สอบถามเรื่อง algorithm des หน่อยครับ ผมไม่เข้าใจ ไกด์ให้ผมหน่อยนะครับท่านผู้กล้า

        private bool Login(string _UserName, string _Password)
        {
            byte[] CurrentIV = new byte[] { 51, 52, 53, 54, 55, 56, 57, 58 };
            byte[] CurrentKey = { };
            if
            {
                int i;
                string AddString = _UserName.Substring(0, 1);
                int TotalLoop = 8 - _UserName.Length;
                string tmpKey = _UserName;
                for (i = 1; i <= TotalLoop; i++)
                {
                    tmpKey = tmpKey + AddString;
                }
                CurrentKey = Encoding.ASCII.GetBytes(tmpKey);
            }
            desCrypt = new DESCryptoServiceProvider();
            desCrypt.IV = CurrentIV;
            desCrypt.Key = CurrentKey;

            ms = new MemoryStream();
            ms.Position = 0;
            cs = new CryptoStream(ms, desCrypt.CreateEncryptor());
            byte[] arrByte = Encoding.ASCII.GetBytes(CurrentKey);
            cs.Write(arrByte, 0, arrByte.Length);
            cs.FlushFinalBlock();
            cs.Close();
            PwdWithEncrypt = Convert.ToBase64String(ms.ToArray());

            var un = from u in db.UserNames 
                     where (u.UserName1 == _UserName && u.Password == PwdWithEncrypt) 
                     && u.IsNormal == "1" select u;
            if (un.Count() > 0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }