yubikey-server-c 0.5-1build2 (amd64 binary) in ubuntu vivid

 Yubikeys are USB tokens that act like keyboards and generate one-time
 passwords. The tokens are produced and sold by Yubico
 .
 This is a server that checks the validity of those OTP tokens. There
 are servers written in Java and PHP, while this one is written in C
 .
 It implements the server side of the API as described on
 http://www.yubico.com/developers/api/ and can be used with any client
 that implements the same API.