如何在SQL Server 2008 R2中存储哈希密码

我试图在SQL Server 2008 R2中存储哈希密码，但当我将存储的版本与原始版本进行比较时，它们不匹配。

string password = "12345";
User user = new User();
user.USERNAME = "JohnDoe";
using (var rngCsp = new RNGCryptoServiceProvider())
{
            byte[] salt = new byte[32];
            rngCsp.GetBytes(salt);
            user.SALT = UTF8Encoding.UTF8.GetString(salt);
}
using (SHA256CryptoServiceProvider sha = new SHA256CryptoServiceProvider())
{
    user.PASSWORD = UTF32Encoding.UTF8.GetString(sha.ComputeHash(UTF8Encoding.UTF8.GetBytes(password + user.SALT)));
}
//store the user on db
db.UserUpdate(user);
// now get the db values that have been saved and compare with original
var userOnDB = db.UsersGet(user.USERNAME);
var passwordOnDb = userOnDB.PASSWORD;
//this returns false
if (passwordOnDb == user.PASSWORD)
{
}

SQL Server表包含以下列：

TABLE [dbo].[USERS]
(
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [SALT] [nvarchar](50) NOT NULL,
    [PASSWORD] [nvarchar](50) NOT NULL,
    .........
)

这是我的数据库访问代码：

public USER UsersGet(string userName)
{
        using (MyEntities ctx = new MyEntities())
        {
            return ctx.USERS.Where(a => a.USERNAME == userName).FirstOrDefault();
        }
}
public void UserUpdate(USER user)
{
    try
    {
            using (MyEntities ctx = new MyEntities())
            {
                if (controller.ID == 0)
                {
                    ctx.Entry(user).State = System.Data.Entity.EntityState.Added;
                }
                else
                {
                    ctx.Entry(user).State = System.Data.Entity.EntityState.Modified;
                }
                ctx.SaveChanges();
            }
        }
        catch (Exception ex)
        {
            throw new Exception(ex.InnerException.InnerException.Message);
        }
    }

这是我的User对象

public int ID { get; set; }
public string FIRSTNAME { get; set; }
public string LASTNAME { get; set; }
public string ADDRESS1 { get; set; }
public string ADDRESS2 { get; set; }
public string ADDRESS3 { get; set; }
public string TOWN { get; set; }
public string POCODE { get; set; }
public string MOBILE { get; set; }
public string COMMENTS { get; set; }
public bool ACTIVE { get; set; }
public string NIC { get; set; }
public string LANDLINE { get; set; }
public string USERNAME { get; set; }
public string EMAIL { get; set; }
public string SALT { get; set; }
public string PASSWORD { get; set; }

所以我想我在SQL Server表中一定有错误的列类型。