initializeSync method

@mustCallSuper @override void initializeSync({ required SecretKeyData secretKey, required List<int> nonce, List<int> aad = const [], })

Re-initializes the sink.

Implementation

@mustCallSuper
@override
void initializeSync({
  required SecretKeyData secretKey,
  required List<int> nonce,
  List<int> aad = const [],
}) {
  _blockLength = 0;
  _isClosed = false;
  _mac = null;
  _length = 0;

  // RFC variable `r`
  final r = _r;
  final keyBytes = secretKey.bytes;

  final key = Uint16List.view(
    keyBytes is Uint8List
        ? keyBytes.buffer
        : Uint8List.fromList(keyBytes).buffer,
  );

  // In RFC:
  //  r = (le_bytes_to_num(key[0..15])
  //  clamp(r)
  final k0 = key[0];
  r[0] = 0x1FFF & k0;
  final k1 = key[1];
  r[1] = 0x1FFF & ((k0 >> 13) | (k1 << 3));
  final k2 = key[2];
  r[2] = 0x1F03 & ((k1 >> 10) | (k2 << 6));
  final k3 = key[3];
  r[3] = 0x1FFF & ((k2 >> 7) | (k3 << 9));
  r[4] = 0xFF & (k3 >> 4);
  final k4 = key[4];
  r[5] = 0x1FFE & (k4 >> 1);
  final k5 = key[5];
  r[6] = 0x1FFF & ((k4 >> 14) | (k5 << 2));
  final k6 = key[6];
  r[7] = 0x1F81 & ((k5 >> 11) | (k6 << 5));
  final k7 = key[7];
  r[8] = 0x1FFF & ((k6 >> 8) | (k7 << 8));
  r[9] = 0x7F & (k7 >> 5);

  // In RFC:
  // s = le_num(key[16..31])
  final s = _s;
  final sBytes = Uint8List.view(s.buffer);
  for (var i = 0; i < 16; i++) {
    sBytes[i] = keyBytes[16 + i];
  }

  // Erase helper `h`
  final h = _a;
  for (var i = 0; i < 10; i++) {
    h[i] = 0;
  }

  final buffer = _buffer;
  buffer.setUint32(0, 0);
  buffer.setUint32(4, 0);
  buffer.setUint32(8, 0);
  buffer.setUint32(12, 0);
  buffer.setUint32(16, 0);

  beforeData(
    secretKey: secretKey,
    nonce: nonce,
    aad: aad,
  );
}