draft-carpenter-anima-grasp-ext-sign.html

<!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>GRASP Flood Signing Extension</title>
<meta content="Carsten Bormann" name="author">
<meta content="Brian E. Carpenter" name="author">
<meta content="Toerless Eckert" name="author">
<meta content="Michael Richardson" name="author">
<meta content="
       This document clarifies how message formats for the GeneRic Autonomic Signaling Protocol (GRASP) defined by RFC 8990 may be updated by adding new options. It also describes one such option for cryptographically signing an M_FLOOD message, and a method of adding a signature to any GRASP objective. 
    " name="description">
<meta content="xml2rfc 3.14.1" name="generator">
<meta content="Internet-Draft" name="keyword">
<meta content="draft-carpenter-anima-grasp-ext-sign-latest" name="ietf.draft">
<!-- Generator version information:
  xml2rfc 3.14.1
    Python 3.8.10
    appdirs 1.4.4
    ConfigArgParse 1.5.3
    google-i18n-address 2.5.2
    html5lib 1.1
    intervaltree 3.1.0
    Jinja2 3.1.2
    kitchen 1.2.6
    lxml 4.9.1
    MarkupSafe 2.1.1
    pycountry 22.3.5
    PyYAML 6.0
    requests 2.28.1
    setuptools 65.3.0
    six 1.16.0
-->
<link href="draft-carpenter-anima-grasp-ext-sign.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">@font-face {
  font-family: 'Lora';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Italic'), local('Lora-Italic'), url('https://martinthomson.github.io/rfc-css/fonts/lora-italic-cyrillic-ext.woff2') format('woff2');
  unicode-range: U+0460-052F, U+1C80-1C88, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
@font-face {
  font-family: 'Lora';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Italic'), local('Lora-Italic'), url('https://martinthomson.github.io/rfc-css/fonts/lora-italic-cyrillic-ext.woff2') format('woff2');
  unicode-range: U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
  font-family: 'Lora';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Italic'), local('Lora-Italic'), url('https://martinthomson.github.io/rfc-css/fonts/lora-italic-vietnamese.woff2') format('woff2');
  unicode-range: U+0102-0103, U+0110-0111, U+1EA0-1EF9, U+20AB;
}
@font-face {
  font-family: 'Lora';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Italic'), local('Lora-Italic'), url('https://martinthomson.github.io/rfc-css/fonts/lora-italic-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}

@font-face {
  font-family: 'Lora';
  font-style: italic;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Italic'), local('Lora-Italic'), url('https://martinthomson.github.io/rfc-css/fonts/lora-italic-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Regular'), local('Lora-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/lora-regular-cyrillic-ext.woff2') format('woff2');
  unicode-range: U+0460-052F, U+1C80-1C88, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Regular'), local('Lora-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/lora-regular-cyrillic.woff2') format('woff2');
  unicode-range: U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Regular'), local('Lora-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/lora-regular-vietnamese.woff2') format('woff2');
  unicode-range: U+0102-0103, U+0110-0111, U+1EA0-1EF9, U+20AB;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Regular'), local('Lora-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/lora-regular-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Lora Regular'), local('Lora-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/lora-regular-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local('Lora Bold'), local('Lora-Bold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-bold-cyrillic-ext.woff2') format('woff2');
  unicode-range: U+0460-052F, U+1C80-1C88, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local('Lora Bold'), local('Lora-Bold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-bold-cyrillic.woff2') format('woff2');
  unicode-range: U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local('Lora Bold'), local('Lora-Bold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-bold-vietnamese.woff2') format('woff2');
  unicode-range: U+0102-0103, U+0110-0111, U+1EA0-1EF9, U+20AB;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local('Lora Bold'), local('Lora-Bold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-bold-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local('Lora Bold'), local('Lora-Bold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-bold-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
  font-family: 'Lora';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: local('Lora SemiBold'), local('Lora-SemiBold'), url('https://martinthomson.github.io/rfc-css/fonts/lora-semibold-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: 'Cabin Condensed';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: local('Cabin Condensed SemiBold'), local('CabinCondensed-SemiBold'), url('https://martinthomson.github.io/rfc-css/fonts/cabincondensed-semibold-vietnamese.woff2') format('woff2');
  unicode-range: U+0102-0103, U+0110-0111, U+1EA0-1EF9, U+20AB;
}
@font-face {
  font-family: 'Cabin Condensed';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: local('Cabin Condensed SemiBold'), local('CabinCondensed-SemiBold'), url('https://martinthomson.github.io/rfc-css/fonts/cabincondensed-semibold-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
  font-family: 'Cabin Condensed';
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: local('Cabin Condensed SemiBold'), local('CabinCondensed-SemiBold'), url('https://martinthomson.github.io/rfc-css/fonts/cabincondensed-semibold-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: 'Oxygen Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Oxygen Mono'), local('OxygenMono-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/oxygenmono-regular-latin-ext.woff2') format('woff2');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
  font-family: 'Oxygen Mono';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local('Oxygen Mono'), local('OxygenMono-Regular'), url('https://martinthomson.github.io/rfc-css/fonts/oxygenmono-regular-latin.woff2') format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  color-scheme: light dark;
  --background-color: #fff;
  --text-color: #222;
  --title-color: #191919;
  --link-color: #2a6496;
  --highlight-color: #f9f9f9;
  --line-color: #eee;
  --pilcrow-weak: #ddd;
  --pilcrow-strong: #bbb;
  --small-font-size: 14.5px;
  --font-mono: 'Oxygen Mono', monospace;
  scrollbar-color: #bbb #eee;
}
body {
  max-width: 600px;
  margin: 75px auto;
  padding: 0 5px;
  color: var(--text-color);
  background-color: var(--background-color);
  font: 16px/22px "Lora", serif;
  scroll-behavior: smooth;
}

