WIP e2e key backup support

Continues from uhoreg's branch

src/client.js

@@ -774,9 +774,27 @@ MatrixClient.prototype.getKeyBackupVersion = function(callback) {
             }
             return res;
         }
+    }).catch(e => {
+        if (e.errcode === 'M_NOT_FOUND') {
+            if (callback) callback(null);
+            return null;
+        } else {
+            throw e;
+        }
     });
 }
 
+/**
+ * @returns {bool} true if the client is configured to back up keys to
+ *     the server, otherwise false.
+ */
+MatrixClient.prototype.getKeyBackupEnabled = function() {
+    if (this._crypto === null) {
+        throw new Error("End-to-end encryption disabled");
+    }
+    return Boolean(this._crypto.backupKey);
+}
+
 /**
  * Enable backing up of keys, using data previously returned from
  * getKeyBackupVersion.
@@ -786,6 +804,7 @@ MatrixClient.prototype.enableKeyBackup = function(info) {
         throw new Error("End-to-end encryption disabled");
     }
 
+    this._crypto.backupInfo = info;
     this._crypto.backupKey = new global.Olm.PkEncryption();
     this._crypto.backupKey.set_recipient_key(info.auth_data.public_key);
 }
@@ -798,7 +817,8 @@ MatrixClient.prototype.disableKeyBackup = function() {
         throw new Error("End-to-end encryption disabled");
     }
 
-    this._crypto.backupKey = undefined;
+    this._crypto.backupInfo = null;
+    this._crypto.backupKey = null;
 }
 
 /**
@@ -836,11 +856,16 @@ MatrixClient.prototype.createKeyBackupVersion = function(info, callback) {
         algorithm: info.algorithm,
         auth_data: info.auth_data, // FIXME: should this be cloned?
     }
-    this._crypto._signObject(data.auth_data);
+    return this._crypto._signObject(data.auth_data).then(() => {
         return this._http.authedRequest(
             undefined, "POST", "/room_keys/version", undefined, data,
-    ).then((res) => {
-        this.enableKeyBackup(info);
+        );
+    }).then((res) => {
+        this.enableKeyBackup({
+            algorithm: info.algorithm,
+            auth_data: info.auth_data,
+            version: res.version,
+        });
         if (callback) {
             callback(null, res);
         }
@@ -848,6 +873,27 @@ MatrixClient.prototype.createKeyBackupVersion = function(info, callback) {
     });
 }
 
+MatrixClient.prototype.deleteKeyBackupVersion = function(version) {
+    if (this._crypto === null) {
+        throw new Error("End-to-end encryption disabled");
+    }
+
+    // If we're currently backing up to this backup... stop.
+    // (We start using it automatically in createKeyBackupVersion
+    // so this is symmetrical).
+    if (this._crypto.backupInfo && this._crypto.backupInfo.version === version) {
+        this.disableKeyBackup();
+    }
+
+    const path = utils.encodeUri("/room_keys/version/$version", {
+        $version: version,
+    });
+
+    return this._http.authedRequest(
+        undefined, "DELETE", path, undefined, undefined,
+    );
+};
+
 MatrixClient.prototype._makeKeyBackupPath = function(roomId, sessionId, version) {
     let path;
     if (sessionId !== undefined) {
@@ -890,6 +936,14 @@ MatrixClient.prototype.sendKeyBackup = function(roomId, sessionId, version, data
     );
 };
 
+MatrixClient.prototype.backupAllGroupSessions = function(version) {
+    if (this._crypto === null) {
+        throw new Error("End-to-end encryption disabled");
+    }
+
+    return this._crypto.backupAllGroupSessions(version);
+};
+
 MatrixClient.prototype.restoreKeyBackups = function(decryptionKey, roomId, sessionId, version, callback) {
     if (this._crypto === null) {
         throw new Error("End-to-end encryption disabled");
@@ -924,7 +978,7 @@ MatrixClient.prototype.restoreKeyBackups = function(decryptionKey, roomId, sessi
     })
 };
 
-MatrixClient.prototype.deleteKeyBackups = function(roomId, sessionId, version, callback) {
+MatrixClient.prototype.deleteKeysFromBackup = function(roomId, sessionId, version, callback) {
     if (this._crypto === null) {
         throw new Error("End-to-end encryption disabled");
     }

src/crypto/algorithms/megolm.js

@@ -263,6 +263,14 @@ MegolmEncryption.prototype._prepareNewSession = async function() {
         key.key, {ed25519: this._olmDevice.deviceEd25519Key},
     );
 
+    if (this._crypto.backupInfo) {
+        // Not strictly necessary to wait for this
+        await this._crypto.backupGroupSession(
+            this._roomId, this._olmDevice.deviceCurve25519Key, [],
+            sessionId, key.key,
+        );
+    }
+
     return new OutboundSessionInfo(sessionId);
 };
 
@@ -840,11 +848,13 @@ MegolmDecryption.prototype.onRoomKeyEvent = function(event) {
         // have another go at decrypting events sent with this session.
         this._retryDecryption(senderKey, sessionId);
     }).then(() => {
-        return this.backupGroupSession(
+        if (this._crypto.backupInfo) {
+            return this._crypto.backupGroupSession(
                 content.room_id, senderKey, forwardingKeyChain,
                 content.session_id, content.session_key, keysClaimed,
                 exportFormat,
             );
+        }
     }).catch((e) => {
         console.error(`Error handling m.room_key_event: ${e}`);
     });
@@ -967,54 +977,6 @@ MegolmDecryption.prototype.importRoomKey = function(session) {
     });
 };
 
