WIP

src/domain/SessionLoadViewModel.js

@@ -29,6 +29,7 @@ export class SessionLoadViewModel extends ViewModel {
         this._loading = false;
         this._error = null;
         this.backUrl = this.urlCreator.urlForSegment("session", true);
+        this._dehydratedDevice = undefined;
     }
 
     async start() {
@@ -110,6 +111,10 @@ export class SessionLoadViewModel extends ViewModel {
         // Statuses related to login are handled by respective login view models
         if (sc) {
             switch (sc.loadStatus.get()) {
+                case LoadStatus.QueryAccount:
+                    return `Querying account encryption setup…`;
+                case LoadStatus.SetupAccount:
+                    return `Please enter your password to restore your encryption setup`;
                 case LoadStatus.SessionSetup:
                     return `Setting up your encryption keys…`;
                 case LoadStatus.Loading:
@@ -136,4 +141,27 @@ export class SessionLoadViewModel extends ViewModel {
         const logExport = await this.logger.export();
         this.platform.saveFileAs(logExport.asBlob(), `hydrogen-logs-${this.platform.clock.now()}.json`);
     }
+
+    get canSetupAccount() {
+        return this._sessionContainer.loadStatus === LoadStatus.SetupAccount;
+    }
+
+    get canDehydrateDevice() {
+        return this.canSetupAccount && !!this._sessionContainer.accountSetup.encryptedDehydratedDevice;
+    }
+
+    tryDecryptDehydratedDevice(password) {
+        const {encryptedDehydratedDevice} = this._sessionContainer.accountSetup;
+        if (encryptedDehydratedDevice) {
+            this._dehydratedDevice = encryptedDehydratedDevice.decrypt(password);
+            return !!this._dehydratedDevice;
+        }
+        return false;
+    }
+
+    finishAccountSetup() {
+        const dehydratedDevice = this._dehydratedDevice;
+        this._dehydratedDevice = undefined;
+        this._sessionContainer.accountSetup.finish(dehydratedDevice);
+    }
 }

src/matrix/Session.js

@@ -248,23 +248,77 @@ export class Session {
     async createIdentity(log) {
         if (this._olm) {
             if (!this._e2eeAccount) {
-                this._e2eeAccount = await E2EEAccount.create({
+                this._e2eeAccount = this._createNewAccount(this._sessionInfo.deviceId, this._storage);
-                    hsApi: this._hsApi,
-                    olm: this._olm,
-                    pickleKey: PICKLE_KEY,
-                    userId: this._sessionInfo.userId,
-                    deviceId: this._sessionInfo.deviceId,
-                    olmWorker: this._olmWorker,
-                    storage: this._storage,
-                });
                 log.set("keys", this._e2eeAccount.identityKeys);
                 this._setupEncryption();
             }
             await this._e2eeAccount.generateOTKsIfNeeded(this._storage, log);
-            await log.wrap("uploadKeys", log => this._e2eeAccount.uploadKeys(this._storage, log));
+            await log.wrap("uploadKeys", log => this._e2eeAccount.uploadKeys(this._storage, undefined, log));
         }
     }
 
