If you only want first-party, you can presumably implement the spec yourself and do whatever you want with the data?

My example was only to point out that there exist self-hostable passkey providers.

Do you use the same SSH keys on multiple devices? I certainly don't. If you need or wanted to (you don't) you'd need some way to sync them across multiple devices securely.

When I use passkeys on a single device, the "provider" is the OS, same as with my SSH keys.

> Do you use the same SSH keys on multiple devices?

Yes. For example, when upgrading or reinstalling a system

> If you need or wanted to (you don't) you'd need some way to sync them across multiple devices securely.

`scp -r`

> the "provider" is the OS, same as with my SSH keys.

And you have full access to ~/.ssh and you can move copy update rename delete them however you like. Without a "Credential Exchange Protocol (CXP) and Credential Exchange Format (CXF)" to move between blackboxes of third-party providers

> And you have full access to ~/.ssh and you can move copy update rename delete them however you like.

I think this comes down to me never having wanted to do a copy or move (I create and maintain new keys when I create new devices) which is exactly the same experience i get with a passkey (and is, generally a more secure experience since my keys cannot be exfiltrated since copying them is implicitly verboten).

> Do you use the same SSH keys on multiple devices?

Assuming you mean client devices, yes, depending on my personal relationship/control of the device. (For servers, the answer is "very yes".)

For example, my personal laptop and desktop may have the same private key, and I will backup/restore that same key onto either of them if they are reinstalled or replaced with new hardware.

However my work laptop gets its own, so that I can more-easily limit what it can access or cancel it in the future.

> Do you use the same SSH keys on multiple devices?

Yes.

> you'd need some way to sync them across multiple devices securely.

I take out my physical keychain and plug in my yubikey. Then, after typing in the password to my yubikey, I can use ssh and pgp until I unplug my yubikey. It is a hell of a lot more secure than storing your ssh keys on disk regardless of whether or not you use a unique key per device. I could lock someone in a room with my computer, my yubikey, and my password, and they still wouldn't be able to copy my ssh key.

pedantic nit: the yubikey is a device so you are arguably using one unique key per device

Haha technically true, but I don't think that was the kind of device they were referring to. Even so, it is possible to use the same key on multiple yubikeys. You generate a PGP key on a secure computer and then load that key onto multiple yubikeys. Then you use gpg as your ssh agent. But this is less secure than using keys generated on-device by the yubikey because your private key exists (hopefully temporarily) as a file on the computer where you generated it.

No this is absolutely what I meant: A passkey and a PGP key function very similarly in this capacity, a passkey for a site can be generated on a yubikey and used across devices in just the same way.

I certainly backup my SSH keys. That way if my laptop dies today, I can be up and running tomorrow without anyone else being involved.

How do I ensure I can access my accounts if my phone-containing-passkeys is lost/stolen/dies without backups?

You don't. Same as a physical key for your home, you have backups.

Whether that's having multiple separate keys/devices registered with your accounts or a single key stored in a password manager, you need to have a fallback plan.