.ears {
  display: none;
}

/* headings */
h1, h2, h3, h4, h5, h6 {
  font-family: "Cabin Condensed", sans-serif;
  font-weight: 600;
  margin: 0.8em 0 0.3em;
  font-size-adjust: 0.5;
  color: var(--title-color);
}
h1#title {
  font-size: 32px;
  line-height: 40px;
  clear: both;
}
h1#title, h1#rfcnum {
  margin: 1.5em 0 0.2em;
}
h1#rfcnum + h1#title {
  margin: 0.2em 0;
}

h1, h2, h3 {
  font-size: 22px;
  line-height: 27px;
}
h4, h5, h6 {
  font-size: 20px;
  line-height: 24px;
}

/* general structure */
.author {
  padding-bottom: 0.3em;
}
#abstract+p {
  font-size: 18px;
  line-height: 24px;
}
#abstract+p code, #abstract+p samp, #abstract+p tt {
  font-size: 16px;
  line-height: 0;
}

p {
  padding: 0;
  margin: 0.5em 0;
  text-align: left;
}
div {
  margin: 0;
}
.alignRight.art-text {
  background-color: var(--highlight-color);
  border: 1px solid var(--line-color);
  border-radius: 3px;
  padding: 0.5em 1em 0;
  margin-bottom: 0.5em;
}
.alignRight.art-text pre {
  padding: 0;
  width: auto;
}
.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;
}
/* font-family isn't space-separated, but =~ will have to do */
svg[font-family~="monospace" i], svg [font-family~="monospace" i] {
  font-family: var(--font-mono);
}
.alignCenter.art-text {
  background-color: var(--highlight-color);
  border: 1px solid var(--line-color);
  border-radius: 3px;
  padding: 0.5em 1em 0;
  margin-bottom: 0.5em;
}
.alignCenter.art-text pre {
  padding: 0;
  width: auto;
}
.alignCenter {
  margin: 1em 0;
}
.alignCenter > *:first-child {
  border: none;
  /* this isn't optimal, but it's an existence proof.  PrinceXML doesn't
     support flexbox yet.
  */
  display: table;
  margin: 0 auto;
}

/* lists */
ol, ul {
  padding: 0;
  margin: 0 0 0.5em 2em;
}
:is(ol, ul) :is(ol, ul) {
  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;
}
:is(ul, ol).compact, .ulCompact, .olCompact {
  line-height: 100%;
  margin: 0 0 0 2em;
}

/* definition lists */
dl {
  clear: left;
  --indent: 3ch;
  /* --indent: attr(indent ch); not supported in any browser, but we can dream */
}
dl > dt {
  float: left;
  margin-right: 1em;
  min-width: 20ch;
}
dl.dlNewline > dt {
  float: none;
}
dl > dd {
  margin-bottom: .8em;
  margin-left: var(--indent) !important; /* stupid element overrides */
  min-height: 2ex;
}
:is(dl.compact, .dlCompact) > dd {
  margin-bottom: 0;
}
:is(dl.compact, .dlCompact) > dd > :is(:first-child, .break:first-child + *) {
  margin-top: 0;
}
:is(dl.compact, .dlCompact) > dd > :is(:last-child) {
  margin-bottom: 0;
}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0;
}
dl .break {
  display: none;
}

/* links */
a, a[href].selfRef:hover {
  text-decoration: none;
}
a[href].selfRef {
  color: var(--text-color);
}
a[href] {
  color: var(--link-color);
}
a[href]:hover {
  text-decoration: underline;
}
a[href].selfRef:hover {
  background-color: var(--highlight-color);
}
a.xref {
  white-space: nowrap;
}

/* Figures */
tt, code, pre {
  background-color: var(--highlight-color);
  font: 14px/22px var(--font-mono);
}
tt, code {
  /* changing the font for inline elements leads to different ascender
     and descender heights; as we want to retain baseline alignment,
     remove leading to avoid altering the final height of lines */
  line-height: 0;
}
:is(h1, h2, h3, h4, h5, h6) :is(tt, code) {
  font-size: 84%;
}
pre {
  border: 1px solid var(--line-color);
  font-size: 13.5px;
  line-height: 16px;
  letter-spacing: -0.2px;
  margin: 5px;
  padding: 5px;
}
img {
  max-width: 100%;
}
figure {
  margin: 0.5em 0;
  padding: 0;
}
figure blockquote {
  margin: 0.8em 0.4em 0.4em;
}
figcaption, caption {
  font-style: italic;
  margin: 0.5em 1.5em;
  text-align: left;
}
@media screen {
  /* Auto-collapse boilerplate. */
  :is(#status-of-memo, #copyright) p {
    margin: -2px 0;
    max-height: 0;
    transition: max-height 2s ease, margin 0.5s ease 0.5s;
    overflow: hidden;
  }
  :is(#status-of-memo, #copyright):hover p,
  :is(#status-of-memo, #copyright) h2:target ~ p {
    margin: 0.5em 0;
    max-height: 500px;
    overflow: auto;
  }
  pre, svg {
    display: inline-block;
    overflow-x: auto;
  }
  pre {
    max-width: 100%;
    width: calc(100% - 22px - 1em);
  }
  svg {
    max-width: calc(100% - 22px - 1em);
  }
  figure pre {
    display: block;
    width: calc(100% - 25px);
  }
  :is(pre, svg) + .pilcrow {
    display: inline-block;
    vertical-align: text-bottom;
    padding-bottom: 8px;
  }
}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 0 2em;
  font-style: italic;
}
blockquote {
  margin: 1em 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}

