Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!tut.cis.ohio-state.edu!udecc.engr.udayton.edu!blackbird.afit.af.mil!kahuna.asd-yf.wpafb.af.mil!nieland_t
From: nieland_t@kahuna.asd-yf.wpafb.af.mil
Newsgroups: comp.sys.dec
Subject: Re: QUEST for VAX users *********
Message-ID: <1991Mar23.162654.79@kahuna.asd-yf.wpafb.af.mil>
Date: 23 Mar 91 21:26:54 GMT
References: <8819.27e524ea@jetson.uh.edu>
Organization: USAF ASD/YF, WPAFB, Dayton, OH
Lines: 38

In article <8819.27e524ea@jetson.uh.edu>, inde5wl@jetson.uh.edu writes:
> 
> I am a amatuer VAX user. I have recently come across a small bug.
> 
> Some VAX operating systems remember old passwords and prevent you
> 
> from using the same password if you wish to change it again.
> 
> Q: How could I display all my previous passwords?
> 
> Why do I ask? Well I like to learn about the system by trying
> 
> to do the impossible. And obsession is my worst vice.
> 
> I wont rest until I find the answer.
> 
> Somebody please help.
> 
> 
-- 
1.  The password history is a feature of VMS 5.4, not a bug.  DECUS
asked that this feature be included in VMS and DEC added it.

2. Old passwords are not stored on the system, just the old has values.  When 
a new password is requested, the system checks the hash value of the new 
password against the stored list of old hash values.  If it finds a duplicate
it complains about the password.

3.  The only way to "find" and list the old passwords is to run a random 
character generator against the hash list until it randomly generates the old 
passwords.  Please note that while this type of program is rather easy to 
write and get running, it uses lots of CPU time.  I would estimate about five 
to six hours on a VAX 9000 to come up with the list of old passwords for one 
user. 

Ted Nieland				nieland_t@kahuna.asd-yf.wpafb.af.mil
Control Data Corporation		nieland@dayfac.cdc.com
(513) 427-6355				ted@nieland.dayton.oh.us