Greetings!
"Ng, Kenneth (US)" wrote:
> I remember that 40 bit encryption was broken a few years ago, but I have no
> idea on what. Does anyone have real numbers on how long it would take to
> break 40 bit DES with current day commercially available hardware (ie: no
> deep crack machines)?
You can get a "DES Deep Crack" machine for ~$100k. The do-it-yourself manual is
available in all bookshops:
"Cracking DES: Secrets of Encryption Research, Wiretap Politics & Chip
Design"
by Electronic Frontier Foundation, John Gilmore (Editor), Paperback - 272
pages (May 1998)
O'Reilly & Associates; ISBN: 1565925203, List Price: $29.95
That machine can crack a 56bit DES within 24h - so 40bit will be cracked in less
than 2 seconds with this custom cracking machine.
Now for plain run-off-the-mill PC hardware and some software:
If you look at the "Distributed.net" statistics,
(http://n0cgi.distributed.net/statistics/stats.html), an older PC (P2/266) can
check ~3Million DES56 keys/s (semi-last column). With DES40 having a keyspace of
2^40 ~1.1e12 a single, old PC will need about 4 days (with the nonoptimal DES56
core) to exhaust the keyspace. A current workhorse PC (750MHz) with an adapted
DES40 core will be able to search the complete keyspace in less than a day which
equals an average half day needed for cracked key.
Key cracking is one of the few problems that scale linearily with the number of
CPUs. If you buy 100 of normal PCs ($1000 each), you will have a DES40 key
cracking rate of 7.5 minutes (average) per key - for the same price as the deep
crack machine (which can do a key per second average).
And Standard DES (56bit)?
single PC: 760 years
100 PCs: 7.6 years
deep crack: 10 days
While that is not as catastrophic as the 40bit scheme, it still are no comforting
numbers - especially if you keep in mind, that these PC numbers are calculated
for screensaver/background crunching. Say, how many PCs does your company use
where you could install a client?
Bye
Volker
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