The HOTP Toolkit package contains tools that are useful when deploying the one-time password HOTP technology. It contains a shared library, a command-line tool to generate and validate one-time passwords, and a PAM module (pam_hotp) to make system login or SSH use HOTP one-time passwords for authentication.
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.
OpenOTP is an implementation of the HOTP protocol using a ZeitControl Cardsystems ZC3.9 BasicCard and standalone balance reader, standalone Spyrus PAR2 (Personal Access Reader), or PCSC-Lite supported smart card reader. Included is a C library implementation of the HOTP protocol and associated user database management, HOTP PAM library, OpenVPN plug-in module, micro RADIUS server with HOTP support, and utilities for managing the smart card, Spyrus reader, and host side HOTP user database. The PCSC-Lite API provides reader support for smart card management.