From 430326dc637f7393bb2298756ad46ae4ee6f27ed Mon Sep 17 00:00:00 2001
From: Mohit Tejani <mohit.tejani@pubnub.com>
Date: Wed, 27 Sep 2023 12:52:34 +0530
Subject: [PATCH] added AesCbcCryptor, ICryptor

---
 pubnub/lib/src/core/crypto/crypto.dart   | 19 ++++++++++++
 pubnub/lib/src/crypto/aesCbcCryptor.dart | 39 ++++++++++++++++++++++++
 pubnub/test/unit/crypto/crypto_test.dart | 13 +++++++-
 3 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 pubnub/lib/src/crypto/aesCbcCryptor.dart

diff --git a/pubnub/lib/src/core/crypto/crypto.dart b/pubnub/lib/src/core/crypto/crypto.dart
index f932ab56..fd6edcf4 100644
--- a/pubnub/lib/src/core/crypto/crypto.dart
+++ b/pubnub/lib/src/core/crypto/crypto.dart
@@ -21,3 +21,22 @@ abstract class ICryptoModule {
   List<int> encryptFileData(CipherKey key, List<int> input);
   List<int> decryptFileData(CipherKey key, List<int> input);
 }
+
+/// @nodoc
+abstract class ICryptor {
+  String get identifier;
+  EncryptedData encrypt(List<int> input);
+  List<int> decrypt(EncryptedData input);
+}
+
+class EncryptedData {
+  List<int> _data;
+  List<int> _metadata;
+
+  List<int> get data => _data;
+  List<int> get metadata => _metadata;
+
+  EncryptedData._(this._data, this._metadata);
+
+  factory EncryptedData.from(data, metadata) => EncryptedData._(data, metadata);
+}
diff --git a/pubnub/lib/src/crypto/aesCbcCryptor.dart b/pubnub/lib/src/crypto/aesCbcCryptor.dart
new file mode 100644
index 00000000..dac4a6e5
--- /dev/null
+++ b/pubnub/lib/src/crypto/aesCbcCryptor.dart
@@ -0,0 +1,39 @@
+import 'package:encrypt/encrypt.dart' as crypto;
+import 'package:crypto/crypto.dart' show sha256;
+import 'dart:typed_data' show Uint8List;
+
+import 'package:pubnub/core.dart';
+class AesCbcCryptor implements ICryptor {
+  static const BLOCK_SIZE = 16;
+  CipherKey cipherKey;
+
+  AesCbcCryptor(this.cipherKey);
+  @override
+  List<int> decrypt(EncryptedData encryptedData) {
+    var encrypter =
+        crypto.Encrypter(crypto.AES(_getKey(), mode: crypto.AESMode.cbc));
+    return encrypter.decryptBytes(
+        crypto.Encrypted(Uint8List.fromList(encryptedData.data.toList())),
+        iv: crypto.IV(Uint8List.fromList(encryptedData.metadata.toList())));
+  }
+
+  @override
+  EncryptedData encrypt(List<int> input) {
+    var encrypter =
+        crypto.Encrypter(crypto.AES(_getKey(), mode: crypto.AESMode.cbc));
+    var iv = _getIv();
+    var data = encrypter.encryptBytes(input, iv: iv).bytes.toList();
+    return EncryptedData.from(data, iv.bytes.toList());
+  }
+
+  @override
+  String get identifier => 'ACRH';
+
+  crypto.IV _getIv() {
+    return crypto.IV.fromSecureRandom(BLOCK_SIZE);
+  }
+
+  crypto.Key _getKey() {
+    return crypto.Key.fromBase16(sha256.convert(cipherKey.data).toString());
+  }
+}
diff --git a/pubnub/test/unit/crypto/crypto_test.dart b/pubnub/test/unit/crypto/crypto_test.dart
index 79ba2c6c..abb57d11 100644
--- a/pubnub/test/unit/crypto/crypto_test.dart
+++ b/pubnub/test/unit/crypto/crypto_test.dart
@@ -1,4 +1,7 @@
+import 'dart:convert';
+
 import 'package:pubnub/core.dart';
+import 'package:pubnub/src/crypto/aesCbcCryptor.dart';
 import 'package:pubnub/src/crypto/crypto.dart';
 
 import 'package:test/test.dart';
@@ -28,8 +31,16 @@ void main() {
       var headerData = [80, 78, 69, 68, 1, 65, 67, 82, 72, 16];
       var expectedBytes = [...headerData, ...List<int>.filled(16, 0)];
 
-      CryptorHeaderV1? header = CryptorHeader.tryParse(encryptedDataWithHeader.codeUnits);
+      var header = CryptorHeader.tryParse(encryptedDataWithHeader.codeUnits);
       expect(header!.data, equals(expectedBytes));
     });
+
+    test('AesCbcCryptor should work as expected', () async {
+      var plainText = 'Hello there!';
+      var cryptor = AesCbcCryptor(CipherKey.fromUtf8('pubnubenigma'));
+      var encryptedData = cryptor.encrypt(plainText.codeUnits);
+      var decrypted = cryptor.decrypt(encryptedData);
+      expect(utf8.decode(decrypted), equals(plainText));
+    });
   });
 }