Is there a way to call the MS Excel =RAND() function from an external programme, like a c++ programme, for example?

I am trying to find a more reliable Random Number Generator than the c++ rand(). I am writing an encryption programme that, of course, needs random prime numbers to function properly. I have found that excel does a decent job in generating random numbers (at least it seems that way, at a first glace, in comparison to the standard c++ rand()). Any pointers, suggestions?