+    /** @internal */
+    dehydrateIdentity(dehydratedDevice, log = null) {
+        this._platform.logger.wrapOrRun(log, "dehydrateIdentity", async log => {
+            log.set("deviceId", dehydratedDevice.deviceId);
+            if (!this._olm) {
+                log.set("no_olm", true);
+                return false;
+            }
+            if (dehydratedDevice.deviceId !== this.deviceId) {
+                log.set("wrong_device", true);
+                return false;
+            }
+            if (this._e2eeAccount) {
+                log.set("account_already_setup", true);
+                return false;
+            }
+            if (!await dehydratedDevice.claim(this._hsApi, log)) {
+                log.set("already_claimed", true);
+                return false;
+            }
+            this._e2eeAccount = await E2EEAccount.adoptDehydratedDevice({
+                dehydratedDevice,
+                hsApi: this._hsApi,
+                olm: this._olm,
+                pickleKey: PICKLE_KEY,
+                userId: this._sessionInfo.userId,
+                olmWorker: this._olmWorker,
+                deviceId,
+                storage,
+            });
+            log.set("keys", this._e2eeAccount.identityKeys);
+            this._setupEncryption();
+            return true;
+        });
+    }
+
+    _createNewAccount(deviceId, storage = undefined) {
+        // storage is optional and if omitted the account won't be persisted (useful for dehydrating devices)
+        return E2EEAccount.create({
+            hsApi: this._hsApi,
+            olm: this._olm,
+            pickleKey: PICKLE_KEY,
+            userId: this._sessionInfo.userId,
+            olmWorker: this._olmWorker,
+            deviceId,
+            storage,
+        });
+    }
+
+    setupDehydratedDevice(key, log = null) {
+        return this._platform.logger.wrapOrRun(log, "setupDehydratedDevice", async log => {
+            const dehydrationAccount = await this._createNewAccount("temp-device-id");
+            try {
+                const deviceId = await uploadAccountAsDehydratedDevice(
+                    dehydrationAccount, this._hsApi, key, "Dehydrated device", log);
+                return deviceId;
+            } finally {
+                dehydrationAccount.dispose();
+            }
+        });
+    }
+
     /** @internal */
     async load(log) {
         const txn = await this._storage.readTxn([
@@ -323,6 +377,7 @@ export class Session {
         this._olmWorker?.dispose();
         this._sessionBackup?.dispose();
         this._megolmDecryption.dispose();
+        this._e2eeAccount?.dispose();
         for (const room of this._rooms.values()) {
             room.dispose();
         }
@@ -517,7 +572,7 @@ export class Session {
         if (!isCatchupSync) {
             const needsToUploadOTKs = await this._e2eeAccount.generateOTKsIfNeeded(this._storage, log);
             if (needsToUploadOTKs) {
-                await log.wrap("uploadKeys", log => this._e2eeAccount.uploadKeys(this._storage, log));
+                await log.wrap("uploadKeys", log => this._e2eeAccount.uploadKeys(this._storage, undefined, log));
             }
         }
     }

src/matrix/SessionContainer.js

@@ -34,6 +34,8 @@ export const LoadStatus = createEnum(
     "NotLoading",
     "Login",
     "LoginFailed",
+    "QueryAccount", // check for dehydrated device after login
+    "SetupAccount", // asked to restore from dehydrated device if present, call sc.accountSetup.finish() to progress to the next stage
     "Loading",
     "SessionSetup", // upload e2ee keys, ...
     "Migrating",    //not used atm, but would fit here
@@ -85,7 +87,7 @@ export class SessionContainer {
                 if (!sessionInfo) {
                     throw new Error("Invalid session id: " + sessionId);
                 }
-                await this._loadSessionInfo(sessionInfo, false, log);
+                await this._loadSessionInfo(sessionInfo, null, log);
                 log.set("status", this._status.get());
             } catch (err) {
                 log.catch(err);
@@ -154,7 +156,6 @@ export class SessionContainer {
                     lastUsed: clock.now()
                 };
                 log.set("id", sessionId);
-                await this._platform.sessionInfoStorage.add(sessionInfo);            
             } catch (err) {
                 this._error = err;
                 if (err.name === "HomeServerError") {
@@ -173,11 +174,16 @@ export class SessionContainer {
                 }
                 return;
             }
+            const dehydratedDevice = await this._inspectAccountAfterLogin(sessionInfo);
+            if (dehydratedDevice) {
+                sessionInfo.deviceId = dehydratedDevice.deviceId;
+            }
+            await this._platform.sessionInfoStorage.add(sessionInfo);            
             // loading the session can only lead to
             // LoadStatus.Error in case of an error,
             // so separate try/catch
             try {
-                await this._loadSessionInfo(sessionInfo, true, log);
+                await this._loadSessionInfo(sessionInfo, dehydratedDevice, log);
                 log.set("status", this._status.get());
             } catch (err) {
                 log.catch(err);
@@ -187,7 +193,7 @@ export class SessionContainer {
         });
     }
 
-    async _loadSessionInfo(sessionInfo, isNewLogin, log) {
+    async _loadSessionInfo(sessionInfo, dehydratedDevice, log) {
         log.set("appVersion", this._platform.version);
         const clock = this._platform.clock;
         this._sessionStartedByReconnector = false;
@@ -233,7 +239,9 @@ export class SessionContainer {
             platform: this._platform,
         });
         await this._session.load(log);
-        if (!this._session.hasIdentity) {
+        if (dehydratedDevice) {
+            await log.wrap("dehydrateIdentity", log => await this._session.dehydrateIdentity(dehydratedDevice, log));
+        } else if (!this._session.hasIdentity) {
             this._status.set(LoadStatus.SessionSetup);
             await log.wrap("createIdentity", log => this._session.createIdentity(log));
         }
@@ -300,6 +308,30 @@ export class SessionContainer {
         }
     }
 
