Re: Post-quantum defaults

"Robert J. Hansen via Gnupg-users" <[email protected]> Mon, 6 Apr 2026 23:47:08 -0400
Newsgroups	gmane.comp.encryption.gpg.user
Message-ID	<[email protected]>
> The issue I see here is that these seem to be specialized for elliptic 
> curve cryptosystems.  In other words, the "free lunch" of shorter keys 
> and better performance by using the more-complicated mathematics of 
> elliptic curves instead of the general integers is going away.

Yes. But attacks only get better over time: they don't get worse. If the 
current defaults of ECC keypairs are at threat, and our original 
projection for RSA-2048 was it would be safe only until 2030 or so (see 
the GnuPG FAQ, section 11.2), then the solution is not to go back to 
RSA-2048 but to find something with long-term prospects. That would seem 
to be Kyber, not RSA-4096.

> This is almost *exactly* what I expected and is the concern that I have 
> long had with EC cryptosystems:  the shorter ECC keys will fall to 
> quantum computing long before the longer RSA keys will.

Perhaps.

I have to say it all feels so very intensely surreal. As an undergrad in 
1993 I read every crypto paper I could get my hands on, and back then 
the tantalizing hot new thing in crypto was elliptical curves. They were 
conjectured to be strong but they relied on the unproven 
Taniyama-Shimura conjecture, which everyone thought was true but nobody 
knew how to solve.

Then around 1995, Andrew Wiles proved Taniyama-Shimura (and, in the 
course of doing so, Fermat's last theorem). ECC was now on 
mathematically rigorous ground. It was a time of great upheaval and 
everyone was eager to get on the ECC bandwagon and ...

Yow. Heady times. Seriously, you have no idea how big of a thing it was 
unless you were there.

Now, thirty years later and approaching the end of my career, I'm seeing 
the end of ECC. The last time I mentioned Taniyama-Shimura, the younger 
cryptologists I was conversing with looked at each other confused until 
another graybeard explained "it's what we used to call what they now 
call the 'modularity theorem'."

I felt like an idiot. Of course nobody calls it Taniyama-Shimura any 
more. It's no longer a conjecture, after all.

Sigh. Sic transit gloria mundi…

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