[OneRNG-Discuss] Debian 12 kernel ignoring entropy from OneRNG?

[Jim Cheetham]

Well, we're going to have to read the current kernel sources to work that out :-) and that's much further into the details than I'm used to going!

However, there are good comments all over the code ... I think I can understand those ...

https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/tree/drivers/char/random.c#n1352

> "Writing to either /dev/random or /dev/urandom adds entropy to the input pool but does not credit it."

The overview tells us about the input pool :-
> "The high level overview is that there is one input pool, into which various pieces of data are hashed. Prior to initialization, some of that data is then "credited" as having a certain number of bits of entropy. When enough bits of entropy are available, the hash is finalized and handed as a key to a stream cipher that expands it indefinitely for various consumers. This key is periodically refreshed as the various entropy collectors, described below, add data to the input pool."

I haven't managed to be confident that I've found the actual code that adds entropy into the input pool when the device files are written to, however. 

-- 
  Jim Cheetham
  jim at cheetham.nz

On Fri, 15 Mar 2024, at 9:15 AM, Andy Smith wrote:
> Hi,
>
> On Thu, Mar 14, 2024 at 08:03:40PM +0000, Denis BEURIVE wrote:
>> Just in case it may help, I have written notes about using ONERNG on Ubuntu 21.10:
>> 
>> https://github.com/denis-beurive/onerng-notes
>
> Do we know if modern Linux kernels do make any use of entropy that
> rngd feeds into /dev/random?
>
> Thanks,
> Andy
>
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