/* tables */
table {
  max-width: 100%;
  margin: 0 0 1em;
  border-collapse: collapse;
}
table.right {
  margin-left: auto;
}
table.center {
  margin-left: auto;
  margin-right: auto;
}
table.left {
  margin-right: auto;
}
thead, tbody {
  border: 1px solid var(--line-color);
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: 5px 10px;
}
th {
  background-color: var(--line-color);
}
:is(tr:nth-child(2n), thead+tbody > tr:nth-child(2n+1)) > td {
  background-color: var(--background-color);
}
:is(tr:nth-child(2n+1), thead+tbody > tr:nth-child(2n)) > td {
  background-color: var(--highlight-color);
}
table caption {
  margin: 0;
  padding: 3px 0 3px 1em;
}
table p {
  margin: 0;
}

/* pilcrow */
a.pilcrow {
  margin-left: 3px;
  opacity: 0.2;
  user-select: none;
}
a.pilcrow[href] { color: var(--pilcrow-weak); }
a.pilcrow[href]:hover { text-decoration: none; }
@media not print {
  :hover > a.pilcrow {
    opacity: 1;
  }
  a.pilcrow[href]:hover {
    color: var(--pilcrow-strong);
    background-color: transparent;
  }
}
@media print {
  a.pilcrow {
    display: none;
  }
}

/* misc */
hr {
  border: 0;
  border-top: 1px solid var(--line-color);
}
.bcp14 {
  font-variant: small-caps;
  font-weight: 600;
  font-size: 14.5px;
}
.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: var(--small-font-size);
  line-height: 18px;
  --identifier-width: 15ch;
}
#identifiers dt {
  width: var(--identifier-width);
  min-width: var(--identifier-width);
  clear: left;
  float: left;
  text-align: right;
}
#identifiers dd {
  margin: 0;
  margin-left: calc(1em + var(--identifier-width)) !important;
  min-width: 5em;
}
#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: #999;
  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;
}
#toc nav ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
#toc nav li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
#toc a.xref {
  white-space: normal;
}
/* references */
.references dt {
  text-align: right;
  font-weight: bold;
  min-width: 7em;
}
.references dt:target::before {
  content: "⇒";
  width: 15px;
  margin: 0 10px 0 -25px;
}
.references dd {
  margin-left: 8em !important;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

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

/* index */
#rfc\.index\.index + ul {
  margin-left: 0;
}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}
address.vcard .nameRole {
  font-weight: 700;
  margin-left: 0;
}
address.vcard .label {
  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);
}
@media (min-width: 500px) {
  #authors-addresses > section {
    column-count: 2;
    column-gap: 20px;
  }
  #authors-addresses > section > h2 {
    column-span: all;
  }
  /* hack for break-inside: avoid-column */
  #authors-addresses address {
    display: inline-block;
    break-inside: avoid-column;
  }
}

.rfcEditorRemove p:first-of-type {
  font-style: italic;
}
.cref {
  background-color: rgba(249, 232, 105, 0.3);
  padding: 2px 4px;
}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 929px) {
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    border-bottom: 1px solid #ccc;
    opacity: 0.6;
  }
  #toc.active {
      opacity: 1;
  }
  #toc h2 {
    margin: 0;
    padding: 2px 0 2px 6px;
    padding-right: 1em;
    font-size: 18px;
    line-height: 24px;
    min-width: 190px;
    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: 8px 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;
    background-color: var(--background-color);
    padding: 0.5em 1em 1em;
    overflow: auto;
    overscroll-behavior: contain;
    height: calc(100vh - 48px);
    border-left: 1px solid #ddd;
  }
  #toc.active nav {
    display: block;
  }
  /* Make the collapsed ToC header render white on gray also when it's a link */
  #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;
  }
  #toc a.toplink {
    margin-top: 2px;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 930px) {
  body {
    padding-right: 360px;
    padding-right: calc(min(180px + 20%, 500px));
  }
  #toc {
    position: fixed;
    bottom: 0;
    right: 0;
    right: calc(50vw - 480px);
    width: 312px;
    margin: 0;
    padding: 0;
    z-index: 1;
  }
  #toc h2 {
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 2em;
    overflow: auto;
    overscroll-behavior: contain;
    scrollbar-width: thin;
  }
  #toc nav > ul  {
    margin-bottom: 2em;
  }
  #toc ul {
    margin: 0 0 0 4px;
    font-size: var(--small-font-size);
  }
  #toc ul :is(p, li) {
    margin: 2px 0;
    line-height: 22px;
  }
  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;
  }
  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;
  }
}

@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;
}

/* Changes introduced to fix issues found during implementation */

/* 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;
}

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

/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin: 8px 0.5em 0;
}

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

/* Make the alternative author contact information 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: 20em;
  margin-right: auto;
}

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

/* Give the table caption label the same styling as the figcaption */

@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 */
  dd {
    page-break-before: avoid;
  }
  .vcard {
    page-break-inside: avoid;
  }

}

/* Dark mode. */
@media (prefers-color-scheme: dark) {
:root {
  --background-color: #121212;
  --text-color: #f0f0f0;
  --title-color: #fff;
  --link-color: #4da4f0;
  --highlight-color: #282828;
  --line-color: #444;
  --pilcrow-weak: #444;
  --pilcrow-strong: #666;
  scrollbar-color: #777 #333;
}
}

/* SVG Trick: a prefix match works because only black and white are allowed */
svg :is([stroke="black"], [stroke^="#000"]) {
  stroke: var(--text-color);
}
svg :is([stroke="white"], [stroke^="#fff"]) {
  stroke: var(--background-color);
}
svg :is([fill="black"], [fill^="#000"], :not([fill])) {
  fill: var(--text-color);
}
svg :is([stroke="fill"], [fill^="#fff"]) {
  fill: var(--background-color);
}
</style>

