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Cryptography doesn't depend on random numbers for its random seed. It depends on unpredictable numbers. These are not the same thing. As long as no-one can pre
by jfindley 6y ago
Cryptography doesn't depend on random numbers for its random seed. It depends on unpredictable numbers. These are not the same thing. As long as no-one can predict what the next number will be it doesn't matter how "random" they are. TFA is sufficiently vague it's unclear if the author understands this.
The more I read it, the more confused the article appears to be (e.g. mersenne twister is NOT a good example of a modern or high quality PRNG). For more about secure random numbers in Linux, I'd suggest reading [0].
0: https://buttondown.email/cryptography-dispatches/archive/cryptography-dispatches-the-linux-csprng-is-now/ https://buttondown.email/cryptography-dispatches/archive/cry...
- UncleMeat 6y agoI wouldn't be so universal with this statement. Some cryptosystems really do need uniform randomness (ECDSA) rather than just negligible probability of choosing values. Other cryptosystems depend on not reusing values, though the values could be predictable. Sometimes there are subtle shifts in these needs based on modes (AES/CBC vs AES/GCM is a good example).
- jfindley 6y agoThanks for the comment, yes I should have phrased that very differently. What I was trying to say is that the kernel CSPRNG (exact mechanism depends on version) mixes together a bunch of things that aren't truly random from an information-theoretical perspective in order to produce uniform random output from the CSPRNG function - and that it doesn't actually matter that those sources aren't information-theoretically random. That'll teach me to comment in haste!