v32.1.0-rc.0

* Migrate own identity trust to rust crypto

* Fix gendoc not happy if msk of IDownloadKeyResult has a signature

* add missing mock

* code review

* Code review

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* review move function down in file

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review gh suggestion

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review: Cleaning tests, renaming

* Review: better comment

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Comment paragraphs

* retry until initial  key query is successfull

* Validate backup private key before migrating it

* post merge fix

* Fix test, missing mock

* Use crypto wasm instead of lib olm to check backup key

* typo

* code review

* quick lint

---------

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

.github/workflows/downstream-artifacts.yml

@@ -16,7 +16,7 @@ concurrency:
 jobs:
     build-element-web:
         name: Build element-web
-        uses: matrix-org/matrix-react-sdk/.github/workflows/element-web.yaml@v3.95.0
+        uses: matrix-org/matrix-react-sdk/.github/workflows/element-web.yaml@v3.96.1
         with:
             matrix-js-sdk-sha: ${{ github.sha }}
             react-sdk-repository: matrix-org/matrix-react-sdk

.github/workflows/pull_request.yaml

@@ -14,7 +14,7 @@ jobs:
         name: Preview Changelog
         runs-on: ubuntu-latest
         steps:
-            - uses: mheap/github-action-required-labels@80a96a4863886addcbc9f681b5b295ba7f5424e1 # v5
+            - uses: mheap/github-action-required-labels@132879b972cb7f2ac593006455875098e73cc7f2 # v5
               if: github.event_name != 'merge_group'
               with:
                   labels: |

.github/workflows/release-make.yml

@@ -59,7 +59,7 @@ jobs:
 
             - name: Get draft release
               id: draft-release
-              uses: cardinalby/git-get-release-action@cedef2faf69cb7c55b285bad07688d04430b7ada # v1
+              uses: cardinalby/git-get-release-action@5172c3a026600b1d459b117738c605fabc9e4e44 # v1
               env:
                   GITHUB_TOKEN: ${{ github.token }}
               with:

.github/workflows/release-npm.yml

@@ -31,7 +31,7 @@ jobs:
 
             - name: 🚀 Publish to npm
               id: npm-publish
-              uses: JS-DevTools/npm-publish@4b07b26a2f6e0a51846e1870223e545bae91c552 # v3.0.1
+              uses: JS-DevTools/npm-publish@19c28f1ef146469e409470805ea4279d47c3d35c # v3.1.1
               with:
                   token: ${{ secrets.NPM_TOKEN }}
                   access: public

.github/workflows/static_analysis.yml

@@ -90,3 +90,19 @@ jobs:
                   path: _docs
                   # We'll only use this in a workflow_run, then we're done with it
                   retention-days: 1
+
+    analyse_dead_code:
+        name: "Analyse Dead Code"
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v4
+
+            - uses: actions/setup-node@v4
+              with:
+                  cache: "yarn"
+
+            - name: Install Deps
+              run: "yarn install --frozen-lockfile"
+
+            - name: Run linter
+              run: "yarn run lint:knip"

knip.ts

@@ -0,0 +1,36 @@
+import { KnipConfig } from "knip";
+
+export default {
+    entry: [
+        "src/index.ts",
+        "src/types.ts",
+        "src/browser-index.ts",
+        "src/indexeddb-worker.ts",
+        "scripts/**",
+        "spec/**",
+        "release.sh",
+        // For now, we include all source files as entrypoints as we have been bad about gutwrenched imports
+        "src/**",
+    ],
+    project: ["**/*.{js,ts}"],
+    ignore: ["examples/**"],
+    ignoreDependencies: [
+        // Required for `action-validator`
+        "@action-validator/*",
+        // Used for git pre-commit hooks
+        "husky",
+        // Used in script which only runs in environment with `@octokit/rest` installed
+        "@octokit/rest",
+        // Used by jest
+        "jest-environment-jsdom",
+        "babel-jest",
+        "ts-node",
+        // Used by `@babel/plugin-transform-runtime`
+        "@babel/runtime",
+    ],
+    ignoreBinaries: [
+        // Used when available by reusable workflow `.github/workflows/release-make.yml`
+        "dist",
+    ],
+    ignoreExportsUsedInFile: true,
+} satisfies KnipConfig;

package.json

@@ -1,6 +1,6 @@
 {
     "name": "matrix-js-sdk",
-    "version": "32.0.0",
+    "version": "32.1.0-rc.0",
     "description": "Matrix Client-Server SDK for Javascript",
     "engines": {
         "node": ">=18.0.0"
@@ -19,6 +19,7 @@
         "lint:js-fix": "prettier --log-level=warn --write . && eslint --fix src spec",
         "lint:types": "tsc --noEmit",
         "lint:workflows": "find .github/workflows -type f \\( -iname '*.yaml' -o -iname '*.yml' \\) | xargs -I {} sh -c 'echo \"Linting {}\"; action-validator \"{}\"'",
+        "lint:knip": "knip",
         "test": "jest",
         "test:watch": "jest --watch",
         "coverage": "yarn test --coverage"
@@ -80,7 +81,6 @@
         "@babel/plugin-transform-runtime": "^7.12.10",
         "@babel/preset-env": "^7.12.11",
         "@babel/preset-typescript": "^7.12.7",
-        "@babel/register": "^7.12.10",
         "@casualbot/jest-sonar-reporter": "2.2.7",
         "@matrix-org/olm": "3.2.15",
         "@peculiar/webcrypto": "^1.4.5",
@@ -115,12 +115,13 @@
         "jest-environment-jsdom": "^29.0.0",
         "jest-localstorage-mock": "^2.4.6",
         "jest-mock": "^29.0.0",
+        "knip": "^4.0.1",
         "lint-staged": "^15.0.2",
         "matrix-mock-request": "^2.5.0",
         "node-fetch": "^2.7.0",
         "prettier": "3.2.5",
         "rimraf": "^5.0.0",
-        "ts-node": "^10.9.1",
+        "ts-node": "^10.9.2",
         "typedoc": "^0.25.10",
         "typedoc-plugin-coverage": "^3.0.0",
         "typedoc-plugin-mdn-links": "^3.0.3",

