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Comment by arunc | Hacker News Reader

FWIW, none of the major cloud providers support ed25519. It's 2020 and no one seems to care about it.

AWS won’t let me add an ED25519 SSH key, but Google Cloud Platform does and it seems to work. YMMV.

(I have no idea why AWS won’t let you do this. I am pretty sure it just passes the SSH key to the VM and that it just writes it to authorized keys by default. But at least in the UI, it doesn’t seem to validate whereas RSA keys do...)

Github suggests it in their docs[1] which I can confirm works as I just added one today. A coworker added my ed25519 key to a DigitalOcean server today as well, and I successfully ssh-ed in with no issue.

Gitlab has not only allowed it but recommended it for several years now iirc. I'm now in the habit of generating ed25519 keys for all of my ssh hosts.

For TLS certificates? That's because none of the CAs support it.

For TLS certs, you can just use ECDSA. Let's Encrypt has a ECDSA root.

ECDSA has some bad footguns as well. I don't see why you'd consider ECDSA to be any more robust than RSA if we're talking about certificates keys for TLS.

EdDSA is better, but is in general not yet supported in the WebPKI (browsers, BRs). I did manage to successfully use it for an internal mTLS setup though, so I think it's only going to be a matter of time.

The point isn't "good crypto must not have footguns", it's "RSA has so many footguns, that we as a community should stop silently accepting uses of it".

For SSH, I’d guess.

Yes, for managed systems (meaning not a SSH inside a VPS), at least I'm sure that both AWS and Azure does not support other standards (no experience on GCP).

That particular curve is less popular. Do they support NIST P-521?

Stop using them. SSH-RSA is deprecated in OpenSSH since a few versions now.

What is deprecated in OpenSSH is not all of RSA in OpenSSH. They've deprecated "ssh-rsa", but there is still e.g., rsa-sha2-256. These describe the algorithms used in key exchange; ssh-rsa uses SHA-1. This is separate from the types of public/private keys, which is what parent is describing.

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