Add Curve448 by twiss · Pull Request #425 · w3c/webcrypto

twiss · 2026-01-28T16:28:25Z

This is not intended to be merged now, but rather to have a placeholder for the code and discussion after we archive https://github.com/WICG/webcrypto-secure-curves/ (and until we have sufficient implementer support to merge it here).

Preview | Diff

tete17

@twiss

tete17 · 2026-04-12T20:33:30Z

+                      </li>
+                      <li>
+                        <p>
+                          If the [= length in bits =] of |data| is not 448 then [= exception/throw =] a {{DataError}}.


Suggested change

If the [= length in bits =] of |data| is not 448 then [= exception/throw =] a {{DataError}}.

If the [= length in bits =] of |data| is not 456 then [= exception/throw =] a {{DataError}}.

Ref: https://www.rfc-editor.org/rfc/rfc8032#section-5.2.5

tete17 · 2026-04-12T20:34:18Z

+                      </li>
+                      <li>
+                        <p>
+                          If the [= length in bits =] of |data| is not 448 then [= exception/throw =] a {{DataError}}.


Suggested change

If the [= length in bits =] of |data| is not 448 then [= exception/throw =] a {{DataError}}.

If the [= length in bits =] of |data| is not 456 then [= exception/throw =] a {{DataError}}.

Ref: https://www.rfc-editor.org/rfc/rfc8032#section-5.2.5

Ed448 public keys are 57 bytes (456 bits), not 56 bytes (448 bits). The curve is named "Ed448" after its 448-bit prime field, but per RFC 8032 Section 5.2.5, the parameter b=456 and both private and public keys are 57 bytes. This caused importKey to reject valid raw Ed448 public keys with a DataError. Note: The spec incorrectly says "not 448" for this check. See w3c/webcrypto#425 (comment)

kkoyung

The conversions are done by step 11 of the generateKey method (https://w3c.github.io/webcrypto/#SubtleCrypto-method-generateKey), and step 10 of the exportKey method (https://w3c.github.io/webcrypto/#SubtleCrypto-method-exportKey).

kkoyung · 2026-07-09T13:21:31Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing
+                          |data|.


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

|data|.

Let |result| be the result of DER-encoding |data|.

kkoyung · 2026-07-09T13:21:54Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing
+                          |data|.


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

|data|.

Let |result| be the result of DER-encoding |data|.

kkoyung · 2026-07-09T13:22:55Z

+                          Let |result| be the result of converting |jwk|
+                          to an ECMAScript Object, as defined by [[WebIDL]].


Suggested change

Let |result| be the result of converting |jwk|

to an ECMAScript Object, as defined by [[WebIDL]].

Let |result| be |jwk|.

kkoyung · 2026-07-09T13:23:27Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

Let |result| be the result of DER-encoding |data|.

kkoyung · 2026-07-09T13:24:58Z

+                  Return the result of converting |result| to an ECMAScript Object, as
+                  defined by [[WebIDL]].


Suggested change

Return the result of converting |result| to an ECMAScript Object, as

defined by [[WebIDL]].

Return |result|.

kkoyung · 2026-07-09T13:26:17Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing
+                          |data|.


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

|data|.

Let |result| be the result of DER-encoding |data|.

kkoyung · 2026-07-09T13:26:32Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing
+                          |data|.


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

|data|.

Let |result| be the result of DER-encoding |data|.

kkoyung · 2026-07-09T13:26:57Z

+                          Let |result| be a new {{ArrayBuffer}} associated with the
+                          [= relevant global object =]
+                          of `this` [[HTML]], and containing
+                          |data|.


Suggested change

Let |result| be a new {{ArrayBuffer}} associated with the

[= relevant global object =]

of `this` [[HTML]], and containing

|data|.

Let |result| be |data|.

kkoyung · 2026-07-09T13:34:24Z

+              <li>
+                <p>
+                  Return the result of converting |result| to an ECMAScript Object, as
+                  defined by [[WebIDL]].


Suggested change

defined by [[WebIDL]].

Return |result|.

kkoyung · 2026-07-09T13:36:07Z

+                          Let |result| be the result of converting |jwk|
+                          to an ECMAScript Object, as defined by [[WebIDL]].


Suggested change

Let |result| be the result of converting |jwk|

to an ECMAScript Object, as defined by [[WebIDL]].

Let |result| be |jwk|.

kkoyung · 2026-07-09T13:40:18Z

Servo has implemented both Ed448 and X448 recently. servo/servo#46140

twiss force-pushed the curve448 branch from d4bb4be to 788b352 Compare January 29, 2026 12:57

Add Ed448 and X448

36ec6cd

twiss force-pushed the curve448 branch from 788b352 to 36ec6cd Compare January 29, 2026 13:17

devgianlu mentioned this pull request Feb 13, 2026

LibWeb/Crypto: Update spec links LadybirdBrowser/ladybird#7937

Merged

panva mentioned this pull request Mar 10, 2026

HPKE WICG/webcrypto-modern-algos#2

Open

tete17 suggested changes Apr 12, 2026

View reviewed changes

tete17 mentioned this pull request Apr 12, 2026

Fix OKP importKey validation for Ed448/Ed25519/X25519/X448 LadybirdBrowser/ladybird#8886

Merged

kkoyung reviewed Jul 9, 2026

View reviewed changes

	If the [= length in bits =] of \|data\| is not 448 then [= exception/throw =] a {{DataError}}.
	If the [= length in bits =] of \|data\| is not 456 then [= exception/throw =] a {{DataError}}.

		Let \|result\| be the result of converting \|jwk\|
		to an ECMAScript Object, as defined by [[WebIDL]].

	Let \|result\| be the result of converting \|jwk\|
	to an ECMAScript Object, as defined by [[WebIDL]].
	Let \|result\| be \|jwk\|.

		Return the result of converting \|result\| to an ECMAScript Object, as
		defined by [[WebIDL]].

	Return the result of converting \|result\| to an ECMAScript Object, as
	defined by [[WebIDL]].
	Return \|result\|.

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kkoyung commented Jul 9, 2026

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twiss commented Jan 28, 2026 •

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