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Re: Is factorization of big primeproducts a solved problem YET?
Posted:
Jan 8, 2013 10:22 AM
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On Jan 8, 8:46 am, mstem...@walkabout.empros.com (Michael Stemper)
wrote:
> In article <kc6gg1$au...@dont-email.me>, David Bernier <david...@videotron.ca> writes:
> >On 01/04/2013 12:01 AM, JT wrote:
> >> Does the RSA challenges have a given time complexity of factoring the
> >> primeproduct, or did they have one that changed during resent years?
>
> >The RSA challenge numbers are still available somewhere.
> >The contests for prize money has been discontinued.
>
> >I think many remain unfactored, as far as the general
> >public knows, i.e. outside cryptologic agencies and
> >government cipher schools.
>
> >They would deliberately choose n = p*q, p, q odd primes
> >with the digit length of p and q being about half that
> >of the composite number `n'.
>
Not 'about half'. Exactly half.
> I'm surpised. I would have expected them to pick p and q with significantly
> different lengths. Doesn't a simplistic attack like Fermat's method get
> much easier when p and q are close in magnitude?
>
I suggest that you compute the effort needed for a Fermat attack for N
= pq,
N is 1024 bits, and p and q are identical in (say) the first 3
digits.
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