Re: [PATCH 1/2] wrapper: add a helper to generate numbers from a CSPRNG

["brian m. carlson" <sandals@crustytoothpaste.net>]

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On 2021-11-17 at 07:39:08, Junio C Hamano wrote:
> "brian m. carlson" <sandals@crustytoothpaste.net> writes:
> 
> > Finally, add a self-test option here to make sure that our buffer
> > handling is correct and we aren't truncating data.  We simply read 64
> > KiB and then make sure we've seen each byte.  The probability of this
> > test failing spuriously is less than 10^-100.
> 
> I saw that 10^-100 math in the other message, and have no problem
> with that, but I am not sure how such a test makes "sure that our
> buffer handling is correct and we aren't truncating data."  If you
> thought you are generate 64kiB of random bytes but a bug caused you
> to actually use 32kiB of random bytes with 32kiB of other garbage,
> wouldn't you still have enough entropy left that you would be likely
> to paint all 256 buckets?

True, but our code processes smaller chunks at a time, which means that
theoretically we'd notice before then.  For example, getentropy(2) won't
process chunks larger than 256 bytes.

If we don't think there's value, I can just remove it.

> I also agree with Peff's comment about making these look as if many
> of them can be specified at once, when only one of them would
> actually be in effect.  Giving one Makefile macro that the builder
> can set to a single value would be much less confusing.

I can use one Makefile macro, sure.  I think we'll still need multiple
macros for the actual C code because we can't really do a string
comparison in the C preprocessor.
-- 
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA

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