key length/size RSA discussion/recommendations in the wiki
Robert J. Hansen
rjh at sixdemonbag.org
Wed Oct 29 22:30:56 CET 2014
> No, I'm using a strict definition of brute force.
Technically, brute force is testing every *possible* value... not values
that you know aren't going to work. Why test those?
If you're trying to factorize 2701, for instance, you can feel free to
skip dividing by 2 (doesn't end in an even number), 3 (sum of the digits
isn't divisible modulo three), 4 (already know it's not divisible by 2),
5 (doesn't end in a 5 or a 0), 6 (not divisible by 3 or by 2), etc.
If your brute-forcer is testing values that cannot possibly be correct,
then you're using an inefficient brute-forcer. Get a better one. :)
> I don't feel the method outlined by Rob is still brute force. That
> brute actually is using his brain. Possibly his brain resembles a
> sieve, but still :). Am I too strict?
Depends. I think so. But if you're taking an exam sometime in the near
future, I think you should answer this however your professor wants. :)
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