OS/2 Shareware BBS: 11 Util/11-Util.zip/pw.zip/PW.DOC

Text File | 1994-07-05 | 4KB | 75 lines

                      Documentation for PW.EXE

CAUTION: THIS PROGRAM CAN BE DANGEROUS IF MISUSED! Worst-case, it can
make it impossible for you to boot your system from the hard drive at
all. Read this documentation CAREFULLY before you try to use it.

The program's purpose is to secure your system against unauthorized
users. To use, place the program in your boot directory and call it
as the last line in your AUTOEXEC.BAT file (i.e., the last line of
that file should read "PW" -- without the quote marks, of course).

The first time you start the program -- whether from the command line
or via AUTOEXEC.BAT -- touch the "ENTER" key when it asks for a
password. It will then ask whether you want to change your password.
You can type in a string of any length up to 255 characters (which
will echo to the screen but is color-blinded). Spaces, or any other
standard keystroke (ASCII range 32 to 126 inclusive), are accepted;
and it IS case-sensitive, so caps and lower-case letters are NOT
interchangeable. It will demand confirmation -- i.e., the same string
again, character for character. That string then becomes your
password. After each use (i.e., after you've entered the correct
password) it offers you an opportunity to change your password, with
the same confirmation requirement.

The program traps all forms of CTRL-BREAK; in other words, once
you're in it, the ONLY way out is to type in the correct password.
You'll have three tries; after that the program goes into an endless
loop and won't either take an input or let you out except with a
reboot. (It also goes IMMEDIATELY into that endless loop if you hit a
CTRL-BREAK combination, so be prepared to reboot if you don't trust
me without trying it yourself.)

The password is stored, in heavily encrypted form (I really don't
think the algorithm is breakable), in a separate data file called
"PW". If you've defined your path to include the subdirectory where
you have the DOS or OS/2 "ATTRIB.EXE" utility, that file will be both
hidden and write-protected. (If not, you may get error messages at
the start and end of the program and the data file won't be protected
in any way, but it'll run otherwise.) Corruption of this data file
could cause the program not to accept your password; if so, the only
way out is to boot via a floppy and either take the PW line out of
your AUTOEXEC.BAT file or use ATTRIB to restore PW (no extension) to
writable, non-hidden status and then delete it. Since a would-be
bootleg user of your machine could do the same, you're probably best
off not advertising the method of protection you're using.

This works in either DOS or OS/2, although you get a flicker of a
system-error message under OS/2; I haven't troubled to do anything
with it, because it doesn't affect functionality. I've also not tried
it as an automatic boot in OS/2, but it should work fine. You can
also use it to protect any OS/2 session by creating a special
AUTOEXEC file for that session, although this is obviously vulnerable
to changing the settings.

NOTO BENE: If you do decide to install and use PW, make sure you
establish a password and protect that password carefully. Any
unauthorized user who can get into your system will be afforded the
same opportunity as you to change the password, meaning YOU might be
the one forbidden entry into your own system.

If you try this, a report on how you like it -- and any suggestions
for improvement -- would be appreciated.

Colin Barrett
12166 Holly Knoll Circle
Great Falls, VA 22066
July 1, 1994

DISCLAIMER: This program is in the public domain, and is made
available at no cost or obligation and at the user's sole risk. The
developer assumes no responsibility or liability for any problems or
injuries that may result from its use or misuse.

CB