Trezor as 2FA-device


If I use my Trezor as 2FA-device and loosing it. Will I be able to restore on a new Trezor with my recovery seed or do I have to reset my account that uses my lost device?


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Hi @u3952,

if you lose your device, you can restore your recovery seed in another Trezor and continue using the new device as your 2FA. No need to reset accounts.

That’s great news to hear as I was researching on this topic. If this is true, it makes trezor a better u2f device than yubikey imo !
That said, could you explain why it would work even if some services uses a counter as is written on trezor’s website titled “what-is-u2f”

How can a new trezor know how many times the previous (lost) trezor has counted on certain services, given that the only info it has is the seed?

We use clever hack: The Trezor U2F counter is set to the Unix timestamp value (number of seconds since 1.1.1970) on restoration. U2F standard mandates that each value should be bigger than the previous one, but it does not have to be immediately following the previous value. That’s why this trick works.