From: William Ono <wmono@Direct.CA>
Date: Sat, 17 Aug 1996 19:23:57 +0800
To: "Carlos L. Mariscal" <al177820@campus.gda.itesm.mx>
Subject: Re: Unix passwd-cracker online?
In-Reply-To: <Pine.A32.3.91.960816161112.53362A-100000@campus.gda.itesm.mx>
Message-ID: <Pine.LNX.3.94.960817000216.1458B-100000@crash.direct.ca>
MIME-Version: 1.0
Content-Type: text/plain


On Fri, 16 Aug 1996, Carlos L. Mariscal may have written:

> person has obtained a specific password by entering the desired 
> adresses'passord on a submnit form in a Web page.
[deletia]
> never have it if there really is such, but this came to my mind when i read 
> the posts  on the plate-numbers-in-Oregon polemica. I would appreciate 

Somehow I have a hard time believing this to be true.  I run crack, a
password searching program that uses a dictionary as its base, on my
/etc/passwd regularly to locate any users with easily guessed entries.
With ultra fast crypt (UFC), the fastest crypt() replacement I can find, I
can run through about 9700 passwords per second on this P6-150.

Now, this is a back-of-the-envelope calculation:  Assuming that the
password can be one to eight characters of the following:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()
we find that we have a set of 72 characters.  That gives us
72^8 + 72^7 + 72^6 + 72^5 + 72^4 + 72^3 + 72^2 + 72^1 or
732376025552520 possible combinations.  At 9700 encryptions per second,
it would take my system 2401 years to brute force -one- password to 
completion.  That means that, most likely, if this 'locate password on
demand' system existed, it would not work in real time, or in any time
during any person's life.  Moore's Law might shorten this timeframe
considerably, but still not to any reasonable time frame.

Continuing with my back-of-the-envelope estimate, we have the length of a
crypt()'d password as being 13 characters.  The password in plaintext has
to follow, with a length of 8 characters.  At a size of 
732376025552520 * 21 characters, we would have a database of
15379896536602920 bytes, or 22565249 650mb CD-ROMs.  That's for the
passwords of one salt, without any formatting.  Even if we could achieve a
95% compression rate on this data (it is text, after all) we would end up
with 237528 CD-ROMs.

Most likely my set of characters will be found to be incorrect, but
anything that includes even a-z, A-Z, and 0-9 in one to eight character
combinations most likely will not be a favourable crack target.

Sorry, I don't think this is feasable, or possible.

(Please do correct my calculations if errors are detected, especially if
the corrected numbers make this possible.. it's getting late at night, and
my mind is fogging up, so these calculations/estimates/wild guesses may be
off more than usual. It does sound like an interesting project to
undertake, if it were possible, but not on my equipment!)


--    ** NOTE NEW KEY **  As of 08/28/95!  Old key 0x2902B621 COMPROMISED!
William Ono <wmono@direct.ca>                                PGP Key: F3F716BD
 fingerprint = A8 0D B9 0F 40 A7 D6 64  B3 00 04 74 FD A7 12 C9 = fingerprint
PGP-encrypted mail welcome!           "640k ought to be enough for everybody."