On 5/26/2023 4:38 AM, J.Witvliet--- via users wrote:
-----Original Message-----
From: Jeffrey Walton <noloader(a)gmail.com>
Sent: Friday, May 26, 2023 4:20 AM
To: Community support for Fedora users <users(a)lists.fedoraproject.org>
Subject: Re: randomization
On Thu, May 25, 2023 at 9:18 PM Bill Cunningham <bill.cu1234(a)gmail.com> wrote:
> How would you access randomization at the system level? No via
> srand or rand, but the randomization the system offers through
> /dev/random. Would this be a fedora level system call ?
>
> I intend to take a 512 or 1024, for example, size chunk and fill
> that with system randomization. Not what you get with srand and rand I
> believe they are inferior to system randomization.
You should use /dev/urandom nowadays, not /dev/random. According to Theodore Ts'o on
the Linux Kernel Crypto mailing list, /dev/random has been deprecated for a decade.
From Re: [RFC PATCH v12 3/4] Linux Random Number Generator:[1]
Practically no one uses /dev/random. It's essentially a deprecated interface; the
primary interfaces that have been recommended for well over a decade is /dev/urandom, and
now, getrandom(2).
There is a difference between random and urandom, mainly the "quality of it
randomness"
Especially when doing crypto related tasks (VPNs) on a virtual machine, you might find
that your entropy pool is small and easiliy depleted.
In such cases, reading from /dev/random will block (bad), but reading from /dev/urandom
get bad quality (perhaps even worse)
However, there are ways to replenish the entropy buffer...
That leads me to the idea of haveged. I have my system set up to ctivate it manually. My
question was about a C related function originally, that would provide powerful
randomness, but this is very interesting. Has anyone actually used haveged?
B