requirement: change users pswd at future pre-determined time wo storing in db - challenge

From: Thomas Miller (thomasamiller_at_rocketmail.com)
Date: 10/30/03 

Date: 30 Oct 2003 07:27:00 -0800

requirement: change users pswd at future pre-determined time

I have a requirment that a users password must be changed in the LDAP
(Active Directory) at a pre-determined time. I have to generate a
password for the user and let them print the password like this:

printout:
Congrats John Anderson. You have been given a username of "johna" and
a password of "coat761". This account will not be activated until
1/1/2004, therefore you cannot login at this time. You an login on
1/1/2004

So my program has to be able to somehow change the password on
1/1/2004. The sticky part is that the requirement states that I cannot
even store the an encrypted password in the database. So I am really
stumped- how in the world can it be done?