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Because Theodore Ts'o, a major Linux contributor and maintainer, created and maintains /dev/random and blocks attempts to make it nonblocking like every other c

Because Theodore Ts'o, a major Linux contributor and maintainer, created and maintains /dev/random and blocks attempts to make it nonblocking like every other cryptographically secure random source. It's a political problem, not a technical one. See https://news.ycombinator.com/item?id=6550256 https://news.ycombinator.com/item?id=6550256 for a much longer argument about it.

matbess 8y ago
I suspected that “politics” was going to end up being the answer to my question. Simply because this seems to be a very contentious issue, even if it doesn’t need to be. Edit: Thanks for the link!
kragormonkey 8y ago
I don't see how this is political. In that link he presents actual problems that have arisen from non-blocking versions. I'd call that a technical justification. I don't necessarily agree with his justification, but that's also a difference in technical opinion. The only way I'd fault him is if I can come up with a an approach that addresses his concerns yet he still refuses to accept them. Full disclosure: I've actually interacted with him on a few occasions. IMO calling him risk/change-averse would be an understatement, which partly explains this stance. While at times frustrating for us, this is exactly the quality you want in someone maintaining such a critical part of the kernel.
John_KZ 8y ago
Why should it be made non-blocking? If you want a large string with little entropy just use /dev/urandom. The political/dogmatic argument is that is should be made non-blocking. The process of acquiring entropy in typical computers is definitely blocking.
- tptacek 8y ago
  What does "acquiring entropy" mean here? There is no reason a properly seeded CSPRNG should ever need to block.
  - John_KZ 8y ago
    I don't think you understand how CSPRNGs work.
    - tptacek 8y ago
      Do go on.
acqq 8y ago
And what is the current state of /dev/urandom on Linux? Does it finally block on cold start with too little entropy? If it does, then effectively everybody can finally just use /dev/urandom, if I understand it correctly? If it's still not blocking, it seems that still the best thing to do is using getrandom( ..., 0 )?

matbess 8y ago

I suspected that “politics” was going to end up being the answer to my question. Simply because this seems to be a very contentious issue, even if it doesn’t need to be. Edit: Thanks for the link!

kragormonkey 8y ago

I don't see how this is political. In that link he presents actual problems that have arisen from non-blocking versions. I'd call that a technical justification. I don't necessarily agree with his justification, but that's also a difference in technical opinion. The only way I'd fault him is if I can come up with a an approach that addresses his concerns yet he still refuses to accept them. Full disclosure: I've actually interacted with him on a few occasions. IMO calling him risk/change-averse would be an understatement, which partly explains this stance. While at times frustrating for us, this is exactly the quality you want in someone maintaining such a critical part of the kernel.

John_KZ 8y ago

Why should it be made non-blocking? If you want a large string with little entropy just use /dev/urandom. The political/dogmatic argument is that is should be made non-blocking. The process of acquiring entropy in typical computers is definitely blocking.

tptacek 8y ago
What does "acquiring entropy" mean here? There is no reason a properly seeded CSPRNG should ever need to block.
- John_KZ 8y ago
  I don't think you understand how CSPRNGs work.
  - tptacek 8y ago
    Do go on.

acqq 8y ago

And what is the current state of /dev/urandom on Linux? Does it finally block on cold start with too little entropy? If it does, then effectively everybody can finally just use /dev/urandom, if I understand it correctly? If it's still not blocking, it seems that still the best thing to do is using getrandom( ..., 0 )?