Oracle APEX Custom Login

create or replace PACKAGE "AUTHENTICATION" 
 is
 
   function hash_pass(
      pi_email           in varchar2   default null
    , pi_password        in varchar2   default null
   ) return varchar2
  ;

  
    Function Authenticate_User(p_User_Name Varchar2
                            ,p_Password  Varchar2) 
    Return Boolean;


  Procedure Process_Login(p_User_Name Varchar2
                         ,p_Password  Varchar2
                         ,p_App_Id    Number);
 
 end authentication;

create or replace PACKAGE BODY "AUTHENTICATION"
 is
  
  function hash_pass(
     pi_email           in varchar2   default null
   , pi_password        in varchar2   default null
   ) return varchar2
   
  is
  v_hash_pass           varchar2(4000);
  v_salt                varchar2(4000) := 'hdjikndbbhitasuihfnnkqyhiplwmneuyndnloidj';
  begin
 
 v_hash_pass :=  DBMS_CRYPTO.Hash (
        UTL_I18N.STRING_TO_RAW (
        pi_password || substr(v_salt,10,13) || LOWER (pi_email) ||      substr(v_salt, 4,10)
        , 'AL32UTF8'),
        2) ;
  
  return v_hash_pass;
  end hash_pass;
------------------------------------------------------------------------------- 
  -- Login for admin
------------------------------------------------------------------------------- 
  Function Authenticate_User(p_User_Name Varchar2
                            ,p_Password  Varchar2) Return Boolean As
     v_Password         varchar2(4000);
     v_Email            varchar2(4000);
     v_Active_yn        varchar2(4000);  
     v_deleted_yn       varchar2(4000);  
     v_name             varchar2(4000);  
  Begin
     Begin
        Select EMAIL
             , PASSWORD
             , Active_yn
             , deleted_yn
             , null
          Into v_Email
             , v_Password
             , v_Active_yn
             , v_deleted_yn
             , v_name 
        From USERS  
        Where  lower(EMAIL) = (p_User_Name);

    -- User not found
    Exception
        When No_Data_Found Then 
            raise_application_error (-20001,'Benutzer nicht gefunden!');  
           Return False;
    End;

    -- passwort not match
    If v_Password <> authentication.hash_pass(lower(p_User_Name),p_Password)  Then 
        raise_application_error (-20001,'Passwort ist falsch!');    
        Return False;
     End If;

    -- user is not active or deleted
    If v_Active_yn = 'NO' or v_deleted_yn = 'YES' Then
        raise_application_error (-20001,'Benutzer ist gelöscht, bitte Admin kontaktieren!'); 
        Return False;
    End If;
 
     Return True;
  End;
--------------------------------------
Procedure Process_Login(p_User_Name Varchar2
                         ,p_Password  Varchar2
                         ,p_App_Id    Number
) 
As
    v_Result Boolean := False;
    
Begin

    -- authenticate the user
    v_Result := Authenticate_User(p_User_Name
                                , p_Password
                                );
     
    If v_Result = True Then
        -- save last login                                     
       update USERS
          set last_login = sysdate
        where lower(email) = lower(p_User_Name);
        
        -- Redirect to Page 1 (Home Page).
        Wwv_Flow_Custom_Auth_Std.Post_Login(p_User_Name -- p_User_Name
                                           ,p_Password -- p_Password
                                           ,v('APP_SESSION') -- p_Session_Id
                                           ,p_App_Id || ':1' -- p_Flow_page
                                            );
     Else
        -- Login Failure, redirect to page 9999 (Login Page).
        Owa_Util.Redirect_Url('f?p=&APP_ID.:9999:&SESSION.');
     End If;
  End;
  
 
  
 end authentication;