Encrypting Passwords

AccountController.cs

        [HttpPost]
        public ActionResult Logon(LoginUserViewModel loginUser)
        {
            if (!ModelState.IsValid)
                return View(loginUser);

            User user = userRepository.GetUser(loginUser.UserName);

            if (user != null)
            {
                string hashedPassword = EncryptionHelper.Encrypt(user.Salt, loginUser.Password);
                if (user.Password == hashedPassword )
                {
                    SignUserIn(user);
                    return RedirectToAction("Index", "Home");
                }
                else
                {
                    ModelState.AddModelError("", "The user name or password are incorrect.");
                }
            }
            else
            {
                ModelState.AddModelError("", "The user name or password are incorrect.");
            }

            return View(loginUser);
        }

EncryptionHelper.cs

using System.Security.Cryptography;
using System.Text;

namespace Web.Helpers
{
    public static class EncryptionHelper
    {
        public static string Encrypt(byte[] salt, string password)
        {
            byte[] passwordBytes = new byte[Encoding.UTF8.GetByteCount(password) + salt.Length];  // Create buffer for password bytes and hash
            int passwordLength = Encoding.UTF8.GetBytes(password, 0, password.Length, passwordBytes, 0);
            salt.CopyTo(passwordBytes, passwordLength);
            byte[] hash = null;
            using (SHA512Managed hasher = new SHA512Managed())
            {
                hash = hasher.ComputeHash(passwordBytes);
            }
            
            System.Text.Encoding enc = System.Text.Encoding.ASCII;
            return enc.GetString(hash);
        }
    }
}        }