Add keyring size to key provider options (#1085)

* Add keyringSize to keyprovider options

* Create serious-buses-travel.md

.changeset/serious-buses-travel.md

@@ -0,0 +1,5 @@
+---
+"livekit-client": patch
+---
+
+Add keyring size to keyprovider options

src/e2ee/constants.ts

@@ -2,11 +2,6 @@ import type { KeyProviderOptions } from './types';
 
 export const ENCRYPTION_ALGORITHM = 'AES-GCM';
 
-// We use a ringbuffer of keys so we can change them and still decode packets that were
-// encrypted with an old key. We use a size of 16 which corresponds to the four bits
-// in the frame trailer.
-export const KEYRING_SIZE = 16;
-
 // How many consecutive frames can fail decrypting before a particular key gets marked as invalid
 export const DECRYPTION_FAILURE_TOLERANCE = 10;
 
@@ -41,6 +36,7 @@ export const KEY_PROVIDER_DEFAULTS: KeyProviderOptions = {
   ratchetSalt: SALT,
   ratchetWindowSize: 8,
   failureTolerance: DECRYPTION_FAILURE_TOLERANCE,
+  keyringSize: 16,
 } as const;
 
 export const MAX_SIF_COUNT = 100;

src/e2ee/types.ts

@@ -128,6 +128,7 @@ export type KeyProviderOptions = {
   ratchetSalt: string;
   ratchetWindowSize: number;
   failureTolerance: number;
+  keyringSize: number;
 };
 
 export type KeyInfo = {

src/e2ee/worker/ParticipantKeyHandler.ts

@@ -1,7 +1,6 @@
 import { EventEmitter } from 'events';
 import type TypedEventEmitter from 'typed-emitter';
 import { workerLogger } from '../../logger';
-import { KEYRING_SIZE } from '../constants';
 import { KeyHandlerEvent, type ParticipantKeyHandlerCallbacks } from '../events';
 import type { KeyProviderOptions, KeySet } from '../types';
 import { deriveKeys, importKey, ratchet } from '../utils';
@@ -39,7 +38,10 @@ export class ParticipantKeyHandler extends (EventEmitter as new () => TypedEvent
   constructor(participantIdentity: string, keyProviderOptions: KeyProviderOptions) {
     super();
     this.currentKeyIndex = 0;
-    this.cryptoKeyRing = new Array(KEYRING_SIZE).fill(undefined);
+    if (keyProviderOptions.keyringSize < 1 || keyProviderOptions.keyringSize > 255) {
+      throw new TypeError('Keyring size needs to be between 1 and 256');
+    }
+    this.cryptoKeyRing = new Array(keyProviderOptions.keyringSize).fill(undefined);
     this.keyProviderOptions = keyProviderOptions;
     this.ratchetPromiseMap = new Map();
     this.participantIdentity = participantIdentity;