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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Modern Algorithms in the Web Cryptography API</title>
<script src="https://www.w3.org/Tools/respec/respec-w3c" class="remove"></script>
<link rel="stylesheet" href="https://w3c.github.io/webcrypto/webcrypto.css" type="text/css" />
<style>
var.overline {
/* We don't use text-decoration: overline because it's rendered way too high */
text-decoration: underline;
text-underline-offset: -1.33ex;
text-decoration-skip-ink: none;
text-decoration-thickness: 1px !important;
}
</style>
<script class='remove'>
"use strict";
// See https://github.com/w3c/respec/wiki/ for how to configure ReSpec
var respecConfig = {
"github": "WICG/webcrypto-modern-algos",
"editors": [
{
name: "Daniel Huigens",
url: "mailto:daniel.huigens@proton.ch",
company: "Proton AG",
companyURL: "https://proton.me/",
},
{
name: "Filip Skokan",
url: "mailto:panva.ip@gmail.com",
company: "Okta",
companyURL: "https://www.okta.com/",
},
],
"shortName": "webcrypto-modern-algos",
"specStatus": "CG-DRAFT",
"group": "wicg",
"xref": ["WebIDL", "webcrypto", "infra", "html"],
localBiblio: {
"JWA": {
aliasOf: "RFC7518"
},
// TODO: move to specref?
"FIPS-202": {
"title": "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions",
"href": "https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf",
"publisher": "NIST",
"date": "August 2015"
},
// TODO: move to specref?
"FIPS-203": {
"title": "Module-Lattice-Based Key-Encapsulation Mechanism Standard",
"href": "https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf",
"publisher": "NIST",
"date": "August 2024"
},
// TODO: move to specref?
"FIPS-204": {
"title": "Module-Lattice-Based Digital Signature Standard",
"href": "https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.204.pdf",
"publisher": "NIST",
"date": "August 2024"
},
// TODO: move to specref?
"FIPS-205": {
"title": "Stateless Hash-Based Digital Signature Standard",
"href": "https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.205.pdf",
"publisher": "NIST",
"date": "August 2024"
},
// TODO: move to specref?
"NIST-SP800-185": {
"title": "NIST Special Publication 800-185: SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash and ParallelHash",
"href": "https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-185.pdf",
"publisher": "NIST",
"date": "December 2016"
},
"RFC9861": {
"title": "KangarooTwelve and TurboSHAKE",
"href": "https://www.rfc-editor.org/rfc/rfc9861.html",
"publisher": "IETF",
"date": "October 2025"
},
"draft-ietf-jose-pqc-kem-05": {
"title": "Post-Quantum Key Encapsulation Mechanisms (PQ KEMs) for JOSE and COSE",
"href": "https://www.ietf.org/archive/id/draft-ietf-jose-pqc-kem-05.html",
"publisher": "IETF",
"date": "December 2025"
},
"CSOR": {
"title": "Computer Security Objects Register",
"href": "https://csrc.nist.gov/projects/computer-security-objects-register/algorithm-registration",
"publisher": "NIST"
},
"draft-ietf-hpke-pq": {
"title": "Post-Quantum Hybrid Key Encapsulation Mechanisms for HPKE",
"href": "https://datatracker.ietf.org/doc/draft-ietf-hpke-pq/",
"publisher": "IETF"
},
"draft-ietf-hpke-hpke": {
"title": "Hybrid Public Key Encryption",
"href": "https://datatracker.ietf.org/doc/draft-ietf-hpke-hpke/",
"publisher": "IETF"
},
},
};
</script>
</head>
<body>
<section id="abstract">
<p>
This specification defines a number of post-quantum secure and
modern cryptographic algorithms for the [[webcrypto | Web Cryptography API]],
namely ML-KEM, ML-DSA, SLH-DSA, AES-OCB, ChaCha20-Poly1305,
SHA-3, cSHAKE, TurboSHAKE, KangarooTwelve, KMAC, and Argon2.
