Biometrics

[dbosk]

To ensure freshness we need challenge--response. Thus to make biometrics secure (i.e. authenticated) we need challenge--response: we give a challenge to the biometric sensor, which incorporates the challenge into the reported data. It's crucial that you cannot take this challenge and just process it with previously recorded data.

[dbosk]

If the system that wants to authenticate someone has an incorporated device, then freshness is ensured. Then security depends on unclonability of the biometric.