AES-GSM mode Decryption issue in flutter(dart)

Ezhilarasan S 0
Viewed 67

I am facing one issue with dart unable to decrypt data for AES-GCM mode with an authentication password. Below is my dart code:

    // Cipher Text Generated by Java.
String cipherText = "c6b80cf9e86e2ec219b4fef448aa73e6eed8e6e6e93211832dee5d45bb6043d6e9193ef084686e482700c86673c5616b10d583b39e0450513de415ce9ce7a32b90a9dcaa9e0b382593a5718d330373344a969013865ad690a6fda81ee47d28746f8bfb9acce9fd8f80d1efa0edd5703693571fafdffe466105488be2c8e78c942eeb3a8b0e81612b5575e2cac3aef4ab0435227483f69c505ad90094a9a50b601ef42663bd09900c20e7ebe8d1a98a29291d81f024304a387194979fbaa940d9d85325ee37c8b2fb70d248cdeeceb552aa157201f374527e4fedfc490c055b256b81a83e877abbf5e8f59972007e9bbd64bfec35343635c681d5916dbbf16e34fadaf1fe6690f06a759b31aac7b64505ac34bf19dfe0b9e21398f0bd9d3d47dbd6773520a71389184c10aaec99aa81dc0a8872d525f94d48160dcae7d74a59f7589ce3cc5205529b7000b23af3b1391abca458f49a96f2dae2148de3ed04c01a0af77e5e4f09f76b4e279e51524d94ff132ad5d2e4a87afe301b3899b9fb3540e1c281a724828f6d643cd597ea0f0952c55702d512a93e162045b738fb1916c85b5cfb4a13c4c20426187fb1f34339d1";

// PassPhare or IV pass Generated by Java.
String passPhare = "myLfN7pToARn4t33RyZwAw==";

// Private Key Used by Both Java and dart.
String privateKey = "DGq1tmmtiXXlCtBAFpFuGZbdWolHcna7kbRJTbTIw4Y=";

I dont know how to decrypt the cipherText with above supported keys in the Flutter(dart) language. Since I am a newbie in flutter, Pls could someone help me to guys to decrypt the above data.

Thanks

aes-gcm dart flutter
1 Answers

This can be done with the pointycastle package (and convert because your ciphertext is hex):

import 'dart:convert';
import 'dart:typed_data';

import 'package:convert/convert.dart';
import 'package:pointycastle/block/aes.dart';
import 'package:pointycastle/block/modes/cbc.dart';
import 'package:pointycastle/pointycastle.dart';

void main() {
  String cipherText =
      "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";
  String iv = "myLfN7pToARn4t33RyZwAw==";
  String secret = "DGq1tmmtiXXlCtBAFpFuGZbdWolHcna7kbRJTbTIw4Y=";

  final binaryCipherText = Uint8List.fromList(hex.decode(cipherText));
  final binaryIV = base64Decode(iv);
  final binarySecret = base64Decode(secret);

  final cipher = CBCBlockCipher(AESEngine());

  cipher.init(
    false,
    ParametersWithIV(
      KeyParameter(binarySecret),
      binaryIV,
    ),
  );

  final binaryPlaintext = cipher.process(binaryCipherText);

  print('plaintext: ${hex.encode(binaryPlaintext)}');
}
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