</p>
</section>
<section id="sotd">
<p>
This is an unofficial proposal.
</p>
</section>
<section id="introduction" class="informative">
<h2>Introduction</h2>
<p>
This proposal aims to modernize the set of cryptographic algorithms
available in the [[webcrypto | Web Cryptography API]], such that
web applications can make use of post-quantum secure and
performant cryptographic algorithms.
To this end, the following cryptographic algorithms are added:
</p>
<ul>
<li><a href="#ml-kem">ML-KEM</a> [[FIPS-203]]</li>
<li><a href="#ml-dsa">ML-DSA</a> [[FIPS-204]]</li>
<li><a href="#slh-dsa">SLH-DSA</a> [[FIPS-205]]</li>
<li><a href="#aes-ocb">AES-OCB</a> [[RFC7253]]</li>
<li><a href="#chacha20-poly1305">ChaCha20-Poly1305</a> [[RFC8439]]</li>
<li><a href="#sha3">SHA3-256, SHA3-384, and SHA3-512</a> [[FIPS-202]]</li>
<li><a href="#cshake">cSHAKE128, cSHAKE256</a>, <a href="#kmac">KMAC128, and KMAC256</a> [[NIST-SP800-185]]</li>
<li><a href="#turboshake">TurboSHAKE128, TurboSHAKE256</a>, <a href="#kangarootwelve">KT128, and KT256</a> [[RFC9861]]</li>
<li><a href="#argon2">Argon2d, Argon2i, and Argon2id</a> [[RFC9106]]</li>
</ul>
<p>
To accommodate the usage of ML-KEM, and possibly future other KEMs,
this proposal introduces functions for key encapsulation and decapsulation;
<a href="#dfn-SubtleCrypto-method-encapsulateKey">`SubtleCrypto.encapsulateKey`</a>,
<a href="#dfn-SubtleCrypto-method-encapsulateBits">`SubtleCrypto.encapsulateBits`</a>,
<a href="#dfn-SubtleCrypto-method-decapsulateKey">`SubtleCrypto.decapsulateKey`</a> and
<a href="#dfn-SubtleCrypto-method-decapsulateBits">`SubtleCrypto.decapsulateBits`</a>.
</p>
<p>
Additionally, this proposal introduces the <a href="#dfn-SubtleCrypto-method-getPublicKey">`SubtleCrypto.getPublicKey`</a> function,
which provides a convenient way to derive a public key from an asymmetric private key,
eliminating the need to store both the public and private key separately when only the private key is needed.
</p>
<p>
Finally, this proposal aims to make feature detection easier,
by adding a <a href="#dfn-SubtleCrypto-method-supports">`SubtleCrypto.supports`</a> function,
which can be used to detect whether a given algorithm identifier
(including any parameters) is supported for the given operation.
</p>
</section>
<section id="specification-conventions">
<h2>Specification Conventions</h2>
<p>
This specification follows the <a data-cite="webcrypto#algorithm-conventions">conventions</a>
laid out in Section 18.3 of [[webcrypto]]. None of the algorithms defined here
are required to be implemented, but if a conforming User Agent implements an
algorithm, it MUST implement all of the supported operations specified in this
document, and must perform the steps to <a data-cite="webcrypto#concept-define-an-algorithm">define an algorithm</a>
specified in section 18.4.3 of [[webcrypto]] for each of the supported operations.
</p>
</section>
<section id="partial-subtlecrypto-interface">
<h2>Partial SubtleCrypto interface</h2>
<p>
This section extends the {{SubtleCrypto}} interface of [[webcrypto]].