</head>
<body>
<table class="ears">
<thead><tr>
<td class="left">Internet-Draft</td>
<td class="center">GRASP Flood Signing</td>
<td class="right">September 2022</td>
</tr></thead>
<tfoot><tr>
<td class="left">Bormann, et al.</td>
<td class="center">Expires 5 March 2023</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">ANIMA</dd>
<dt class="label-internet-draft">Internet-Draft:</dt>
<dd class="internet-draft">draft-carpenter-anima-grasp-ext-sign-latest</dd>
<dt class="label-updates">Updates:</dt>
<dd class="updates">
<a href="https://www.rfc-editor.org/rfc/rfc8990" class="eref">8990</a> (if approved)</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2022-09-01" class="published">1 September 2022</time>
    </dd>
<dt class="label-intended-status">Intended Status:</dt>
<dd class="intended-status">Standards Track</dd>
<dt class="label-expires">Expires:</dt>
<dd class="expires"><time datetime="2023-03-05">5 March 2023</time></dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">C. Bormann</div>
<div class="org">TZI</div>
</div>
<div class="author">
      <div class="author-name">B. E. Carpenter</div>
<div class="org">Univ. of Auckland</div>
</div>
<div class="author">
      <div class="author-name">T. Eckert</div>
<div class="org">Futurewei</div>
</div>
<div class="author">
      <div class="author-name">M. Richardson</div>
<div class="org">Sandelman</div>
</div>
</dd>
</dl>
</div>
<h1 id="title">GRASP Flood Signing Extension</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document clarifies how message formats for the GeneRic Autonomic Signaling Protocol (GRASP) defined by RFC 8990 may be updated by adding new options. It also describes one such option for cryptographically signing an M_FLOOD message, and a method of adding a signature to any GRASP objective.<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 Internet-Draft is submitted in full conformance with the
        provisions of BCP 78 and BCP 79.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
        Internet-Drafts are working documents of the Internet Engineering Task
        Force (IETF). Note that other groups may also distribute working
        documents as Internet-Drafts. The list of current Internet-Drafts is
        at <span><a href="https://datatracker.ietf.org/drafts/current/">https://datatracker.ietf.org/drafts/current/</a></span>.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
        Internet-Drafts are draft documents valid for a maximum of six months
        and may be updated, replaced, or obsoleted by other documents at any
        time. It is inappropriate to use Internet-Drafts as reference
        material or to cite them other than as "work in progress."<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-4">
        This Internet-Draft will expire on 5 March 2023.<a href="#section-boilerplate.1-4" 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" class="keepWithNext"><a href="#section-3" class="xref">3</a>.  <a href="#name-extensibility-of-grasp-mess" class="xref">Extensibility of GRASP message formats</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="xref">4</a>.  <a href="#name-format-of-the-grasp-m_flood" class="xref">Format of the GRASP M_FLOOD Signature Option</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.1">
                <p id="section-toc.1-1.4.2.1.1"><a href="#section-4.1" class="xref">4.1</a>.  <a href="#name-signing-a-message" class="xref">Signing a message</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.2">
                <p id="section-toc.1-1.4.2.2.1"><a href="#section-4.2" class="xref">4.2</a>.  <a href="#name-verifying-a-message" class="xref">Verifying a message</a></p>
</li>
            </ul>
</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-format-of-the-grasp-objecti" class="xref">Format of the GRASP Objective Signature Option</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="xref">5.1</a>.  <a href="#name-signing-an-objective" class="xref">Signing an objective</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="xref">5.2</a>.  <a href="#name-verifying-a-signed-objectiv" class="xref">Verifying a signed objective</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="#section-6" class="xref">6</a>.  <a href="#name-open-issues-rfc-editor-plea" class="xref">Open Issues [RFC Editor: please remove]</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-implementation-status-rfc-e" class="xref">Implementation Status [RFC Editor: please remove]</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-revised-cddl-specification-" class="xref">Revised CDDL Specification of GRASP</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>
</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">Appendix A</a>.  <a href="#name-change-log" class="xref">Change Log</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.12.2.1">
                <p id="section-toc.1-1.12.2.1.1"><a href="#appendix-A.1" class="xref">A.1</a>.  <a href="#name-draft-00" class="xref">Draft-00</a></p>
</li>
            </ul>
</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">Appendix B</a>.  <a href="#name-acknowledgements" class="xref">Acknowledgements</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.14">
            <p id="section-toc.1-1.14.1"><a href="#appendix-C" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</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 GeneRic Autonomic Signaling Protocol (GRASP) is specified in <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span>.
For the general model of an autonomic network, and for terminology not otherwise
defined here or in RFC 8990, see <span>[<a href="#RFC8993" class="xref">RFC8993</a>]</span>.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">One important feature of GRASP is its flooding mechanism, the M_FLOOD message,
which distributes GRASP objectives (as defined in RFC 8990)
to all GRASP nodes within range. Such messages are sent as multicasts,
which unlike GRASP unicast messages, cannot be protected
with TLS. To mitigate any risk of malicious M_FLOOD messages, this document
specifies a method of cryptographically signing such messages.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">This version describes two approaches, one of which should be chosen for
standardization:
signing the message as a whole, or signing just the embedded objective(s).<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">Preparing this specification revealed a weakness in the way RFC 8990
describes extensibility by the addition of new options to GRASP messages.
This document therefore starts by clarifying this aspect of RFC 8990.<a href="#section-1-4" 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 "<strong>MUST</strong>", "<strong>MUST NOT</strong>", "<strong>REQUIRED</strong>", "<strong>SHALL</strong>", "<strong>SHALL NOT</strong>", "<strong>SHOULD</strong>", "<strong>SHOULD NOT</strong>", "<strong>RECOMMENDED</strong>", "<strong>NOT RECOMMENDED</strong>", "<strong>MAY</strong>", and "<strong>OPTIONAL</strong>" 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>
</section>
</div>
<div id="extensibility-of-grasp-message-formats">
<section id="section-3">
      <h2 id="name-extensibility-of-grasp-mess">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-extensibility-of-grasp-mess" class="section-name selfRef">Extensibility of GRASP message formats</a>
      </h2>
<p id="section-3-1">Although RFC 8990 defines a finite set of GRASP message types and their contents, it also implies that extensions are expected. In particular, the general definition of the message format (Section 2.8.2 of <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span>) states that:<a href="#section-3-1" class="pilcrow">¶</a></p>
<blockquote id="section-3-2">
The MESSAGE_TYPE indicates the type of the message and thus defines the expected options. Any options received that are not consistent with the MESSAGE_TYPE SHOULD be silently discarded.<a href="#section-3-2" class="pilcrow">¶</a>
</blockquote>
<p id="section-3-3">The general structure of a GRASP message is an integer MESSAGE_TYPE followed by various elements, some of which are options in the form [OPTION_TYPE, ...]. The intention of the quoted statement was to allow new options to be defined without invalidating existing implementations. However, the formal CDDL definitions in <span>[<a href="#RFC8610" class="xref">RFC8610</a>]</span>  of the various individual message types do not include explicit extension points where new options could be included. Thus, the implementer of a message decoder that adheres strictly to the CDDL might not implement the silent discard, because an unexpected option would violate the CDDL definition and trigger a decoding error. This creates a risk of interoperability failure when new options are introduced.<a href="#section-3-3" class="pilcrow">¶</a></p>
<p id="section-3-4">This document revises the CDDL definition of GRASP to clarify this point. Specifically, the CDDL now starts as follows:<a href="#section-3-4" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-3-5">
<pre>
grasp-message = (message .within message-structure) / noop-message
message-structure = [MESSAGE_TYPE, session-id, ?initiator,
                      *grasp-element]
grasp-element = (option .within option-structure) / objective / any
option-structure = [OPTION_TYPE, *any]
</pre><a href="#section-3-5" class="pilcrow">¶</a>
</div>
<p id="section-3-6">This allows future extensions to be made by specifying elements in the two "any" components shown. The complete revised CDDL definition is given in <a href="#grasp-cddl" class="xref">Section 9</a>. Consistent with RFC 8990, implementations <strong>SHOULD</strong> silently discard unknown options, with <strong>OPTIONAL</strong> logging for diagnostic purposes.<a href="#section-3-6" class="pilcrow">¶</a></p>
<p id="section-3-7">It is not expected that the basic GRASP message formats and options will require frequent extensions. In general, extended capabilities <strong>SHOULD</strong> be created by designing suitable GRASP objectives, as defined in Section 2.10 of <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span> and discussed in <span>[<a href="#RFC9222" class="xref">RFC9222</a>]</span>.<a href="#section-3-7" class="pilcrow">¶</a></p>
</section>
</div>
<div id="format-of-the-grasp-mflood-signature-option">
<section id="section-4">
      <h2 id="name-format-of-the-grasp-m_flood">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-format-of-the-grasp-m_flood" class="section-name selfRef">Format of the GRASP M_FLOOD Signature Option</a>
      </h2>
<p id="section-4-1">This section describes how a signature can be attached to a complete
GRASP M_FLOOD message.<a href="#section-4-1" class="pilcrow">¶</a></p>
<div id="signing-a-message">
<section id="section-4.1">
        <h3 id="name-signing-a-message">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-signing-a-message" class="section-name selfRef">Signing a message</a>
        </h3>
<p id="section-4.1-1">This section describes how a M_FLOOD message may be signed as a whole,
covering all the embedded objectives if there are several.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">The formal definition of the GRASP M_FLOOD message is extended as follows, defined
in fragmentary CDDL <span>[<a href="#RFC8610" class="xref">RFC8610</a>]</span>.<a href="#section-4.1-2" class="pilcrow">¶</a></p>
<p id="section-4.1-3">The statement given in <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span>:<a href="#section-4.1-3" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-4.1-4">
<pre>
    flood-message = [M_FLOOD, session-id, initiator, ttl,
                 +[objective, (locator-option / [])]]
</pre><a href="#section-4.1-4" class="pilcrow">¶</a>
</div>
<p id="section-4.1-5">is replaced by:<a href="#section-4.1-5" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-4.1-6">
<pre>
   flood-message = [M_FLOOD, session-id, initiator, ttl,
                 +[objective, (locator-option / [])], ?sign-option]

