move get device key API from client to crypto (#3899)

MatrixClient API was exposing two methods that only worked for legacy crypto:
- getDeviceEd25519Key
- getDeviceCurve25519Key

=> These are used in the react-sdk for some functionality (rageshake, sentry, rendez-vous).

I have deprecated those calls from MatrixClient and created a new API in CryptoApi (where it belongs):

getOwnDeviceKeys(): Promise<OwnDeviceKeys>

spec/integ/crypto/crypto.spec.ts

@@ -397,6 +397,19 @@ describe.each(Object.entries(CRYPTO_BACKENDS))("crypto (%s)", (backend: string,
         expect(aliceClient.getCrypto()).toHaveProperty("globalBlacklistUnverifiedDevices");
     });
 
+    it("CryptoAPI.getOwnedDeviceKeys returns the correct values", async () => {
+        const homeserverUrl = aliceClient.getHomeserverUrl();
+
+        keyResponder = new E2EKeyResponder(homeserverUrl);
+        await startClientAndAwaitFirstSync();
+        keyResponder.addKeyReceiver("@alice:localhost", keyReceiver);
+
+        const deviceKeys = await aliceClient.getCrypto()!.getOwnDeviceKeys();
+
+        expect(deviceKeys.curve25519).toEqual(keyReceiver.getDeviceKey());
+        expect(deviceKeys.ed25519).toEqual(keyReceiver.getSigningKey());
+    });
+
     it("Alice receives a megolm message", async () => {
         expectAliceKeyQuery({ device_keys: { "@alice:localhost": {} }, failures: {} });
         await startClientAndAwaitFirstSync();

src/client.ts

@@ -2393,6 +2393,8 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      *
      * @returns base64-encoded ed25519 key. Null if crypto is
      *    disabled.
+     *
+     * @deprecated Prefer {@link CryptoApi.getOwnDeviceKeys}
      */
     public getDeviceEd25519Key(): string | null {
         return this.crypto?.getDeviceEd25519Key() ?? null;
@@ -2403,6 +2405,8 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      *
      * @returns base64-encoded curve25519 key. Null if crypto is
      *    disabled.
+     *
+     * @deprecated Use {@link CryptoApi.getOwnDeviceKeys}
      */
     public getDeviceCurve25519Key(): string | null {
         return this.crypto?.getDeviceCurve25519Key() ?? null;

src/crypto-api.ts

@@ -46,6 +46,13 @@ export interface CryptoApi {
      */
     getVersion(): string;
 
+    /**
+     * Get the public part of the device keys for the current device.
+     *
+     * @returns The public device keys.
+     */
+    getOwnDeviceKeys(): Promise<OwnDeviceKeys>;
+
     /**
      * Perform any background tasks that can be done before a message is ready to
      * send, in order to speed up sending of the message.
@@ -764,5 +771,13 @@ export enum EventShieldReason {
     MISMATCHED_SENDER_KEY,
 }
 
+/** The result of a call to {@link CryptoApi.getOwnDeviceKeys} */
+export interface OwnDeviceKeys {
+    /** Public part of the Ed25519 fingerprint key for the current device, base64 encoded. */
+    ed25519: string;
+    /** Public part of the Curve25519 identity key for the current device, base64 encoded. */
+    curve25519: string;
+}
+
 export * from "./crypto-api/verification";
 export * from "./crypto-api/keybackup";

src/crypto/index.ts

@@ -98,6 +98,7 @@ import {
     KeyBackupCheck,
     KeyBackupInfo,
     VerificationRequest as CryptoApiVerificationRequest,
+    OwnDeviceKeys,
 } from "../crypto-api";
 import { Device, DeviceMap } from "../models/device";
 import { deviceInfoToDevice } from "./device-converter";
@@ -1968,6 +1969,8 @@ export class Crypto extends TypedEventEmitter<CryptoEvent, CryptoEventHandlerMap
      * Get the Ed25519 key for this device
      *
      * @returns base64-encoded ed25519 key.
+     *
+     * @deprecated Use {@link CryptoApi#getOwnDeviceKeys}.
      */
     public getDeviceEd25519Key(): string | null {
         return this.olmDevice.deviceEd25519Key;
@@ -1977,11 +1980,29 @@ export class Crypto extends TypedEventEmitter<CryptoEvent, CryptoEventHandlerMap
      * Get the Curve25519 key for this device
      *
      * @returns base64-encoded curve25519 key.
+     *
+     * @deprecated Use {@link CryptoApi#getOwnDeviceKeys}
      */
     public getDeviceCurve25519Key(): string | null {
         return this.olmDevice.deviceCurve25519Key;
     }
 
+    /**
+     * Implementation of {@link CryptoApi#getOwnDeviceKeys}.
+     */
+    public async getOwnDeviceKeys(): Promise<OwnDeviceKeys> {
+        if (!this.olmDevice.deviceCurve25519Key) {
+            throw new Error("Curve25519 key not yet created");
+        }
+        if (!this.olmDevice.deviceEd25519Key) {
+            throw new Error("Ed25519 key not yet created");
+        }
+        return {
+            ed25519: this.olmDevice.deviceEd25519Key,
+            curve25519: this.olmDevice.deviceCurve25519Key,
+        };
+    }
+
     /**
      * Set the global override for whether the client should ever send encrypted
      * messages to unverified devices.  This provides the default for rooms which

src/rust-crypto/rust-crypto.ts

@@ -49,6 +49,7 @@ import {
     KeyBackupCheck,
     KeyBackupInfo,
     KeyBackupSession,
+    OwnDeviceKeys,
     UserVerificationStatus,
     VerificationRequest,
 } from "../crypto-api";
@@ -371,6 +372,24 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         return `Rust SDK ${versions.matrix_sdk_crypto} (${versions.git_sha}), Vodozemac ${versions.vodozemac}`;
     }
 
+    /**
+     * Implementation of {@link CryptoApi#getOwnDeviceKeys}.
+     */
+    public async getOwnDeviceKeys(): Promise<OwnDeviceKeys> {
+        const device: RustSdkCryptoJs.Device = await this.olmMachine.getDevice(
+            this.olmMachine.userId,
+            this.olmMachine.deviceId,
+        );
+        // could be undefined if there is no such algorithm for that device.
+        if (device.curve25519Key && device.ed25519Key) {
+            return {
+                ed25519: device.ed25519Key.toBase64(),
+                curve25519: device.curve25519Key.toBase64(),
+            };
+        }
+        throw new Error("Device keys not found");
+    }
+
     public prepareToEncrypt(room: Room): void {
         const encryptor = this.roomEncryptors[room.roomId];