XORing numbers does decrease entropy to the extent that there is correlation between the numbers. But you're correct that you can accumulate entropy by taking p

XORing numbers does decrease entropy to the extent that there is correlation between the numbers. But you're correct that you can accumulate entropy by taking poorly-random streams and XORing them, as long as they are independently poorly-random. In cases where they might be non-independent, a simple hash function like even the otherwise broken MD5 would be better at combining them than XOR. But of course, we're now three steps down the path of constructing our own replacement for what the kernel and/or OpenSSL should be doing for us already.