spec/integ/crypto/device-dehydration.spec.ts

@@ -0,0 +1,181 @@
+/*
+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 "fake-indexeddb/auto";
+import fetchMock from "fetch-mock-jest";
+
+import { createClient, ClientEvent, MatrixClient, MatrixEvent } from "../../../src";
+import { RustCrypto } from "../../../src/rust-crypto/rust-crypto";
+import { AddSecretStorageKeyOpts } from "../../../src/secret-storage";
+import { E2EKeyReceiver } from "../../test-utils/E2EKeyReceiver";
+import { E2EKeyResponder } from "../../test-utils/E2EKeyResponder";
+
+describe("Device dehydration", () => {
+    it("should rehydrate and dehydrate a device", async () => {
+        jest.useFakeTimers({ doNotFake: ["queueMicrotask"] });
+
+        const matrixClient = createClient({
+            baseUrl: "http://test.server",
+            userId: "@alice:localhost",
+            deviceId: "aliceDevice",
+            cryptoCallbacks: {
+                getSecretStorageKey: async (keys: any, name: string) => {
+                    return [[...Object.keys(keys.keys)][0], new Uint8Array(32)];
+                },
+            },
+        });
+
+        await initializeSecretStorage(matrixClient, "@alice:localhost", "http://test.server");
+
+        // count the number of times the dehydration key gets set
+        let setDehydrationCount = 0;
+        matrixClient.on(ClientEvent.AccountData, (event: MatrixEvent) => {
+            if (event.getType() === "org.matrix.msc3814") {
+                setDehydrationCount++;
+            }
+        });
+
+        const crypto = matrixClient.getCrypto()!;
+        fetchMock.config.overwriteRoutes = true;
+
+        // start dehydration -- we start with no dehydrated device, and we
+        // store the dehydrated device that we create
+        fetchMock.get("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", {
+            status: 404,
+            body: {
+                errcode: "M_NOT_FOUND",
+                error: "Not found",
+            },
+        });
+        let dehydratedDeviceBody: any;
+        let dehydrationCount = 0;
+        let resolveDehydrationPromise: () => void;
+        fetchMock.put("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", (_, opts) => {
+            dehydratedDeviceBody = JSON.parse(opts.body as string);
+            dehydrationCount++;
+            if (resolveDehydrationPromise) {
+                resolveDehydrationPromise();
+            }
+            return {};
+        });
+        await crypto.startDehydration();
+
+        expect(dehydrationCount).toEqual(1);
+
+        // a week later, we should have created another dehydrated device
+        const dehydrationPromise = new Promise<void>((resolve, reject) => {
+            resolveDehydrationPromise = resolve;
+        });
+        jest.advanceTimersByTime(7 * 24 * 60 * 60 * 1000);
+        await dehydrationPromise;
+        expect(dehydrationCount).toEqual(2);
+
+        // restart dehydration -- rehydrate the device that we created above,
+        // and create a new dehydrated device.  We also set `createNewKey`, so
+        // a new dehydration key will be set
+        fetchMock.get("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", {
+            device_id: dehydratedDeviceBody.device_id,
+            device_data: dehydratedDeviceBody.device_data,
+        });
+        const eventsResponse = jest.fn((url, opts) => {
+            // rehydrating should make two calls to the /events endpoint.
+            // The first time will return a single event, and the second
+            // time will return no events (which will signal to the
+            // rehydration function that it can stop)
+            const body = JSON.parse(opts.body as string);
+            const nextBatch = body.next_batch ?? "0";
+            const events = nextBatch === "0" ? [{ sender: "@alice:localhost", type: "m.dummy", content: {} }] : [];
+            return {
+                events,
+                next_batch: nextBatch + "1",
+            };
+        });
+        fetchMock.post(
+            `path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device/${encodeURIComponent(dehydratedDeviceBody.device_id)}/events`,
+            eventsResponse,
+        );
+        await crypto.startDehydration(true);
+        expect(dehydrationCount).toEqual(3);
+
+        expect(setDehydrationCount).toEqual(2);
+        expect(eventsResponse.mock.calls).toHaveLength(2);
+
+        matrixClient.stopClient();
+    });
+});
+
+/** create a new secret storage and cross-signing keys */
+async function initializeSecretStorage(
+    matrixClient: MatrixClient,
+    userId: string,
+    homeserverUrl: string,
+): Promise<void> {
+    fetchMock.get("path:/_matrix/client/v3/room_keys/version", {
+        status: 404,
+        body: {
+            errcode: "M_NOT_FOUND",
+            error: "Not found",
+        },
+    });
+    const e2eKeyReceiver = new E2EKeyReceiver(homeserverUrl);
+    const e2eKeyResponder = new E2EKeyResponder(homeserverUrl);
+    e2eKeyResponder.addKeyReceiver(userId, e2eKeyReceiver);
+    fetchMock.post("path:/_matrix/client/v3/keys/device_signing/upload", {});
+    fetchMock.post("path:/_matrix/client/v3/keys/signatures/upload", {});
+    const accountData: Map<string, object> = new Map();
+    fetchMock.get("glob:http://*/_matrix/client/v3/user/*/account_data/*", (url, opts) => {
+        const name = url.split("/").pop()!;
+        const value = accountData.get(name);
+        if (value) {
+            return value;
+        } else {
+            return {
+                status: 404,
+                body: {
+                    errcode: "M_NOT_FOUND",
+                    error: "Not found",
+                },
+            };
+        }
+    });
+    fetchMock.put("glob:http://*/_matrix/client/v3/user/*/account_data/*", (url, opts) => {
+        const name = url.split("/").pop()!;
+        const value = JSON.parse(opts.body as string);
+        accountData.set(name, value);
+        matrixClient.emit(ClientEvent.AccountData, new MatrixEvent({ type: name, content: value }));
+        return {};
+    });
+
+    await matrixClient.initRustCrypto();
+    const crypto = matrixClient.getCrypto()! as RustCrypto;
+    // we need to process a sync so that the OlmMachine will upload keys
+    await crypto.preprocessToDeviceMessages([]);
+    await crypto.onSyncCompleted({});
+
+    // create initial secret storage
+    async function createSecretStorageKey() {
+        return {
+            keyInfo: {} as AddSecretStorageKeyOpts,
+            privateKey: new Uint8Array(32),
+        };
+    }
+    await matrixClient.bootstrapCrossSigning({ setupNewCrossSigning: true });
+    await matrixClient.bootstrapSecretStorage({
+        createSecretStorageKey,
+        setupNewSecretStorage: true,
+        setupNewKeyBackup: false,
+    });
+}

spec/integ/crypto/rust-crypto.spec.ts

@@ -162,6 +162,110 @@ describe("MatrixClient.initRustCrypto", () => {
             expect(progressListener).toHaveBeenLastCalledWith(-1, -1);
         }, 60000);
 
