[RC5] DES coming...
b.ford at qut.edu.au
Mon Nov 30 12:30:27 EST 1998
> Yes, it's less than two months to DES-II 3!
> And thanks to EFF the rules are like this:
> "The 'previous winner's' time that will be used for this next
> contest is 56 hours so the prizes are $10,000 for a break within
> 14 hours, $5000 for a break within 28 hours and $1,000 for a break
> within 42 hours. After that - nothing."
> Right, we are pretty much faster than in July, but can we do it in as few
> hours as 42 or even 14 ??
Well EFF did us a bit of a disservice by only searching 25% of the
keyspace to find the DES-II-2 key.
By 13 January 1999 we should be able to do approximately 200 Gkeys/s. If
we could put all of that online immediately our chances are:
14 hours: 14.0%
28 hours: 28.0%
42 hours: 42.0%
However, our ramp up for DES-II-2 fitted closely to
rate=max_possible*(1-exp(-t/36.94)) where t is in hours.
This would give d.n chances of:
14 hours: 2.3%
28 hours: 8.4%
42 hours: 16.9%
The EFF pages give 92 Gkeys/s as their stated keyrate giving:
14 hours: 6.4%
28 hours 12.9%
42 hours: 19.3%
So even if we combine with EFF, the chance of finding the key in 42 hours
is less than 100% and is probably closer to 36% than 61%.
This assumes EFF have not upgraded their hardware.
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