The capabilities of the YubiKey 5 Series are dependent on the different combinations of firmware + connector type + protocol. This section covers connector types (form factors). Capabilities brought to the YubiKey 5 Series by the firmware are covered in Firmware: Overview of Features & Capabilities and in Protocols and Applications.
The YubiKey 5Ci is the first hardware authenticator of its kind with both USB-C and Lightning® connectors on a single security key. With multi-protocol capabilities that support OTP, U2F, FIDO2/WebAuthn, and Smart Card requirements, the YubiKey 5Ci provides a unified solution for secure logins on mobile and computing devices.
The YubiKey 5Ci introduced support for Apple’s Lightning® connector. All features of the YubiKey 5 are supported over Lightning®, including FIDO2, PIV, OpenPGP, OATH and OTP. The YubiKey 5Ci is the first YubiKey to roll out new feature enhancements to FIDO2 and OpenPGP. Details on the new functionality can be found in the Enhancements to FIDO 2 Support and in the Enhancements to OpenPGP Support.
Like the USB interface, the YubiKey 5Ci’s Lightning® interface also uses a variety of channels for communication between the YubiKey and iOS.
The YubiKey 5Ci presents itself as an Apple iOS peripheral. It is able to interact with:
- Any iOS app using the Yubico YubiKey iOS SDK
- Any app input data field via touch-triggered OTP.
- Any WebAuthn-compliant application (starting in iOS 13). This includes the Safari browser.
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.
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 strings that show up when connecting via Lightning® or USB are specific to the connection type. They are described in the YubiKey USB ID Values guide.
iPad and iPad Pro
For users of keys in the YubiKey 5 Series, because the iPad Pro does not have a Lightning port, support depends on what you want to do. The second part of this article covers all those aspects: Can I use my YubiKey with iPads?
From the developer perspective, support for the iPad Pro has some limitations. Consult Supporting U2F or FIDO2 Security Keys on iOS or iPadOS | Security Key Compatibility for detailed instructions on working around those limitations.
Expanding the options for quick tap-n-go authentication across desktops, laptops, and mobile devices, all of the applications - including FIDO2 - are available over NFC.
The YubiKey 5 NFC and YubiKey 5C NFC support the iPhone 7 and newer.
Background tag reading is supported in the iPhone XS and newer.
The YubiKey 5 NFC and YubiKey 5C NFC provide an NFC wireless interface In addition to USB. 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.
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.
See also Understanding the USB Interfaces.
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