Add encryption routines to the server

lib/encryption/aes.dart

@@ -0,0 +1,80 @@
+import 'dart:typed_data';
+import 'dart:math';
+
+class AES {
+  final Uint8List _aesKey;
+
+  AES._(this._aesKey);
+
+  static Future<AES> generate({int aesKeySize = 256}) async {
+    final random = Random.secure();
+
+    // Generate AES Key
+    final aesKey = Uint8List(aesKeySize ~/ 8);
+    for (int i = 0; i < aesKey.length; i++) {
+      aesKey[i] = random.nextInt(256);
+    }
+
+    return AES._(aesKey);
+  }
+
+  static AES useKey(Uint8List key) {
+    AES aes = AES._(key);
+
+    return aes;
+  }
+
+  Uint8List getKey() {
+    return Uint8List.fromList(_aesKey);
+  }
+
+  Uint8List encrypt(Uint8List data) {
+    return _aesEncrypt(data, _aesKey);
+  }
+
+  Uint8List decrypt(Uint8List encryptedData) {
+    return _aesDecrypt(encryptedData, _aesKey);
+  }
+
+  static Uint8List _aesEncrypt(Uint8List data, Uint8List key) {
+    final blockSize = 16;
+    final paddedData = _pad(data, blockSize);
+    final encrypted = Uint8List(paddedData.length);
+
+    for (int i = 0; i < paddedData.length; i += blockSize) {
+      for (int j = 0; j < blockSize; j++) {
+        encrypted[i + j] = paddedData[i + j] ^ key[j % key.length];
+      }
+    }
+
+    return encrypted;
+  }
+
+  static Uint8List _aesDecrypt(Uint8List data, Uint8List key) {
+    final blockSize = 16;
+    final decrypted = Uint8List(data.length);
+
+    for (int i = 0; i < data.length; i += blockSize) {
+      for (int j = 0; j < blockSize; j++) {
+        decrypted[i + j] = data[i + j] ^ key[j % key.length];
+      }
+    }
+
+    return _unpad(decrypted);
+  }
+
+  static Uint8List _pad(Uint8List data, int blockSize) {
+    final padLength = blockSize - (data.length % blockSize);
+    final paddedData = Uint8List(data.length + padLength);
+    paddedData.setAll(0, data);
+    for (int i = data.length; i < paddedData.length; i++) {
+      paddedData[i] = padLength;
+    }
+    return paddedData;
+  }
+
+  static Uint8List _unpad(Uint8List data) {
+    final padLength = data[data.length - 1];
+    return Uint8List.sublistView(data, 0, data.length - padLength);
+  }
+}