+        describe("Private key backup migration", () => {
+            it("should not migrate the backup private key if backup has changed", async () => {
+                // Here we have a new backup server side, and the migrated account has the previous backup key.
+                fetchMock.get("path:/_matrix/client/v3/room_keys/version", MSK_NOT_CACHED_DATASET.newBackupResponse);
+
+                fetchMock.post("path:/_matrix/client/v3/keys/query", MSK_NOT_CACHED_DATASET.keyQueryResponse);
+
+                await populateStore("test-store", MSK_NOT_CACHED_DATASET.dumpPath);
+                const cryptoStore = new IndexedDBCryptoStore(indexedDB, "test-store");
+
+                const matrixClient = createClient({
+                    baseUrl: "http://test.server",
+                    userId: MSK_NOT_CACHED_DATASET.userId,
+                    deviceId: MSK_NOT_CACHED_DATASET.deviceId,
+                    cryptoStore,
+                    pickleKey: MSK_NOT_CACHED_DATASET.pickleKey,
+                });
+
+                await matrixClient.initRustCrypto();
+
+                const privateBackupKey = await matrixClient.getCrypto()?.getSessionBackupPrivateKey();
+                expect(privateBackupKey).toBeNull();
+            });
+
+            it("should not migrate the backup private key if backup has unknown algorithm", async () => {
+                // Here we have a new backup server side, and the migrated account has the previous backup key.
+                const backupResponse = {
+                    ...MSK_NOT_CACHED_DATASET.backupResponse,
+                    algorithm: "m.megolm_backup.v8",
+                };
+                fetchMock.get("path:/_matrix/client/v3/room_keys/version", backupResponse);
+
+                fetchMock.post("path:/_matrix/client/v3/keys/query", MSK_NOT_CACHED_DATASET.keyQueryResponse);
+
+                await populateStore("test-store", MSK_NOT_CACHED_DATASET.dumpPath);
+                const cryptoStore = new IndexedDBCryptoStore(indexedDB, "test-store");
+
+                const matrixClient = createClient({
+                    baseUrl: "http://test.server",
+                    userId: MSK_NOT_CACHED_DATASET.userId,
+                    deviceId: MSK_NOT_CACHED_DATASET.deviceId,
+                    cryptoStore,
+                    pickleKey: MSK_NOT_CACHED_DATASET.pickleKey,
+                });
+
+                await matrixClient.initRustCrypto();
+
+                const privateBackupKey = await matrixClient.getCrypto()?.getSessionBackupPrivateKey();
+                expect(privateBackupKey).toBeNull();
+            });
+
+            it("should not migrate the backup private key if the backup has been deleted", async () => {
+                // The old backup has been deleted server side.
+                fetchMock.get("path:/_matrix/client/v3/room_keys/version", {
+                    status: 404,
+                    body: {
+                        errcode: "M_NOT_FOUND",
+                        error: "No backup found",
+                    },
+                });
+
+                fetchMock.post("path:/_matrix/client/v3/keys/query", MSK_NOT_CACHED_DATASET.keyQueryResponse);
+
+                await populateStore("test-store", MSK_NOT_CACHED_DATASET.dumpPath);
+                const cryptoStore = new IndexedDBCryptoStore(indexedDB, "test-store");
+
+                const matrixClient = createClient({
+                    baseUrl: "http://test.server",
+                    userId: MSK_NOT_CACHED_DATASET.userId,
+                    deviceId: MSK_NOT_CACHED_DATASET.deviceId,
+                    cryptoStore,
+                    pickleKey: MSK_NOT_CACHED_DATASET.pickleKey,
+                });
+
+                await matrixClient.initRustCrypto();
+
+                const privateBackupKey = await matrixClient.getCrypto()?.getSessionBackupPrivateKey();
+                expect(privateBackupKey).toBeNull();
+            });
+
+            it("should migrate the backup private key if the backup matches", async () => {
+                // The old backup has been deleted server side.
+                fetchMock.get("path:/_matrix/client/v3/room_keys/version", MSK_NOT_CACHED_DATASET.backupResponse);
+
+                fetchMock.post("path:/_matrix/client/v3/keys/query", MSK_NOT_CACHED_DATASET.keyQueryResponse);
+
+                await populateStore("test-store", MSK_NOT_CACHED_DATASET.dumpPath);
+                const cryptoStore = new IndexedDBCryptoStore(indexedDB, "test-store");
+
+                const matrixClient = createClient({
+                    baseUrl: "http://test.server",
+                    userId: MSK_NOT_CACHED_DATASET.userId,
+                    deviceId: MSK_NOT_CACHED_DATASET.deviceId,
+                    cryptoStore,
+                    pickleKey: MSK_NOT_CACHED_DATASET.pickleKey,
+                });
+
+                await matrixClient.initRustCrypto();
+
+                const privateBackupKey = await matrixClient.getCrypto()?.getSessionBackupPrivateKey();
+                expect(privateBackupKey).toBeDefined();
+            });
+        });
+
         describe("Legacy trust migration", () => {
             async function populateAndStartLegacyCryptoStore(dumpPath: string): Promise<IndexedDBCryptoStore> {
                 const testStoreName = "test-store";

spec/test-utils/oidc.ts

@@ -44,6 +44,7 @@ export const mockOpenIdConfiguration = (issuer = "https://auth.org/"): Validated
     token_endpoint: issuer + "token",
     authorization_endpoint: issuer + "auth",
     registration_endpoint: issuer + "registration",
+    device_authorization_endpoint: issuer + "device",
     jwks_uri: issuer + "jwks",
     response_types_supported: ["code"],
     grant_types_supported: ["authorization_code", "refresh_token"],

spec/test-utils/test_indexeddb_cryptostore_dump/no_cached_msk_dump/index.ts

@@ -245,6 +245,28 @@ const BACKUP_RESPONSE: KeyBackupInfo = {
     count: 0,
 };
 
+/**
+ * This was generated by doing a backup reset on the account.
+ * This is a new valid backup for this account.
+ */
+const NEW_BACKUP_RESPONSE: KeyBackupInfo = {
+    auth_data: {
+        public_key: "CkDxWALi3lcChgjEZFEM6clYq5x768XBwsL++eaOzTI",
+        signatures: {
+            "@migration:localhost": {
+                "ed25519:YVEGEYPYWX":
+                    "ZSYuQDdwgB9WKXQ+z5aWWfqSolBCGRw53kur1Vy956gFefgzCBkMbw5M0I2UgfU2Cukri7jZ4ig201zmLNmaAA",
+                "ed25519:rXCrBin/+xyh+yW//vWte+2UV0et1ZHTWfalp/Ekack":
+                    "+UQ8EA507LoIqgK9rPsqPoGrj+iRBJeY2Oz0mMtXmVf8c1y8G0KWJNUWqvOysnOhsoJf1bt8ey48CxjjtSQ2AA",
+            },
+        },
+    },
+    version: "3",
+    algorithm: "m.megolm_backup.v1.curve25519-aes-sha2",
+    etag: "0",
+    count: 0,
+};
+
 /**
  * A dataset containing the information for the tested user.
  * To be used during tests.
@@ -256,5 +278,6 @@ export const MSK_NOT_CACHED_DATASET: DumpDataSetInfo = {
     keyQueryResponse: KEY_QUERY_RESPONSE,
     rotatedKeyQueryResponse: ROTATED_KEY_QUERY_RESPONSE,
     backupResponse: BACKUP_RESPONSE,
+    newBackupResponse: NEW_BACKUP_RESPONSE,
     dumpPath: "spec/test-utils/test_indexeddb_cryptostore_dump/no_cached_msk_dump/dump.json",
 };

