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 From:  Peter Curran <peter at closeconsultants dot com>
 To:  Ryan Giobbi <rgiobbi at zoominternet dot net>
 Cc:  Manuel Kasper <mk at neon1 dot net>, m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] recommended wireless?
 Date:  Tue, 6 Jul 2004 19:06:29 +0100

I am well aware of the literature (I am pretty sure Manuel is as well), I even 
have a copy of 'Cracking DES' that somebody gave me as a joke present a 
couple of years ago.  The fact remains that you still can't buy a DES-cracker 
in CompUSA, Frys or equivalent.

If I was managing security for a mega-corp with really sensitive and important 
data flying around (which is my day job on occasion) then I worry about 
whether to trust AES-256.  For securing my home network, PLOD (PLain Old DES) 
is perfectly OK.  If somebody has the knowledge and need to crack it, then 
they will find many easier ways of getting in.

Peter Curran

On Tuesday 06 July 2004 18:25, Ryan Giobbi wrote:
> http://en.wikipedia.org/wiki/DES#Vulnerabilities
> "...a corporation willing to spend 10 million dollars to build a similar
> device today might break DES dozens if not hundreds of times per hour."
> I do not know of any more examples other than the few listed in the
> article in 1999.
> Peter Curran wrote:
> >I think that there are 2 different issues here.
> >
> >1.  PBKDF1 (and similar) algorithms (such as the one used by Kerberos -
> > ISTR this is a different way of doing the same thing) are really designed
> > at producing a good quality key with minimal entropy.  The idea being
> > that a simple brute-force attack on the whole key space is not
> > 'short-cuttable'. Whilst they may be successful in achieving that
> > objective, they will not help if the user selecting the password chooses
> > a weak example, such as a dictionary word, car registration number or
> > similar.  (I know that you made the caveat about 'usual precautions', but
> > the reality is that these are broadly ignored/unenforceable).
> >
> >2.  56 bit DES tends to be dismissed as 'too weak'.   Well, I don't know
> > if you have any knowledge of anybody ever having any DES-encrypted data
> > compromised by a brute force attack - I certainly don't.  [password
> > guessing, on the other hand, is sadly familiar].  As you say, a couple of
> > PC's are not going to help much when it comes to attempting a brute-force
> > attack on a 56-bit DES encryption.  I think it is a shame that it has
> > become received wisdom that anything with a key length < 128 bits is bad.
> >  For your average man in the street, 56-bit DES is perfectly adequate and
> > likely to remain so for a few years yet.  (I had this problem a few days
> > ago when trying to explain to a company that using plain DES to support
> > Windows/UNIX integration using Kerberos was OK).  They just did not
> > accept it!  Why, because they had seen a TV programme where some pundit
> > had explained that <128-bit == BAD CRYPTO!
> >
> >Peter
> >
> >On Tuesday 06 July 2004 15:49, Manuel Kasper wrote:
> >>On 06.07.2004 15:25 +0100, Peter Curran wrote:
> >>>I think encyrption is intriguing as a solution to the
> >>>confidentiality issues,  but as they are using DES on the Netgear
> >>>stuff I assume that you have to  pre-configure all the devices with
> >>>a shared key.  As this tends to be derived  from a passord it could
> >>>be relatively easy to attack.
> >>
> >>I did a little analysis of HomePlug powerline networking about a year
> >>ago. The password hashing is done as per PBKDF1 - it involves using
> >>MD5 1000 times, so with the usual password precautions in place, the
> >>resulting 56-bit DES key should be good. Also, provided that the
> >>implementation in HomePlug doesn't suffer from similar flaws as WEP,
> >>56-bit encryption is IMHO enough for home users. I mean, it's not
> >>like you can brute-force-search a 56-bit key in a useful amount of
> >>time with only a few PCs at hand...
> >>
> >>- Manuel
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