While Yubico has a security key that plugs into your iPhone via Lightning, the app also supports NFC YubiKeys now.
Instead of storing the time-based one-time passcodes on a mobile phone or computer, Yubico Authenticator generates and stores one-time codes on the YubiKey. A user must present their physical key in order to receive the code for login. This not only eliminates security vulnerabilities associated with a multi-purpose computing device, but also offers an added layer of convenience for users that work between various machines.
Check It Out: Yubico Authenticator iOS App Now Supports NFC
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