spec/unit/oidc/register.spec.ts

@@ -90,4 +90,31 @@ describe("registerOidcClient()", () => {
             OidcError.DynamicRegistrationInvalid,
         );
     });
+
+    it("should throw when required endpoints are unavailable", async () => {
+        await expect(() =>
+            registerOidcClient(
+                {
+                    ...delegatedAuthConfig,
+                    registrationEndpoint: undefined,
+                },
+                metadata,
+            ),
+        ).rejects.toThrow(OidcError.DynamicRegistrationNotSupported);
+    });
+
+    it("should throw when required scopes are unavailable", async () => {
+        await expect(() =>
+            registerOidcClient(
+                {
+                    ...delegatedAuthConfig,
+                    metadata: {
+                        ...delegatedAuthConfig.metadata,
+                        grant_types_supported: [delegatedAuthConfig.metadata.grant_types_supported[0]],
+                    },
+                },
+                metadata,
+            ),
+        ).rejects.toThrow(OidcError.DynamicRegistrationNotSupported);
+    });
 });

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

@@ -22,6 +22,7 @@ import {
     KeysClaimRequest,
     KeysQueryRequest,
     KeysUploadRequest,
+    PutDehydratedDeviceRequest,
     RoomMessageRequest,
     SignatureUploadRequest,
     UploadSigningKeysRequest,
@@ -233,6 +234,35 @@ describe("OutgoingRequestProcessor", () => {
         httpBackend.verifyNoOutstandingRequests();
     });
 
+    it("should handle PutDehydratedDeviceRequest", async () => {
+        // first, mock up a request as we might expect to receive it from the Rust layer ...
+        const testReq = { foo: "bar" };
+        const outgoingRequest = new PutDehydratedDeviceRequest(JSON.stringify(testReq));
+
+        // ... then poke the request into the OutgoingRequestProcessor under test
+        const reqProm = processor.makeOutgoingRequest(outgoingRequest);
+
+        // Now: check that it makes a matching HTTP request.
+        const testResponse = '{"result":1}';
+        httpBackend
+            .when("PUT", "/_matrix")
+            .check((req) => {
+                expect(req.path).toEqual(
+                    "https://example.com/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device",
+                );
+                expect(JSON.parse(req.rawData)).toEqual(testReq);
+                expect(req.headers["Accept"]).toEqual("application/json");
+                expect(req.headers["Content-Type"]).toEqual("application/json");
+            })
+            .respond(200, testResponse, true);
+
+        // PutDehydratedDeviceRequest does not need to be marked as sent, so no call to OlmMachine.markAsSent is expected.
+
+        await httpBackend.flushAllExpected();
+        await reqProm;
+        httpBackend.verifyNoOutstandingRequests();
+    });
+
     it("does not explode with unknown requests", async () => {
         const outgoingRequest = { id: "5678", type: 987 };
         const markSentCallPromise = awaitCallToMarkAsSent();

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

@@ -205,7 +205,20 @@ describe("initRustCrypto", () => {
             createMegolmSessions(legacyStore, nDevices, nSessionsPerDevice);
             await legacyStore.markSessionsNeedingBackup([{ senderKey: pad43("device5"), sessionId: "session5" }]);
 
-            fetchMock.get("path:/_matrix/client/v3/room_keys/version", { version: "45" });
+            fetchMock.get("path:/_matrix/client/v3/room_keys/version", {
+                auth_data: {
+                    public_key: "backup_key_public",
+                },
+                version: "45",
+                algorithm: "m.megolm_backup.v1.curve25519-aes-sha2",
+            });
+            // The cached key should be valid for the backup
+            const mockBackupDecryptionKey: any = {
+                megolmV1PublicKey: {
+                    publicKeyBase64: "backup_key_public",
+                },
+            };
+            jest.spyOn(RustSdkCryptoJs.BackupDecryptionKey, "fromBase64").mockReturnValue(mockBackupDecryptionKey);
 
             function legacyMigrationProgressListener(progress: number, total: number): void {
                 logger.log(`migrated ${progress} of ${total}`);
@@ -762,8 +775,11 @@ describe("RustCrypto", () => {
                             },
                         },
                     };
-                } else if (request instanceof RustSdkCryptoJs.UploadSigningKeysRequest) {
-                    // SigningKeysUploadRequest does not implement OutgoingRequest and does not need to be marked as sent.
+                } else if (
+                    request instanceof RustSdkCryptoJs.UploadSigningKeysRequest ||
+                    request instanceof RustSdkCryptoJs.PutDehydratedDeviceRequest
+                ) {
+                    // These request types do not implement OutgoingRequest and do not need to be marked as sent.
                     return;
                 }
                 if (request.id) {
@@ -1395,6 +1411,34 @@ describe("RustCrypto", () => {
             });
         });
     });
+
+    describe("device dehydration", () => {
+        it("should detect if dehydration is supported", async () => {
+            const rustCrypto = await makeTestRustCrypto(makeMatrixHttpApi());
+            fetchMock.config.overwriteRoutes = true;
+            fetchMock.get("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", {
+                status: 404,
+                body: {
+                    errcode: "M_UNRECOGNIZED",
+                    error: "Unknown endpoint",
+                },
+            });
+            expect(await rustCrypto.isDehydrationSupported()).toBe(false);
+            fetchMock.get("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", {
+                status: 404,
+                body: {
+                    errcode: "M_NOT_FOUND",
+                    error: "Not found",
+                },
+            });
+            expect(await rustCrypto.isDehydrationSupported()).toBe(true);
+            fetchMock.get("path:/_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device", {
+                device_id: "DEVICE_ID",
+                device_data: "data",
+            });
+            expect(await rustCrypto.isDehydrationSupported()).toBe(true);
+        });
+    });
 });
 
 /** Build a MatrixHttpApi instance */

src/@types/oidc-client-ts.d.ts

@@ -0,0 +1,24 @@
+/*
+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 "oidc-client-ts";
+
+declare module "oidc-client-ts" {
+    interface OidcMetadata {
+        // Add the missing device_authorization_endpoint field to the OidcMetadata interface
+        device_authorization_endpoint?: string;
+    }
+}

src/crypto-api.ts

@@ -496,6 +496,42 @@ export interface CryptoApi {
      * @param version - The backup version to delete.
      */
     deleteKeyBackupVersion(version: string): Promise<void>;
+
+    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+    //
+    // Dehydrated devices
+    //
+    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+    /**
+     * Returns whether MSC3814 dehydrated devices are supported by the crypto
+     * backend and by the server.
+     *
+     * This should be called before calling `startDehydration`, and if this
+     * returns `false`, `startDehydration` should not be called.
+     */
+    isDehydrationSupported(): Promise<boolean>;
+
+    /**
+     * Start using device dehydration.
+     *
+     * - Rehydrates a dehydrated device, if one is available.
+     * - Creates a new dehydration key, if necessary, and stores it in Secret
+     *   Storage.
+     *   - If `createNewKey` is set to true, always creates a new key.
+     *   - If a dehydration key is not available, creates a new one.
+     * - Creates a new dehydrated device, and schedules periodically creating
+     *   new dehydrated devices.
+     *
+     * This function must not be called unless `isDehydrationSupported` returns
+     * `true`, and must not be called until after cross-signing and secret
+     * storage have been set up.
+     *
+     * @param createNewKey - whether to force creation of a new dehydration key.
+     *   This can be used, for example, if Secret Storage is being reset.  Defaults
+     *   to false.
+     */
+    startDehydration(createNewKey?: boolean): Promise<void>;
 }
 
