3 ms·
You should read the article to answer your own question in depth. The short version is: on Linux, both /dev/random and /dev/urandom are fed from the same CSPRNG
by tjgq 13y ago
You should read the article to answer your own question in depth. The short version is: on Linux, both /dev/random and /dev/urandom are fed from the same CSPRNG. A CSPRNG only needs to be seeded with a few bits of entropy to generate a whole stream of unpredictable numbers. After the CSPRNG is seeded (at system boot) it no longer matters that you run out of entropy.
Disclaimer: I am not a cryptographer.
- Spittie 13y agoI have (actually, twice. Once when it was posted sometimes ago on HN, and once now before writing the comment). What threw me off was that part: "Still, if you insist on never handing out random numbers that are not “backed” by sufficient entropy, you might be nervous here. I'm sleeping sound because I don't care about the entropy estimate." I was missing the fact that the CSPRNG only needs to be seeded once to be safe, and reseeding is only a "nice thing" that's not really needed. To be fair, the article cover this, I guess I just didn't understand that part really well. I've got it now, and it actually make sense. Thanks to you, and everyone else that used some time to educate me.