Perl module to authenticate a Yubikey against the Yubico Web API

 Auth::Yubikey_WebClient is a Perl module to validate a Yubikey one-time
 password against the public Yubico Web API. Yubikeys are hardware
 authentication devices produced by yubico.com, which support different
 one-time password and two-factor authentication protocols as well as PGP
 cryptography.