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e2ee improve.
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-357
lines changed

10 files changed

+1057
-357
lines changed

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

Lines changed: 113 additions & 181 deletions
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‎lib/src/e2ee.worker/e2ee.keyhandler.dart

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import 'dart:async';
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import 'dart:html';
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import 'dart:js_util' as jsutil;
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import 'dart:typed_data';
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import 'crypto.dart' as crypto;
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import 'e2ee.logger.dart';
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import 'e2ee.utils.dart';
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class KeyOptions {
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KeyOptions({
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required this.sharedKey,
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required this.ratchetSalt,
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required this.ratchetWindowSize,
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this.uncryptedMagicBytes,
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this.failureTolerance = -1,
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});
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bool sharedKey;
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Uint8List ratchetSalt;
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int ratchetWindowSize = 0;
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int failureTolerance;
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Uint8List? uncryptedMagicBytes;
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@override
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String toString() {
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return 'KeyOptions{sharedKey: $sharedKey, ratchetWindowSize: $ratchetWindowSize, failureTolerance: $failureTolerance, uncryptedMagicBytes: $uncryptedMagicBytes, ratchetSalt: $ratchetSalt}';
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}
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}
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const KEYRING_SIZE = 16;
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class KeySet {
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KeySet(this.material, this.encryptionKey);
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CryptoKey material;
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CryptoKey encryptionKey;
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}
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class ParticipantKeyHandler {
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ParticipantKeyHandler({
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required this.worker,
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required this.keyOptions,
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required this.participantIdentity,
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});
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int currentKeyIndex = 0;
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List<KeySet?> cryptoKeyRing = List.filled(KEYRING_SIZE, null);
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bool _hasValidKey = false;
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bool get hasValidKey => _hasValidKey;
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final KeyOptions keyOptions;
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final DedicatedWorkerGlobalScope worker;
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final String participantIdentity;
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int _decryptionFailureCount = 0;
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void decryptionFailure() {
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if (keyOptions.failureTolerance < 0) {
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return;
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}
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_decryptionFailureCount += 1;
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if (_decryptionFailureCount > keyOptions.failureTolerance) {
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logger.warning('key for $participantIdentity is being marked as invalid');
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_hasValidKey = false;
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}
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}
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void decryptionSuccess() {
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resetKeyStatus();
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}
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/// Call this after user initiated ratchet or a new key has been set in order
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/// to make sure to mark potentially invalid keys as valid again
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void resetKeyStatus() {
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_decryptionFailureCount = 0;
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_hasValidKey = true;
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}
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Future<Uint8List?> exportKey(int? keyIndex) async {
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var currentMaterial = getKeySet(keyIndex)?.material;
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if (currentMaterial == null) {
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return null;
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}
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try {
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var key = await jsutil.promiseToFuture<ByteBuffer>(
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crypto.exportKey('raw', currentMaterial));
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return key.asUint8List();
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} catch (e) {
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logger.warning('exportKey: $e');
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return null;
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}
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}
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Future<Uint8List?> ratchetKey(int? keyIndex) async {
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var currentMaterial = getKeySet(keyIndex)?.material;
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if (currentMaterial == null) {
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return null;
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}
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var newKey = await ratchet(currentMaterial, keyOptions.ratchetSalt);
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var newMaterial = await ratchetMaterial(
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currentMaterial, crypto.jsArrayBufferFrom(newKey));
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var newKeySet = await deriveKeys(newMaterial, keyOptions.ratchetSalt);
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await setKeySetFromMaterial(newKeySet, keyIndex ?? currentKeyIndex);
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return newKey;
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}
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Future<CryptoKey> ratchetMaterial(
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CryptoKey currentMaterial, ByteBuffer newKeyBuffer) async {
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var newMaterial = await jsutil.promiseToFuture(crypto.importKey(
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'raw',
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newKeyBuffer,
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(currentMaterial.algorithm as crypto.Algorithm).name,
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false,
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['deriveBits', 'deriveKey'],
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));
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return newMaterial;
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}
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KeySet? getKeySet(int? keyIndex) {
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return cryptoKeyRing[keyIndex ?? currentKeyIndex];
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}
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Future<void> setKey(Uint8List key, {int keyIndex = 0}) async {
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var keyMaterial = await crypto.impportKeyFromRawData(key,
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webCryptoAlgorithm: 'PBKDF2', keyUsages: ['deriveBits', 'deriveKey']);
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var keySet = await deriveKeys(
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keyMaterial,
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keyOptions.ratchetSalt,
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);
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await setKeySetFromMaterial(keySet, keyIndex);
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resetKeyStatus();
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}
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Future<void> setKeySetFromMaterial(KeySet keySet, int keyIndex) async {
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logger.config('setKeySetFromMaterial: set new key, index: $keyIndex');
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if (keyIndex >= 0) {
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currentKeyIndex = keyIndex % cryptoKeyRing.length;
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}
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cryptoKeyRing[currentKeyIndex] = keySet;
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}
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/// Derives a set of keys from the master key.
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/// See https://tools.ietf.org/html/draft-omara-sframe-00#section-4.3.1
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Future<KeySet> deriveKeys(CryptoKey material, Uint8List salt) async {
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var algorithmOptions =
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getAlgoOptions((material.algorithm as crypto.Algorithm).name, salt);
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// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/deriveKey#HKDF
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// https://developer.mozilla.org/en-US/docs/Web/API/HkdfParams
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var encryptionKey =
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await jsutil.promiseToFuture<CryptoKey>(crypto.deriveKey(
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jsutil.jsify(algorithmOptions),
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material,
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jsutil.jsify({'name': 'AES-GCM', 'length': 128}),
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false,
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['encrypt', 'decrypt'],
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));
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return KeySet(material, encryptionKey);
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}
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/// Ratchets a key. See
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/// https://tools.ietf.org/html/draft-omara-sframe-00#section-4.3.5.1
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Future<Uint8List> ratchet(CryptoKey material, Uint8List salt) async {
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var algorithmOptions = getAlgoOptions('PBKDF2', salt);
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// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/deriveBits
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var newKey = await jsutil.promiseToFuture<ByteBuffer>(
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crypto.deriveBits(jsutil.jsify(algorithmOptions), material, 256));
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return newKey.asUint8List();
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}
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}