</p>
<pre class="idl">
[SecureContext,Exposed=(Window,Worker)]
partial interface SubtleCrypto {
Promise<EncapsulatedKey> encapsulateKey(
AlgorithmIdentifier encapsulationAlgorithm,
CryptoKey encapsulationKey,
AlgorithmIdentifier sharedKeyAlgorithm,
boolean extractable,
sequence<KeyUsage> keyUsages
);
Promise<EncapsulatedBits> encapsulateBits(
AlgorithmIdentifier encapsulationAlgorithm,
CryptoKey encapsulationKey
);
Promise<CryptoKey> decapsulateKey(
AlgorithmIdentifier decapsulationAlgorithm,
CryptoKey decapsulationKey,
BufferSource ciphertext,
AlgorithmIdentifier sharedKeyAlgorithm,
boolean extractable,
sequence<KeyUsage> keyUsages
);
Promise<ArrayBuffer> decapsulateBits(
AlgorithmIdentifier decapsulationAlgorithm,
CryptoKey decapsulationKey,
BufferSource ciphertext
);
Promise<CryptoKey> getPublicKey(
CryptoKey key,
sequence<KeyUsage> keyUsages
);
static boolean supports(DOMString operation,
AlgorithmIdentifier algorithm,
optional unsigned long? length = null);
static boolean supports(DOMString operation,
AlgorithmIdentifier algorithm,
AlgorithmIdentifier additionalAlgorithm);
};
</pre>
<section id="subtlecrypto-interface-datatypes">
<h3>Data Types</h3>
<section id="subtlecrypto-interface-keyformat">
<h4>Key Formats</h4>
<p>
This specification replaces the definition of <a data-cite="webcrypto#dfn-KeyFormat">`KeyFormat`</a>
in [[webcrypto]] with the following:
</p>
<pre class="idl">
enum KeyFormat { "raw-public", "raw-private", "raw-seed", "raw-secret", "raw", "spki", "pkcs8", "jwk" };
</pre>
<p>
This specification specifies a number of new <a data-cite="webcrypto#dfn-RecognizedKeyFormats">recognized key format values</a>:
</p>
<dl data-dfn-for=KeyFormat>
<dt><dfn data-idl>raw-public</dfn></dt>
<dd>An unformatted sequence of public key bytes.</dd>
<dt><dfn data-idl>raw-private</dfn></dt>
<dd>An unformatted sequence of private key bytes.</dd>
<dt><dfn data-idl>raw-seed</dfn></dt>
<dd>An unformatted sequence of private key seed bytes.</dd>
<dt><dfn data-idl>raw-secret</dfn></dt>
<dd>An unformatted sequence of secret key bytes.</dd>
</dl>
<p>
For all existing symmetric algorithms in [[webcrypto]],
{{KeyFormat/"raw-secret"}} acts as an alias of {{KeyFormat/"raw"}}.
</p>
<p>
For all existing asymmetric algorithms in [[webcrypto]],
{{KeyFormat/"raw-public"}} acts as an alias of {{KeyFormat/"raw"}}.
</p>
<p>
In the {{SubtleCrypto/deriveKey()}} method, in the import key step,
{{KeyFormat/"raw-secret"}} must be used as the format instead of {{KeyFormat/"raw"}}.
