Re: obviscating python code for distribution

From	Hans Georg Schaathun <hg@schaathun.net>
Newsgroups	comp.lang.python
Subject	Re: obviscating python code for distribution
Date	2011-05-19 10:16 +0100
Organization	University of Bergen
Message-ID	<6p3fa8-bnt.ln1@svn.schaathun.net> (permalink)
References	(6 earlier) <mailman.1769.1305745672.9059.python-list@python.org> <1skda8-3as.ln1@svn.schaathun.net> <mailman.1773.1305754489.9059.python-list@python.org> <4vlea8-55t.ln1@svn.schaathun.net> <4dd4d920$0$29968$c3e8da3$5496439d@news.astraweb.com>

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On 19 May 2011 08:47:28 GMT, Steven D'Aprano
  <steve+comp.lang.python@pearwood.info> wrote:
:  The real barrier to cracking Oyster cards is not that the source code is 
:  unavailable, but that the intersection of the set of those who know how
:  to break encryption, and the set of those who want to break Oyster cards, 
:  is relatively small. I don't know how long it took to break the encryption, 
:  but I'd guess that it was probably a few days of effort by somebody 
:  skilled in the art.
: 
:  http://www.usenix.org/events/sec08/tech/full_papers/nohl/nohl_html/index.html

In that paper, more than one art seem to have been applied.  An open 
design would have eliminated the need for image analysis and reduced
the requirement on hardware/electronics skills.  Hence, the obfuscation
has made that intersection you talk about smaller, and increased the
cost of mounting the attack.  As the system was broken anyway, it is
hardly a victory for obfuscation, but that's beside the point.

The work of that paper is almost certainly more than just «a few
days of effort».  There are simply to many technical issues to tackle,
and they must be tackled one by one.  The cost of mounting the attack
is to figure out what it takes to do it, before spend the resources
barking up the wrong tree.  For each successful attack, there probably
is a number of failed ones.

Thanks for the reference.

BTW.  That's not the only attack on MIFARE.  I cannot remember the
details of the other.

-- 
:-- Hans Georg

Thread

Re: obviscating python code for distribution Daniel Kluev <dan.kluev@gmail.com> - 2011-05-16 13:21 +1100
  Re: obviscating python code for distribution "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2011-05-16 23:42 +0100
    Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-18 08:36 +0100
      Re: obviscating python code for distribution Dotan Cohen <dotancohen@gmail.com> - 2011-05-18 17:42 +0300
      Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-18 09:54 -0700
        Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-18 18:33 +0100
          Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-18 12:07 -0700
            Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-18 20:56 +0100
              Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-18 14:34 -0700
                Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-19 06:21 +0100
                Re: obviscating python code for distribution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-19 08:47 +0000
                Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-19 10:16 +0100
                Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-19 10:23 -0700
                Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-19 19:23 +0100
                Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-19 17:56 -0700
                Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-20 05:48 +0100
                Re: obviscating python code for distribution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-20 07:04 +0000
                Re: obviscating python code for distribution Hans Georg Schaathun <hg@schaathun.net> - 2011-05-20 09:54 +0100
                Re: obviscating python code for distribution harrismh777 <harrismh777@charter.net> - 2011-05-20 15:24 -0500
                Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-20 15:45 -0700
                Re: obviscating python code for distribution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-21 00:54 +0000
                Re: obviscating python code for distribution harrismh777 <harrismh777@charter.net> - 2011-05-20 23:26 -0500
                Re: obviscating python code for distribution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-20 07:10 +0000
                Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-20 09:26 -0700
                Re: obviscating python code for distribution Nobody <nobody@nowhere.com> - 2011-05-20 18:48 +0100
                Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-20 11:33 +1000
                Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-19 19:30 -0700
                Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-20 12:35 +1000
      Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-19 03:24 +1000
        Re: obviscating python code for distribution John Bokma <john@castleamber.com> - 2011-05-18 12:31 -0500
          Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-19 03:52 +1000
      Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-18 10:40 -0700
      Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-19 04:07 +1000
      Re: obviscating python code for distribution "Littlefield, Tyler" <tyler@tysdomain.com> - 2011-05-18 12:26 -0600
        Re: obviscating python code for distribution harrismh777 <harrismh777@charter.net> - 2011-05-18 21:54 -0500
          Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-19 10:50 -0700
            Re: obviscating python code for distribution harrismh777 <harrismh777@charter.net> - 2011-05-20 01:17 -0500
      Re: obviscating python code for distribution Dotan Cohen <dotancohen@gmail.com> - 2011-05-18 21:30 +0300
      Re: obviscating python code for distribution Dotan Cohen <dotancohen@gmail.com> - 2011-05-18 21:31 +0300
      Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-19 04:37 +1000
      Re: obviscating python code for distribution Chris Angelico <rosuav@gmail.com> - 2011-05-19 04:49 +1000
      Re: obviscating python code for distribution geremy condra <debatem1@gmail.com> - 2011-05-18 14:47 -0700

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