   sign-option = [O_COSE_SIGN, bytes] ; see text description
   O_COSE_SIGN = 107
</pre><a href="#section-4.1-6" class="pilcrow">¶</a>
</div>
<p id="section-4.1-7">Note that signed M_FLOOD messages are relayed exactly as desccribed in
Section 2.5.6.2 of <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span>, including decrementing the loop count,
which is therefore excluded from the following signature process.<a href="#section-4.1-7" class="pilcrow">¶</a></p>
<p id="section-4.1-8">The bytestring content of the sign-option is a COSE signature with a detached
payload, as described in <span>[<a href="#RFC9052" class="xref">RFC9052</a>]</span>. The payload that is signed is a copy
of the entire flood-message contents encoded as CBOR <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>, but
without the sign-option component, and with the loop-count component of the first
GRASP objective replaced by zero.<a href="#section-4.1-8" class="pilcrow">¶</a></p>
<p id="section-4.1-9">In more detail, a node that sends a signed M_FLOOD proceeds as follows:<a href="#section-4.1-9" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.1-10">
<li id="section-4.1-10.1">Build the M_FLOOD message with no signature.<a href="#section-4.1-10.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.2">Make a copy of this structure.<a href="#section-4.1-10.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.3">Set the loop-count of the first objective to zero.<a href="#section-4.1-10.3" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.4">Encode this copy in CBOR to be used as the COSE payload, as described in <span>[<a href="#RFC9052" class="xref">RFC9052</a>]</span>.<a href="#section-4.1-10.4" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.5">Create a COSE signature expressed in CBOR with this payload, as described in <span>[<a href="#RFC9052" class="xref">RFC9052</a>]</span>, using this node's key.<a href="#section-4.1-10.5" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.6">Decode this signature from CBOR, typically using a loads() function.<a href="#section-4.1-10.6" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.7">Replace the payload component by nil.<a href="#section-4.1-10.7" class="pilcrow">¶</a>
</li>
          <li id="section-4.1-10.8">Re-encode this signature in CBOR, typically using a dumps() function.<a href="#section-4.1-10.8" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.1-11">The result is the bytestring to be included in the sign-option.<a href="#section-4.1-11" class="pilcrow">¶</a></p>
<p id="section-4.1-12">The COSE signature uses the following choices according to RFC 9052:<a href="#section-4.1-12" class="pilcrow">¶</a></p>
<p id="section-4.1-13">TBD TBD<a href="#section-4.1-13" class="pilcrow">¶</a></p>
<p id="section-4.1-14">The process by which the relevant COSE keys are generated and distributed is out of scope for the present document.<a href="#section-4.1-14" class="pilcrow">¶</a></p>
</section>
</div>
<div id="verifying-a-message">
<section id="section-4.2">
        <h3 id="name-verifying-a-message">
<a href="#section-4.2" class="section-number selfRef">4.2. </a><a href="#name-verifying-a-message" class="section-name selfRef">Verifying a message</a>
        </h3>
<p id="section-4.2-1">Upon receipt of a signed M_FLOOD message, each GRASP node <strong>SHOULD</strong>
verify it with a key related to the node identified by the 'initiator' element.
If verification succeeds, the message is processed as normal. If
verification fails, the message <strong>MUST</strong> be ignored and the event <strong>MAY</strong> be logged.<a href="#section-4.2-1" class="pilcrow">¶</a></p>
<p id="section-4.2-2">Verification proceeds as follows:<a href="#section-4.2-2" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.2-3">
<li id="section-4.2-3.1">Extract the signature bytes from the sign-option and decoding them
from CBOR, typically using a loads() function. The resulting object is
the COSE signature with a detached payload.<a href="#section-4.2-3.1" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.2">Make a copy of the received M_FLOOD message.<a href="#section-4.2-3.2" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.3">Remove the sign-option from that copy.<a href="#section-4.2-3.3" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.4">Set the loop-count component of the first GRASP objective in that copy to zero.<a href="#section-4.2-3.4" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.5">Re-encode this copy as CBOR, typically using a dumps() function.<a href="#section-4.2-3.5" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.6">Insert the result as the 'payload' component of the COSE signature.<a href="#section-4.2-3.6" class="pilcrow">¶</a>
</li>
          <li id="section-4.2-3.7">Verify the signature as defined in <span>[<a href="#RFC9052" class="xref">RFC9052</a>]</span>.<a href="#section-4.2-3.7" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-4.2-4">A node that does not support verification of  a signed M_FLOOD message
<strong>MAY</strong> process the message as normal, ignoring the sign-option, and
<strong>MAY</strong> log the presence of the extra option.<a href="#section-4.2-4" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="format-of-the-grasp-objective-signature-option">
<section id="section-5">
      <h2 id="name-format-of-the-grasp-objecti">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-format-of-the-grasp-objecti" class="section-name selfRef">Format of the GRASP Objective Signature Option</a>
      </h2>
<p id="section-5-1">This section describes how a signature can be attached to a single
GRASP objective. It is primarily intended for use in an M_FLOOD
message but MAY be used more widely.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">The syntax of a GRASP objective is extended to allow an optional
COSE signature when the objective value is present:<a href="#section-5-2" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-5-3">
<pre>
objective = [objective-name, objective-flags,
             loop-count, ?objective-value] /
            [objective-name, objective-flags,
             loop-count, objective-value, objective-signature]

