encodeShares static method

Iterable<Uint8List> encodeShares({ required Uint8List secretBytes, int threshold = 2, int? seed, })

Implementation

static Iterable<Uint8List> encodeShares(
    {required Uint8List secretBytes, int threshold = 2, int? seed}) sync* {
  if (threshold < 1 || threshold > 255) {
    throw Exception('Threshold must be 1-255');
  }

  Random random = seed == null ? Random.secure() : Random(seed);
  List<Uint8List> coefficients = [];
  BytesBuilder bb = BytesBuilder();

  for (int j = 0; j < secretBytes.length; j++) {
    Uint8List coef = Uint8List(threshold);
    coef[0] = secretBytes[j];
    for (int d = 1; d < threshold; d++) {
      coef[d] = random.nextInt(256);
    }
    bb.add(coef);
    coefficients.add(bb.takeBytes());
  }

  int shareIndex = 0;
  while (shareIndex < 256) {
    shareIndex++;
    bb.addByte(shareIndex);
    for (int j = 0; j < secretBytes.length; j++) {
      bb.addByte(evaluate(coefficients[j], shareIndex));
    }

    yield bb.takeBytes();
  }
}