# How can I simulate and measure brute force hacking using RSA?

I want to implement brute force hacking using RSA. How can I simulate and measure time duration? What software (or software-based simulator) would be needed?

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First, you shoudl specify, what you actually want to brute-force. Is it factoring $n$, or finding $d$, or finding $m$ to a certain ciphertext $c$? Anyway, brute force in general is a bad idea here, since the "try out everything" approach has a MUCH higher complexity than factoring with the GNFS (very rough approximation: $2^{n}$ vs $2^{n/3}$) – tylo Feb 10 '14 at 13:38
Maybe you meant RSA hacking using brute force? – catpnosis Feb 11 '14 at 3:23

Firstly, I assume we are talking about classical computers

Implementing a brute force attack on a RSA may not be the most sensible thing, unless of course the security parameter of your target system is small.. (160 bit numbers! )

Even then you may not want to implement a brute force here.. try using Fermat's Factoring or Pollards $\rho$ method.

If you just want to measure time try to do a more theoretical research, i.e. use the time take per multiplication op. and the no. of operations your computer can perform in a sec to determine exactly how long will it take you to brute force a $n-$bit security.

To sum it up, YOU CANNOT BRUTE FORCE THE (properly implemented) MODERN DAY RSA (~4096 bit numbers) even if you use all computers in your state.

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Did you mean 160 digits (about 530 bits) rather than 160 bit? That's more like the limit of brute-forcing RSA for an individual. – fgrieu Feb 9 '14 at 17:00
160 bits sound about right if by "brute force" one means literally iterating through all odd numbers from $\sqrt(N)$ and checking if the value divides $N$. – Henrick Hellström Feb 10 '14 at 1:33
@fgrieu 530 bit is in the ballpark of brute force, however, it will take some time (months) to do that with a modern day PC (I assume the asker does not have access to supercomputers or clusters). – Subhayan Feb 11 '14 at 3:18

I don't understand what you mean simulate, but if you need a toy example in python the code is at the end of the message. If you need to show the performance of more advanced algorithms use factor(x) in pari/gp. See here for details.

import gmpy, time, random, math

def genprime(bits):
p=1
while(gmpy.is_prime(p)==0):
p = random.randrange(math.pow(2,bits-1),math.pow(2,bits))
return p

BITS=20
found=False
p=genprime(BITS)
q=genprime(BITS)
n=p*q
cnt=2
s_time=time.time()