Efficiently generating random bytes of data in C++11/14

Question

My requirement is to generate random bytes of data (not random numbers) aka uniformly distributed bits.

As such I was wondering what are the correct/efficient w

Answer 1

What you're looking for is the std::independent_bits_engine adaptor:

#include 
#include 
#include 
#include 
#include 

using random_bytes_engine = std::independent_bits_engine<
    std::default_random_engine, CHAR_BIT, unsigned char>;

int main()
{
    random_bytes_engine rbe;
    std::vector data(1000);
    std::generate(begin(data), end(data), std::ref(rbe));
}

Note that the accepted answer is not strictly correct in a general case – random engines produce unsigned values belonging to a range [min(), max()], which doesn't necessarily cover all possible values of the result type (for instance, std::minstd_rand0::min() == 1) and thus you may get random bytes that are not uniformly distributed if using an engine directly. However, for std::random_device the range is [std::numeric_limits::min(), std::numeric_limits::max()], so this particular engine would also work well without the adaptor.