20101118, 07:48  #1 
Nov 2010
101_{2} Posts 
how long it will take factoring a big number 512b
how long it will take factoring a big number 512bit with modern hardware?

20101118, 09:27  #3 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
9,629 Posts 
But, Professor, not everyone has access to TeraGrid!

20101118, 12:15  #4 
Nov 2010
5_{8} Posts 
three days how to do that?

20101118, 14:33  #5  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
11·17·59 Posts 
Quote:
So, how much of what modern hardware do you have? BTW, you still haven't answered the question: which RSA key is it and why do you want the factors? You are rather unlikely to get much useful assistance here until you come clean. Paul 

20101118, 14:43  #6 
Nov 2003
2^{2}·5·373 Posts 

20101118, 18:20  #8 
Oct 2004
Austria
2×17×73 Posts 
512 bits  that would be 154 decimal digits.
I did a GNFSfactorization of a c153 (so it is one digit smaller than your number) for the cunningham project here (see posts #141, #144, #157 and #159), using one core2duo @ 1.8 GHZ (running 24/7), one core2duo @ 2.0 GHz (NOT running 24/7; it was on approx. 3040% of the calender time) and a fistfull of CPUdays of a P4 @ 3.4 GHz. This took me approx. 70 calender days. On an intel i7 (8 threads, running 24/7) I guess this should be doable within approx. a month or maybe a little bit more. Note: for postprocessing (i.e. matrix step) you will need 2 GB RAM on a 64 bit(!) system. (a 32 bit system will fail because it can't allocate enough memory (see here, discussion about the problem and it's solution continued in this thread.)) Last fiddled with by Andi47 on 20101118 at 18:31 Reason: Typo 
20101119, 08:03  #9 
Nov 2010
5 Posts 
i use ggnfs to do that, my pc is E8400 3GHz,2G RAM.
in the lattice sieving step,i use 3PCs,now i have run 7 days 
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