-MegolmDecryption.prototype.backupGroupSession = async function(
-    roomId, senderKey, forwardingCurve25519KeyChain,
-    sessionId, sessionKey, keysClaimed,
-    exportFormat,
-) {
-    // new session.
-    const session = new Olm.InboundGroupSession();
-    let first_known_index;
-    try {
-        if (exportFormat) {
-            session.import_session(sessionKey);
-        } else {
-            session.create(sessionKey);
-        }
-        if (sessionId != session.session_id()) {
-            throw new Error(
-                "Mismatched group session ID from senderKey: " +
-                    senderKey,
-            );
-        }
-
-        if (!exportFormat) {
-            sessionKey = session.export_session();
-        }
-        const first_known_index = session.first_known_index();
-
-        const sessionData = {
-            algorithm: olmlib.MEGOLM_ALGORITHM,
-            sender_key: senderKey,
-            sender_claimed_keys: keysClaimed,
-            forwardingCurve25519KeyChain: forwardingCurve25519KeyChain,
-            session_key: sessionKey
-        };
-        const encrypted = this._crypto.backupKey.encrypt(JSON.stringify(sessionData));
-        const data = {
-            first_message_index: first_known_index,
-            forwarded_count: forwardingCurve25519KeyChain.length,
-            is_verified: false, // FIXME: how do we determine this?
-            session_data: encrypted
-        };
-        return this._baseApis.sendKeyBackup(roomId, sessionId, data);
-    } catch (e) {
-        return Promise.reject(e);
-    } finally {
-        session.free();
-    }
-}
-
 /**
  * Have another go at decrypting events after we receive a key
  *

src/crypto/index.js

@@ -75,7 +75,8 @@ function Crypto(baseApis, sessionStore, userId, deviceId,
     // track whether this device's megolm keys are being backed up incrementally
     // to the server or not.
     // XXX: this should probably have a single source of truth from OlmAccount
-    this.backupKey = null;
+    this.backupInfo = null; // The info dict from /room_keys/version
+    this.backupKey = null; // The encryption key object
 
     this._olmDevice = new OlmDevice(sessionStore, cryptoStore);
     this._deviceList = new DeviceList(
@@ -848,6 +849,83 @@ Crypto.prototype.importRoomKeys = function(keys) {
         },
     );
 };
+
+Crypto.prototype._backupPayloadForSession = function(
+    senderKey, forwardingCurve25519KeyChain,
+    sessionId, sessionKey, keysClaimed,
+    exportFormat,
+) {
+    // new session.
+    const session = new Olm.InboundGroupSession();
+    let first_known_index;
+    try {
+        if (exportFormat) {
+            session.import_session(sessionKey);
+        } else {
+            session.create(sessionKey);
+        }
+        if (sessionId != session.session_id()) {
+            throw new Error(
+                "Mismatched group session ID from senderKey: " +
+                    senderKey,
+            );
+        }
+
+        if (!exportFormat) {
+            sessionKey = session.export_session();
+        }
+        const first_known_index = session.first_known_index();
+
+        const sessionData = {
+            algorithm: olmlib.MEGOLM_ALGORITHM,
+            sender_key: senderKey,
+            sender_claimed_keys: keysClaimed,
+            session_key: sessionKey,
+            forwarding_curve25519_key_chain: forwardingCurve25519KeyChain,
+        };
+        const encrypted = this.backupKey.encrypt(JSON.stringify(sessionData));
+        return {
+            first_message_index: first_known_index,
+            forwarded_count: forwardingCurve25519KeyChain.length,
+            is_verified: false, // FIXME: how do we determine this?
+            session_data: encrypted,
+        };
+    } finally {
+        session.free();
+    }
+};
+
+Crypto.prototype.backupGroupSession = function(
+    roomId, senderKey, forwardingCurve25519KeyChain,
+    sessionId, sessionKey, keysClaimed,
+    exportFormat,
+) {
+    if (!this.backupInfo) {
+        throw new Error("Key backups are not enabled");
+    }
+
+    const data = this._backupPayloadForSession(
+        senderKey, forwardingCurve25519KeyChain,
+        sessionId, sessionKey, keysClaimed,
+        exportFormat,
+    );
+    return this._baseApis.sendKeyBackup(roomId, sessionId, this.backupInfo.version, data);
+};
+
+Crypto.prototype.backupAllGroupSessions = async function(version) {
+    const keys = await this.exportRoomKeys();
+    const data = {};
+    for (const key of keys) {
+        if (data[key.room_id] === undefined) data[key.room_id] = {sessions: {}};
+
+        data[key.room_id]['sessions'][key.session_id] = this._backupPayloadForSession(
+            key.sender_key, key.forwarding_curve25519_key_chain,
+            key.session_id, key.session_key, key.sender_claimed_keys, true,
+        );
+    }
+    return this._baseApis.sendKeyBackup(undefined, undefined, version, {rooms: data});
+};
+
 /* eslint-disable valid-jsdoc */    //https://github.com/eslint/eslint/issues/7307
 /**
  * Encrypt an event according to the configuration of the room.