GA4PHP is a class for PHP that allows a coder to provide a method for allowing two-factor authentication for users. Primarily focused on the Google authenticator for iOS, Blackberry, and Android, the system can also support hardware and software tokens based on the TOTP and HOTP standards. The system is designed such that a programmer would simply extend the PHP class to provide storage for the token data.
The OATH Toolkit makes it easy to build one-time password authentication systems. It contains shared libraries, commandline tools, and a PAM module. Supported technologies include the event-based HOTP algorithm (RFC4226) and the time-based TOTP algorithm (RFC6238). OATH stands for Open AuTHentication, which is the organization which specifies the algorithms. For managing secret key files, the Portable Symmetric Key Container (PSKC) format described in RFC6030 is supported.