I've been looking at the FIDO alliance's U2F specification and there's something which I can't seem to find documented.

If I was to use a Yubikey or something similar as part of the authentication when registering for a service on my desktop, how would I then be able to authenticate myself if I wanted to log in on my phone?

My understanding is that the private key would be stored on the current device when you registered and the public key would be provided to the service. This would mean that to allow me to authenticate myself on different devices I would need to copy the private key from my desktop to my phone

Is this correct or have I misunderstood something around the FIDO specification?

  • 2
    Why do you thinking that the key would be stored on the desktop at all? The point of a Yubikey is that it 'stores' everything.
    – schroeder
    Commented Feb 18, 2015 at 0:57

1 Answer 1


Nothing is stored in the Desktop in the case of USB Security Key Based FIDO U2F (Yubikey, PlugUp, HyperFIDO, IDKey, Neowave) implementation. There are other implementation (e.g. Entersekt) which are tied to the client computer.

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