encrypt method

@override Future<SecretBox> encrypt(List<int> clearText, { required SecretKey secretKey, List<int>? nonce, List<int> aad = const <int>[], int keyStreamIndex = 0, })

Encrypts a cleartext.

Parameter keyStreamIndex allows you to choose offset in the keystream.

For other arguments, see Cipher.encrypt.

Implementation

@override
Future<SecretBox> encrypt(
  List<int> clearText, {
  required SecretKey secretKey,
  List<int>? nonce,
  List<int> aad = const <int>[],
  int keyStreamIndex = 0,
}) async {
  nonce ??= newNonce();

  // New secret key for normal Chacha20
  final derivedSecretKey = await _xchacha20SecretKey(
    secretKey: secretKey,
    nonce: nonce,
  );

  // New nonce for normal Chacha20
  final derivedNonce = _xchacha20Nonce(nonce);

  // Encrypt
  final secretBox = await _chacha20.encrypt(
    clearText,
    secretKey: derivedSecretKey,
    nonce: derivedNonce,
    aad: aad,
    keyStreamIndex: keyStreamIndex,
  );

  // New secret box
  return SecretBox(
    secretBox.cipherText,
    nonce: nonce,
    mac: secretBox.mac,
  );
}