Hi, I have a question how would i use boost to generate a 160 bit random integer. Heres the random number generator i wrote thanks to some of the boost community help. #ifndef RANDOM_NUMBER_HPP #define RANDOM_NUMBER_HPP #include <boost/random/shuffle_output.hpp> #include <boost/random/mersenne_twister.hpp> #include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> #include <Windows.h> #ifdef _linux_ #include <boost/nondet_random.hpp> #endif #include <boost/cast.hpp> // credit and thanks to Andrew Holden for help on this. namespace Random { typedef boost::kreutzer1986 base_generator_type; // typedef boost::mt19937 base_generator_type; typedef boost::uniform_int<> distribution_type; typedef boost::variate_generator<base_generator_type&, distribution_type> gen_type; // boost::random_device nondet_generator; //Declare the generator as a global variable for easy reuse #ifdef __linux__ boost::random_device dev; base_generator_type generator(dev()); #else base_generator_type generator(GetTickCount()); #endif /*************************************************** * initializes the random number generator * **************************************************/ void initialize() { for (int i = 0; i < 900; ++i) { #ifdef __linux__ generator.seed(dev()); #else generator.seed(GetTickCount()); #endif } } /*************************************************** * generates a random number between a and b * * @param a the starting range * * @param b the integer ending range * * @return N such that a <= N <= b * **************************************************/ template <class T> T randint (const T& a, const T& b) { //Check the parameters BOOST_STATIC_ASSERT(boost::is_integral<T>::value); assert (b >= a); //Set up the desired distribution gen_type ran_gen(generator, distribution_type(a, b)); //Get a random number return ran_gen(); } } #endif /* RANDOM_NUMBER_HPP */ Heres a code to generate random prime number. /*************************************************** * n <- random number with num_digits digits * * if n is even then n = n + 1; * * while is_prime(n, 150) * * { * * n = n + 2; * * } * * return n; * ***************************************************/ template <typename T> T boost::random_prime(boost::function<bool(const T&, const T&)> f, const unsigned int& num_digits) { BOOST_STATIC_ASSERT(is_integral<T>::value); T n(Random::randint<T>(numeric_cast<T>(pow(2.0, num_digits - 1)), numeric_cast<T>(pow(2.0, num_digits))) ); if (n%2 == 0) { ++n; } while (f(n, 20)) { n += 2; } return n; } now num_digits is number of bits. If i pass 160 bit as like for DSA algorithm the program crashes. I pass 8 and it works, how come? Is there a better way to do this? Oh f is any function that can deteremine if a number is most likely a prime or not.... Thanks.