public static BigInteger calculateK(Digest digest,
    BigInteger N,
    BigInteger g) 
{
            
        return hashPaddedPair(digest, N, N, g);
}

 public static BigInteger calculateU(Digest digest,
    BigInteger N,
    BigInteger A,
    BigInteger B) 
{
        return hashPaddedPair(digest, N, A, B);
}

 public static BigInteger calculateX(Digest digest,
    BigInteger N,
    byte[] salt,
    byte[] identity,
    byte[] password) 
{
        byte[] output = new byte[digest.getDigestSize()];
        digest.update(identity, 0, identity.length);
        digest.update((byte)':");
        digest.update(password, 0, password.length);
        digest.doFinal(output, 0);
        digest.update(salt, 0, salt.length);
        digest.update(output, 0, output.length);
        digest.doFinal(output, 0);
        return new BigInteger(1, output).mod(N);
}

 public static BigInteger generatePrivateValue(Digest digest,
    BigInteger N,
    BigInteger g,
    SecureRandom random) 
{
        int minBits = Math.min(256, N.bitLength() / 2);
        BigInteger min = ONE.shiftLeft(minBits - 1);
        BigInteger max = N.subtract(ONE);
        return BigIntegers.createRandomInRange(min, max, random);
}

 public static BigInteger validatePublicValue(BigInteger N,
    BigInteger val) throws CryptoException 
{
        val = val.mod(N);
        // Check that val % N != 0
        if (val.equals(ZERO))
        {
            throw new CryptoException("Invalid public value: 0");
        }
        return val;
}