objective-signature = bytes ; see "Signing an objective"
</pre><a href="#section-5-3" class="pilcrow">¶</a>
</div>
<div id="signing-an-objective">
<section id="section-5.1">
        <h3 id="name-signing-an-objective">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-signing-an-objective" class="section-name selfRef">Signing an objective</a>
        </h3>
<p id="section-5.1-1">TBD (Similar to above)<a href="#section-5.1-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="verifying-a-signed-objective">
<section id="section-5.2">
        <h3 id="name-verifying-a-signed-objectiv">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-verifying-a-signed-objectiv" class="section-name selfRef">Verifying a signed objective</a>
        </h3>
<p id="section-5.2-1">TBD (Similar to above)<a href="#section-5.2-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="open-issues-rfc-editor-please-remove">
<section id="section-6">
      <h2 id="name-open-issues-rfc-editor-plea">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-open-issues-rfc-editor-plea" class="section-name selfRef">Open Issues [RFC Editor: please remove]</a>
      </h2>
<ol start="1" type="1" class="normal type-1" id="section-6-1">
<li id="section-6-1.1">The above describes a "voluntary-to-verify" signature, i.e. nodes that do not support COSE signing can simply ignore the signature. Is this OK, or do we also need a "mandatory-to-verify" version?<a href="#section-6-1.1" class="pilcrow">¶</a>
</li>
        <li id="section-6-1.2">Is the current arbitrary limitation to 256 option types necessary?<a href="#section-6-1.2" class="pilcrow">¶</a>
</li>
        <li id="section-6-1.3">Should the signature be applied to a whole message, or to an individual objective?<a href="#section-6-1.3" class="pilcrow">¶</a>
</li>
      </ol>
</section>
</div>
<div id="implementation-status-rfc-editor-please-remove">
<section id="section-7">
      <h2 id="name-implementation-status-rfc-e">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-implementation-status-rfc-e" class="section-name selfRef">Implementation Status [RFC Editor: please remove]</a>
      </h2>
<p id="section-7-1">TBD. Code will be <a href="https://github.com/becarpenter/graspy">on Github</a>.<a href="#section-7-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="security-considerations">
<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">The security considerations of <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span> apply. This document enhances protection against malicious nodes by defining a verifiable COSE signature for flooded objectives. It does not describe the keying process.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">In a network where only some nodes are capable of verifying the signature of flooded GRASP objectives, the operator must consider which objectives require to be signed, and what is the impact of some nodes using the flooded information without verification. An operator might choose to disallow nodes that cannot verify such messages.<a href="#section-8-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="grasp-cddl">
<section id="section-9">
      <h2 id="name-revised-cddl-specification-">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-revised-cddl-specification-" class="section-name selfRef">Revised CDDL Specification of GRASP</a>
      </h2>
<p id="section-9-1">This section replaces Section 4 of <span>[<a href="#RFC8990" class="xref">RFC8990</a>]</span>.<a href="#section-9-1" class="pilcrow">¶</a></p>
<div id="section-9-2">
<pre class="breakable sourcecode">&lt;CODE BEGINS&gt;
;This version includes syntax for both signing an M_FLOOD and
;for signing any objective. It does not include arbitrary message
;or option extensibility (under study).

