Physical Interfaces: USB, NFC, Apple Lightning®¶
We refer to the ways that a computer, phone, tablet, etc. can connect with a YubiKey as the physical interfaces.
All of the models in the YubiKey 5 Series provide a USB 2.0 interface, regardless of the form factor of the USB connector. The YubiKey will present itself as a USB composite device in addition to each individual USB interface.
The USB PID and iProduct string changes depending on which of the USB interfaces are enabled. They are described in the YubiKey USB ID Values guide.
For more information, see Understanding the USB Interfaces.
The YubiKey 5Ci introduced support for Apple Lightning®. The YubiKey 5Ci presents itself as an Apple iOS peripheral. It is able to interact with:
- Any iOS app utilizing the Yubico YubiKey iOS SDK
- Any app input data field via touch-triggered OTP.
- Any WebAuthn compliant appliction (starting in iOS 13). This includes the Safari browser.
All features of the YubiKey 5 are supported over Lightning®, including FIDO2, PIV, OpenPGP, OATH and OTP.
When connecting the YubiKey 5Ci via Lightning®, the interfaces enabled setting is common to both USB-C and Lightning®. Enabling or disabling an interface will apply to both connections.
Like the USB interface, the YubiKey 5Ci communication over Lightning® will also use a variety of channels for communication between iOS and the YubiKey.
Developers: for apps within iOS to be able to use advanced protocols that send and receive information from the YubiKey 5Ci, the Yubico SDK is required (the Yubico iOS SDK can be accessed at https://github.com/YubicoLabs/yubikit-ios) and the app registered with Yubico. This can be done via the Yubico iOS SDK App submission page.
The USB and iProduct string when connecting via Lightning® is described in the YubiKey USB ID Values guide.
In addition to USB, the YubiKey 5 NFC and YubiKey 5C NFC also provide an NFC wireless interface. The YubiKey 5 NFC and YubiKey 5C NFC include the RFID standard specific to the ISO/IEC 14443-A and ISO/IEC 14443-4 NFC format; RFID implementations not included in the listed ISO standards are not supported.
The NDEF URI has been updated to a new format; an example of the new format is provided below. The
<OTP> value is replaced with the OTP generated by the YubiKey.
For operations that require a touch, all touch requests within the first 20 seconds of the operation will succeed. After a period of inactivity, a YubiKey placed on a desktop NFC reader may power down to help prevent unintended access. To regain connectivity with an NFC reader, remove the YubiKey from the reader and reposition it on the reader. Some NFC readers may power-cycle and in doing so, prevent the YubiKey from powering down.