create or replace function encrypt (in_string varchar2,shift number) return varchar2 is 
    lv_out_string varchar2(100); 
    lv_in_string varchar2(100); 
    lv_length number(5); 
    lv_count number(5); 
    lv_temp varchar2(1); 
    lv_shift number(5); 
begin 
    lv_shift := mod(shift,26); 
    lv_in_string := lower(in_string); 
    select LENGTH(lv_in_string),1,'' into lv_length,lv_count,lv_out_string from dual; 
     
    for lv_count in    1.. lv_length loop 
                             lv_temp := substr(lv_in_string,lv_count,1); 
                             if ascii(lv_temp) <97    or ascii(lv_temp) >122 then 
                                    lv_out_string := lv_out_string || lv_temp; 
                             else 
                                    if ascii(lv_temp)+lv_shift>122 then 
                                         lv_temp :=chr(ascii(lv_temp)+lv_shift - 26); 
                                    else 
                                         lv_temp := chr(ascii(lv_temp)+lv_shift); 
                                    end if; 
                                     lv_out_string := lv_out_string || lv_temp; 
                             end if; 
    end loop; 
    return lv_out_string; 
end encrypt ;

create or replace function decrypt (in_string varchar2,shift number) return varchar2 
is 
lv_out_string varchar2(10); 
lv_length number(3); 
lv_count number(3); 
lv_temp    varchar2(100); 
lv_shift number(3); 

begin 
                 lv_shift := mod(shift,26); 
                 select length(in_string),1,'' into lv_length, lv_count,lv_out_string from dual; 
                 for lv_count    in 1.. lv_length loop 
                         lv_temp :=substr(in_string,lv_count,1); 
                         if ascii(lv_temp) <97 or ascii(lv_temp)>122 then 
                                lv_out_string := lv_out_string || lv_temp; 
                             else 
                                    if ascii(lv_temp)-lv_shift    <97 then 
                                         lv_temp := chr(ascii(lv_temp) - lv_shift +26); 

                                         else 
                                         lv_temp := CHR(ASCII(lv_temp) - lv_shift); 
                                    end if; 
                                    lv_out_string := lv_out_string || lv_temp; 
                         end if; 
                 end loop; 
                 return    lv_out_string; 
end decrypt;