="#section-7-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="security">
<section id="section-8">
      <h2 id="name-security-considerations">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-8-1">This document is an extension to <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>. All
      security considerations from that document apply here as well.<a href="#section-8-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="privacy">
<section id="section-9">
      <h2 id="name-privacy-considerations">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-privacy-considerations" class="section-name selfRef">Privacy Considerations</a>
      </h2>
<p id="section-9-1">This document is an extension to <span>[<a href="#RFC9200" class="xref">RFC9200</a>]</span>. All
      privacy considerations from that document apply here as well.<a href="#section-9-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="iana">
<section id="section-10">
      <h2 id="name-iana-considerations">
<a href="#section-10" class="section-number selfRef">10. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<div id="IANAOAuthParameter">
<section id="section-10.1">
        <h3 id="name-oauth-parameter-registratio">
<a href="#section-10.1" class="section-number selfRef">10.1. </a><a href="#name-oauth-parameter-registratio" class="section-name selfRef">OAuth Parameter Registration</a>
        </h3>
<p id="section-10.1-1">This section registers the following parameters in the "OAuth
 Parameters" registry <span>[<a href="#IANA.OAuthParameters" class="xref">IANA.OAuthParameters</a>]</span>:<a href="#section-10.1-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.1-2">
          <dt id="section-10.1-2.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-2.2">
            <code>req_cnf</code><a href="#section-10.1-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-2.3">Parameter Usage Location:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-2.4">token request<a href="#section-10.1-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-2.5">Change Controller:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-2.6">IETF<a href="#section-10.1-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-2.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-2.8">
            <a href="#paramCnf" class="xref">Section 5</a> of RFC 9201<a href="#section-10.1-2.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.1-3">
          <dt id="section-10.1-3.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.2">
            <code>rs_cnf</code><a href="#section-10.1-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.3">Parameter Usage Location:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.4">token response<a href="#section-10.1-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.5">Change Controller:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.6">IETF<a href="#section-10.1-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-3.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-3.8">
            <a href="#paramCnf" class="xref">Section 5</a> of RFC 9201<a href="#section-10.1-3.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.1-4">
          <dt id="section-10.1-4.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.2">
            <code>cnf</code><a href="#section-10.1-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.3">Parameter Usage Location:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.4">token response<a href="#section-10.1-4.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.5">Change Controller:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.6">IETF<a href="#section-10.1-4.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.1-4.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.1-4.8">
            <a href="#paramCnf" class="xref">Section 5</a> of RFC 9201<a href="#section-10.1-4.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="IANATokenCBORMappingRegistration">
<section id="section-10.2">
        <h3 id="name-oauth-parameters-cbor-mappi">
<a href="#section-10.2" class="section-number selfRef">10.2. </a><a href="#name-oauth-parameters-cbor-mappi" class="section-name selfRef">OAuth Parameters CBOR Mappings Registration</a>
        </h3>
<p id="section-10.2-1">This section registers the following parameter mappings
 in the "OAuth Parameters CBOR Mappings" registry established in
 <span><a href="https://www.rfc-editor.org/rfc/rfc9200#section-8.10" class="relref">Section 8.10</a> of [<a href="#RFC9200" class="xref">RFC9200</a>]</span>.<a href="#section-10.2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.2-2">
          <dt id="section-10.2-2.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-2.2">
            <code>req_cnf</code><a href="#section-10.2-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-2.3">CBOR Key:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-2.4">4<a href="#section-10.2-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-2.5">Value Type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-2.6">map<a href="#section-10.2-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-2.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-2.8">
            <a href="#tokenRequest" class="xref">Section 3.1</a> of RFC 9201<a href="#section-10.2-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-2.9">Original Specification:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-2.10">RFC 9201<a href="#section-10.2-2.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.2-3">
          <dt id="section-10.2-3.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-3.2">
