aesCbcEncrypt function

Uint8List aesCbcEncrypt(Uint8List plaintext, Uint8List key)

AES-256-CBC encrypt. Random 16-byte IV prepended to ciphertext. Matches Python's iv_scramble.

Implementation

Uint8List aesCbcEncrypt(Uint8List plaintext, Uint8List key) {
  final rng = Random.secure();
  final iv = Uint8List.fromList(List.generate(16, (_) => rng.nextInt(256)));

  final padded = _pkcs7Pad(plaintext);
  final cipher = CBCBlockCipher(AESEngine())
    ..init(true, ParametersWithIV(KeyParameter(key), iv));

  final out = Uint8List(padded.length);
  for (var offset = 0; offset < padded.length; offset += 16) {
    cipher.processBlock(padded, offset, out, offset);
  }

  // IV + ciphertext
  final result = Uint8List(16 + out.length);
  result.setAll(0, iv);
  result.setAll(16, out);
  return result;
}