</p>
</section>
<section id="subtlecrypto-interface-keyusage">
<h4>Key Usages</h4>
<p>
This specification replaces the definition of <a data-cite="webcrypto#dfn-KeyUsage">`KeyUsage`</a>
in [[webcrypto]] with the following:
</p>
<pre class="idl">
enum KeyUsage { "encrypt", "decrypt", "sign", "verify", "deriveKey", "deriveBits", "wrapKey", "unwrapKey", "encapsulateKey", "encapsulateBits", "decapsulateKey", "decapsulateBits" };
</pre>
<p>
This specification specifies a number of new <a data-cite="webcrypto#dfn-RecognizedKeyUsage">recognized key usage values</a>:
</p>
<dl data-dfn-for=KeyUsage>
<dt><dfn data-idl>encapsulateKey</dfn></dt>
<dd>Enable using the key with {{SubtleCrypto.encapsulateKey}}.</dd>
<dt><dfn data-idl>encapsulateBits</dfn></dt>
<dd>Enable using the key with {{SubtleCrypto.encapsulateBits}}.</dd>
<dt><dfn data-idl>decapsulateKey</dfn></dt>
<dd>Enable using the key with {{SubtleCrypto.decapsulateKey}}.</dd>
<dt><dfn data-idl>decapsulateBits</dfn></dt>
<dd>Enable using the key with {{SubtleCrypto.decapsulateBits}}.</dd>
</dl>
</section>
</section>
<section id="partial-subtlecrypto-interface-methods">
<h3>Methods and Parameters</h3>
<section id="SubtleCrypto-method-encapsulateKey">
<h4>The encapsulateKey method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-encapsulateKey" data-dfn-for=SubtleCrypto data-lt="encapsulateKey">encapsulateKey(|encapsulationAlgorithm|, |encapsulationKey|, |sharedKeyAlgorithm|, |extractable|, |usages|)</dfn>
method encapsulates a key and returns an {{EncapsulatedKey}} object.
It behaves as follows:
</p>
<ol>
<li>
<p>
Let |encapsulationAlgorithm|, |encapsulationKey|, |sharedKeyAlgorithm|,
|extractable| and |usages| be the `encapsulationAlgorithm`, `encapsulationKey`,
`sharedKeyAlgorithm`, `extractable` and `keyUsages` parameters passed to the
{{SubtleCrypto/encapsulateKey()}} method,
respectively.
</p>
</li>
<li>
<p>
Let |normalizedEncapsulationAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |encapsulationAlgorithm| and `op` set to
"`encapsulate`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedEncapsulationAlgorithm|.
</p>
</li>
<li>
<p>
Let |normalizedSharedKeyAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |sharedKeyAlgorithm| and `op` set to
"`importKey`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedSharedKeyAlgorithm|.
</p>
</li>
<li>
<p>
Let |realm| be the [= relevant realm =] of [= this =].
</p>
</li>
<li>
<p>
Let |promise| be a new Promise.
</p>
</li>
<li>
<p>
Return |promise| and perform the remaining steps [= in parallel =].
</p>
</li>
<li>
<p>
If the following steps or referenced procedures say to
[= exception/throw =] an error,
[= queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object,
to reject |promise| with the returned error;
and then <a data-cite="webcrypto#terminate-the-algorithm">terminate the algorithm</a>.
</p>
</li>
<li>
<p>
If the {{Algorithm/name}} member of
|normalizedEncapsulationAlgorithm| is not equal to the
{{KeyAlgorithm/name}} attribute of the
<a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|encapsulationKey| then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
If the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|encapsulationKey| does not contain an entry that is "`encapsulateKey`",
then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
Let |encapsulatedBits| be the result of performing the encapsulate operation specified by
the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|encapsulationKey| using |encapsulationKey|.
</p>
</li>
<li>
<p>
Let |sharedKey| be the result of performing the import key operation specified by
|normalizedSharedKeyAlgorithm| using {{KeyFormat/"raw-secret"}} as
|format|, the {{EncapsulatedBits/sharedKey}} field of
|encapsulatedBits| as |keyData|, |sharedKeyAlgorithm| as
|algorithm| and using
|extractable| and |usages|.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-extractable">`[[extractable]]`</a> internal
slot of |sharedKey| to |extractable|.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|sharedKey| to the <a data-cite="webcrypto#concept-normalized-usages">normalized value</a>
of |usages|.
</p>
</li>
<li>
<p>
Let |encapsulatedKey| be a new {{EncapsulatedKey}} dictionary
with {{EncapsulatedKey/sharedKey}} set to |sharedKey|
and {{EncapsulatedKey/ciphertext}} set to the
{{EncapsulatedBits/ciphertext}} field of |encapsulatedBits|.
