1 PAM two-factor Yubikey One-Time Password authentication.Of most interest are libpam-yubikey and libpam-u2f, but libpam-pkcs11, libpam-radius-auth, and several htop/totp modules are also likely usable with the yubikey. PAM modules for the Yubikey make it possible to use it for single or multi-factor authentication schemes on workstations and servers. Yubico, the company which sells the Yubikey, also provides software for many 2FA purposes.

Some models also support these features over NFC with Android devices. Yubikey supports OAUTH TOTP and HOTP standards for one-time passwords as well, and can be used with open PGP and PIV digital signatures and encryption. The newest Yubikey models (4 and Neo) also support U2F, a standard created by the FIDO Alliance for strong 2nd factor authentication. There is also support for static passwords and HMAC-SHA1 challenge/response authentication. The Yubikey is a security token, intended to be used for two-factor authentication, that emulates a keyboard to enter one-time passwords generated using an AES encryption key embedded on the device.

Duo yubikey