backporting sntrup761x25519-sha512 key exchange to OpenSSH 8.9-9.8

[Damien Miller]

On Tue, 12 Aug 2025, Colin Watson wrote:

> On Tue, Aug 12, 2025 at 09:42:02AM +1000, Damien Miller wrote:
> > If you are a maintainer for OpenSSH in a LTS operating system, please
> > consider including this change, cherrypicked from the relevant branch
> > for the OpenSSH release you ship (e.g. from the V_9_0 branch for
> > OpenSSH 9.0). Please let me know if there is anything I can do to
> > assist.
> 
> I was going to do this for Debian 12 (bookworm) which is the only affected
> Debian release, but then realized that I already did it in December 2024 and
> forgot about it. :-)
> 
>   https://bugs.debian.org/1088873

Well done :)

> Any reason you didn't include the documentation changes from
> https://anongit.mindrot.org/openssh.git/commit/?id=aee54878255d71bf93aa6e91bbd4eb1825c0d1b9
> as well?  Encouraging distributors to keep that in sync seems like a good idea
> (and when I cherry-picked the new alias into Debian I included the
> documentation changes).

Good point, I've done so now.