+    async _inspectAccountAfterLogin(sessionInfo) {
+        this._status.set(LoadStatus.QueryAccount);
+        const hsApi = new HomeServerApi({
+            homeserver: sessionInfo.homeServer,
+            accessToken: sessionInfo.accessToken,
+            request: this._platform.request,
+        });
+        const olm = await this._olmPromise;
+        const encryptedDehydratedDevice = await getDehydratedDevice(hsApi, olm);
+        if (encryptedDehydratedDevice) {
+            let resolveStageFinish;
+            const promiseStageFinish = new Promise(r => resolveStageFinish = r);
+            this._accountSetup = new AccountSetup(encryptedDehydratedDevice, resolveStageFinish);
+            this._status.set(LoadStatus.SetupAccount);
+            await promiseStageFinish;
+            const dehydratedDevice = this._accountSetup?._dehydratedDevice;
+            this._accountSetup = null;
+            return dehydratedDevice;
+        }
+    }
+
+    get accountSetup() {
+        return this._accountSetup;
+    }
 
     get loadStatus() {
         return this._status;
@@ -378,3 +410,20 @@ export class SessionContainer {
         this._loginFailure = null;
     }
 }
+
+class AccountSetup {
+    constructor(encryptedDehydratedDevice, finishStage) {
+        this._encryptedDehydratedDevice = encryptedDehydratedDevice;
+        this._dehydratedDevice = undefined;
+        this._finishStage = finishStage;
+    }
+
+    get encryptedDehydratedDevice() {
+        return this._encryptedDehydratedDevice;
+    }
+
+    finish(dehydratedDevice) {
+        this._dehydratedDevice = dehydratedDevice;
+        this._finishStage();
+    }
+}

src/matrix/e2ee/Account.js

@@ -22,6 +22,24 @@ const ACCOUNT_SESSION_KEY = SESSION_E2EE_KEY_PREFIX + "olmAccount";
 const DEVICE_KEY_FLAG_SESSION_KEY = SESSION_E2EE_KEY_PREFIX + "areDeviceKeysUploaded";
 const SERVER_OTK_COUNT_SESSION_KEY = SESSION_E2EE_KEY_PREFIX + "serverOTKCount";
 
+async function initiallyStoreAccount(account, pickleKey, areDeviceKeysUploaded, serverOTKCount, storage) {
+    const pickledAccount = account.pickle(pickleKey);
+    const txn = await storage.readWriteTxn([
+        storage.storeNames.session
+    ]);
+    try {
+        // add will throw if the key already exists
+        // we would not want to overwrite olmAccount here
+        txn.session.add(ACCOUNT_SESSION_KEY, pickledAccount);
+        txn.session.add(DEVICE_KEY_FLAG_SESSION_KEY, areDeviceKeysUploaded);
+        txn.session.add(SERVER_OTK_COUNT_SESSION_KEY, serverOTKCount);
+    } catch (err) {
+        txn.abort();
+        throw err;
+    }
+    await txn.complete();
+}
+
 export class Account {
     static async load({olm, pickleKey, hsApi, userId, deviceId, olmWorker, txn}) {
         const pickledAccount = await txn.session.get(ACCOUNT_SESSION_KEY);
@@ -35,6 +53,21 @@ export class Account {
         }
     }
     
+    static async adoptDehydratedDevice({olm, dehydratedDevice, pickleKey, hsApi, userId, olmWorker, storage}) {
+        const account = dehydratedDevice.adoptUnpickledOlmAccount();
+        const areDeviceKeysUploaded = true;
+        const oneTimeKeys = JSON.parse(this._account.one_time_keys());
+        // only one algorithm supported by olm atm, so hardcode its name
+        const oneTimeKeysEntries = Object.entries(oneTimeKeys.curve25519);
+        const serverOTKCount = oneTimeKeysEntries.length;
+        await initiallyStoreAccount(account, pickleKey, areDeviceKeysUploaded, serverOTKCount, storage);
+        return new Account({
+            pickleKey, hsApi, account, userId,
+            deviceId: dehydratedDevice.deviceId,
+            areDeviceKeysUploaded, serverOTKCount, olm, olmWorker
+        });
+    }
+
     static async create({olm, pickleKey, hsApi, userId, deviceId, olmWorker, storage}) {
         const account = new olm.Account();
         if (olmWorker) {
@@ -43,22 +76,9 @@ export class Account {
             account.create();
             account.generate_one_time_keys(account.max_number_of_one_time_keys());
         }
-        const pickledAccount = account.pickle(pickleKey);
+        if (storage) {
-        const areDeviceKeysUploaded = false;
+            await initiallyStoreAccount(account, pickleKey, false, 0, storage);
-        const txn = await storage.readWriteTxn([
-            storage.storeNames.session
-        ]);
-        try {
-            // add will throw if the key already exists
-            // we would not want to overwrite olmAccount here
-            txn.session.add(ACCOUNT_SESSION_KEY, pickledAccount);
-            txn.session.add(DEVICE_KEY_FLAG_SESSION_KEY, areDeviceKeysUploaded);
-            txn.session.add(SERVER_OTK_COUNT_SESSION_KEY, 0);
-        } catch (err) {
-            txn.abort();
-            throw err;
         }
-        await txn.complete();
         return new Account({pickleKey, hsApi, account, userId,
             deviceId, areDeviceKeysUploaded, serverOTKCount: 0, olm, olmWorker});
     }
@@ -80,7 +100,7 @@ export class Account {
         return this._identityKeys;
     }
 
