fix: Skip decryption when ratchet exceeded.

Author: cloudwebrtc

lib/src/e2ee.worker/e2ee.cryptor.dart

@@ -159,7 +159,7 @@ class FrameCryptor {
   CryptorError lastError = CryptorError.kNew;
   final DedicatedWorkerGlobalScope worker;
   int currentKeyIndex = 0;
-
+  bool hasValidKey = false;
   Completer? _ratchetCompleter;
 
   List<KeySet?> cryptoKeyRing = List.filled(KEYRING_SIZE, null);
@@ -242,6 +242,7 @@ class FrameCryptor {
       keyOptions.ratchetSalt,
     );
     await setKeySetFromMaterial(keySet, keyIndex);
+    hasValidKey = true;
   }
 
   Future<void> setKeySetFromMaterial(KeySet keySet, int keyIndex) async {
@@ -526,7 +527,7 @@ class FrameCryptor {
       var initialKeySet = getKeySet(keyIndex);
       initialKeyIndex = keyIndex;
 
-      if (initialKeySet == null) {
+      if (initialKeySet == null || !hasValidKey) {
         if (lastError != CryptorError.kMissingKey) {
           lastError = CryptorError.kMissingKey;
           postMessage({
@@ -635,6 +636,7 @@ class FrameCryptor {
       /// yet and ratcheting, of course, did not solve the problem. So if we fail RATCHET_WINDOW_SIZE times,
       ///  we come back to the initial key.
       await setKeySetFromMaterial(initialKeySet!, initialKeyIndex);
+      hasValidKey = false;
     }
   }
 }