Add crypto methods for export and import of secrets bundle

spec/unit/rust-crypto/rust-crypto.spec.ts

@@ -1515,6 +1515,44 @@ describe("RustCrypto", () => {
             expect(await rustCrypto.isDehydrationSupported()).toBe(true);
         });
     });
+
+    describe("import & export secrets bundle", () => {
+        let rustCrypto: RustCrypto;
+
+        beforeEach(async () => {
+            rustCrypto = await makeTestRustCrypto(
+                new MatrixHttpApi(new TypedEventEmitter<HttpApiEvent, HttpApiEventHandlerMap>(), {
+                    baseUrl: "http://server/",
+                    prefix: "",
+                    onlyData: true,
+                }),
+                testData.TEST_USER_ID,
+            );
+        });
+
+        it("should throw an error if there is nothing to export", async () => {
+            await expect(rustCrypto.exportsSecretsBundle()).rejects.toThrow(
+                "The store doesn't contain any cross-signing keys",
+            );
+        });
+
+        it("should correctly import & export a secrets bundle", async () => {
+            const bundle = {
+                cross_signing: {
+                    master_key: "bMnVpkHI4S2wXRxy+IpaKM5PIAUUkl6DE+n0YLIW/qs",
+                    user_signing_key: "8tlgLjUrrb/zGJo4YKGhDTIDCEjtJTAS/Sh2AGNLuIo",
+                    self_signing_key: "pfDknmP5a0fVVRE54zhkUgJfzbNmvKcNfIWEW796bQs",
+                },
+                backup: {
+                    algorithm: "m.megolm_backup.v1.curve25519-aes-sha2",
+                    key: "bYYv3aFLQ49jMNcOjuTtBY9EKDby2x1m3gfX81nIKRQ",
+                    backup_version: "9",
+                },
+            };
+            await rustCrypto.importSecretsBundle(bundle);
+            await expect(rustCrypto.exportsSecretsBundle()).resolves.toEqual(expect.objectContaining(bundle));
+        });
+    });
 });
 
 /** Build a MatrixHttpApi instance */

src/@types/matrix-sdk-crypto-wasm.d.ts

@@ -0,0 +1,40 @@
+/*
+Copyright 2024 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import type * as RustSdkCryptoJs from "@matrix-org/matrix-sdk-crypto-wasm";
+
+declare module "@matrix-org/matrix-sdk-crypto-wasm" {
+    interface OlmMachine {
+        importSecretsBundle(bundle: RustSdkCryptoJs.SecretsBundle): Promise<void>;
+        exportSecretsBundle(): Promise<RustSdkCryptoJs.SecretsBundle>;
+    }
+
+    interface SecretsBundle {
+        // eslint-disable-next-line @typescript-eslint/naming-convention
+        to_json(): Promise<{
+            cross_signing: {
+                master_key: string;
+                self_signing_key: string;
+                user_signing_key: string;
+            };
+            backup?: {
+                algorithm: string;
+                key: string;
+                backup_version: string;
+            };
+        }>;
+    }
+}

src/crypto-api.ts

@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import type { SecretsBundle } from "@matrix-org/matrix-sdk-crypto-wasm";
 import type { IMegolmSessionData } from "./@types/crypto";
 import { Room } from "./models/room";
 import { DeviceMap } from "./models/device";
@@ -532,6 +533,23 @@ export interface CryptoApi {
      *   to false.
      */
     startDehydration(createNewKey?: boolean): Promise<void>;
+
+    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+    //
+    // Import/export of secret keys
+    //
+    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+    /**
+     * Export secrets bundle for transmitting to another device as part of OIDC QR login
+     */
+    exportSecretsBundle?(): Promise<Awaited<ReturnType<SecretsBundle["to_json"]>>>;
+
+    /**
+     * Import secrets bundle transmitted from another device.
+     * @param secrets - The secrets bundle received from the other device
+     */
+    importSecretsBundle?(secrets: Awaited<ReturnType<SecretsBundle["to_json"]>>): Promise<void>;
 }
 
 /** A reason code for a failure to decrypt an event. */

src/rust-crypto/rust-crypto.ts

@@ -38,6 +38,7 @@ import {
     CrossSigningKey,
     CrossSigningKeyInfo,
     CrossSigningStatus,
+    CryptoApi,
     CryptoCallbacks,
     Curve25519AuthData,
     DecryptionFailureCode,
@@ -1165,6 +1166,26 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         this.checkKeyBackupAndEnable();
     }
 
+    /**
+     * Implementation of {@link CryptoApi#importSecretsBundle}.
+     */
+    public async importSecretsBundle(
+        secrets: Parameters<NonNullable<CryptoApi["importSecretsBundle"]>>[0],
+    ): Promise<void> {
+        const secretsBundle = RustSdkCryptoJs.SecretsBundle.from_json(secrets);
+        await this.getOlmMachineOrThrow().importSecretsBundle(secretsBundle); // this method frees the SecretsBundle
+    }
+
+    /**
+     * Implementation of {@link CryptoApi#exportSecretsBundle}.
+     */
+    public async exportsSecretsBundle(): ReturnType<NonNullable<CryptoApi["exportSecretsBundle"]>> {
+        const secretsBundle = await this.getOlmMachineOrThrow().exportSecretsBundle();
+        const secrets = secretsBundle.to_json();
+        secretsBundle.free();
+        return secrets;
+    }
+
     /**
      * Signs the given object with the current device and current identity (if available).
      * As defined in {@link https://spec.matrix.org/v1.8/appendices/#signing-json | Signing JSON}.