</p>
</li>
<li>
<p>
[= Queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object, to perform the remaining steps.
</p>
</li>
<li>
<p>
Let |result| be the result of converting |encapsulatedKey| to an ECMAScript Object in |realm|,
as defined by [[WebIDL]].
</p>
</li>
<li>
<p>
Resolve |promise| with
|result|.
</p>
</li>
</ol>
</section>
<section id="SubtleCrypto-method-encapsulateBits">
<h4>The encapsulateBits method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-encapsulateBits" data-dfn-for=SubtleCrypto data-lt="encapsulateBits">encapsulateBits(|encapsulationAlgorithm|, |encapsulationKey|)</dfn>
method encapsulates a key and returns an {{EncapsulatedBits}} object.
It behaves as follows:
</p>
<ol>
<li>
<p>
Let |encapsulationAlgorithm| and |encapsulationKey| be the `encapsulationAlgorithm`
and `encapsulationKey` parameters passed to the
{{SubtleCrypto/encapsulateBits()}} method,
respectively.
</p>
</li>
<li>
<p>
Let |normalizedEncapsulationAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |encapsulationAlgorithm| and `op` set to
"`encapsulate`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedEncapsulationAlgorithm|.
</p>
</li>
<li>
<p>
Let |realm| be the [= relevant realm =] of [= this =].
</p>
</li>
<li>
<p>
Let |promise| be a new Promise.
</p>
</li>
<li>
<p>
Return |promise| and perform the remaining steps [= in parallel =].
</p>
</li>
<li>
<p>
If the following steps or referenced procedures say to
[= exception/throw =] an error,
[= queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object,
to reject |promise| with the returned error;
and then <a data-cite="webcrypto#terminate-the-algorithm">terminate the algorithm</a>.
</p>
</li>
<li>
<p>
If the {{Algorithm/name}} member of
|normalizedEncapsulationAlgorithm| is not equal to the
{{KeyAlgorithm/name}} attribute of the
<a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|encapsulationKey| then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
If the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|encapsulationKey| does not contain an entry that is "`encapsulateBits`",
then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
Let |encapsulatedBits| be the result of performing the encapsulate operation specified by
the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|encapsulationKey| using |encapsulationKey|.
</p>
</li>
<li>
<p>
[= Queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object, to perform the remaining steps.
</p>
</li>
<li>
<p>
Let |result| be the result of converting |encapsulatedBits| to an ECMAScript Object in |realm|,
as defined by [[WebIDL]].
</p>
</li>
<li>
<p>
Resolve |promise| with
|result|.
</p>
</li>
</ol>
</section>
<section id="SubtleCrypto-method-decapsulateKey">
<h4>The decapsulateKey method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-decapsulateKey" data-dfn-for=SubtleCrypto data-lt="decapsulateKey">decapsulateKey(|decapsulationAlgorithm|, |decapsulationKey|, |ciphertext|, |sharedKeyAlgorithm|, |extractable|, |usages|)</dfn>
method decapsulates a key and returns a {{CryptoKey}} object.
It behaves as follows:
</p>
<ol>
<li>
<p>
Let |decapsulationAlgorithm|, |decapsulationKey|, |sharedKeyAlgorithm|,
|extractable| and |usages| be the `decapsulationAlgorithm`, `decapsulationKey`, `sharedKeyAlgorithm`, `extractable` and `keyUsages` parameters passed to the
{{SubtleCrypto/decapsulateKey()}} method,
respectively.
</p>
</li>
<li>
<p>
Let |normalizedDecapsulationAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |decapsulationAlgorithm| and `op` set to
"`decapsulate`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedDecapsulationAlgorithm|.
</p>
</li>
<li>
<p>
Let |normalizedSharedKeyAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |sharedKeyAlgorithm| and `op` set to
"`importKey`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedSharedKeyAlgorithm|.
