how long it will take factoring a big number 512b

[sinide]

how long it will take factoring a big number 512bit with modern hardware?

[frmky]

Only three days.

[Batalov]

But, Professor, not everyone has access to TeraGrid!

[sinide]

three days how to do that?

[xilman]

Originally Posted by sinide

how long it will take factoring a big number 512bit with modern hardware?

Dependent on your resources, the answer is anywhere between days and decades.

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

[R.D. Silverman]

Originally Posted by sinide

three days how to do that?

Use the General Number Field Sieve along with multiple, tightly coupled
CPUs.

[frmky]

Originally Posted by sinide

three days how to do that?

Use sufficiently "modern hardware." This will do.

[Andi47]

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.))

[sinide]

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