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support pre-sharing room keys in room encryption

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This commit is contained in:
Bruno Windels 2020-11-06 10:32:37 +01:00
parent 85ba1676e5
commit 5d12aef6db
2 changed files with 63 additions and 23 deletions
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23
src/matrix/e2ee/RoomEncryption.js
View file

@ -244,7 +244,26 @@ export class RoomEncryption {
}
return matches;
}
/** shares the encryption key for the next message if needed */
async ensureNextMessageEncryptionKeyIsShared(hsApi) {
const txn = this._storage.readWriteTxn([
this._storage.storeNames.operations,
this._storage.storeNames.outboundGroupSessions,
this._storage.storeNames.inboundGroupSessions,
]);
let roomKeyMessage;
try {
roomKeyMessage = await this._megolmEncryption.ensureOutboundSession(this._room.id, this._encryptionParams, txn);
} catch (err) {
txn.abort();
throw err;
}
// will complete the txn
if (roomKeyMessage) {
await this._shareNewRoomKey(roomKeyMessage, hsApi, txn);
}
}
async encrypt(type, content, hsApi) {
@ -269,12 +288,12 @@ export class RoomEncryption {
return false;
}
async _shareNewRoomKey(roomKeyMessage, hsApi) {
async _shareNewRoomKey(roomKeyMessage, hsApi, txn = null) {
const devices = await this._deviceTracker.devicesForTrackedRoom(this._room.id, hsApi);
const userIds = Array.from(devices.reduce((set, device) => set.add(device.userId), new Set()));
// store operation for room key share, in case we don't finish here
const writeOpTxn = this._storage.readWriteTxn([this._storage.storeNames.operations]);
const writeOpTxn = txn || this._storage.readWriteTxn([this._storage.storeNames.operations]);
let operationId;
try {
operationId = this._writeRoomKeyShareOperation(roomKeyMessage, userIds, writeOpTxn);

61
src/matrix/e2ee/megolm/Encryption.js
View file

@ -43,6 +43,45 @@ export class Encryption {
}
}
async ensureOutboundSession(roomId, encryptionParams, txn) {
let session = new this._olm.OutboundGroupSession();
try {
let sessionEntry = await txn.outboundGroupSessions.get(roomId);
const roomKeyMessage = this._readOrCreateSession(session, sessionEntry, roomId, encryptionParams, txn);
if (roomKeyMessage) {
this._writeSession(sessionEntry, session, roomId, txn);
return roomKeyMessage;
}
} finally {
session.free();
}
}
_readOrCreateSession(session, sessionEntry, roomId, encryptionParams, txn) {
if (sessionEntry) {
session.unpickle(this._pickleKey, sessionEntry.session);
}
if (!sessionEntry || this._needsToRotate(session, sessionEntry.createdAt, encryptionParams)) {
// in the case of rotating, recreate a session as we already unpickled into it
if (sessionEntry) {
session.free();
session = new this._olm.OutboundGroupSession();
}
session.create();
const roomKeyMessage = this._createRoomKeyMessage(session, roomId);
this._storeAsInboundSession(session, roomId, txn);
return roomKeyMessage;
}
}
_writeSession(sessionEntry, session, roomId, txn) {
txn.outboundGroupSessions.set({
roomId,
session: session.pickle(this._pickleKey),
createdAt: sessionEntry?.createdAt || this._now(),
});
}
/**
* Encrypts a message with megolm
* @param {string} roomId
@ -61,28 +100,10 @@ export class Encryption {
let roomKeyMessage;
let encryptedContent;
try {
// TODO: we could consider keeping the session in memory for the current room
let sessionEntry = await txn.outboundGroupSessions.get(roomId);
if (sessionEntry) {
session.unpickle(this._pickleKey, sessionEntry.session);
}
if (!sessionEntry || this._needsToRotate(session, sessionEntry.createdAt, encryptionParams)) {
// in the case of rotating, recreate a session as we already unpickled into it
if (sessionEntry) {
session.free();
session = new this._olm.OutboundGroupSession();
}
session.create();
roomKeyMessage = this._createRoomKeyMessage(session, roomId);
this._storeAsInboundSession(session, roomId, txn);
// TODO: we could tell the Decryption here that we have a new session so it can add it to its cache
}
roomKeyMessage = this._readOrCreateSession(session, sessionEntry, roomId, encryptionParams, txn);
encryptedContent = this._encryptContent(roomId, session, type, content);
txn.outboundGroupSessions.set({
roomId,
session: session.pickle(this._pickleKey),
createdAt: sessionEntry?.createdAt || this._now(),
});
this._writeSession(sessionEntry, session, roomId, txn);
} catch (err) {
txn.abort();