Add support for cross signing the bot's device by uhoreg · Pull Request #389 · turt2live/matrix-bot-sdk

uhoreg · 2026-03-31T21:40:27Z

Adds functions to cross-sign the bot's device using a recovery key.

Depends on matrix-org/matrix-rust-sdk-crypto-nodejs#67, so merging will need to wait for that, plus a release of matrix-rust-sdk-crypto-nodejs, plus bumping package.json.

Cross-signing can be done by doing something like:

if (config.recoveryKey) {
    client.on("crypto.ready", async () => {
        await client.crypto.confirmIdentityWithRecoveryKey(config.recoveryKey);
    });
}

Checklist

Tests written for all new code
Linter has been satisfied
Sign-off given on the changes (see CONTRIBUTING.md)

Signed-off-by: Hubert Chathi hubertc@element.io

uhoreg · 2026-03-31T21:40:53Z

tests incoming, but this PR should be otherwise reviewable

Co-authored-by: Andrew Ferrazzutti <af_0_af@hotmail.com>

AndrewFerr · 2026-04-10T13:40:49Z

        LogService.debug("CryptoClient", "Running with device Ed25519 identity:", this.deviceEd25519); // info so all bots know for debugging

        this.ready = true;
+        this.client.emit("crypto.ready");


This looks like there are currently no listeners for this. Are there plans for there to be? IMO it's not all that useful to emit here, since the preparation of a MatrixClient / Intent already includes an await on crypto to be ready, i.e. there are already checks in place to make sure that crypto is prepared before it gets used.

This is so that the bot can verify itself once the crypto is set up, i.e.

client.on("crypto.ready", async () => { await client.crypto.confirmIdentityWithRecoveryKey(config.recoveryKey); });

Co-authored-by: Andrew Ferrazzutti <af_0_af@hotmail.com>

AndrewFerr · 2026-04-15T16:00:57Z

To compliment this PR, I'm preparing a separate PR that adds a helper class for using the Secret Storage API, which will resemble the JS-SDK's ServerSideSecretStorage. It may then be used by CryptoClient as an alternative to calling getAccountData directly for retrieving cross-signing secrets.

uhoreg · 2026-04-19T01:52:29Z

tests incoming, but this PR should be otherwise reviewable

I've added a test. Though CI of course will fail until we do a release of crypto-nodejs.

@AndrewFerr do you have any more changes planned for matrix-rust-sdk-crypto-nodejs? If not, I'll try to make a new release soon.

AndrewFerr · 2026-04-19T02:19:30Z

@AndrewFerr do you have any more changes planned for matrix-rust-sdk-crypto-nodejs? If not, I'll try to make a new release soon.

No, I'm done. Thanks for asking! Go ahead with that release.

AndrewFerr · 2026-04-21T15:10:54Z

+        const ownDevice = await machine.getDevice(machine.userId, machine.deviceId);
+        if (ownDevice.isCrossSigningTrusted()) {


machine.getDevice can apparently return null, though I'd expect that to not happen after crypto is ready. Nevertheless, consider guarding against it here.

ownDevice is also never used elsewhere, so consider inlining it into the if condition.

Suggested change

const ownDevice = await machine.getDevice(machine.userId, machine.deviceId);

if (ownDevice.isCrossSigningTrusted()) {

if ((await machine.getDevice(machine.userId, machine.deviceId))?.isCrossSigningTrusted()) {

Actually, if we can get our own device, then cross-signing won't work, so I'm going to throw an error in that case. (Though I wonder why TypeScript didn't complain about ownDevice possibly being null.)

Though I wonder why TypeScript didn't complain about ownDevice possibly being null.

It's because the TSConfig file doesn't have the strict flag enabled. It can't be turned on yet, but I've been using it temporarily in local development to help test new code.

AndrewFerr · 2026-04-21T15:26:14Z

+        if (bootstrapRequests.uploadKeysReq) {
+            this.engine.processOutgoingRequests([bootstrapRequests.uploadKeysReq]);
+        }
+        await client.doRequest("POST", "/_matrix/client/v3/keys/device_signing/upload", null, JSON.parse(bootstrapRequests.uploadSigningKeysReq));
+        await this.engine.processOutgoingRequests([bootstrapRequests.uploadSignaturesReq]);


If the processing of uploadKeysReq does need to be awaited, it could be processed together with the uploadSignaturesReq:

Suggested change

if (bootstrapRequests.uploadKeysReq) {

this.engine.processOutgoingRequests([bootstrapRequests.uploadKeysReq]);

}

await client.doRequest("POST", "/_matrix/client/v3/keys/device_signing/upload", null, JSON.parse(bootstrapRequests.uploadSigningKeysReq));

await this.engine.processOutgoingRequests([bootstrapRequests.uploadSignaturesReq]);

const outgoingRequests = [

bootstrapRequests.uploadSignaturesReq,

...(bootstrapRequests.uploadKeysReq ? [bootstrapRequests.uploadKeysReq] : []),

];

await client.doRequest("POST", "/_matrix/client/v3/keys/device_signing/upload", null, JSON.parse(bootstrapRequests.uploadSigningKeysReq));

await this.engine.processOutgoingRequests(outgoingRequests);

Actually, I was wrong -- I hadn't seen the docstrings on CrossSigningBootstrapRequests that explain the order in which the requests should be sent out. The order you have was correct.

