[CFRG] Re: Silithium - A Compact, Efficient and Non-separable Hybrid Signature

[Ilari Liusvaara <[e-mail]>]

On Thu, Jul 16, 2026 at 08:16:48AM +0000, John Mattsson wrote:
> On 2026-07-16, 08:57, "Simon Josefsson" <simon=[e-mail]> wrote:
> 
> >I believe the point of using hybrids is to continue using old crypto as
> >a black-box in parallel with new crypto, in a safe way. A hybrid that
> >doesn't re-use traditional crypto as a black box seems esoteric to me.
> 
> There seem to be different opinions about the purpose of hybrids. The
> more obsolete cryptographic components PQ/T hybrids rely on, the more
> important it is to enable a migration path for removing those
> components once they become pure overhead and no longer provide
> meaningful security. In my view that will happen sometime around 2035.

I think hybrids are about relying on multiple cryptographic assumptions
as alternatives to each other. Hybrids can be inseparable into black-box
components, and there exists problems that are inherently inseparable
(not admitting a black-box solution, even if overall solution exists or
is even known).

There are costs and benefits for breaking a black box. All the former
contets of the black box become complexity. But the black box itself is
no longer around to cause problems.




-Ilari