Google recently announced two-step authentication for google apps. Fortunately they started from the beginning with open-source code, and released a PAM module that allows us to use it for something else: use a Time-based One-time Password (TOTP) to login to your Linux PC. TOTP algorithm is still a draft RFC: TOTP(K,T) = Truncate(HMAC-SHA-1(K,T)) K shared secret between client and server; each TOT
![Use Google Authenticator to login to a Linux PC](https://cdn-ak-scissors.b.st-hatena.com/image/square/a1e2c84807cb95b8fc7a383bcdaebedb051e8e97/height=288;version=1;width=512/https%3A%2F%2Fblogger.googleusercontent.com%2Fimg%2Fb%2FR29vZ2xl%2FAVvXsEh_U5K4y-U4MBWcpaHDWnPmMonDH3Sj4ySwN2wntu7ESNkaKZRX84rEBhRaD1kxH7lJKF_7tU1KudgZkAMGhTCVmkF0FsH3qeSVfyu3z7EEhlXVnDDooLtm7hZ8qAVXc_qpKUuPByYEU9xp%2Fw1200-h630-p-k-no-nu%2Fchart.png)