Re: arc4random - are you sure we want these?

From: Paul Eggert <eggert@cs.ucla.edu>
To: libc-alpha@sourceware.org, linux-crypto@vger.kernel.org
Subject: Re: arc4random - are you sure we want these?
Date: Sat, 23 Jul 2022 17:18:05 +0000	[thread overview]
Message-ID: <555f2208-6a04-8c3c-ea52-41ad02b33b0c@cs.ucla.edu> (raw)
In-Reply-To: <Ytwg8YEJn+76h5g9@zx2c4.com>

On 7/23/22 09:25, Jason A. Donenfeld via Libc-alpha wrote:
> it's hard to recommend that anybody really use these functions.
> Just keep using getrandom(2), which has mostly favorable semantics.

Yes, that's what I plan to do in GNU projects like Coreutils and Emacs.

Although I don't recommend arc4random, I suppose it was added for 
source-code compatibility with the BSDs (I wasn't involved in the decision).

> is there anyway that glibc can *not*  do this, or has that
> ship fully sailed

It hasn't fully sailed since we haven't done a release.

> it's fun to make a random number generator, and so lots
> of projects figure out some way to make yet another one somewhere
> somehow.

That's a bit harsh. Coreutils still has its own random number generator 
because it needed to be portable to a bunch of platforms and there was 
no standard. Eventually we'll rip it out but there's no rush. Having 
written much of that code I can reliably assert that it was not fun.