            <code>cnf</code><a href="#section-10.2-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-3.3">CBOR Key:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-3.4">8<a href="#section-10.2-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-3.5">Value Type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-3.6">map<a href="#section-10.2-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-3.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-3.8">
            <a href="#tokenResponse" class="xref">Section 3.2</a> of RFC 9201<a href="#section-10.2-3.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-3.9">Original Specification:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-3.10">RFC 9201<a href="#section-10.2-3.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.2-4">
          <dt id="section-10.2-4.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-4.2">
            <code>rs_cnf</code><a href="#section-10.2-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-4.3">CBOR Key:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-4.4">41<a href="#section-10.2-4.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-4.5">Value Type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-4.6">map<a href="#section-10.2-4.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-4.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-4.8">
            <a href="#tokenResponse" class="xref">Section 3.2</a> of RFC 9201<a href="#section-10.2-4.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.2-4.9">Original Specification:</dt>
          <dd style="margin-left: 1.5em" id="section-10.2-4.10">RFC 9201<a href="#section-10.2-4.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="IANAIntrospectCBORMappingRegistration">
<section id="section-10.3">
        <h3 id="name-oauth-token-introspection-r">
<a href="#section-10.3" class="section-number selfRef">10.3. </a><a href="#name-oauth-token-introspection-r" class="section-name selfRef">OAuth Token Introspection Response CBOR Mappings Registration</a>
        </h3>
<p id="section-10.3-1">This section registers the following parameter mapping
 in the "OAuth Token Introspection Response CBOR Mappings" registry
 established in <span><a href="https://www.rfc-editor.org/rfc/rfc9200#section-8.12" class="relref">Section 8.12</a> of [<a href="#RFC9200" class="xref">RFC9200</a>]</span>.<a href="#section-10.3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlCompact dlParallel" id="section-10.3-2">
          <dt id="section-10.3-2.1">Name:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.2">
            <code>cnf</code><a href="#section-10.3-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.3">CBOR Key:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.4">8<a href="#section-10.3-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.5">Value Type:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.6">map<a href="#section-10.3-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.7">Reference:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.8">
            <a href="#introsp" class="xref">Section 4</a> of RFC 9201<a href="#section-10.3-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-10.3-2.9">Original Specification:</dt>
          <dd style="margin-left: 1.5em" id="section-10.3-2.10">
            <span>[<a href="#RFC8705" class="xref">RFC8705</a>]</span><a href="#section-10.3-2.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
</section>
</div>
<section id="section-11">
      <h2 id="name-references">
<a href="#section-11" class="section-number selfRef">11. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-11.1">
        <h3 id="name-normative-references">
<a href="#section-11.1" class="section-number selfRef">11.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="IANA.OAuthParameters">[IANA.OAuthParameters]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"OAuth Parameters"</span>, <span>&lt;<a href="https://www.iana.org/assignments/oauth-parameters">https://www.iana.org/assignments/oauth-parameters</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2119">[RFC2119]</dt>
        <dd>
<span class="refAuthor">Bradner, S.</span>, <span class="refTitle">"Key words for use in RFCs to Indicate Requirement Levels"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 2119</span>, <span class="seriesInfo">DOI 10.17487/RFC2119</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2119">https://www.rfc-editor.org/info/rfc2119</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6749">[RFC6749]</dt>
        <dd>
<span class="refAuthor">Hardt, D., Ed.</span>, <span class="refTitle">"The OAuth 2.0 Authorization Framework"</span>, <span class="seriesInfo">RFC 6749</span>, <span class="seriesInfo">DOI 10.17487/RFC6749</span>, <time datetime="2012-10" class="refDate">October 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6749">https://www.rfc-editor.org/info/rfc6749</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7800">[RFC7800]</dt>
        <dd>
<span class="refAuthor">Jones, M.</span>, <span class="refAuthor">Bradley, J.</span>, and <span class="refAuthor">H. Tschofenig</span>, <span class="refTitle">"Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)"</span>, <span class="seriesInfo">RFC 7800</span>, <span class="seriesInfo">DOI 10.17487/RFC7800</span>, <time datetime="2016-04" class="refDate">April 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7800">https://www.rfc-editor.org/info/rfc7800</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8152">[RFC8152]</dt>
        <dd>
