I prefer security keys. At work I use a yubikey, and I have Google’s security keys for my personal stuff. I tend to use totp as a backup.

For everything not banking, it’s great, I agree. I still prefer my security keys to everything. It’s hard to duplicate a digital key when it only exists on protected storage on a physical device, where that key never exists outside of that physical device.

In case anyone doesn’t know: FIDO works using a pair of asymmetric digital keys, the public key is sent to the remote site, and only the private key can decrypt anything encrypted by the public key. So a challenge (usually some mathematical calculation, not sure), is encrypted by the site/service that is handling the login, it sends over the encrypted request, which is passed, in it’s entirety to the fob. The fob requires a physical activation to process the challenge (usually a touch, but some require a fingerprint). The challenge is then decrypted, processed, the response is encrypted, and sent to the site for login, which decrypts the response with the public key, and compares the result to the result of the challenge that was sent.

There’s no part of this that can really be compromised. An eavesdropper can obtain the encrypted challenge (unable to be decrypted in any reasonable manner), and the response/public key… The public key isn’t useful, and the response is only valid for that specific login because there are aspects of the challenge that are unique per login.

All information in flight is unreadable nonsense. The only unique information to the key that is sent anywhere is the public key, which is supposed to be public.

Totp has the vulnerability of needing to relay the seed, usually by QR code. The only vulnerability there is when you set it up and the seed is shared to you, it can be intercepted. If that seed is stored anywhere that becomes compromised, then it becomes meaningless. It can be mined from an authenticator, or captured in flight.

Both of these are better than alternatives. Email/sms codes can be intercepted, either by an administrator or by an internet relay, or by sim duplication, etc. You know that already.

I don’t hate totp, I just recognize the faults in it.

There’s problems with physical security keys too, mainly in the fact that, if you lose the fob, you’re screwed. So it’s recommended to have a backup. Either in the form of a second fob, which is setup for all the same accounts which is stored securely, or in the form of another authentication method like totp.

Personally, I use a backup FIDO key for my accounts whenever possible. I also have a password manager that can store my totp so everything is in a single vault. If the vault is compromised then I’m screwed though… 90% of my accounts use a password reset email which is not stored in my vault. Only two things are not in my manager: that recovery email login (secured by my Fido key) and my bank (obviously also the vault login).

At work, I use the yubikey for everything that supports it, with totp as backup in my work’s duo authenticator account (duo is also setup to use my yubikey). So it’s all Fido/totp.

The only service I really want to use my security keys with that doesn’t support it, is my bank account… I suppose, also my government stuff, but almost all of that is informational. I can’t really make changes to my government stuff from their webpages. It’s generally just the government telling me things about my tax returns and whatnot (all SMS secured).

I hate the trend of companies requiring an app for 2FA… Something that’s not totp, but similar. You have a specific authenticator app for a single service on your phone only and it’s not great… Obvious examples include steam and Blizzard. Fuck that. I hate it. Go away. Give me normal MFA options… Dick.

I’ve ranted enough. Back to work for me.