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From: vinsci@abo.fi (Leonard Norrgard)
Newsgroups: comp.misc,sci.crypt
Subject: Re: DES Busting
Message-ID: <6096@abo.fi>
Date: 6 Mar 89 03:30:01 GMT
References: <15057@cup.portal.com> <5555@abo.fi>
Organization: Abo Academy, Finland
Lines: 54

In article <5555@abo.fi>, vinsci@abo.fi (Leonard Norrgard) writes:
> [cross-posted to comp.os.vms & comp.misc]
> 
> In article <15057@cup.portal.com>, Tim_C_May@cup.portal.com writes:
>> Saying that a Cray can do it in tens of hours is wrong (roughly 10 to the
>> 17th keys need to be examined...figure it from there).
> 
>   I remember someone stating that DES had been broken over in the USSR,
> with a PC, in only a few hours. *IF* my memory serves me right, the algorithm
> (cluster-something) was published in one of their journals. Also, in the
> message, probably posted in sci.crypt or comp.os.vms (info-vax), the name of
> the journal was given.
> 
>   I searched my arhive, but had no luck. Anyone else remembering this?

  The answer showed up in comp.os.vms:

>Newsgroups: comp.os.vms
>Subject: Re: DES Busting
>From: jensen%hsr.uninett@NORUNIX.BITNET ("Tarjei T. Jensen")
>Date: 3 Mar 89 07:20:00 GMT
>
>This is what I found on the spring 87 vax tape. I believe that it also appears
>on the recent Languages and Tools SIG tape.
>===============================================================================
>
>        Data Encryption Standard
>
>        The NSA has announced that the Data Encryption Standard, or
>DES for short, would not be supported when it expired. Various banks
>have pushed for its retention on the grounds that it's secure enough
>for the time being.
>        This is to advise all and sundry that in the 1979 to 1980 period
>there appeared an article in the Proceedings of the Soviet Academy of
>Science giving a simple way of pruning decision trees for DES ciphers
>which describes equivalence classes of keys and allows greatly reduced
>processing to break a DES cipher. The reduction in processing is such
>that breaking a DES cipher would amount to on order 1.5 hours on a
>standard IBM PC. There have been rumors that such a program is in
>circulation and that a copy of it at NSA led to its withdrawal of
>support for DES.
>        Be advised that DES is EXTREMELY likely to be vulnerable and
>that other crypto methods are probably needed to secure data.
>        The Soviet article goes on to give some conditions on the
>factors used for public key encryption which prevent or allow easy
>breaking of those ciphers, so it is probably required reading for anyone
>serious about protecting information.
>

  I suppose that anybody with DES-protected data understands how they should
feel about this.

-- 
Leonard Norrgaard, vinsci@abo.fi, vinsci@finabo.bitnet, +358-21-654474, EET.