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 2018-05-10, 06:55 #1 eric   May 2018 1 Posts 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?
2018-05-10, 10:52   #2
xilman
Bamboozled!

"πΊππ·π·π­"
May 2003
Down not across

246268 Posts

Quote:
 Originally Posted by eric 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?

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.

2018-05-10, 11:03   #3
retina
Undefined

"The unspeakable one"
Jun 2006
My evil lair

23×32×5×17 Posts

Quote:
 Originally Posted by xilman 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 2βΉβΆβ° quite easily and there are no factors above 2.
Quote:
 Originally Posted by xilman ... and lots (if N=p*q where p and q have 1404 and 145 digits respectively and you've no other information about them).

 2018-05-10, 12:10 #4 MisterBitcoin     "Nuri, the dragon :P" Jul 2016 Good old Germany 2×13×31 Posts 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.
 2018-05-10, 12:12 #5 VictordeHolland     "Victor de Hollander" Aug 2011 the Netherlands 49816 Posts 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)
2018-05-10, 12:59   #6
LaurV
Romulan Interpreter

Jun 2011
Thailand

83×113 Posts

Quote:
 Originally Posted by eric 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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