[jazoom]

Could someone use Firefox and Chrome extension on the same device as two different devices?

[Zinggi]

Yes, but it's a very bad idea. If you'd do this, you could unlock your passwords with a single device by confirming on Firefox or vice-versa on Chrome. This of course also means that if someone steals this device, they can unlock it too.

So don't do it.

[jazoom]

Yeah. That's what I don't want. So how do you prevent someone doing just that? They have Chrome open. They then confirm setup in Firefox using Chrome on the same device.

[Zinggi]

When pairing a new device (or in this case a new browser), that device doesn't automatically get any keys! When adding a new device, to complete the setup you also have to be able to unlock a password group, for which you need another device that already has keys.

In short, a new device doesn't have the same power as the others from the start, first new keys have to be generated which can only happen if you are able to unlock your passwords.

So just don't setup both the Firefox and Chrome extension and you're golden.

[jazoom]

Ah. So you essentially need 2 devices to set up a new device.

[Zinggi]

Exactly. Or even 3 if you make use of security level 3.

The only exception is at the start when there are no passwords stored yet.

[jazoom]

That's pretty interesting. It's a trade-off between remembering a password and making sure you have enough devices. I personally would trust my brain (and a backup piece of paper) more than one of my devices that might die at any moment. I use KeePass, but NoKey seems great.