refactor!: Room's Key ID generation (#33329)

Co-authored-by: Hugo Costa <hugocarreiracosta@gmail.com>
Co-authored-by: Guilherme Gazzo <guilhermegazzo@gmail.com>

.changeset/spicy-eggs-march.md

@@ -0,0 +1,8 @@
+---
+"@rocket.chat/meteor": major
+---
+
+Randomizes `e2eKeyId` generation instead of derive it from encoded key. Previously, we used the stringified & encoded version of the key to extract a keyID, however this generated the same keyID for all rooms. As we didn't use this keyID, and rooms didn't have the capability of having multiple keys, this was harmless.
+This PR introduces a new way of generating that identifier, making it random and unique, so multiple room keys can be used on the same room as long as the keyID is different.
+
+NOTE: new E2EE rooms created _after_ this PR is merged will not be compatible with older versions of Rocket.Chat. Old rooms created before this update will continue to be compatible.

apps/meteor/app/e2e/client/helper.js

@@ -146,3 +146,10 @@ export async function generateMnemonicPhrase(n, sep = ' ') {
 	}
 	return result.join(sep);
 }
+
+export async function createSha256Hash(data) {
+	const hash = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(data));
+	return Array.from(new Uint8Array(hash))
+		.map((b) => b.toString(16).padStart(2, '0'))
+		.join('');
+}

apps/meteor/app/e2e/client/rocketchat.e2e.room.js

@@ -24,6 +24,7 @@ import {
 	readFileAsArrayBuffer,
 	encryptAESCTR,
 	generateAESCTRKey,
+	createSha256Hash,
 } from './helper';
 import { log, logError } from './logger';
 import { e2e } from './rocketchat.e2e';
@@ -67,12 +68,13 @@ export class E2ERoom extends Emitter {
 
 	[PAUSED] = undefined;
 
-	constructor(userId, roomId, t) {
+	constructor(userId, room) {
 		super();
 
 		this.userId = userId;
-		this.roomId = roomId;
-		this.typeOfRoom = t;
+		this.roomId = room._id;
+		this.typeOfRoom = room.t;
+		this.roomKeyId = room.e2eKeyId;
 
 		this.once(E2ERoomState.READY, () => this.decryptPendingMessages());
 		this.once(E2ERoomState.READY, () => this.decryptSubscription());
@@ -280,7 +282,11 @@ export class E2ERoom extends Emitter {
 			return false;
 		}
 
-		this.keyID = Base64.encode(this.sessionKeyExportedString).slice(0, 12);
+		// When a new e2e room is created, it will be initialized without an e2e key id
+		// This will prevent new rooms from storing `undefined` as the keyid
+		if (!this.keyID) {
+			this.keyID = this.roomKeyId || (await createSha256Hash(this.sessionKeyExportedString)).slice(0, 12);
+		}
 
 		// Import session key for use.
 		try {
@@ -308,7 +314,7 @@ export class E2ERoom extends Emitter {
 		try {
 			const sessionKeyExported = await exportJWKKey(this.groupSessionKey);
 			this.sessionKeyExportedString = JSON.stringify(sessionKeyExported);
-			this.keyID = Base64.encode(this.sessionKeyExportedString).slice(0, 12);
+			this.keyID = (await createSha256Hash(this.sessionKeyExportedString)).slice(0, 12);
 
 			await sdk.call('e2e.setRoomKeyID', this.roomId, this.keyID);
 			await this.encryptKeyForOtherParticipants();

apps/meteor/app/e2e/client/rocketchat.e2e.ts

@@ -145,52 +145,54 @@ class E2E extends Emitter {
 		this.log('observing subscriptions');
 	}
 
-	observeSubscriptions() {
-		this.observable?.stop();
+	async onSubscriptionChanged(sub: ISubscription) {
+		this.log('Subscription changed', sub);
+		if (!sub.encrypted && !sub.E2EKey) {
+			this.removeInstanceByRoomId(sub.rid);
+			return;
+		}
 
-		this.observable = Subscriptions.find().observe({
-			changed: (sub: ISubscription) => {
-				setTimeout(async () => {
-					this.log('Subscription changed', sub);
-					if (!sub.encrypted && !sub.E2EKey) {
-						this.removeInstanceByRoomId(sub.rid);
-						return;
-					}
+		const e2eRoom = await this.getInstanceByRoomId(sub.rid);
+		if (!e2eRoom) {
+			return;
+		}
 
-					const e2eRoom = await this.getInstanceByRoomId(sub.rid);
-					if (!e2eRoom) {
-						return;
-					}
+		if (sub.E2ESuggestedKey) {
+			if (await e2eRoom.importGroupKey(sub.E2ESuggestedKey)) {
+				await this.acceptSuggestedKey(sub.rid);
+				e2eRoom.keyReceived();
+			} else {
+				console.warn('Invalid E2ESuggestedKey, rejecting', sub.E2ESuggestedKey);
+				await this.rejectSuggestedKey(sub.rid);
+			}
+		}
 
-					if (sub.E2ESuggestedKey) {
-						if (await e2eRoom.importGroupKey(sub.E2ESuggestedKey)) {
-							await this.acceptSuggestedKey(sub.rid);
-							e2eRoom.keyReceived();
-						} else {
-							console.warn('Invalid E2ESuggestedKey, rejecting', sub.E2ESuggestedKey);
-							await this.rejectSuggestedKey(sub.rid);
-						}
-					}
+		sub.encrypted ? e2eRoom.resume() : e2eRoom.pause();
 
-					sub.encrypted ? e2eRoom.resume() : e2eRoom.pause();
+		// Cover private groups and direct messages
+		if (!e2eRoom.isSupportedRoomType(sub.t)) {
+			e2eRoom.disable();
+			return;
+		}
 
-					// Cover private groups and direct messages
-					if (!e2eRoom.isSupportedRoomType(sub.t)) {
-						e2eRoom.disable();
-						return;
-					}
+		if (sub.E2EKey && e2eRoom.isWaitingKeys()) {
+			e2eRoom.keyReceived();
+			return;
+		}
 
-					if (sub.E2EKey && e2eRoom.isWaitingKeys()) {
-						e2eRoom.keyReceived();
-						return;
-					}
+		if (!e2eRoom.isReady()) {
+			return;
+		}
 
-					if (!e2eRoom.isReady()) {
-						return;
-					}
+		await e2eRoom.decryptSubscription();
+	}
 
-					await e2eRoom.decryptSubscription();
-				}, 0);
+	observeSubscriptions() {
+		this.observable?.stop();
+
+		this.observable = Subscriptions.find().observe({
+			changed: (sub: ISubscription) => {
+				setTimeout(() => this.onSubscriptionChanged(sub), 0);
 			},
 			added: (sub: ISubscription) => {
 				setTimeout(async () => {
@@ -263,7 +265,7 @@ class E2E extends Emitter {
 		}
 
 		if (!this.instancesByRoomId[rid]) {
-			this.instancesByRoomId[rid] = new E2ERoom(Meteor.userId(), rid, room.t);
+			this.instancesByRoomId[rid] = new E2ERoom(Meteor.userId(), room);
 		}
 
 		return this.instancesByRoomId[rid];