 /** A reason code for a failure to decrypt an event. */

src/crypto/backup.ts

@@ -871,6 +871,9 @@ export const algorithmsByName: Record<string, BackupAlgorithmClass> = {
     [Aes256.algorithmName]: Aes256,
 };
 
+// the linter doesn't like this but knip does
+// eslint-disable-next-line tsdoc/syntax
+/** @alias */
 export const DefaultAlgorithm: BackupAlgorithmClass = Curve25519;
 
 /**

src/crypto/index.ts

@@ -4287,6 +4287,21 @@ export class Crypto extends TypedEventEmitter<CryptoEvent, CryptoEventHandlerMap
     public getRoomEncryption(roomId: string): IRoomEncryption | null {
         return this.roomList.getRoomEncryption(roomId);
     }
+
+    /**
+     * Returns whether dehydrated devices are supported by the crypto backend
+     * and by the server.
+     */
+    public async isDehydrationSupported(): Promise<boolean> {
+        return false;
+    }
+
+    /**
+     * Stub function -- dehydration is not implemented here, so throw error
+     */
+    public async startDehydration(createNewKey?: boolean): Promise<void> {
+        throw new Error("Not implemented");
+    }
 }
 
 /**

src/models/device.ts

@@ -51,6 +51,9 @@ export class Device {
     /** display name of the device */
     public readonly displayName?: string;
 
+    /** whether the device is a dehydrated device */
+    public readonly dehydrated: boolean = false;
+
     public constructor(opts: DeviceParameters) {
         this.deviceId = opts.deviceId;
         this.userId = opts.userId;
@@ -59,6 +62,7 @@ export class Device {
         this.verified = opts.verified || DeviceVerification.Unverified;
         this.signatures = opts.signatures || new Map();
         this.displayName = opts.displayName;
+        this.dehydrated = !!opts.dehydrated;
     }
 
     /**

src/oidc/register.ts

@@ -50,23 +50,31 @@ interface OidcRegistrationRequestBody {
 }
 
 /**
- * Make the client registration request
- * @param registrationEndpoint - URL as returned from issuer ./well-known/openid-configuration
- * @param clientMetadata - registration metadata
- * @returns resolves to the registered client id when registration is successful
- * @throws An `Error` with `message` set to an entry in {@link OidcError},
- *      when the registration request fails, or the response is invalid.
+ * Attempts dynamic registration against the configured registration endpoint
+ * @param delegatedAuthConfig - Auth config from {@link discoverAndValidateOIDCIssuerWellKnown}
+ * @param clientMetadata - The metadata for the client which to register
+ * @returns Promise<string> resolved with registered clientId
+ * @throws when registration is not supported, on failed request or invalid response
  */
-const doRegistration = async (
-    registrationEndpoint: string,
+export const registerOidcClient = async (
+    delegatedAuthConfig: OidcClientConfig,
     clientMetadata: OidcRegistrationClientMetadata,
 ): Promise<string> => {
+    if (!delegatedAuthConfig.registrationEndpoint) {
+        throw new Error(OidcError.DynamicRegistrationNotSupported);
+    }
+
+    const grantTypes: NonEmptyArray<string> = ["authorization_code", "refresh_token"];
+    if (grantTypes.some((scope) => !delegatedAuthConfig.metadata.grant_types_supported.includes(scope))) {
+        throw new Error(OidcError.DynamicRegistrationNotSupported);
+    }
+
     // https://openid.net/specs/openid-connect-registration-1_0.html
     const metadata: OidcRegistrationRequestBody = {
         client_name: clientMetadata.clientName,
         client_uri: clientMetadata.clientUri,
         response_types: ["code"],
-        grant_types: ["authorization_code", "refresh_token"],
+        grant_types: grantTypes,
         redirect_uris: clientMetadata.redirectUris,
         id_token_signed_response_alg: "RS256",
         token_endpoint_auth_method: "none",
@@ -82,7 +90,7 @@ const doRegistration = async (
     };
 
     try {
-        const response = await fetch(registrationEndpoint, {
+        const response = await fetch(delegatedAuthConfig.registrationEndpoint, {
             method: Method.Post,
             headers,
             body: JSON.stringify(metadata),
@@ -108,20 +116,3 @@ const doRegistration = async (
         }
     }
 };
-
-/**
- * Attempts dynamic registration against the configured registration endpoint
- * @param delegatedAuthConfig - Auth config from {@link discoverAndValidateOIDCIssuerWellKnown}
- * @param clientMetadata - The metadata for the client which to register
- * @returns Promise<string> resolved with registered clientId
- * @throws when registration is not supported, on failed request or invalid response
- */
-export const registerOidcClient = async (
-    delegatedAuthConfig: OidcClientConfig,
-    clientMetadata: OidcRegistrationClientMetadata,
-): Promise<string> => {
-    if (!delegatedAuthConfig.registrationEndpoint) {
-        throw new Error(OidcError.DynamicRegistrationNotSupported);
-    }
-    return doRegistration(delegatedAuthConfig.registrationEndpoint, clientMetadata);
-};

