Expected Date of Completion

Rocke Verser (rcv@dopey.verser.frii.com)
Wed, 28 May 1997 12:46:41 -0600


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RSA DES Challenge Time-Of-Completion estimate
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Produced 03:00 MDT 05/28/97

Introduction:

Many people have observed that DESCHALL's "time to 50% completion"
published in the "desstat.htm" Web page is rapidly becoming a
meaningless statistic.

A more accurate measure is the time remaining to search 50% of
the remaining keys.

Noting that SolNet is a major player in the RSA DES Challenge,
I've developed a model that accounts for DESCHALL and SolNet
as the only two major players in the RSA DES Challenge.

[Rumor has it there is at least one more major player undertaking
the RSA DES Challenge, privately. If anyone would care to offer
accurate "factual data" of the form shown below, I will attempt
to include them in the model.]

Given the "factual data" and the "assumptions" below, the "results"
of this model are believed (not guaranteed) to be mathematically
correct to within 1 day and to within 2 percentage points.

Factual data:

DESCHALL keyrate over last 24 hours: 4.014 billion keys per second
SolNet keyrate over last 24 hours: 1.738 billion keys per second

DESCHALL keyspace complete: 12.193%
Solnet keyspace complete: 7.8487%

Assumptions:

DESCHALL and SolNet are working independently.

Each group's keyspace rate remains constant at the levels shown above.

Nobody else on the planet is working on the RSA DES Challenge.

Results:

50% done: 54 days from now. [This is when 1/2 of the *total* keyspace
will have been searched by DESCHALL and/or SolNet.]

Expected date of solution: 73 days from now. [There is a 50% chance
the solution will be found prior to this date, and a 50% chance
the solution will be found after this date. This is the date on
which we should expect to have searched 50% of the *remaining*
keyspace.]

Probability that a DESCHALL client will find the key: 79%
Probability that a SolNet client will find the key: 21%

Notes:

These results are highly sensitive to each group's keyspace rates
(billions of keys per second).

If DESCHALL and SolNet each doubled our keyspace rates every 28 days,
the "expected date of solution" would be 42 days from now.

Giving SolNet an instant 30% increase in keyspace rate, while
holding DESCHALL's rate constant would shorten the "expected date of
solution" to 68 days and increases SolNet's chances of finding the
key to 27%.

Giving DESCHALL an instant 30% increase in keyspace rate, while
holding SolNet's rate constant would shorten the "expected date of
solution" to 59 days and decrease SolNet's chances of finding the
key to 16%.

- -- Rocke Verser
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