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Old 2018-05-10, 06:55   #1
eric
 
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Default how much time does it need to factor a number of 289 digits?

It has taken me 5 days to factor a 289 digits number,I WANT TO KNOW how much time does it need to factor a number of 289 digits?
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Old 2018-05-10, 10:52   #2
xilman
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Quote:
Originally Posted by eric View Post
It has taken me 5 days to factor a 289 digits number,I WANT TO KNOW how much time does it need to factor a number of 289 digits?
PLEASE DON'T SHOUT. IT'S IMPOLITE.

The answer to your question is that the time is between negligible (for instance if N=2*p where p is prime) and lots (if N=p*q where p and q have 1404 and 145 digits respectively and you've no other information about them).

The precise value of "lots" depends on the performance of your computer and how many of them you can use in concert.
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Old 2018-05-10, 11:03   #3
retina
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Quote:
Originally Posted by xilman View Post
The answer to your question is that the time is between negligible (for instance if N=2*p where p is prime) ...
One could factor 2⁹⁢⁰ quite easily and there are no factors above 2.
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Originally Posted by xilman View Post
... and lots (if N=p*q where p and q have 1404 and 145 digits respectively and you've no other information about them).
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Old 2018-05-10, 12:10   #4
MisterBitcoin
 
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We had this discussion (nearly the same topic) in the number theory discussion group.
You should read this thread.



Anyway, I was able to fully factor an C311 after ~2700 secs by finding a P27 and P31.
It was just luck, nothing more. Sometime you only get an P8 and the remaining cofactor is PRP.
Or the number you enter is a semiprime; which would make it very very hard to factor it.


Assuming the number is semiprime it might take some CPU weeks to fully factor the number, strongly depending on your computing power.
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Old 2018-05-10, 12:12   #5
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Does your number have a special form, did you check for small factors (say <60 digits)?

If it doesn't have a special form and no small factors you will not factor it unless you work for the NSA. (Hit: the largest factorization using GNFS is RSA768 at 232 digits)
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Old 2018-05-10, 12:59   #6
LaurV
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Quote:
Originally Posted by eric View Post
It has taken me 5 days to factor a 289 digits number,I WANT TO KNOW how much time does it need to factor a number of 289 digits?
We don't believe that. Please post logs. It took me few seconds to factor a well chosen 300 digits number...

Last fiddled with by LaurV on 2018-05-10 at 13:00
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