src/oidc/validate.ts

@@ -83,6 +83,7 @@ export const validateOIDCIssuerWellKnown = (wellKnown: unknown): ValidatedIssuer
         requiredStringProperty(wellKnown, "revocation_endpoint"),
         optionalStringProperty(wellKnown, "registration_endpoint"),
         optionalStringProperty(wellKnown, "account_management_uri"),
+        optionalStringProperty(wellKnown, "device_authorization_endpoint"),
         optionalStringArrayProperty(wellKnown, "account_management_actions_supported"),
         requiredArrayValue(wellKnown, "response_types_supported", "code"),
         requiredArrayValue(wellKnown, "grant_types_supported", "authorization_code"),
@@ -118,6 +119,7 @@ export type ValidatedIssuerMetadata = Partial<OidcMetadata> &
         | "response_types_supported"
         | "grant_types_supported"
         | "code_challenge_methods_supported"
+        | "device_authorization_endpoint"
     > & {
         // MSC2965 extensions to the OIDC spec
         account_management_uri?: string;
@@ -176,7 +178,12 @@ const decodeIdToken = (token: string): IdTokenClaims => {
  * @param nonce - nonce used in the authentication request
  * @throws when id token is invalid
  */
-export const validateIdToken = (idToken: string | undefined, issuer: string, clientId: string, nonce: string): void => {
+export const validateIdToken = (
+    idToken: string | undefined,
+    issuer: string,
+    clientId: string,
+    nonce: string | undefined,
+): void => {
     try {
         if (!idToken) {
             throw new Error("No ID token");
@@ -201,7 +208,7 @@ export const validateIdToken = (idToken: string | undefined, issuer: string, cli
          * If a nonce value was sent in the Authentication Request, a nonce Claim MUST be present and its value checked
          * to verify that it is the same value as the one that was sent in the Authentication Request.
          */
-        if (claims.nonce !== nonce) {
+        if (nonce !== undefined && claims.nonce !== nonce) {
             throw new Error("Invalid nonce");
         }
 

src/rust-crypto/DehydratedDeviceManager.ts

@@ -0,0 +1,307 @@
+/*
+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 * as RustSdkCryptoJs from "@matrix-org/matrix-sdk-crypto-wasm";
+
+import { OutgoingRequestProcessor } from "./OutgoingRequestProcessor";
+import { encodeUri } from "../utils";
+import { IHttpOpts, MatrixError, MatrixHttpApi, Method } from "../http-api";
+import { IToDeviceEvent } from "../sync-accumulator";
+import { ServerSideSecretStorage } from "../secret-storage";
+import { crypto } from "../crypto/crypto";
+import { decodeBase64, encodeUnpaddedBase64 } from "../base64";
+import { Logger } from "../logger";
+
+/**
+ * The response body of `GET /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device`.
+ */
+interface DehydratedDeviceResp {
+    device_id: string;
+    device_data: {
+        algorithm: string;
+    };
+}
+/**
+ * The response body of `POST /_matrix/client/unstable/org.matrix.msc3814.v1/dehydrated_device/events`.
+ */
+interface DehydratedDeviceEventsResp {
+    events: IToDeviceEvent[];
+    next_batch: string;
+}
+
+/**
+ * The unstable URL prefix for dehydrated device endpoints
+ */
+export const UnstablePrefix = "/_matrix/client/unstable/org.matrix.msc3814.v1";
+/**
+ * The name used for the dehydration key in Secret Storage
+ */
+const SECRET_STORAGE_NAME = "org.matrix.msc3814";
+
+/**
+ * The interval between creating dehydrated devices. (one week)
+ */
+const DEHYDRATION_INTERVAL = 7 * 24 * 60 * 60 * 1000;
+
+/**
+ * Manages dehydrated devices
+ *
+ * We have one of these per `RustCrypto`.  It's responsible for
+ *
+ * * determining server support for dehydrated devices
+ * * creating new dehydrated devices when requested, including periodically
+ *   replacing the dehydrated device with a new one
+ * * rehydrating a device when requested, and when present
+ *
+ * @internal
+ */
+export class DehydratedDeviceManager {
+    /** the secret key used for dehydrating and rehydrating */
+    private key?: Uint8Array;
+    /** the ID of the interval for periodically replacing the dehydrated device */
+    private intervalId?: ReturnType<typeof setInterval>;
+
+    public constructor(
+        private readonly logger: Logger,
+        private readonly olmMachine: RustSdkCryptoJs.OlmMachine,
+        private readonly http: MatrixHttpApi<IHttpOpts & { onlyData: true }>,
+        private readonly outgoingRequestProcessor: OutgoingRequestProcessor,
+        private readonly secretStorage: ServerSideSecretStorage,
+    ) {}
+
+    /**
+     * Return whether the server supports dehydrated devices.
+     */
+    public async isSupported(): Promise<boolean> {
+        // call the endpoint to get a dehydrated device.  If it returns an
+        // M_UNRECOGNIZED error, then dehydration is unsupported.  If it returns
+        // a successful response, or an M_NOT_FOUND, then dehydration is supported.
+        // Any other exceptions are passed through.
+        try {
+            await this.http.authedRequest<DehydratedDeviceResp>(
+                Method.Get,
+                "/dehydrated_device",
+                undefined,
+                undefined,
+                {
+                    prefix: UnstablePrefix,
+                },
+            );
+        } catch (error) {
+            const err = error as MatrixError;
+            if (err.errcode === "M_UNRECOGNIZED") {
+                return false;
+            } else if (err.errcode === "M_NOT_FOUND") {
+                return true;
+            }
+            throw error;
+        }
+        return true;
+    }
+
+    /**
+     * Start using device dehydration.
+     *
+     * - Rehydrates a dehydrated device, if one is available.
+     * - Creates a new dehydration key, if necessary, and stores it in Secret
+     *   Storage.
+     *   - If `createNewKey` is set to true, always creates a new key.
+     *   - If a dehydration key is not available, creates a new one.
+     * - Creates a new dehydrated device, and schedules periodically creating
+     *   new dehydrated devices.
+     *
+     * @param createNewKey - whether to force creation of a new dehydration key.
+     *   This can be used, for example, if Secret Storage is being reset.
+     */
+    public async start(createNewKey?: boolean): Promise<void> {
+        this.stop();
+        try {
+            await this.rehydrateDeviceIfAvailable();
+        } catch (e) {
+            // If rehydration fails, there isn't much we can do about it.  Log
+            // the error, and create a new device.
+            this.logger.info("dehydration: Error rehydrating device:", e);
+        }
+        if (createNewKey) {
+            await this.resetKey();
+        }
+        await this.scheduleDeviceDehydration();
+    }
+
+    /**
+     * Return whether the dehydration key is stored in Secret Storage.
+     */
+    public async isKeyStored(): Promise<boolean> {
+        return Boolean(await this.secretStorage.isStored(SECRET_STORAGE_NAME));
+    }
+
+    /**
+     * Reset the dehydration key.
+     *
+     * Creates a new key and stores it in secret storage.
+     */
+    public async resetKey(): Promise<void> {
+        const key = new Uint8Array(32);
+        crypto.getRandomValues(key);
+        await this.secretStorage.store(SECRET_STORAGE_NAME, encodeUnpaddedBase64(key));
+        this.key = key;
+    }
+
+    /**
+     * Get and cache the encryption key from secret storage.
+     *
+     * If `create` is `true`, creates a new key if no existing key is present.
+     *
+     * @returns the key, if available, or `null` if no key is available
+     */
+    private async getKey(create: boolean): Promise<Uint8Array | null> {
+        if (this.key === undefined) {
+            const keyB64 = await this.secretStorage.get(SECRET_STORAGE_NAME);
+            if (keyB64 === undefined) {
+                if (!create) {
+                    return null;
+                }
+                await this.resetKey();
+            } else {
+                this.key = decodeBase64(keyB64);
+            }
+        }
+        return this.key!;
+    }
+
+    /**
+     * Rehydrate the dehydrated device stored on the server.
+     *
+     * Checks if there is a dehydrated device on the server.  If so, rehydrates
+     * the device and processes the to-device events.
+     *
+     * Returns whether or not a dehydrated device was found.
+     */
+    public async rehydrateDeviceIfAvailable(): Promise<boolean> {
+        const key = await this.getKey(false);
+        if (!key) {
+            return false;
+        }
+
+        let dehydratedDeviceResp;
+        try {
+            dehydratedDeviceResp = await this.http.authedRequest<DehydratedDeviceResp>(
+                Method.Get,
+                "/dehydrated_device",
+                undefined,
+                undefined,
+                {
+                    prefix: UnstablePrefix,
+                },
+            );
+        } catch (error) {
+            const err = error as MatrixError;
+            // We ignore M_NOT_FOUND (there is no dehydrated device, so nothing
+            // us to do) and M_UNRECOGNIZED (the server does not understand the
+            // endpoint).  We pass through any other errors.
+            if (err.errcode === "M_NOT_FOUND" || err.errcode === "M_UNRECOGNIZED") {
+                this.logger.info("dehydration: No dehydrated device");
+                return false;
+            }
+            throw err;
+        }
+
+        this.logger.info("dehydration: dehydrated device found");
+
+        const rehydratedDevice = await this.olmMachine
+            .dehydratedDevices()
+            .rehydrate(
+                key,
+                new RustSdkCryptoJs.DeviceId(dehydratedDeviceResp.device_id),
+                JSON.stringify(dehydratedDeviceResp.device_data),
+            );
+
+        this.logger.info("dehydration: device rehydrated");
+
+        let nextBatch: string | undefined = undefined;
+        let toDeviceCount = 0;
+        let roomKeyCount = 0;
+        const path = encodeUri("/dehydrated_device/$device_id/events", {
+            $device_id: dehydratedDeviceResp.device_id,
+        });
+        // eslint-disable-next-line no-constant-condition
+        while (true) {
+            const eventResp: DehydratedDeviceEventsResp = await this.http.authedRequest<DehydratedDeviceEventsResp>(
+                Method.Post,
+                path,
+                undefined,
+                nextBatch ? { next_batch: nextBatch } : {},
+                {
+                    prefix: UnstablePrefix,
+                },
+            );
+
+            if (eventResp.events.length === 0) {
+                break;
+            }
+            toDeviceCount += eventResp.events.length;
+            nextBatch = eventResp.next_batch;
+            const roomKeyInfos = await rehydratedDevice.receiveEvents(JSON.stringify(eventResp.events));
+            roomKeyCount += roomKeyInfos.length;
+        }
+        this.logger.info(`dehydration: received ${roomKeyCount} room keys from ${toDeviceCount} to-device events`);
+
+        return true;
+    }
+
+    /**
+     * Creates and uploads a new dehydrated device.
+     *
+     * Creates and stores a new key in secret storage if none is available.
+     */
+    public async createAndUploadDehydratedDevice(): Promise<void> {
+        const key = (await this.getKey(true))!;
+
+        const dehydratedDevice = await this.olmMachine.dehydratedDevices().create();
+        const request = await dehydratedDevice.keysForUpload("Dehydrated device", key);
+
+        await this.outgoingRequestProcessor.makeOutgoingRequest(request);
+
+        this.logger.info("dehydration: uploaded device");
+    }
+
+    /**
+     * Schedule periodic creation of dehydrated devices.
+     */
+    public async scheduleDeviceDehydration(): Promise<void> {
+        // cancel any previously-scheduled tasks
+        this.stop();
+
+        await this.createAndUploadDehydratedDevice();
+        this.intervalId = setInterval(() => {
+            this.createAndUploadDehydratedDevice().catch((error) => {
+                this.logger.error("Error creating dehydrated device:", error);
+            });
+        }, DEHYDRATION_INTERVAL);
+    }
+
+    /**
+     * Stop the dehydrated device manager.
+     *
+     * Cancels any scheduled dehydration tasks.
+     */
+    public stop(): void {
+        if (this.intervalId) {
+            clearInterval(this.intervalId);
+            this.intervalId = undefined;
+        }
+    }
+}

