How to use

MGF1BytesGeneratorExt

in

io.yggdrash.common.crypto

  @Test
  public void getDigest() {
    MGF1BytesGeneratorExt ext = new MGF1BytesGeneratorExt(new SHA1Digest(), 1);
    byte[] VZ = BigIntegers.asUnsignedByteArray(1, BigInteger.ONE);

    DerivationParameters kdfParam = new MGFParameters(VZ);

    ext.init(kdfParam);

    byte[] K1 = new byte[4];
    assert ext.generateBytes(K1, 0, K1.length) > 0;

    assert ext.getDigest() != null;
  }
}

if (len > this.hLen) {
  do {
    this.ItoOSP(hashCounter++, C);
    this.digest.update(this.seed, 0, this.seed.length);
    this.digest.update(C, 0, C.length);
  this.ItoOSP(hashCounter, C);
  this.digest.update(this.seed, 0, this.seed.length);
  this.digest.update(C, 0, C.length);

/**
 * Encryption equivalent to the Crypto++ default ECIES<ECP> settings:
 * <p>
 * DL_KeyAgreementAlgorithm:        DL_KeyAgreementAlgorithm_DH<struct ECPPoint,struct EnumToType<enum CofactorMultiplicationOption,0> >
 * DL_KeyDerivationAlgorithm:       DL_KeyDerivationAlgorithm_P1363<struct ECPPoint,0,class P1363_KDF2<class SHA1> >
 * DL_SymmetricEncryptionAlgorithm: DL_EncryptionAlgorithm_Xor<class HMAC<class SHA1>,0>
 * DL_PrivateKey:                   DL_Key<ECPPoint>
 * DL_PrivateKey_EC<class ECP>
 * <p>
 * Used for Whisper V3
 */
public static byte[] decryptSimple(BigInteger privKey, byte[] cipher) throws InvalidCipherTextException {
  EthereumIESEngine iesEngine = new EthereumIESEngine(
      new ECDHBasicAgreement(),
      new MGF1BytesGeneratorExt(new SHA1Digest(), 1),
      new HMac(new SHA1Digest()),
      new SHA1Digest(),
      null);
  IESParameters p = new IESParameters(null, null, KEY_SIZE);
  ParametersWithIV parametersWithIV = new ParametersWithIV(p, new byte[0]);
  iesEngine.setHashMacKey(false);
  iesEngine.init(new ECPrivateKeyParameters(privKey, CURVE), parametersWithIV,
      new ECIESPublicKeyParser(ECKey.CURVE));
  return iesEngine.processBlock(cipher, 0, cipher.length);
}

EthereumIESEngine iesEngine = new EthereumIESEngine(
    new ECDHBasicAgreement(),
    new MGF1BytesGeneratorExt(new SHA1Digest(), 1),
    new HMac(new SHA1Digest()),
    new SHA1Digest(),