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[Ssh] Re: PQ signatures - where do we want to end up?

Matt Johnston <matt@ucc.asn.au> Tue, 28 April 2026 15:28 UTC

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From: Matt Johnston <matt@ucc.asn.au>
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Subject: [Ssh] Re: PQ signatures - where do we want to end up?
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On Tue 28/4/2026, at 8:09 pm, Stephen Farrell <stephen.farrell@cs.tcd.ie> wrote:
> 
> Hiya,
> 
> People are starting to propose PQ signature drafts for the
> WG to consider. Before we go there, I'd like to understand
> where WG participants would like us to end up, and which of
> the bazillion options we think might actually be implemented
> and get deployed.
> 
> So, opinions on the above are welcome...

As a first option I'd be inclined to implement a hybrid ed25519 and ml-dsa (either -44 or -65),
with a combiner that is simple and adequate for SSH protocol.

Uses beyond SSH protocol are secondary - if software signing can use it then that's nice, but it shouldn't add complexity.

It might be worth specifying a ml-dsa private key format based on a seed for ml-dsa
(at a high level, even if the byte format isn't specced)?

Cheers,
Matt

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