<span class="refAuthor">Schaad, J.</span>, <span class="refTitle">"CBOR Object Signing and Encryption (COSE)"</span>, <span class="seriesInfo">RFC 8152</span>, <span class="seriesInfo">DOI 10.17487/RFC8152</span>, <time datetime="2017-07" class="refDate">July 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8152">https://www.rfc-editor.org/info/rfc8152</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
        <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8259">[RFC8259]</dt>
        <dd>
<span class="refAuthor">Bray, T., Ed.</span>, <span class="refTitle">"The JavaScript Object Notation (JSON) Data Interchange Format"</span>, <span class="seriesInfo">STD 90</span>, <span class="seriesInfo">RFC 8259</span>, <span class="seriesInfo">DOI 10.17487/RFC8259</span>, <time datetime="2017-12" class="refDate">December 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8259">https://www.rfc-editor.org/info/rfc8259</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8705">[RFC8705]</dt>
        <dd>
<span class="refAuthor">Campbell, B.</span>, <span class="refAuthor">Bradley, J.</span>, <span class="refAuthor">Sakimura, N.</span>, and <span class="refAuthor">T. Lodderstedt</span>, <span class="refTitle">"OAuth 2.0 Mutual-TLS Client Authentication and Certificate-Bound Access Tokens"</span>, <span class="seriesInfo">RFC 8705</span>, <span class="seriesInfo">DOI 10.17487/RFC8705</span>, <time datetime="2020-02" class="refDate">February 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8705">https://www.rfc-editor.org/info/rfc8705</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8747">[RFC8747]</dt>
        <dd>
<span class="refAuthor">Jones, M.</span>, <span class="refAuthor">Seitz, L.</span>, <span class="refAuthor">Selander, G.</span>, <span class="refAuthor">Erdtman, S.</span>, and <span class="refAuthor">H. Tschofenig</span>, <span class="refTitle">"Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs)"</span>, <span class="seriesInfo">RFC 8747</span>, <span class="seriesInfo">DOI 10.17487/RFC8747</span>, <time datetime="2020-03" class="refDate">March 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8747">https://www.rfc-editor.org/info/rfc8747</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8949">[RFC8949]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span> and <span class="refAuthor">P. Hoffman</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR)"</span>, <span class="seriesInfo">STD 94</span>, <span class="seriesInfo">RFC 8949</span>, <span class="seriesInfo">DOI 10.17487/RFC8949</span>, <time datetime="2020-12" class="refDate">December 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8949">https://www.rfc-editor.org/info/rfc8949</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9200">[RFC9200]</dt>
      <dd>
<span class="refAuthor">Seitz, L.</span>, <span class="refAuthor">Selander, G.</span>, <span class="refAuthor">Wahlstroem, E.</span>, <span class="refAuthor">Erdtman, S.</span>, and <span class="refAuthor">H. Tschofenig</span>, <span class="refTitle">"Authentication and Authorization for Constrained Environments (ACE) Using the OAuth 2.0 Framework (ACE-OAuth)"</span>, <span class="seriesInfo">RFC 9200</span>, <span class="seriesInfo">DOI 10.17487/RFC9200</span>, <time datetime="2022-08" class="refDate">August 2022</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9200">https://www.rfc-editor.org/info/rfc9200</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-11.2">
        <h3 id="name-informative-references">
<a href="#section-11.2" class="section-number selfRef">11.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="RFC7252">[RFC7252]</dt>
      <dd>
<span class="refAuthor">Shelby, Z.</span>, <span class="refAuthor">Hartke, K.</span>, and <span class="refAuthor">C. Bormann</span>, <span class="refTitle">"The Constrained Application Protocol (CoAP)"</span>, <span class="seriesInfo">RFC 7252</span>, <span class="seriesInfo">DOI 10.17487/RFC7252</span>, <time datetime="2014-06" class="refDate">June 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7252">https://www.rfc-editor.org/info/rfc7252</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="Acknowledgments">
<section id="appendix-A">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="appendix-A-1">This document is a product of the ACE Working Group of the IETF.
      Special thanks to <span class="contact-name">Brian Campbell</span> for his thorough review of
      this document.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
<p id="appendix-A-2"><span class="contact-name">Ludwig Seitz</span> worked on this document as part of the
      CelticNext projects CyberWI and CRITISEC with funding from Vinnova.<a href="#appendix-A-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="appendix-B">
      <h2 id="name-authors-address">
<a href="#name-authors-address" class="section-name selfRef">Author's Address</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Ludwig Seitz</span></div>
<div dir="auto" class="left"><span class="org">Combitech</span></div>
<div dir="auto" class="left"><span class="street-address">Djäknegatan 31</span></div>
<div dir="auto" class="left">SE-<span class="postal-code">211 35</span> <span class="locality">Malmö</span>
</div>
<div dir="auto" class="left"><span class="country-name">Sweden</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ludwig.seitz@combitech.com" class="email">ludwig.seitz@combitech.com</a>
</div>
</address>
</section>
</div>
<script>const toc = document.getElementById("toc");
toc.querySelector("h2").addEventListener("click", e => {
  toc.classList.toggle("active");
});
toc.querySelector("nav").addEventListener("click", e => {
  toc.classList.remove("active");
});
</script>
</body>
</html>