derivePrivateKey function

Uint8List derivePrivateKey(dynamic seed, int index, { bool isSeedHexa = true, })

Implementation

Uint8List derivePrivateKey(dynamic seed, int index, {bool isSeedHexa = true}) {
  if (seed is String) {
    if (isSeedHexa && !isHex(seed)) {
      throw const FormatException("'seed' must be an hexadecimal string");
    }

    if (isSeedHexa) {
      seed = Uint8List.fromList(hexToUint8List(seed));
    } else {
      seed = Uint8List.fromList(utf8.encode(seed));
    }
  }

  /// Derive master keys
  final sha512 = Digest('SHA-512');
  final buf = sha512.process(seed);
  final masterKey = buf.sublist(0, 32);
  final masterEntropy = buf.sublist(32, 64);

  /// Derive the final seed
  final hmac = crypto.Hmac(crypto.sha512, masterEntropy);
  final indexBuf = toByteArray(index, length: 4);
  final extendedSeed = concatUint8List(<Uint8List>[masterKey, indexBuf]);
  final digest = hmac.convert(extendedSeed);

  final hmacBuf = Uint8List.fromList(digest.bytes.sublist(0, 32));

  return hmacBuf;
}