encrypt static method

Future<Uint8List> encrypt(Uint8List plain, Uint8List key, { int keyId = 0, String label = '', })

Encrypts plain and returns LRTC-formatted bytes.

label identifies the model and is bound into both the envelope and key derivation; the same label must be present when decrypting (it travels inside the envelope, so callers do not need to track it).

Implementation

static Future<Uint8List> encrypt(
  Uint8List plain,
  Uint8List key, {
  int keyId = 0,
  String label = '',
}) async {
  _checkKey(key);
  if (keyId < 0 || keyId > 0xFFFF) {
    throw ArgumentError.value(keyId, 'keyId', 'must fit in uint16');
  }
  final iv = Uint8List(LrtcEnvelope.ivLength);
  fillRandomBytes(iv);
  final header = LrtcEnvelope.buildHeader(
    version: LrtcEnvelope.currentVersion,
    keyId: keyId,
    label: label,
    iv: iv,
  );

  final encKey = await _deriveKey(key, label);
  try {
    final aes = await AesGcmSecretKey.importRawKey(encKey);
    final sealed = await aes.encryptBytes(
      plain,
      iv,
      additionalData: header,
      tagLength: _tagBits,
    );
    return LrtcEnvelope(
      version: LrtcEnvelope.currentVersion,
      keyId: keyId,
      label: label,
      header: header,
      iv: iv,
      sealed: sealed,
    ).serialize();
  } finally {
    wipe(encKey);
  }
}