diff --git a/.gitignore b/.gitignore
index f395ff9..d86649d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -133,4 +133,8 @@ agents.md
 
 # Environment variables
 .env
-.env.*
\ No newline at end of file
+.env.*
+# Локальные дампы трафика и скрипты анализа (содержат секреты)
+komet.txt
+original_app.txt
+fingerprint.py
diff --git a/lib/backend/api.dart b/lib/backend/api.dart
index c767808..8b10cf9 100644
--- a/lib/backend/api.dart
+++ b/lib/backend/api.dart
@@ -39,6 +39,12 @@ class Api {
 
   Map<dynamic, dynamic>? get userAgent => _userAgent;
 
+  int? _callsSeed;
+  String? _deviceId;
+
+  int? get callsSeed => _callsSeed;
+  String? get deviceId => _deviceId;
+
   List<CountryName>? _registrationCountries;
 
   List<CountryName> get registrationCountries =>
@@ -111,6 +117,7 @@ class Api {
     try {
       final response = await sendHandshake();
       if (response.isOk) {
+        _callsSeed = response.payload['callsSeed'] as int?;
         _registrationCountries = _parseRegistrationCountries(response.payload);
         _setSessionState(SessionState.online);
         _startPinging();
@@ -242,6 +249,8 @@ class Api {
       'buildNumber': buildNumber,
     };
 
+    _deviceId = deviceId;
+
     final payload = <dynamic, dynamic>{
       'mt_instanceid': await DeviceIdentity.instanceId(),
       'clientSessionId': DeviceIdentity.clientSessionId,
diff --git a/lib/backend/modules/account.dart b/lib/backend/modules/account.dart
index 70b4b9a..522901b 100644
--- a/lib/backend/modules/account.dart
+++ b/lib/backend/modules/account.dart
@@ -1,6 +1,8 @@
 import 'dart:async';
 import 'dart:convert';
+import 'dart:typed_data';
 import '../api.dart';
+import '../../core/protocol/chat_cache_fingerprint.dart';
 import '../../core/protocol/opcode_map.dart';
 import '../../core/protocol/packet.dart';
 import '../../core/storage/app_database.dart';
@@ -1048,9 +1050,18 @@ class AccountModule {
     final payload = <dynamic, dynamic>{
       'token': token,
       'interactive': true,
-      if (_api.userAgent != null) 'userAgent': _api.userAgent,
+      'exp': {
+        'chatsCountGroups': Uint8List.fromList([0x0b, 0x32]),
+      },
     };
 
+    final callsSeed = _api.callsSeed;
+    final deviceId = _api.deviceId;
+    if (callsSeed != null && deviceId != null) {
+      payload['chatCacheFingerprint'] =
+          ChatCacheFingerprint.compute(callsSeed, deviceId);
+    }
+
     if (sync != null) {
       payload['presenceSync'] = sync.presenceSync;
       payload['chatsSync'] = sync.chatsSync;
@@ -1060,9 +1071,6 @@ class AccountModule {
       payload['bannersSync'] = sync.bannersSync;
       payload['lastLogin'] = sync.lastLogin;
       if (sync.configHash != null) payload['configHash'] = sync.configHash;
-      if (sync.chatCacheFingerprint != null) {
-        payload['chatCacheFingerprint'] = sync.chatCacheFingerprint;
-      }
     } else {
       payload['presenceSync'] = 0;
     }
diff --git a/lib/core/protocol/chat_cache_fingerprint.dart b/lib/core/protocol/chat_cache_fingerprint.dart
new file mode 100644
index 0000000..b2ab84a
--- /dev/null
+++ b/lib/core/protocol/chat_cache_fingerprint.dart
@@ -0,0 +1,47 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:crypto/crypto.dart';
+
+class ChatCacheFingerprint {
+  static final Uint8List _signatureDigest = _hex(
+    '1684414033eb263e2c615f8b7df5ed8793850a07656304997fbf07e9e21e1e93',
+  );
+  static final Uint8List _soDigest = _hex(
+    'c77b89270f44bd26c218a946c18911f2b156312693ea00b419d169b71c1ed111',
+  );
+  static final Uint8List _dexDigest = _hex(
+    '490a2746c7ebbff050353c575a186ca65bc708f9b6e0c1329b59a3bfab6c3924',
+  );
+
+  static Uint8List compute(int callsSeed, String deviceId) {
+    final seed = _int64BigEndian(callsSeed);
+    final device = Uint8List.fromList(utf8.encode(deviceId));
+    final result = BytesBuilder();
+    result.add(_sha256(_signatureDigest, seed, device));
+    result.add(_sha256(_soDigest, seed, device));
+    result.add(_sha256(_dexDigest, seed, device));
+    return result.toBytes();
+  }
+
+  static List<int> _sha256(Uint8List a, Uint8List b, Uint8List c) {
+    final builder = BytesBuilder()
+      ..add(a)
+      ..add(b)
+      ..add(c);
+    return sha256.convert(builder.toBytes()).bytes;
+  }
+
+  static Uint8List _int64BigEndian(int value) {
+    final data = ByteData(8)..setInt64(0, value, Endian.big);
+    return data.buffer.asUint8List();
+  }
+
+  static Uint8List _hex(String hex) {
+    final out = Uint8List(hex.length ~/ 2);
+    for (var i = 0; i < out.length; i++) {
+      out[i] = int.parse(hex.substring(i * 2, i * 2 + 2), radix: 16);
+    }
+    return out;
+  }
+}
diff --git a/pubspec.lock b/pubspec.lock
index 0545e63..9dab85f 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -130,7 +130,7 @@ packages:
     source: hosted
     version: "0.3.5+2"
   crypto:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: crypto
       sha256: c8ea0233063ba03258fbcf2ca4d6dadfefe14f02fab57702265467a19f27fadf
diff --git a/pubspec.yaml b/pubspec.yaml
index 6fbaeec..edae9ba 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -39,6 +39,7 @@ dependencies:
   dart_lz4: ^1.0.0
   libcompress: ^1.0.0
   msgpack_dart: ^1.0.1
+  crypto: ^3.0.7
   logger: ^2.6.2
   device_info_plus: 12.3.0
   flutter_timezone: ^5.0.1