/// <summary>
/// Creates a user credential from the provided data.
/// </summary>
/// <param name="username"></param>
/// <param name="password"></param>
/// <param name="strength"></param>
/// <param name="saltSize"></param>
/// <param name="iterations"></param>
/// <returns></returns>
public SrpUserCredential(string username, string password, SrpStrength strength = SrpStrength.Bits1024, int saltSize = 32, int iterations = 4000)
{
username = username.Normalize(NormalizationForm.FormKC);
password = password.Normalize(NormalizationForm.FormKC);
UsernameBytes = Encoding.UTF8.GetBytes(username);
var constants = SrpConstants.Lookup(strength);
BigInteger N = constants.N;
BigInteger g = constants.g;
byte[] s = SaltGenerator.Create(saltSize);
byte[] hashPassword = PBKDF2.ComputeSaltedPassword(HMACMethod.SHA512, Encoding.UTF8.GetBytes(password), s, iterations, 64);
Sha512Digest hash = new Sha512Digest();
byte[] output = new byte[hash.GetDigestSize()];
hash.BlockUpdate(UsernameBytes, 0, UsernameBytes.Length);
hash.Update((byte)':');
hash.BlockUpdate(hashPassword, 0, hashPassword.Length);
hash.DoFinal(output, 0);
hash.BlockUpdate(s, 0, s.Length);
hash.BlockUpdate(output, 0, output.Length);
hash.DoFinal(output, 0);
BigInteger x = new BigInteger(1, output).Mod(N);
BigInteger v = g.ModPow(x, N);
UserName = username;
Salt = s;
Verification = v.ToByteArray();
Iterations = iterations;
SrpStrength = strength;
VerificationInteger = new BigInteger(1, Verification);
}