Hi! everybody,

I see an encryption function in my database.

select  f_pwd_encrypt('password') from dual

-->12412913141313139139130121

My question is

How to write a decryption function?

Like:

select f_pwd_decrypt('12412913141313139139130121') from dual

-->password

CREATE OR REPLACE FUNCTION EPADM."F_PWD_ENCRYPT" ( vpwd in varchar2)
return varchar2
is
    vother_p   varchar2(9);
    vtr_pwd  varchar2(2048);
    i       number;
    j         number;
    vsubstr varchar2(9);
    vtemp1 varchar2(08);
    vvalue number := 0;
    vdb_pwd varchar2(100);


    function str_2_bit(vstring in varchar2)
    return varchar2
    is
       i number;
       vtemp number;
       v1 varchar(2048);


     function single_byte(vin in number)
       return varchar2
       is
         i number;
         vresult varchar2(08);
         vtemp number := vin;
       begin
         for i in 1..8 loop
           vresult := to_char(mod(vtemp,2))||vresult;
           vtemp := trunc(vtemp/2);
         end loop;
         return(vresult);
       end;
  --
    begin
      for i in 1..lengthb(vstring) loop
        select to_number(substrb(dump( vstring ,10,i,1),instr(dump( vstring ,10,i,1),' ',-1)+1))
          into vtemp
        from dual;
        v1 := v1 || single_byte(vtemp);
      end loop;


      return(v1);
    end;


begin
  vtr_pwd := str_2_bit(vpwd);
  vtr_pwd := substrb(vtr_pwd,4)||substrb(vtr_pwd,1,3);
  vvalue := 0;
  vdb_pwd := null;


   for i in  1..(lengthb(vtr_pwd)/4)  loop
     vtemp1 := substrb(vtr_pwd,(i-1)*4+1,4);
     for j in 1..4 loop
       vvalue :=  vvalue + to_number(substrb(vtemp1,j,1)) * power(2,j-1);
       dbms_output.put_line(j||' '||vvalue);
     end loop;
          vdb_pwd := to_char(vvalue) ||vdb_pwd;
          vvalue := 0;
   end loop;
  return(vdb_pwd);


END;
/