SRP6 for TC in C#/csharp

SRP6CryptoHasher.cs

using System;
using System.Security.Cryptography;
using System.Text;
using System.Numerics;
using System.Collections.Generic;
using System.Linq;
using System.Globalization;

public static class SRP6CryptoHasher {
  private static readonly RNGCryptoServiceProvider rngCsp = new RNGCryptoServiceProvider();

  // algorithm constants
  private static readonly BigInteger g = 7;
  private static readonly BigInteger N = BigInteger.Parse("894B645E89E1535BBDAD5B8B290650530801B18EBFBF5E8FAB3C82872A3E9BB7", NumberStyles.AllowHexSpecifier);

  public static(byte[] Salt, byte[] Verifier) GetSRP6RegistrationData(string username, string password) {
    // generate a random salt
    byte[] salt = new byte[32];
    rngCsp.GetBytes(salt);

    // calculate verifier using this salt
    byte[] verifier = CalculateSRP6Verifier(username, password, salt);

    // done - this is what you put in the account table!
    return (salt, verifier);
  }

  public static byte[] CalculateSRP6Verifier(string username, string password, byte[] salt_bytes) {
    SHA1 sha1 = SHA1.Create();

    // calculate first hash
    byte[] login_bytes = Encoding.UTF8.GetBytes((username + ':' + password).ToUpper());
    byte[] h1_bytes = sha1.ComputeHash(login_bytes);

    // calculate second hash
    byte[] h2_bytes = sha1.ComputeHash(salt_bytes.Concat(h1_bytes).ToArray());

    // convert to integer (little-endian)
    BigInteger h2 = new BigInteger(h2_bytes, true);

    // g^h2 mod N
    BigInteger verifier = BigInteger.ModPow(g, h2, N);

    // convert back to a byte array (little-endian)
    byte[] verifier_bytes = verifier.ToByteArray();

    // pad to 32 bytes, remember that zeros go on the end in little-endian!
    byte[] verifier_bytes_padded = new byte[Math.Max(32, verifier_bytes.Length)];
    Buffer.BlockCopy(verifier_bytes, 0, verifier_bytes_padded, 0, verifier_bytes.Length);

    // done!
    return verifier_bytes_padded;
  }

  public static bool VerifySRP6Login(string username, string password, byte[] salt, byte[] verifier) {
    // re-calculate the verifier using the provided username + password and the stored salt
    byte[] checkVerifier = CalculateSRP6Verifier(username, password, salt);

    // compare it against the stored verifier
    return verifier.SequenceEqual(checkVerifier);
  }

  public static void Main(string[] args) {
    // Example code

    // When creating account
    // store the returned data to database
    // Never store the actual password
    var data = GetSRP6RegistrationData("username", "password");

    // When logging in
    // verify login
    bool validLoginInfo = VerifySRP6Login("username", "password", data.Salt, data.Verifier);
    Console.WriteLine("Username and password match the stored data: " + validLoginInfo);

    // When program should close
    rngCsp.Dispose();
  }
}