</p>
</li>
<li>
<p>
Let |ciphertext| be the result of
[= get a copy of the buffer source |
getting a copy of the bytes held by =] the `ciphertext` parameter passed to the
{{SubtleCrypto/decapsulateKey()}} method.
</p>
</li>
<li>
<p>
Let |realm| be the [= relevant realm =] of [= this =].
</p>
</li>
<li>
<p>
Let |promise| be a new Promise.
</p>
</li>
<li>
<p>
Return |promise| and perform the remaining steps [= in parallel =].
</p>
</li>
<li>
<p>
If the following steps or referenced procedures say to
[= exception/throw =] an error,
[= queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object,
to reject |promise| with the returned error;
and then <a data-cite="webcrypto#terminate-the-algorithm">terminate the algorithm</a>.
</p>
</li>
<li>
<p>
If the {{Algorithm/name}} member of
|normalizedDecapsulationAlgorithm| is not equal to the
{{KeyAlgorithm/name}} attribute of the
<a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|decapsulationKey| then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
If the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|decapsulationKey| does not contain an entry that is "`decapsulateKey`",
then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
Let |decapsulatedBits| be the result of performing the decapsulate operation specified by
the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of |decapsulationKey| using |decapsulationKey| and |ciphertext|.
</p>
</li>
<li>
<p>
Let |sharedKey| be the result of performing the import key operation specified by
|normalizedSharedKeyAlgorithm| using {{KeyFormat/"raw-secret"}} as
|format|, the |decapsulatedBits| as |keyData|, |sharedKeyAlgorithm| as
|algorithm| and using
|extractable| and |usages|.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-extractable">`[[extractable]]`</a> internal
slot of |sharedKey| to |extractable|.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|sharedKey| to the <a data-cite="webcrypto#concept-normalized-usages">normalized value</a>
of |usages|.
</p>
</li>
<li>
<p>
[= Queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object, to perform the remaining steps.
</p>
</li>
<li>
<p>
Let |result| be the result of converting |sharedKey| to an ECMAScript Object in |realm|, as defined by [[WebIDL]].
</p>
</li>
<li>
<p>
Resolve |promise| with
|result|.
</p>
</li>
</ol>
</section>
<section id="SubtleCrypto-method-decapsulateBits">
<h4>The decapsulateBits method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-decapsulateBits" data-dfn-for=SubtleCrypto data-lt="decapsulateBits">decapsulateBits(|decapsulationAlgorithm|, |decapsulationKey|, |ciphertext|)</dfn>
method decapsulates a key and returns an {{ArrayBuffer}} object.
It behaves as follows:
</p>
<ol>
<li>
<p>
Let |decapsulationAlgorithm| and |decapsulationKey| be the `decapsulationAlgorithm` and `decapsulationKey` parameters passed to the
{{SubtleCrypto/decapsulateBits()}} method,
respectively.
</p>
</li>
<li>
<p>
Let |normalizedDecapsulationAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |decapsulationAlgorithm| and `op` set to
"`decapsulate`".
</p>
</li>
<li>
<p>
If an error occurred, return a Promise rejected with
|normalizedDecapsulationAlgorithm|.
</p>
</li>
<li>
<p>
Let |ciphertext| be the result of
[= get a copy of the buffer source |
getting a copy of the bytes held by =] the `ciphertext` parameter passed to the
{{SubtleCrypto/decapsulateBits()}} method.
</p>
</li>
<li>
<p>
Let |realm| be the [= relevant realm =] of [= this =].
</p>
</li>
<li>
<p>
Let |promise| be a new Promise.
</p>
</li>
<li>
<p>
Return |promise| and perform the remaining steps [= in parallel =].
</p>
</li>
<li>
<p>
If the following steps or referenced procedures say to
[= exception/throw =] an error,
[= queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object,
to reject |promise| with the returned error;
and then <a data-cite="webcrypto#terminate-the-algorithm">terminate the algorithm</a>.