src/rust-crypto/OutgoingRequestProcessor.ts

@@ -20,6 +20,7 @@ import {
     KeysQueryRequest,
     KeysUploadRequest,
     OlmMachine,
+    PutDehydratedDeviceRequest,
     RoomMessageRequest,
     SignatureUploadRequest,
     ToDeviceRequest,
@@ -32,6 +33,7 @@ import { logDuration, QueryDict, sleep } from "../utils";
 import { AuthDict, UIAuthCallback } from "../interactive-auth";
 import { UIAResponse } from "../@types/uia";
 import { ToDeviceMessageId } from "../@types/event";
+import { UnstablePrefix as DehydrationUnstablePrefix } from "./DehydratedDeviceManager";
 
 /**
  * Common interface for all the request types returned by `OlmMachine.outgoingRequests`.
@@ -62,7 +64,7 @@ export class OutgoingRequestProcessor {
     ) {}
 
     public async makeOutgoingRequest<T>(
-        msg: OutgoingRequest | UploadSigningKeysRequest,
+        msg: OutgoingRequest | UploadSigningKeysRequest | PutDehydratedDeviceRequest,
         uiaCallback?: UIAuthCallback<T>,
     ): Promise<void> {
         let resp: string;
@@ -102,6 +104,11 @@ export class OutgoingRequestProcessor {
             );
             // SigningKeysUploadRequest does not implement OutgoingRequest and does not need to be marked as sent.
             return;
+        } else if (msg instanceof PutDehydratedDeviceRequest) {
+            const path = DehydrationUnstablePrefix + "/dehydrated_device";
+            await this.rawJsonRequest(Method.Put, path, {}, msg.body);
+            // PutDehydratedDeviceRequest does not implement OutgoingRequest and does not need to be marked as sent.
+            return;
         } else {
             logger.warn("Unsupported outgoing message", Object.getPrototypeOf(msg));
             resp = "";

src/rust-crypto/device-converter.ts

@@ -80,6 +80,7 @@ export function rustDeviceToJsDevice(device: RustSdkCryptoJs.Device, userId: Rus
         verified,
         signatures,
         displayName: device.displayName,
+        dehydrated: device.isDehydrated,
     });
 }
 

src/rust-crypto/libolm_migration.ts

@@ -23,8 +23,10 @@ import { decryptAES, IEncryptedPayload } from "../crypto/aes";
 import { IHttpOpts, MatrixHttpApi } from "../http-api";
 import { requestKeyBackupVersion } from "./backup";
 import { IRoomEncryption } from "../crypto/RoomList";
-import { CrossSigningKeyInfo } from "../crypto-api";
+import { CrossSigningKeyInfo, Curve25519AuthData } from "../crypto-api";
 import { RustCrypto } from "./rust-crypto";
+import { KeyBackupInfo } from "../crypto-api/keybackup";
+import { sleep } from "../utils";
 