-    async uploadKeys(storage, log) {
+    async uploadKeys(storage, dehydratedDeviceId, log) {
         const oneTimeKeys = JSON.parse(this._account.one_time_keys());
         // only one algorithm supported by olm atm, so hardcode its name
         const oneTimeKeysEntries = Object.entries(oneTimeKeys.curve25519);
@@ -95,7 +115,7 @@ export class Account {
                 log.set("otks", true);
                 payload.one_time_keys = this._oneTimeKeysPayload(oneTimeKeysEntries);
             }
-            const response = await this._hsApi.uploadKeys(payload, {log}).response();
+            const response = await this._hsApi.uploadKeys(dehydratedDeviceId, payload, {log}).response();
             this._serverOTKCount = response?.one_time_key_counts?.signed_curve25519;
             log.set("serverOTKCount", this._serverOTKCount);
             // TODO: should we not modify this in the txn like we do elsewhere?
@@ -105,12 +125,12 @@ export class Account {
             await this._updateSessionStorage(storage, sessionStore => {
                 if (oneTimeKeysEntries.length) {
                     this._account.mark_keys_as_published();
-                    sessionStore.set(ACCOUNT_SESSION_KEY, this._account.pickle(this._pickleKey));
+                    sessionStore?.set(ACCOUNT_SESSION_KEY, this._account.pickle(this._pickleKey));
-                    sessionStore.set(SERVER_OTK_COUNT_SESSION_KEY, this._serverOTKCount);
+                    sessionStore?.set(SERVER_OTK_COUNT_SESSION_KEY, this._serverOTKCount);
                 }
                 if (!this._areDeviceKeysUploaded) {
                     this._areDeviceKeysUploaded = true;
-                    sessionStore.set(DEVICE_KEY_FLAG_SESSION_KEY, this._areDeviceKeysUploaded);
+                    sessionStore?.set(DEVICE_KEY_FLAG_SESSION_KEY, this._areDeviceKeysUploaded);
                 }
             });
         }
@@ -246,6 +266,7 @@ export class Account {
     }
 
     async _updateSessionStorage(storage, callback) {
+        if (storage) {
             const txn = await storage.readWriteTxn([
                 storage.storeNames.session
             ]);
@@ -256,6 +277,9 @@ export class Account {
                 throw err;
             }
             await txn.complete();
+        } else {
+            await callback(undefined);
+        }
     }
 
     signObject(obj) {
@@ -273,4 +297,12 @@ export class Account {
             obj.unsigned = unsigned;
         }
     }
+
+    pickleWithKey(key) {
+        return this._account.pickle(key);
+    }
+
+    dispose() {
+        this._account.free();
+    }
 }

