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 2010-11-18, 07:48 #1 sinide   Nov 2010 1012 Posts how long it will take factoring a big number 512b how long it will take factoring a big number 512bit with modern hardware?
 2010-11-18, 08:41 #2 frmky     Jul 2003 So Cal 2·3·7·53 Posts
 2010-11-18, 09:27 #3 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 9,629 Posts But, Professor, not everyone has access to TeraGrid!
 2010-11-18, 12:15 #4 sinide   Nov 2010 58 Posts three days how to do that?
2010-11-18, 14:33   #5
xilman
Bamboozled!

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

11·17·59 Posts

Quote:
 Originally Posted by sinide how long it will take factoring a big number 512bit with modern hardware?

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

2010-11-18, 14:43   #6
R.D. Silverman

Nov 2003

22·5·373 Posts

Quote:
 Originally Posted by sinide three days how to do that?
Use the General Number Field Sieve along with multiple, tightly coupled
CPUs.

2010-11-18, 18:14   #7
frmky

Jul 2003
So Cal

2·3·7·53 Posts

Quote:
 Originally Posted by sinide three days how to do that?
Use sufficiently "modern hardware." This will do.

 2010-11-18, 18:20 #8 Andi47     Oct 2004 Austria 2×17×73 Posts 512 bits - that would be 154 decimal digits. I did a GNFS-factorization 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. 30-40% of the calender time) and a fistfull of CPU-days 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 2010-11-18 at 18:31 Reason: Typo
 2010-11-19, 08:03 #9 sinide   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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