How does Python generate random numbers?

Question

I understand that I should use os.urandom() or SystemRandom in Python for 'secure' pseudo-random numbers.

But how does Python generate these random numbers logically?

Also is there a way to generate a number in Python that is 'more random' than others?

I've answered a very similar question as this in great detail(It covers both Random and SystemRandom). ANSWER LINK — Blastosphere
– Blastosphere, Commented Jul 25, 2019 at 3:05

Wyzard · Accepted Answer · 2014-10-07 15:59:31Z

7

For "secure" random numbers, Python doesn't actually generate them: it gets them from the operating system, which has a special driver that gathers entropy from various real-world sources, such as variations in timing between keystrokes and disk seeks.

answered Oct 7, 2014 at 15:59

Wyzard

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16 Comments

ruben_KAI Over a year ago

How can we be sure that these are truly random events? And would you happen to know what the driver is called?

Wyzard Over a year ago

It depends on the operating system. For Linux, read about /dev/random and /dev/urandom.

ruben_KAI Over a year ago

Thanks! I'll come back to upvote once I get the rep - lol. What about Windows?

Tony Suffolk 66 Over a year ago

Can you predict exactly the time to the next key press, or which key that will be, or when the next disk seek will happen, or how long it will take - all of these are essentially unpredictable (even with physical access to the machine) so they can be used to generate a random number - so long as they are combined in a way that maintains their key characteristics - that is what things like /dev/random does.

Wyzard Over a year ago

@BillalBEGUERADJ, the documentation for os.urandom explains exactly how it gets random data from the OS, and the documentation for SystemRandom says that it calls os.urandom. As for how the OS gets the data, you can read about how /dev/random and /dev/urandom work.

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