Article View: sci.crypt
Article #915RSA-129 contest
From: jbs
Date: Thu, 20 Aug 1992 23:35
Date: Thu, 20 Aug 1992 23:35
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1557 bytes
I asked:
:> How small do the coefficients have to be? I have been led to
:>believe that the speed of the GNFS overall does not depend much on the
:>efficiency of the search for a good polynomial. If this is the case it
:>would seem to be unwise to devote a lot of effort to finding a good poly-
:>nomial. What is the point of this contest?
Robert D. Silverman replied:
>This is NOT the case. The performance is VERY sensitive to the size
>of the coefficients and it is worthwhile spending a significant amount
>of time trying to find small coefficients.
and also:
>I estimate that to be competitive with the Quadratic sieve they need
>to find coefficients of 'about' 14 digits. I am not sure it is
>possible.
Well, let us estimate how many numbers between 10**128 and
10**129 can be so represented. m will be about 10**23 (so that c5*
m**5 is 10**129). There are about 10**23 choices for m, 10**14 for
each of the ci. This gives 10**23*(10**14)**6 or 10**107 representa-
tions. Hence the chance that a random number between 10**128 and
10**129 has such a representation is below 10**-20. It would appear
to me that running ECM would be a better bet than this.
James B. Shearer
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Path: arc1-ca.pugleaf.net!sparky!uunet!stanford.edu!agate!ucbvax!WATSON.IBM.COM!jbs From: jbs@WATSON.IBM.COM Newsgroups: sci.crypt Subject: RSA-129 contest Message-ID: <9208202353.AA21728@ucbvax.Berkeley.EDU> Date: 20 Aug 92 23:35:49 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 23