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?
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.