thanks :) this code helped me:
public virtual string CreatePasswordHash(string password, string saltkey, string passwordFormat = "SHA1")
{
if (String.IsNullOrEmpty(passwordFormat))
passwordFormat = "SHA1";
string saltAndPassword = String.Concat(password, saltkey);
var algorithm = HashAlgorithm.Create(passwordFormat);
if (algorithm == null)
throw new ArgumentException("Unrecognized hash name", "hashName");
var hashByteArray = algorithm.ComputeHash(Encoding.UTF8.GetBytes(saltAndPassword));
return BitConverter.ToString(hashByteArray).Replace("-", "");
}