SQL & PL/SQL

Hello,

I encrypted a field using the following update statement:

UPDATE table1

  SET dob= dbms_obfuscation_toolkit.md5( input_string => ''31-MAY-2001' )

WHERE table1id= 123;

Now my dob field is encrypted.  How can I decrypt it to see the date of '31-MAY-2001' again?  I was trying to get this to work, but not sure I'm on the right track:

select dob,dbms_obfuscation_toolkit.DESEncrypt(

                   input_string => dob,

                   key_string => 'scottsco',

                   encrypted_string => '˜}Ê<Mæ×^u.ò†Œ­ß]' )

from table1 where table1id = 123;

Thanks very much in advance!