[2679] in bugtraq
Selecting Good Passwords
daemon@ATHENA.MIT.EDU (mdr@vodka.sse.att.com)
Tue Jun 4 18:54:21 1996
Date: Tue, 4 Jun 1996 08:34:59 -0400
Reply-To: Bugtraq List <BUGTRAQ@NETSPACE.ORG>
From: mdr@vodka.sse.att.com
To: Multiple recipients of list BUGTRAQ <BUGTRAQ@NETSPACE.ORG>
In-Reply-To: <Pine.SOL.3.93.960603144707.25688A-100000@dazed.nol.net> from
"Brett L. Hawn" at Jun 3, 96 02:49:03 pm
Brett wrote:
> nifty 'dictfile' like I did a few years back. All it takes is some simple
> brain power and a LOT of disk space, a quick file that prints all variations
> of 5-8 charater length combinations to a file. I stopped mine at 238megs and
> it was still going strong.
>
If your dictionary can be generated as such, then why store it to
disk? Just generate/test passwords one by one.
But generally that's not why dictionary attacks work! They work
because people often use common words for passords, unless the
software prevents them. That's why some password programs require
users to choose numerics and punctuation characters; it prevents the
use of common words and makes guessing the password harder. Of course
some people often use mnemonics such as:
0: 0
1: l
3: e
5: s
...
which almost totally defeats the purpose of requiring numbers in the
first place.
We use a password generator that produces pronounceable gibberish.
Actual system output:
> $ passwd
> UX:passwd: INFO: Changing password for mdr
> Old password:
>
> Automatic generation of password enabled. Please wait.
>
> xe5_na 7qev6zum 9risnig6 quxaxe hudefwog
> .qi8yu 9vem2ced zawvengat _wiwu+ towsuweh
> jishu63 6zinip_ cid01re fuk6zo1 04gokzo
> 13zowa -fejum5 jek5vox2 ziz.0ja _2nebi
> ceh69vej 0lera7 jegnal98 xiv2jaw0 noyep+5
>
> Select new password from passwords provided:
>
From the above list Olera7 jishu63 6zinip_ and zawvengat are all
relatively easy to remember and will not fall to dictionary attacks.
Of course sometimes the password generator resorts to profanity
(sheerly by combinitorics!) but, that only indicates its lack of
inteligence. :)
Of course, reusable passwords really aren't worth anything if they cross
the network in plain text. In fact they're worth is actually
less than zero, because someone may actually be trusting the password to
protect something that it is no longer capable of protecting.
Mark Riggins
Secure Systems Engineering
AT&T Bell Labs
PS: my real passwd was _not_ chosen from the above list.