The processing of uploadKeysReq should be awaited, though:

Suggested change

if (bootstrapRequests.uploadKeysReq) {

this.engine.processOutgoingRequests([bootstrapRequests.uploadKeysReq]);

}

await client.doRequest("POST", "/_matrix/client/v3/keys/device_signing/upload", null, JSON.parse(bootstrapRequests.uploadSigningKeysReq));

await this.engine.processOutgoingRequests([bootstrapRequests.uploadSignaturesReq]);

if (bootstrapRequests.uploadKeysReq) {

await this.engine.processOutgoingRequests([bootstrapRequests.uploadKeysReq]);

}

await client.doRequest("POST", "/_matrix/client/v3/keys/device_signing/upload", null, JSON.parse(bootstrapRequests.uploadSigningKeysReq));

await this.engine.processOutgoingRequests([bootstrapRequests.uploadSignaturesReq]);

AndrewFerr · 2026-04-21T15:31:53Z

+        let secretStorageKey: SecretStorageKey;
+        if (key === undefined) {
+            secretStorageKey = SecretStorageKey.createRandomKey();
+        } else {
+            secretStorageKey = await this.getDefaultSecretStorageKey(key);
+        }


secretStorageKey can be made const and without a typehint by using a ternary operator:

Suggested change

let secretStorageKey: SecretStorageKey;

if (key === undefined) {

secretStorageKey = SecretStorageKey.createRandomKey();

} else {

secretStorageKey = await this.getDefaultSecretStorageKey(key);

}

const secretStorageKey =

key === undefined

? SecretStorageKey.createRandomKey()

: await this.getDefaultSecretStorageKey(key);

AndrewFerr · 2026-04-21T20:21:34Z

+            for (let i = 0; i < 5; i++) {
+                http1.when("PUT", "/user/%40alice%3Aexample.org/account_data/").respond(200, (path, obj) => {


This would benefit from a comment to explain why this loop needs to run 5 times. AIUI it's because createIdentity hits this endpoint that many times, to upload account data for the default key ID, the metadata of that key (i.e. algorithm & passphrase), and the 3 cross-signing secrets.

AndrewFerr · 2026-04-23T18:08:02Z

matrix-org/matrix-rust-sdk-crypto-nodejs#67 is finally available in v0.5.1.

Note that the tests may fail when run in bulk. If that gives CI trouble, these PRs may help:

uhoreg · 2026-04-27T19:37:25Z

Changes made. I've also updated element-hq#87 to match the current changes in this PR

uhoreg added 4 commits March 31, 2026 16:19

separate processing the requests into a different function

d3352bd

add support for signature upload requests

a9d7de4

add functions for confirming the bot's identity

51e6105

emit an event when the crypto client is ready

9c38904

update to latest draft of nodejs bindings

23eede5

uhoreg mentioned this pull request Apr 2, 2026

Add support for cross-signing the bot's device element-hq/matrix-bot-sdk#87

Merged

2 of 3 tasks

AndrewFerr reviewed Apr 6, 2026

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Comment thread src/e2ee/RustEngine.ts Outdated

Use the right variable name

d82abeb

Co-authored-by: Andrew Ferrazzutti <af_0_af@hotmail.com>

AndrewFerr mentioned this pull request Apr 8, 2026

Fix ESLint #390

Open

3 tasks done

AndrewFerr suggested changes Apr 8, 2026

View reviewed changes

Comment thread src/e2ee/CryptoClient.ts Outdated

Comment thread src/e2ee/CryptoClient.ts Outdated

Comment thread src/e2ee/CryptoClient.ts Outdated

Comment thread src/e2ee/CryptoClient.ts Outdated

Comment thread src/e2ee/CryptoClient.ts

AndrewFerr reviewed Apr 10, 2026

View reviewed changes

Comment thread src/e2ee/CryptoClient.ts Outdated

Comment thread src/e2ee/CryptoClient.ts Outdated

AndrewFerr reviewed Apr 10, 2026

View reviewed changes

Comment thread src/e2ee/CryptoClient.ts Outdated

uhoreg and others added 2 commits April 13, 2026 16:50

Apply suggestions from code review

c4bff11

Co-authored-by: Andrew Ferrazzutti <af_0_af@hotmail.com>

add a check for the structure of the key info

ca3308d

uhoreg added 3 commits April 15, 2026 16:39

allow specifying a recovery key when creating new cryptographic identity

c6cc6eb

fix some bugs in createIdentity

27a1634

add test for cross-signing

65fe0ef

AndrewFerr reviewed Apr 21, 2026

View reviewed changes

uhoreg and others added 4 commits April 23, 2026 16:28

bump dependency on @matrix-org/matrix-sdk-crypto-nodejs

2119cd2

apply changes from review

a774e52

Merge branch 'main' into cross-signing

76a65fa

bump NodeJS requirement to match matrix-sdk-crypto-nodejs

4c9c6ff

		const ownDevice = await machine.getDevice(machine.userId, machine.deviceId);
		if (ownDevice.isCrossSigningTrusted()) {

	const ownDevice = await machine.getDevice(machine.userId, machine.deviceId);
	if (ownDevice.isCrossSigningTrusted()) {
	if ((await machine.getDevice(machine.userId, machine.deviceId))?.isCrossSigningTrusted()) {

		for (let i = 0; i < 5; i++) {
		http1.when("PUT", "/user/%40alice%3Aexample.org/account_data/").respond(200, (path, obj) => {

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uhoreg commented Mar 31, 2026

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AndrewFerr commented Apr 23, 2026

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