‎lib/src/e2ee.worker/e2ee.logger.dart

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// Copyright 2024 LiveKit, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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import 'package:logging/logging.dart';
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enum LoggerLevel {
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kALL,
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kFINEST,
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kFINER,
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kFINE,
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kCONFIG,
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kINFO,
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kWARNING,
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kSEVERE,
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kSHOUT,
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kOFF
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}
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final logger = Logger('E2EE.Worker');
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/// disable logging
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void disableLogging() {
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logger.level = Level.OFF;
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}
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/// set the logging level
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void setLoggingLevel(LoggerLevel level) {
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switch (level) {
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case LoggerLevel.kALL:
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logger.level = Level.ALL;
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break;
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case LoggerLevel.kFINEST:
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logger.level = Level.FINEST;
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break;
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case LoggerLevel.kFINER:
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logger.level = Level.FINER;
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break;
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case LoggerLevel.kFINE:
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logger.level = Level.FINE;
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break;
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case LoggerLevel.kCONFIG:
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logger.level = Level.CONFIG;
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break;
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case LoggerLevel.kINFO:
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logger.level = Level.INFO;
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break;
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case LoggerLevel.kWARNING:
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logger.level = Level.WARNING;
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break;
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case LoggerLevel.kSEVERE:
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logger.level = Level.SEVERE;
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break;
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case LoggerLevel.kSHOUT:
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logger.level = Level.SHOUT;
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break;
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case LoggerLevel.kOFF:
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logger.level = Level.OFF;
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break;
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}
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}
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/// get the current logging level
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Level getLoggingLevel() {
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return logger.level;
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}
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/// set a custom logging handler
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void setLoggingHandler(Function(LogRecord) handler) {
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logger.onRecord.listen(handler);
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}

‎lib/src/e2ee.worker/e2ee.sfi_guard.dart

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const MAX_SIF_COUNT = 100;
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const MAX_SIF_DURATION = 2000;
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class SifGuard {
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int consecutiveSifCount = 0;
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int? sifSequenceStartedAt;
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int lastSifReceivedAt = 0;
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int userFramesSinceSif = 0;
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void recordSif() {
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consecutiveSifCount += 1;
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sifSequenceStartedAt ??= DateTime.now().millisecondsSinceEpoch;
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lastSifReceivedAt = DateTime.now().millisecondsSinceEpoch;
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}
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void recordUserFrame() {
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if (sifSequenceStartedAt == null) {
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return;
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} else {
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userFramesSinceSif += 1;
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}
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if (
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// reset if we received more user frames than SIFs
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userFramesSinceSif > consecutiveSifCount ||
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// also reset if we got a new user frame and the latest SIF frame hasn't been updated in a while
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DateTime.now().millisecondsSinceEpoch - lastSifReceivedAt >
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MAX_SIF_DURATION) {
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reset();
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}
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}
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bool isSifAllowed() {
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return consecutiveSifCount < MAX_SIF_COUNT &&
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(sifSequenceStartedAt == null ||
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DateTime.now().millisecondsSinceEpoch - sifSequenceStartedAt! <
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MAX_SIF_DURATION);
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}
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void reset() {
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userFramesSinceSif = 0;
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consecutiveSifCount = 0;
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sifSequenceStartedAt = null;
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}
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}

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