implement storing room keys

src/matrix/DeviceMessageHandler.js

@@ -20,10 +20,15 @@ import {OLM_ALGORITHM, MEGOLM_ALGORITHM} from "./e2ee/common.js";
 const PENDING_ENCRYPTED_EVENTS = "pendingEncryptedDeviceEvents";
 
 export class DeviceMessageHandler {
-    constructor({storage, olmDecryption, megolmEncryption}) {
+    constructor({storage}) {
         this._storage = storage;
+        this._olmDecryption = null;
+        this._megolmDecryption = null;
+    }
+
+    enableEncryption({olmDecryption, megolmDecryption}) {
         this._olmDecryption = olmDecryption;
-        this._megolmEncryption = megolmEncryption;
+        this._megolmDecryption = megolmDecryption;
     }
 
     async writeSync(toDeviceEvents, txn) {
@@ -35,25 +40,28 @@ export class DeviceMessageHandler {
         // we don't handle anything other for now
     }
 
-    async _handleDecryptedEvents(payloads, txn) {
+    async _writeDecryptedEvents(payloads, txn) {
         const megOlmRoomKeysPayloads = payloads.filter(p => {
-            return p.event.type === "m.room_key" && p.event.content?.algorithm === MEGOLM_ALGORITHM;
+            return p.event?.type === "m.room_key" && p.event.content?.algorithm === MEGOLM_ALGORITHM;
         });
         let megolmChanges;
         if (megOlmRoomKeysPayloads.length) {
-            megolmChanges = await this._megolmEncryption.addRoomKeys(megOlmRoomKeysPayloads, txn);
+            megolmChanges = await this._megolmDecryption.addRoomKeys(megOlmRoomKeysPayloads, txn);
         }
         return {megolmChanges};
     }
 
     applyChanges({megolmChanges}) {
         if (megolmChanges) {
-            this._megolmEncryption.applyRoomKeyChanges(megolmChanges);
+            this._megolmDecryption.applyRoomKeyChanges(megolmChanges);
         }
     }
 
     // not safe to call multiple times without awaiting first call
     async decryptPending() {
+        if (!this._olmDecryption) {
+            return;
+        }
         const readTxn = await this._storage.readTxn([this._storage.storeNames.session]);
         const pendingEvents = this._getPendingEvents(readTxn);
         // only know olm for now
@@ -66,11 +74,11 @@ export class DeviceMessageHandler {
             // both to remove the pending events and to modify the olm account
             this._storage.storeNames.session,
             this._storage.storeNames.olmSessions,
-            // this._storage.storeNames.megolmInboundSessions,
+            this._storage.storeNames.inboundGroupSessions,
         ]);
         let changes;
         try {
-            changes = await this._handleDecryptedEvent(decryptChanges.payloads, txn);
+            changes = await this._writeDecryptedEvents(decryptChanges.payloads, txn);
             decryptChanges.write(txn);
             txn.session.remove(PENDING_ENCRYPTED_EVENTS);
         } catch (err) {

src/matrix/e2ee/megolm/Decryption.js

@@ -0,0 +1,68 @@
+/*
+Copyright 2020 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.
+*/
+
+// senderKey is a curve25519 key
+export class Decryption {
+    constructor({pickleKey}) {
+        this._pickleKey = pickleKey;
+    }
+
+    async addRoomKeys(payloads, txn) {
+        const newSessions = [];
+        for (const {senderKey, event} of payloads) {
+            const roomId = event.content?.["room_id"];
+            const sessionId = event.content?.["session_id"];
+            const sessionKey = event.content?.["session_key"];
+
+            if (
+                typeof roomId !== "string" || 
+                typeof sessionId !== "string" || 
+                typeof senderKey !== "string" ||
+                typeof sessionKey !== "string"
+            ) {
+                return;
+            }
+
+            const hasSession = await txn.inboundGroupSessions.has(roomId, senderKey, sessionId);
+            if (!hasSession) {
+                const session = new this._olm.InboundGroupSession();
+                try {
+                    session.create(sessionKey);
+                    const sessionEntry = {
+                        roomId,
+                        senderKey,
+                        sessionId,
+                        session: session.pickle(this._pickleKey),
+                        claimedKeys: event.keys,
+                    };
+                    txn.megOlmInboundSessions.set(sessionEntry);
+                    newSessions.push(sessionEntry);
+                } finally {
+                    session.free();
+                }
+            }
+
+        }
+        return newSessions;
+    }
+
+    applyRoomKeyChanges(newSessions) {
+        // retry decryption with the new sessions
+        if (newSessions.length) {
+            console.log(`I have ${newSessions.length} new inbound group sessions`, newSessions)
+        }
+    }
+}

src/matrix/storage/common.js

@@ -25,6 +25,7 @@ export const STORE_NAMES = Object.freeze([
     "userIdentities",
     "deviceIdentities",
     "olmSessions",
+    "inboundGroupSessions",
 ]);
 
 export const STORE_MAP = Object.freeze(STORE_NAMES.reduce((nameMap, name) => {

src/matrix/storage/idb/Transaction.js

@@ -27,6 +27,7 @@ import {PendingEventStore} from "./stores/PendingEventStore.js";
 import {UserIdentityStore} from "./stores/UserIdentityStore.js";
 import {DeviceIdentityStore} from "./stores/DeviceIdentityStore.js";
 import {OlmSessionStore} from "./stores/OlmSessionStore.js";
+import {InboundGroupSessionStore} from "./stores/InboundGroupSessionStore.js";
 
 export class Transaction {
     constructor(txn, allowedStoreNames) {
@@ -96,6 +97,10 @@ export class Transaction {
         return this._store("olmSessions", idbStore => new OlmSessionStore(idbStore));
     }
     
+    get inboundGroupSessions() {
+        return this._store("inboundGroupSessions", idbStore => new InboundGroupSessionStore(idbStore));
+    }
+
     complete() {
         return txnAsPromise(this._txn);
     }

src/matrix/storage/idb/schema.js

@@ -11,6 +11,7 @@ export const schema = [
     migrateSession,
     createIdentityStores,
     createOlmSessionStore,
+    createInboundGroupSessionsStore,
 ];
 // TODO: how to deal with git merge conflicts of this array?
 
@@ -76,3 +77,8 @@ function createIdentityStores(db) {
 function createOlmSessionStore(db) {
     db.createObjectStore("olmSessions", {keyPath: "key"});
 }
+
+//v6
+function createInboundGroupSessionsStore(db) {
+    db.createObjectStore("inboundGroupSessions", {keyPath: "key"});
+}

src/matrix/storage/idb/stores/InboundGroupSessionStore.js

@@ -0,0 +1,36 @@
+/*
+Copyright 2020 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.
+*/
+
+function encodeKey(roomId, senderKey, sessionId) {
+    return `${roomId}|${senderKey}|${sessionId}`;
+}
+
+export class InboundGroupSessionStore {
+    constructor(store) {
+        this._store = store;
+    }
+
+    async has(roomId, senderKey, sessionId) {
+        const key = encodeKey(roomId, senderKey, sessionId);
+        const fetchedKey = await this._store.getKey(key);
+        return key === fetchedKey;
+    }
+
+    set(session) {
+        session.key = encodeKey(session.roomId, session.senderKey, session.sessionId);
+        this._store.put(session);
+    }
+}