grasp-message = (message .within message-structure) / noop-message

message-structure = [MESSAGE_TYPE, session-id, ?initiator,
                     *grasp-option]

MESSAGE_TYPE = 0..255
session-id = 0..4294967295 ; up to 32 bits
grasp-option = any

message /= discovery-message
discovery-message = [M_DISCOVERY, session-id, initiator, objective]

message /= response-message ; response to Discovery
response-message = [M_RESPONSE, session-id, initiator, ttl,
                    (+locator-option // divert-option), ?objective]

message /= synch-message ; response to Synchronization request
synch-message = [M_SYNCH, session-id, objective]

message /= flood-message
flood-message = [M_FLOOD, session-id, initiator, ttl,
                 +[objective, (locator-option / [])], ?sign-option]

message /= request-negotiation-message
request-negotiation-message = [M_REQ_NEG, session-id, objective]

message /= request-synchronization-message
request-synchronization-message = [M_REQ_SYN, session-id, objective]

message /= negotiation-message
negotiation-message = [M_NEGOTIATE, session-id, objective]

message /= end-message
end-message = [M_END, session-id, accept-option / decline-option]

message /= wait-message
wait-message = [M_WAIT, session-id, waiting-time]

message /= invalid-message
invalid-message = [M_INVALID, session-id, ?any]

noop-message = [M_NOOP]

divert-option = [O_DIVERT, +locator-option]

accept-option = [O_ACCEPT]

decline-option = [O_DECLINE, ?reason]
reason = text  ; optional UTF-8 error message

waiting-time = 0..4294967295 ; in milliseconds
ttl = 0..4294967295 ; in milliseconds

locator-option /= [O_IPv4_LOCATOR, ipv4-address,
                   transport-proto, port-number]
ipv4-address = bytes .size 4

locator-option /= [O_IPv6_LOCATOR, ipv6-address,
                   transport-proto, port-number]
ipv6-address = bytes .size 16

locator-option /= [O_FQDN_LOCATOR, text, transport-proto,
                   port-number]

locator-option /= [O_URI_LOCATOR, text,
                   transport-proto / null, port-number / null]

transport-proto = IPPROTO_TCP / IPPROTO_UDP
IPPROTO_TCP = 6
IPPROTO_UDP = 17
port-number = 0..65535

sign-option = [O_COSE_SIGN, bytes] ; see "Signing a message"

initiator = ipv4-address / ipv6-address

objective-flags = uint .bits objective-flag

objective-flag = &amp;(
  F_DISC: 0    ; valid for discovery
  F_NEG: 1     ; valid for negotiation
  F_SYNCH: 2   ; valid for synchronization
  F_NEG_DRY: 3 ; negotiation is a dry run
)

objective /= [objective-name, objective-flags,
             loop-count, ?objective-value]

objective /= [objective-name, objective-flags,
             loop-count, objective-value, objective-signature]

objective-name = text ; see section "Format of Objective Options"

objective-value = any

objective-signature = bytes ; see "Signing an objective"


loop-count = 0..255

; Constants for message types and option types

M_NOOP = 0
M_DISCOVERY = 1
M_RESPONSE = 2
M_REQ_NEG = 3
M_REQ_SYN = 4
M_NEGOTIATE = 5
M_END = 6
M_WAIT = 7
M_SYNCH = 8
M_FLOOD = 9
M_INVALID = 99

