The key word is actually conservative, as in conservative estimate.
Conservative here means less than or equal to.
> And yes, it still mixes in the random data, but since it doesn't account
> for the randomness, that only helps /dev/urandom.
> And helping /dev/urandom is _fine_. Don't get me wrong. It just doesn't
> make /dev/random any more useful - quite the reverse. Your patch will just
> make more people say "/dev/random isn't useful, use /dev/urandom instead".
No, it says /dev/random is primarily useful for generating large
(>>160 bit) keys.
> Do you not see the fallacy of that approach? You're trying to make
> /dev/random safer, but what you are actually _doing_ is to make people not
> use it, and use /dev/urandom instead. Which makes all of the estimation
> code useless.
> THIS is my argument. Randomness is like security: if you make it too hard
> to use, then you're shooting yourself in the foot, since people end up
> unable to practically use it.
Actually, half of the point here is in fact to make /dev/urandom safer
too, by allowing mixing of untrusted data that would otherwise
compromise /dev/random. 99.9% of users aren't using network sampling
currently, after these patches we can turn it on for everyone and
still sleep well at night. See?
> The point of /dev/random was to make it _easy_ for people to get random
> numbers that we can feel comfortable about. The point of the accounting is
> not a theoretical argument, but a way to make us feel _comfortable_ with
> the amount of true randomness we're seeding in. It was not meant as a
> theoretical exercise.
That is an interesting point. A counterpoint is if we account so much
as 1 bit of entropy per network interrupt on a typical system, the
system will basically _always_ feel comfortable (see
/proc/interrupts). It will practically never block and thus it is
again identical to /dev/urandom.
With my scheme, it's usefully distinguished from /dev/urandom for the
purposes of things such as one-time public key generation.
See my note to RML about who actually uses it currently.
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