That's all well and good, but a few weeks later I have another service I'm going to sign up for... I have to... first go to my safe deposit box to grab my third key? If I don't, then seems like it's a lot of bookkeeping.

Needless to say, I don't use these devices on my home depot account. I use them for Google, Github, Dropbox, I don't actually remember anything else. My DNS registrar doesn't support it :P

I also don't use my personal key for work stuff and recovering my work key is my sysadmins problem :)

That said, when I had admin accounts at work, we used TOTP with a similar scheme: when we registered important (admin) accounts we shared the second factor (the QR code) between 2 people and sometimes I printed the QR code itself. This works for AWS, gsuite, github, etc. I still receive calls from old colleges for TOTP codes occasionally :)

I actually just changed my DNS registrar to namecheap specifically because it supports U2F. I figure my domain is too important to risk losing because I use my domain for email.

You don't need to make it as elaborate as 'safe deposit box' or 'implanted into spouse' and most accounts that matter have other ways of recovery, e.g. an app-based authenticator, one-time recovery codes (a recovery code is something you might want to stick in a safe deposit box). You can just get, say, three hw keys, put one on a keychain another somewhere on your desk and a third in a drawer somewhere.

This is vulnerable to a house fire/other natural disaster. In general, I recommend having at least one thing offsite - whether that’s in a security deposit box, with a trusted friend or family member, in your desk at the office, or whatever.

'implanted into spouse'

What about steganography in tattoos? That would be pretty interesting. Perhaps combining that data with a short code or seed that you memorize.

Periodically generated seeds, encoded on actual seeds that you and your partner eat for breakfast.

I love it.

The tech exists. My neighbor works for a company that does encoding of data on packaging. Goal is that every cereal box on the grocery aisle can be individually tracked.

I do this! (but for weed) track-and-trace chains are fun!

Doesn't that mean that stealing any of the 3 yubikeys means full permanent compromise of all your and your spouse's account?

I think a good with system should include some sort of revocation, like a master key you can keep in a safe to revoke other devices.

No, it does not mean that. At least in my experience, every service where I have multiple YubiKeys registered still requires my username and password. Without those, someone who stole the YubiKey would not be able to login to my accounts.

The 2 in U2F stands for second factor, these devices are useless on their own.

You can un-register any of the keys when you're logged in. So if you lose one key, log in using the others and remove it. No need for a master key.

Your idea works well for recovery.

But I'm thinking of a revocation scenario, where a key is stolen. In that case the attacker can just remove your keys first.

So, the "something you have" element of security is to primarily avoid remote compromise. And even make local compromise require an additional theft step.

If the hacker gets your key, and your password it's game over.

But hacking the password will take some time hopefully, and systems usually have retry limits etc. so if you discover your lost key, you hopefully have some time to revoke the lost key.

I personally would not use it for password-less login, as it is only good as a second factor.

If your threat model includes any real likelihood of people capable of stealing your keys and cracking your passwords, then 2FA is only a small part of the opsec you need.

Things like NSA's Zero Trust Security model comes to mind https://news.ycombinator.com/item?id=26549363

If you're at that level, you probably need specialist infra.

But potential compromises don't mean you're not less secure than before, Yubikey would still make you more difficult to hack.

Yubikey still acts as a second factor, so for the average person's threat model this should be fine provided you use strong, unique passwords for your accounts (i.e. a password manager). 1Password supports U2F as a second factor to access your account, but you still need to know your secret key and master password; you cannot decrypt your vault with only a hardware token.

They need my password too, so they’ll have to have cracked my 1Password account as well. My third key is indeed in a safe, but it’s not special in any way.