Tom Lane <tgl@sss.pgh.pa.us> writes:
> David CARLIER <devnexen@gmail.com> writes:
>> I m not against as such that depends of the implementation but I ve seen in
>> quick glance it s RC4 ?
arc4random uses ChaCha20 since OpenBSD 5.5 (and libbsd 0.8.0 on Linux).
It uses getentropy(2) to seed itself at regular intervals and at fork().
http://man.openbsd.org/arc4random.3
> More generally, why should we bother with an additional implementation?
> Is this better than /dev/urandom, and if so why?
If what is wanted is something more like /dev/urandom, one can call
getentropy(2) (or on Linux, getrandom(2)) directly, which avoids having
to open the device file each time.
http://man.openbsd.org/getentropy.2
https://manpages.debian.org/stretch/manpages-dev/getrandom.2.en.html
- ilmari
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"The surreality of the universe tends towards a maximum" -- Skud's Law
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