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("-", "");
        }