src/matrix/e2ee/Dehydration.js

@@ -0,0 +1,88 @@
+/*
+Copyright 2021 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.
+*/
+
+export const DEHYDRATION_LIBOLM_PICKLE_ALGORITHM = "org.matrix.msc2697.v1.olm.libolm_pickle"; 
+
+async function getDehydratedDevice(hsApi, olm) {
+    const response = await hsApi.getDehydratedDevice().response();
+    if (response.device_data.algorithm === DEHYDRATION_LIBOLM_PICKLE_ALGORITHM) {
+        return new DehydratedDevice(response, olm);
+    }
+}
+
+async function hasRemainingDevice(ownUserId, ownDeviceId, storage) {
+
+}
+
+async function uploadAccountAsDehydratedDevice(account, hsApi, key, deviceDisplayName, log) {
+    const response = await hsApi.createDehydratedDevice({
+        device_data: {
+            algorithm: DEHYDRATION_LIBOLM_PICKLE_ALGORITHM,
+            account: account.pickleWithKey(new Uint8Array(key)),
+            passphrase: {}
+        },
+        initial_device_display_name: deviceDisplayName
+    }).response();
+    const deviceId = response.device_id;
+    await account.uploadKeys(undefined, deviceId, log);
+    return deviceId;
+}
+
+class EncryptedDehydratedDevice {
+    constructor(dehydratedDevice, olm) {
+        this._dehydratedDevice = dehydratedDevice;
+        this._olm = olm;
+    }
+
+    decrypt(key) {
+        const account = new this._olm.Account();
+        try {
+            const pickledAccount = this._dehydratedDevice.device_data.account;
+            account.unpickle(key, pickledAccount);
+            return new DehydratedDevice(this._dehydratedDevice, account);
+        } catch (err) {
+            account.free();
+            return null;
+        }
+    }
+}
+
+class DehydratedDevice {
+    constructor(dehydratedDevice, account) {
+        this._dehydratedDevice = dehydratedDevice;
+        this._account = account;
+    }
+
+    claim(hsApi, log) {
+        try {
+            const response = await hsApi.claimDehydratedDevice(this.deviceId, {log}).response();
+            return response.success;
+        } catch (err) {
+            return false;
+        }
+    }
+
+    // make it clear that ownership is transfered upon calling this
+    adoptUnpickledOlmAccount() {
+        const account = this._account;
+        this._account = null;
+        return account;
+    }
+
+    get deviceId() {
+        this._dehydratedDevice.device_id;
+    }
+}

src/matrix/net/HomeServerApi.js

@@ -18,6 +18,9 @@ limitations under the License.
 import {encodeQueryParams, encodeBody} from "./common.js";
 import {HomeServerRequest} from "./HomeServerRequest.js";
 
+const CS_R0_PREFIX = "/_matrix/client/r0";
+const DEHYDRATION_PREFIX = "/unstable/org.matrix.msc2697.v2";
+
 export class HomeServerApi {
     constructor({homeserver, accessToken, request, reconnector}) {
         // store these both in a closure somehow so it's harder to get at in case of XSS?
@@ -28,8 +31,8 @@ export class HomeServerApi {
         this._reconnector = reconnector;
     }
 
-    _url(csPath) {
+    _url(csPath, prefix) {
-        return `${this._homeserver}/_matrix/client/r0${csPath}`;
+        return this._homeserver + prefix + csPath;
     }
 
     _baseRequest(method, url, queryParams, body, options, accessToken) {
@@ -92,15 +95,15 @@ export class HomeServerApi {
     }
 
     _post(csPath, queryParams, body, options) {
-        return this._authedRequest("POST", this._url(csPath), queryParams, body, options);
+        return this._authedRequest("POST", this._url(csPath, options?.prefix || CS_R0_PREFIX), queryParams, body, options);
     }
 
     _put(csPath, queryParams, body, options) {
-        return this._authedRequest("PUT", this._url(csPath), queryParams, body, options);
+        return this._authedRequest("PUT", this._url(csPath, options?.prefix || CS_R0_PREFIX), queryParams, body, options);
     }
 
     _get(csPath, queryParams, body, options) {
-        return this._authedRequest("GET", this._url(csPath), queryParams, body, options);
+        return this._authedRequest("GET", this._url(csPath, options?.prefix || CS_R0_PREFIX), queryParams, body, options);
     }
 
     sync(since, filter, timeout, options = null) {
@@ -170,8 +173,12 @@ export class HomeServerApi {
         return this._unauthedRequest("GET", `${this._homeserver}/_matrix/client/versions`, null, null, options);
     }
 
-    uploadKeys(payload, options = null) {
+    uploadKeys(dehydratedDeviceId, payload, options = null) {
-        return this._post("/keys/upload", null, payload, options);
+        let path = "/keys/upload";
+        if (dehydratedDeviceId) {
+            path = path + `/${encodeURIComponent(dehydratedDeviceId)}`;
+        }
+        return this._post(path, null, payload, options);
     }
 
     queryKeys(queryRequest, options = null) {
@@ -229,6 +236,21 @@ export class HomeServerApi {
     logout(options = null) {
         return this._post(`/logout`, null, null, options);
     }
+
+    getDehydratedDevice(options = {}) {
+        options.prefix = DEHYDRATION_PREFIX;
+        return this._get(`/dehydrated_device`, null, null, options);
+    }
+
+    createDehydratedDevice(payload, options = null) {
+        options.prefix = DEHYDRATION_PREFIX;
+        return this._put(`/dehydrated_device`, null, payload, options);
+    }
+
+    claimDehydratedDevice(deviceId) {
+        options.prefix = DEHYDRATION_PREFIX;
+        return this._post(`/dehydrated_device/claim`, null, {device_id: deviceId}, options);
+    }
 }
 
 import {Request as MockRequest} from "../../mocks/Request.js";