 /**
  * Determine if any data needs migrating from the legacy store, and do so.
@@ -105,7 +107,7 @@ export async function migrateFromLegacyCrypto(args: {
 
     if (migrationState === MigrationState.NOT_STARTED) {
         logger.info("Migrating data from legacy crypto store. Step 1: base data");
-        await migrateBaseData(args.http, args.userId, args.deviceId, legacyStore, pickleKey, args.storeHandle);
+        await migrateBaseData(args.http, args.userId, args.deviceId, legacyStore, pickleKey, args.storeHandle, logger);
 
         migrationState = MigrationState.INITIAL_DATA_MIGRATED;
         await legacyStore.setMigrationState(migrationState);
@@ -144,6 +146,7 @@ async function migrateBaseData(
     legacyStore: CryptoStore,
     pickleKey: Uint8Array,
     storeHandle: RustSdkCryptoJs.StoreHandle,
+    logger: Logger,
 ): Promise<void> {
     const migrationData = new RustSdkCryptoJs.BaseMigrationData();
     migrationData.userId = new RustSdkCryptoJs.UserId(userId);
@@ -158,12 +161,41 @@ async function migrateBaseData(
     const recoveryKey = await getAndDecryptCachedSecretKey(legacyStore, pickleKey, "m.megolm_backup.v1");
 
     // If we have a backup recovery key, we need to try to figure out which backup version it is for.
-    // All we can really do is ask the server for the most recent version.
+    // All we can really do is ask the server for the most recent version and check if the cached key we have matches.
+    // It is possible that the backup has changed since last time his session was opened.
     if (recoveryKey) {
-        const backupInfo = await requestKeyBackupVersion(http);
-        if (backupInfo) {
-            migrationData.backupVersion = backupInfo.version;
-            migrationData.backupRecoveryKey = recoveryKey;
+        let backupCallDone = false;
+        let backupInfo: KeyBackupInfo | null = null;
+        while (!backupCallDone) {
+            try {
+                backupInfo = await requestKeyBackupVersion(http);
+                backupCallDone = true;
+            } catch (e) {
+                logger.info("Failed to get backup version during migration, retrying in 2 seconds", e);
+                // Retry until successful, use simple constant delay
+                await sleep(2000);
+            }
+        }
+        if (backupInfo && backupInfo.algorithm == "m.megolm_backup.v1.curve25519-aes-sha2") {
+            // check if the recovery key matches, as the active backup version may have changed since the key was cached
+            // and the migration started.
+            try {
+                const decryptionKey = RustSdkCryptoJs.BackupDecryptionKey.fromBase64(recoveryKey);
+                const publicKey = (backupInfo.auth_data as Curve25519AuthData)?.public_key;
+                const isValid = decryptionKey.megolmV1PublicKey.publicKeyBase64 == publicKey;
+                if (isValid) {
+                    migrationData.backupVersion = backupInfo.version;
+                    migrationData.backupRecoveryKey = recoveryKey;
+                } else {
+                    logger.debug(
+                        "The backup key to migrate does not match the active backup version",
+                        `Cached pub key: ${decryptionKey.megolmV1PublicKey.publicKeyBase64}`,
+                        `Active pub key: ${publicKey}`,
+                    );
+                }
+            } catch (e) {
+                logger.warn("Failed to check if the backup key to migrate matches the active backup version", e);
+            }
         }
     }
 

src/rust-crypto/rust-crypto.ts

@@ -73,6 +73,7 @@ import { ISignatures } from "../@types/signed";
 import { encodeBase64 } from "../base64";
 import { OutgoingRequestsManager } from "./OutgoingRequestsManager";
 import { PerSessionKeyBackupDownloader } from "./PerSessionKeyBackupDownloader";
+import { DehydratedDeviceManager } from "./DehydratedDeviceManager";
 import { VerificationMethod } from "../types";
 
 const ALL_VERIFICATION_METHODS = [
@@ -107,9 +108,8 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
     private crossSigningIdentity: CrossSigningIdentity;
     private readonly backupManager: RustBackupManager;
     private outgoingRequestsManager: OutgoingRequestsManager;
-
     private readonly perSessionBackupDownloader: PerSessionKeyBackupDownloader;
-
+    private readonly dehydratedDeviceManager: DehydratedDeviceManager;
     private readonly reemitter = new TypedReEmitter<RustCryptoEvents, RustCryptoEventMap>(this);
 
     public constructor(
@@ -148,14 +148,19 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         this.keyClaimManager = new KeyClaimManager(olmMachine, this.outgoingRequestProcessor);
 
         this.backupManager = new RustBackupManager(olmMachine, http, this.outgoingRequestProcessor);
-
         this.perSessionBackupDownloader = new PerSessionKeyBackupDownloader(
             this.logger,
             this.olmMachine,
             this.http,
             this.backupManager,
         );
-
+        this.dehydratedDeviceManager = new DehydratedDeviceManager(
+            this.logger,
+            olmMachine,
+            http,
+            this.outgoingRequestProcessor,
+            secretStorage,
+        );
         this.eventDecryptor = new EventDecryptor(this.logger, olmMachine, this.perSessionBackupDownloader);
 
         this.reemitter.reEmit(this.backupManager, [
@@ -212,6 +217,7 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         this.backupManager.stop();
         this.outgoingRequestsManager.stop();
         this.perSessionBackupDownloader.stop();
+        this.dehydratedDeviceManager.stop();
 
         // make sure we close() the OlmMachine; doing so means that all the Rust objects will be
         // cleaned up; in particular, the indexeddb connections will be closed, which means they
@@ -1212,6 +1218,23 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
         return await this.backupManager.importBackedUpRoomKeys(keys, opts);
     }
 
+    /**
+     * Implementation of {@link CryptoBackend#isDehydrationSupported}.
+     */
+    public async isDehydrationSupported(): Promise<boolean> {
+        return await this.dehydratedDeviceManager.isSupported();
+    }
+
+    /**
+     * Implementation of {@link CryptoBackend#startDehydration}.
+     */
+    public async startDehydration(createNewKey?: boolean): Promise<void> {
+        if (!(await this.isCrossSigningReady()) || !(await this.isSecretStorageReady())) {
+            throw new Error("Device dehydration requires cross-signing and secret storage to be set up");
+        }
+        return await this.dehydratedDeviceManager.start(createNewKey);
+    }
+
     ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     //
     // SyncCryptoCallbacks implementation