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- ///////////////////////////////////////////////////////////////
- // Copyright 2012 John Maddock. Distributed under the Boost
- // Software License, Version 1.0. (See accompanying file
- // LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
- //[safe_prime
- #include <boost/multiprecision/cpp_int.hpp>
- #include <boost/multiprecision/miller_rabin.hpp>
- #include <iostream>
- #include <iomanip>
- int main()
- {
- using namespace boost::random;
- using namespace boost::multiprecision;
- typedef cpp_int int_type;
- mt11213b base_gen(clock());
- independent_bits_engine<mt11213b, 256, int_type> gen(base_gen);
- //
- // We must use a different generator for the tests and number generation, otherwise
- // we get false positives.
- //
- mt19937 gen2(clock());
- for(unsigned i = 0; i < 100000; ++i)
- {
- int_type n = gen();
- if(miller_rabin_test(n, 25, gen2))
- {
- // Value n is probably prime, see if (n-1)/2 is also prime:
- std::cout << "We have a probable prime with value: " << std::hex << std::showbase << n << std::endl;
- if(miller_rabin_test((n-1)/2, 25, gen2))
- {
- std::cout << "We have a safe prime with value: " << std::hex << std::showbase << n << std::endl;
- return 0;
- }
- }
- }
- std::cout << "Ooops, no safe primes were found - probably a bad choice of seed values!" << std::endl;
- return 0;
- }
- //]
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