Xref: cantaloupe.srv.cs.cmu.edu sci.crypt:15926 alt.security.pgp:2689 alt.privacy.clipper:118
Newsgroups: sci.crypt,alt.security.pgp,alt.privacy.clipper
Path: cantaloupe.srv.cs.cmu.edu!crabapple.srv.cs.cmu.edu!bb3.andrew.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!howland.reston.ans.net!ira.uka.de!news.dfn.de!solaris.rz.tu-clausthal.de!sun.rz.tu-clausthal.de!injc
From: injc@sun.rz.tu-clausthal.de (Joerg Czeranski)
Subject: Re: Off the shelf cheap DES keyseach machine (Was: Re: Corporate acceptance of the wiretap chip)
Message-ID: <1993Apr24.152713.15792@solaris.rz.tu-clausthal.de>
Sender: root@solaris.rz.tu-clausthal.de (Operator)
Organization: Techn. Univ. Clausthal
X-Newsreader: Tin 1.1 PL5
References: <C5uvn4.MF7@austin.ibm.com>
Date: Sat, 24 Apr 1993 15:27:13 GMT
Lines: 31

AG Russell (arussell@austin.ibm.com) wrote:
: At the company I worked for previously, I received a file that was
: des encryped
: and the person that had sent it, went on vaction.  Rather than wait
: two weeks
: I set up a straight frontal attack with one key at a time.  It only
: took two(2)
: days to crack the file.  No, I don't have any faith in DES.

Then it was either _really_ good luck or you had some _very_ fast
machine.  DES has 2^56 possible keys, each two of which are simply
to convert into each other, so you have to expect 2^54 trial encryptions
in the mean case, assuming known plaintext.
2^54 / 2 / (24*60*60) / 1000000 is ca. 104250.
So you must have managed to do 104250 encryptions per microsecond.
CE Infosys builds a very fast DES chip that manages 2 (!) encryptions
per microsecond.

Yes, I'm not very seriously bothered about the security of DES yet;
though you might prefer to use triple DES or IDEA, both of which
use more key bits.

joerg

--
Joerg Czeranski                EMail czeranski@rz.tu-clausthal.de
Osteroeder Strasse 55          SMTP  injc@[139.174.2.10]
W-3392 Clausthal-Zellerfeld    Voice (at work)  +49-5323-72-3896
Germany                        Voice (at home)  +49-5323-78858

To obtain PGP public key, finger injc@sun.rz.tu-clausthal.de, or email me.
