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Comment by notpushkin | Hacker News Reader

I know I’m asking for too much, but.

The macOS app Secretive [1] stores SSH keys in the Secure Enclave. To make it work, they’ve selected an algorithm supported by the SE, namely ecdsa-sha2-nistp256.

I don’t think SE supports PQ algorithms, but would it be possible to use a “hybrid key” with a combined algorithm like mlkem768×ecdsa-sha2-nistp256, in a way that the ECDSA part is performed by the SE?

[1]: https://github.com/maxgoedjen/secretive

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The notice at stake is about key agreements (aka KEX aka Key Exchange), not about the keys themselves.

If you look at http://mdoc.su/o/ssh_config.5#KexAlgorithms and http://bxr.su/o/usr.bin/ssh/kex-names.c#kexalgs, `ecdsa-sha2-nistp256` is not a valid option for the setting (although `ecdh-sha2-nistp256` is).

Ohh, this is distinct from the pubkey algorithms. Looks like I need a refresher on how SSH works then :-)

Thanks!

https://www.openssh.com/legacy.html - Legacy algorithms in OpenSSH, which explains a little what they do. Then there is also your Identity key that you authenticate yourself with, which is placed in the servers authorized_keys.

To comment on the part about what keys Secretive uses, I looked at this recently and I think it looks like the SE will be able to do ML-KEM soon.

https://developer.apple.com/documentation/cryptokit/secureen...

Not totally sure that I'm reading it right, since I've never done MacOS development before, but I'm a big fan of Secretive and use it whenever possible. If I've got it right, maybe Secretive can add PQ support once ML-KEM is out of beta.

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