[RC5] At 10 Billion Per Second

Glen Hoag hoag at ro.com
Fri Apr 24 21:34:58 EDT 1998


At 2:39 AM -0500 4/24/98, Michael Heacock wrote:
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>I was looking at the stats page.  Currently we are averaging about 12
>billion keys per second.  At this rate would it take us 48 years to
>crack the key (given that the we need to solve all the keys before
>success).

That assumes that the keyrate is constant.  It is not.  There are several
factors that come into play:

1. We have been accumulating participants over time.
2. Users upgrade their machines, so the average participant's keyrate
increases over time.

Over the past eight weeks, our rate has been increasing *very roughly*
linearly at about 89Mkeys/sec/day.  (this is based on a visual curvefit of
the eight week plot of the keyrate at
<http://www.distributed.net/statistics>)  If this is a valid approximation,
we would exhaust the keyspace in roughly 2000 days, or about five and a
half years.

Other projects (the DES-II series of contests, for instance) will draw
computing power away from RC5-64, so there is no way to tell, given the
small sample so far, when the keyspace will be exhausted.  Since the key is
at a random point in the keyspace, we probably will not have to check every
key to find the correct one.  DES-I and RC5-56 fell relatively early in the
search.  DES-II-1 fell near the end.

>
>Perhaps my calculation is wrong (if so, please correct), but I suspect
>we need a lot more processing power (i.e. a lot more computers in the
>network).

Lots more computers would certainly help the situation, but the picture is
nowhere near as bleak as your calculation suggests.

--Glen Hoag
  hoag at ro.com


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