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.
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.