</p>
</li>
<li>
<p>
If the {{Algorithm/name}} member of
|normalizedDecapsulationAlgorithm| is not equal to the
{{KeyAlgorithm/name}} attribute of the
<a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of
|decapsulationKey| then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
If the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|decapsulationKey| does not contain an entry that is "`decapsulateBits`",
then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
Let |decapsulatedBits| be the result of performing the decapsulate operation specified by
the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of |decapsulationKey| using |decapsulationKey| and |ciphertext|.
</p>
</li>
<li>
<p>
[= Queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object, to perform the remaining steps.
</p>
</li>
<li>
<p>
Let |result| be the result of [= ArrayBuffer/create | creating =] an {{ArrayBuffer}}
in |realm|, containing |decapsulatedBits|.
</p>
</li>
<li>
<p>
Resolve |promise| with
|result|.
</p>
</li>
</ol>
</section>
<section id="SubtleCrypto-method-getPublicKey">
<h4>The getPublicKey method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-getPublicKey" data-dfn-for=SubtleCrypto data-lt="getPublicKey">getPublicKey(|key|, |usages|)</dfn>
method returns the public key corresponding to a given private key.
It behaves as follows:
</p>
<ol>
<li>
<p>
Let |key| and |usages| be the `key` and `keyUsages` parameters passed to the
{{SubtleCrypto/getPublicKey()}} method,
respectively.
</p>
</li>
<li>
<p>
Let |algorithm| be the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal slot of |key|.
</p>
</li>
<li>
<p>
If the cryptographic algorithm identified by |algorithm|
does not support deriving a public key from a private key,
then return a Promise rejected with a {{NotSupportedError}}.
</p>
</li>
<li>
<p>
Let |realm| be the [= relevant realm =] of [= this =].
</p>
</li>
<li>
<p>
Let |promise| be a new Promise.
</p>
</li>
<li>
<p>
Return |promise| and perform the remaining steps [= in parallel =].
</p>
</li>
<li>
<p>
If the following steps or referenced procedures say to
[= exception/throw =] an error,
[= queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object,
to reject |promise| with the returned error;
and then <a data-cite="webcrypto#terminate-the-algorithm">terminate the algorithm</a>.
</p>
</li>
<li>
<p>
If the <a data-cite="webcrypto#dfn-CryptoKey-slot-type">`[[type]]`</a> internal slot of
|key| is not {{KeyType/"private"}}, then [= exception/throw =] an {{InvalidAccessError}}.
</p>
</li>
<li>
<p>
If |usages| contains an entry which is not supported for a public key
by the algorithm identified by |algorithm|,
then [= exception/throw =] a {{SyntaxError}}.
</p>
</li>
<li>
<p>
Let |publicKey| be a new {{CryptoKey}} representing the public key corresponding to
the private key represented by the <a data-cite="webcrypto#dfn-CryptoKey-slot-handle">`[[handle]]`</a>
internal slot of |key|.
</p>
</li>
<li>
<p>
If an error occurred, then [= exception/throw =] a {{OperationError}}.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-type">`[[type]]`</a> internal slot of
|publicKey| to {{KeyType/"public"}}.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-algorithm">`[[algorithm]]`</a> internal
slot of |publicKey| to |algorithm|.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-extractable">`[[extractable]]`</a> internal
slot of |publicKey| to true.
</p>
</li>
<li>
<p>
Set the <a data-cite="webcrypto#dfn-CryptoKey-slot-usages">`[[usages]]`</a> internal slot of
|publicKey| to |usages|.
</p>
</li>
<li>
<p>
[= Queue a global task =] on the <a data-cite="webcrypto#dfn-crypto-task-source">crypto task source</a>,
given |realm|'s global object, to perform the remaining steps.
</p>
</li>
<li>
<p>
Let |result| be the result of converting |publicKey| to an ECMAScript Object in |realm|, as defined by [[WebIDL]].
