You plug it in your computer, place the cursor in a form field, press the button on the Yubikey, and it sends out a text string of 44 characters to the computer like you are typing those 44 characters. Since U2F is an open standard (that is also pushed by corporations like Google), there are several alternative inexpensive U2F hardware tokens available (search for ' FIDO U2F key').Īs I understand it, Yubikey acts like a USB keyboard. Using the key-handle, the U2f device is then able to sign a challenge, thus creating a response as part of a multi factor authentication. Like other inexpensive U2F devices, the private keys are not stored, instead they are symmetrically encrypted (with an internal key) and returned as the key handle.

a device that is able to generate a origin specific public/private key pair and returns a key handle and a public key to the caller.

The YubiKey U2F is only a U2F device, i.e. For example, classic hardware chipcard readers (perhaps even featuring a keypad) in combination with an OpenPGP compatible chipcard. There are alternative solutions available that provide similar or a subset of the multi-feature YubiKey 4.

act as PIV device (up to 2K bit RSA or 256 bit ECC private key size)įor some of its features it presents itself as a USB HID device.

emulate a chipcard reader with inserted OpenPGP chipcard (up to 4K bit RSA or 256 bit ECC private key size).

The YubiKey 4 provides several functions: The variants differ regarding form factor and the number of supported features. Most feature an inductive button and one model also has NFC (the YubiKey Neo). All YubiKeys are hardware tokens and are connected to a USB port. The YubiKey comes in different variants, for example the YubiKey 4 and the YubiKey U2F.

Yubikey open source alternative