if (vAdmin == true)
            {
                LoginInfo.Admin Ad_log = new LoginInfo.Admin();
                int i = 0;
                foreach(Byte b in EncodedPass)
                {
                    Ad_log.ad_Password[i] = EncodedPass[i];//Error is here
                    i++;
                }
            }

//Class with Ad_log

  public struct Admin
        {
            private string a_UserName;
            private Byte[] a_Password;

            public string ad_UserName
            {
                get { return a_UserName; }
                set { a_UserName = value; }
            }
            public Byte[] ad_Password
            {
                get { return a_Password; }
                set { a_Password = value; }
            }
        }