Date: Tue, 1 Aug 2006 12:37:21 -0500 From: "Nikolas Britton" <nikolas.britton@gmail.com> To: "Robert Huff" <roberthuff@rcn.com> Cc: Xiao-Yong Jin <xj2106@columbia.edu>, freebsd-questions@freebsd.org, User Freebsd <freebsd@hub.org> Subject: Re: Gotta start somewhere ... how many of us are really out there? Message-ID: <ef10de9a0608011037w3609b5a6k1709aea61d43ed0f@mail.gmail.com> In-Reply-To: <17615.30414.314802.792740@jerusalem.litteratus.org> References: <20060728164526.E27679@ganymede.hub.org> <20060730233839.I27679@ganymede.hub.org> <44CDAA98.3030702@freebsd.org> <44CDE02F.4090604@dial.pipex.com> <44CE7DD0.9070902@childeric.freeserve.co.uk> <871ws1v261.fsf@photon.homelinux.org> <20060731220830.B27679@ganymede.hub.org> <ef10de9a0608010121j154c7ael7ece0997a479572e@mail.gmail.com> <20060801120058.O27679@ganymede.hub.org> <17615.30414.314802.792740@jerusalem.litteratus.org>
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On 8/1/06, Robert Huff <roberthuff@rcn.com> wrote:
> User Freebsd writes:
> > Actually, using ifconfig wouldn't work ... it would give unique, but as
> > soon as you add another IP (ie. alias), the ID would change ... you'd need
> > to do something like:
> >
> > ifconfig | grep ether | sha256 | md5
> >
> > since the 'ether' would never change ...
>
> At least some cards (+ FreeBSD drivers) allow you to set the
> MAC address ....
>
>
>
You still don't get it! Maybe this simple perl program will illustrate
the problem:
my $number = "100000000000000000000";
my $randomkey = "";
while (0 == 0) {
$randomkey = `echo $number | md5`;
print "fetch http://www.hub.org/freebsd_stats.php?HOSTID=$randomkey";
$number++
}
Also by using only the mac address output of ifconfig you have limited
the pool of unique keys to 16^12 (281,474,976,710,656)!!! All I need
to do to find your mac address is compute all possible mac address
combinations into MD5 and then just simply match it up with yours.
Anonymity only works if the input is large then the output!!! Because
it's computationally impossible to compute all values of a 500+ byte
string etc. etc. The MD5 string maps back to at least (how do you
compute the collisions?) two SHA256 keys and the SHA256 maps back to
at least two ifconfig strings.
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