</p>
</li>
<li>
<p>
Resolve |promise| with
|result|.
</p>
</li>
</ol>
</section>
<section id="SubtleCrypto-method-supports">
<h4>The supports method</h4>
<p>
The <dfn id="dfn-SubtleCrypto-method-supports" data-dfn-for=SubtleCrypto data-lt="supports">supports(|operation|, |algorithm|, |length|)</dfn>
method returns a boolean indicating whether the implementation
supports the given operation using the specified {{AlgorithmIdentifier}},
with an optional `length` parameter to indicate the number of bits to be derived when `operation` is "`deriveBits`".
It behaves as follows:
</p>
<ol>
<li>
<p>
If |operation| is not one of
"`encrypt`", "`decrypt`", "`sign`", "`verify`",
"`digest`", "`generateKey`", "`deriveKey`", "`deriveBits`",
"`importKey`", "`exportKey`", "`wrapKey`", "`unwrapKey`",
"`encapsulateKey`", "`encapsulateBits`",
"`decapsulateKey`", "`decapsulateBits`" or "`getPublicKey`",
return false.
</p>
</li>
<li>
<p>
Return the result of [= check support for an algorithm | checking support for an algorithm =],
with `op` set to |operation|, `alg` set to |algorithm|,
and `length` set to |length|.
</p>
</li>
</ol>
<p>
The <dfn id="dfn-SubtleCrypto-method-supports-additionalAlgorithm" data-dfn-for=SubtleCrypto data-lt="supports!overload-1">supports(|operation|, |algorithm|, |additionalAlgorithm|)</dfn>
method returns a boolean indicating whether the implementation
supports the given operation using the specified {{AlgorithmIdentifier}}.
The additional algorithm indicates the type of key to be derived when `operation` is "`deriveKey`",
the type of key to be exported before wrapping when `operation` is "`wrapKey`",
and the type of key to be imported after unwrapping when `operation` is "`unwrapKey`".
It behaves as follows:
</p>
<ol>
<li>
<p>
If |operation| is not one of
"`encrypt`", "`decrypt`", "`sign`", "`verify`",
"`digest`", "`generateKey`", "`deriveKey`", "`deriveBits`",
"`importKey`", "`exportKey`", "`wrapKey`", "`unwrapKey`",
"`encapsulateKey`", "`encapsulateBits`",
"`decapsulateKey`", "`decapsulateBits`" or "`getPublicKey`",
return false.
</p>
</li>
<li>
<dl class="switch">
<dt>If |operation| is "`deriveKey`", "`unwrapKey`", "`encapsulateKey`" or "`decapsulateKey`":</dt>
<dd>
<p>
If the result of [= check support for an algorithm | checking support for an algorithm =]
with `op` set to "`importKey`"
and `alg` set to |additionalAlgorithm|
is false,
return false.
</p>
</dd>
<dt>If |operation| is "`wrapKey`":</dt>
<dd>
<p>
If the result of [= check support for an algorithm | checking support for an algorithm =]
with `op` set to "`exportKey`"
and `alg` set to |additionalAlgorithm|
is false,
return false.
</p>
</dd>
</dl>
</li>
<li>
<p>
Let |length| be null.
</p>
</li>
<li>
<dl class="switch">
<dt>If |operation| is "`deriveKey`":</dt>
<dd>
<ol>
<li>
<p>
If the result of [= check support for an algorithm | checking support for an algorithm =]
with `op` set to "`get key length`"
and `alg` set to |additionalAlgorithm|
is false,
return false.
</p>
</li>
<li>
<p>
Let |normalizedAdditionalAlgorithm| be the result of
<a data-cite="webcrypto#dfn-normalize-an-algorithm">normalizing an algorithm</a>, with
`alg` set to |additionalAlgorithm| and `op` set to
"`get key length`".
</p>
</li>
<li>
<p>