Truly random number generator

Question

From what I understand PRNG uses a seed that generates a sequence of numbers that is not truly random. Would it be possible to create a truly random number generator by reusing PRNG over and over with different seeds each time it is used. The seed could be extracted from dev/random or the current time or clock tick. If not then is there a truly random number generator implemented in software?

Thanks

Answer 1

If you re-seed the PRNG every time you need a random number you can just cut out the middle man and use the seed directly as random number.

But what you're talking about is done in practice. Those are so-called cryptographically-secure PRNGs and they are employed in many operating systems to provide random numbers for cryptographic applications. They get re-seeded frequently from the entropy pool and are designed so that it is computationally very hard to figure out the next number from knowing past ones (something that's very trivial to do for an LCG, for example) and also to figure out past numbers from the current one.

The benefot of this approach is that you don't block generating random numbers. Entropy in a system is a limited resource and can only come from outside sources, so by using a CSPRNG you can safely stretch it and not compromise security at the same time.

Answer 2

The simple answer is that there is no such implementation because, as far as I know, it's simply not possible. To generate truly random numbers you need an outside source of entropy like a hardware random number generator.

Answer 3

The clock is not very random, but /dev/random has some randomness - it's actually like a bucket of randomness that you can deplete depending on the rate of randomness production and consumption. If you use dev/random, then you don't have use an RNG. Seeding an RNG from /dev/random is redundant.

Answer 4

Intel is working on something that could be truly groundbreaking if it works as advertised. It would practically render hardware PRNGs redundant.