O_DIVERT = 100
O_ACCEPT = 101
O_DECLINE = 102
O_IPv6_LOCATOR = 103
O_IPv4_LOCATOR = 104
O_FQDN_LOCATOR = 105
O_URI_LOCATOR = 106
O_COSE_SIGN = 107

&lt;CODE ENDS&gt;</pre><a href="#section-9-2" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="iana-considerations">
<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>
<p id="section-10-1">IANA is requested to add one entry to the GRASP Messages and Options registry, and update
the unassigned values accordingly:<a href="#section-10-1" class="pilcrow">¶</a></p>
<div class="alignLeft art-text artwork" id="section-10-2">
<pre>
107       O_COSE_SIGN   [RFCxxxx]
108-255   Unassigned
</pre><a href="#section-10-2" class="pilcrow">¶</a>
</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="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="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="RFC8610">[RFC8610]</dt>
        <dd>
<span class="refAuthor">Birkholz, H.</span>, <span class="refAuthor">Vigano, C.</span>, and <span class="refAuthor">C. Bormann</span>, <span class="refTitle">"Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures"</span>, <span class="seriesInfo">RFC 8610</span>, <span class="seriesInfo">DOI 10.17487/RFC8610</span>, <time datetime="2019-06" class="refDate">June 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8610">https://www.rfc-editor.org/info/rfc8610</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="RFC8990">[RFC8990]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span>, <span class="refAuthor">Carpenter, B., Ed.</span>, and <span class="refAuthor">B. Liu, Ed.</span>, <span class="refTitle">"GeneRic Autonomic Signaling Protocol (GRASP)"</span>, <span class="seriesInfo">RFC 8990</span>, <span class="seriesInfo">DOI 10.17487/RFC8990</span>, <time datetime="2021-05" class="refDate">May 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8990">https://www.rfc-editor.org/info/rfc8990</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9052">[RFC9052]</dt>
      <dd>
<span class="refAuthor">Schaad, J.</span>, <span class="refTitle">"CBOR Object Signing and Encryption (COSE): Structures and Process"</span>, <span class="seriesInfo">STD 96</span>, <span class="seriesInfo">RFC 9052</span>, <span class="seriesInfo">DOI 10.17487/RFC9052</span>, <time datetime="2022-08" class="refDate">August 2022</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9052">https://www.rfc-editor.org/info/rfc9052</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="RFC8993">[RFC8993]</dt>
        <dd>
<span class="refAuthor">Behringer, M., Ed.</span>, <span class="refAuthor">Carpenter, B.</span>, <span class="refAuthor">Eckert, T.</span>, <span class="refAuthor">Ciavaglia, L.</span>, and <span class="refAuthor">J. Nobre</span>, <span class="refTitle">"A Reference Model for Autonomic Networking"</span>, <span class="seriesInfo">RFC 8993</span>, <span class="seriesInfo">DOI 10.17487/RFC8993</span>, <time datetime="2021-05" class="refDate">May 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8993">https://www.rfc-editor.org/info/rfc8993</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC9222">[RFC9222]</dt>
      <dd>
<span class="refAuthor">Carpenter, B. E.</span>, <span class="refAuthor">Ciavaglia, L.</span>, <span class="refAuthor">Jiang, S.</span>, and <span class="refAuthor">P. Peloso</span>, <span class="refTitle">"Guidelines for Autonomic Service Agents"</span>, <span class="seriesInfo">RFC 9222</span>, <span class="seriesInfo">DOI 10.17487/RFC9222</span>, <time datetime="2022-03" class="refDate">March 2022</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc9222">https://www.rfc-editor.org/info/rfc9222</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="change-log">
<section id="appendix-A">
      <h2 id="name-change-log">
<a href="#appendix-A" class="section-number selfRef">Appendix A. </a><a href="#name-change-log" class="section-name selfRef">Change Log</a>
      </h2>
<div id="draft-00">
<section id="appendix-A.1">
        <h3 id="name-draft-00">
<a href="#appendix-A.1" class="section-number selfRef">A.1. </a><a href="#name-draft-00" class="section-name selfRef">Draft-00</a>
        </h3>
<ul class="normal">
<li class="normal" id="appendix-A.1-1.1">Original version<a href="#appendix-A.1-1.1" class="pilcrow">¶</a>
</li>
        </ul>
</section>
</div>
</section>
</div>
<div id="acknowledgements">
<section id="appendix-B">
      <h2 id="name-acknowledgements">
<a href="#appendix-B" class="section-number selfRef">Appendix B. </a><a href="#name-acknowledgements" class="section-name selfRef">Acknowledgements</a>
      </h2>
<p id="appendix-B-1">TBD<a href="#appendix-B-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="appendix-C">
      <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">Carsten Bormann</span></div>
<div dir="auto" class="left"><span class="org">TZI</span></div>
<div dir="auto" class="left"><span class="country-name">Germany</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:cabo@tzi.org" class="email">cabo@tzi.org</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Brian E. Carpenter</span></div>
<div dir="auto" class="left"><span class="org">The University of Auckland</span></div>
<div dir="auto" class="left"><span class="street-address">School of Computer Science<br>The University of Auckland<br>PB 92019<br>Auckland 1142</span></div>
<div dir="auto" class="left"><span class="country-name">New Zealand</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:brian.e.carpenter@gmail.com" class="email">brian.e.carpenter@gmail.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Toerless Eckert</span></div>
<div dir="auto" class="left"><span class="org">Futurewei</span></div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:tte@cs.fau.de" class="email">tte@cs.fau.de</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Michael Richardson</span></div>
<div dir="auto" class="left"><span class="org">Sandelman</span></div>
<div dir="auto" class="left"><span class="country-name">Canada</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:mcr@sandelman.ca" class="email">mcr@sandelman.ca</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>