# [RC5] Re: Estimated time of completion of DES-II-2, please.

Bruce Ford b.ford at qut.edu.au
Mon Jun 22 15:11:00 EDT 1998

```> Could someone calculate an estimation of the duration of the
> upcoming DES-II-2 challenge by comparing the data aquired in the
> first contest with the growth that we had since. This could help us
> to see if we'll get the full 10 000\$ prize, because we have now to
> find the key in 10 days!

Given that we double our rate every 133 days, come 13 July 1998 we
will be completing 7558275 RC5 blocks of 2^28 keys per day.

When DES-II-1 finished we were doing approximately 29000 Mkeys/s.
Our RC5 rate increased by approximately 7500 Mkeys/s which gives a
factor of 3.867.

Assume that 90% of clients change over.

DES blocks/day = 7558275 * 3.867 * 0.9
= 26305064

Maximum blocks = 2^28 = 268435456

Maximum days to complete DES-II-2 = 268435456 / 26305064
= 10.20

This ignores growth during the contest and time required to switch
contests.

I would say we are a good bet for the \$10000.

However DES-II-3 will be very difficult, particularly if we find the
key quickly in DES-II-2.

Bruce Ford
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