phpSecurePages is a PHP module to secure pages with a login name and password. It can handle multiple user groups (each with their own viewing rights), store data in a MySQL database or a configuration file, and be used to identify your Web site viewers. It also has multiple language support and optional IP-based access restrictions.
pks-commands.php3 allows your Web server to search and add PGP/GPG keys from the public keys out there. It takes the TCP 11371 port connection and does it all on the web server. It is good in environments where the client machines are unable to get to arbitrary TCP ports (such as behind tightened firewalls).
The Analysis Console for Intrusion Databases (ACID) is a PHP-based analysis engine to search and process a database of incidents generated by security-related software such as IDSes and firewalls (e.g., Snort or ipchains). It provides a search interface for finding alerts matching practically any criteria. This includes arrival time, signature time, source/dest address/port, flags, payload, etc. ACID also provides the ability to annotate and logically group related events, delete false positives, or archive alerts among databases. Finally, a variety of statistics and graphs can be generated based on time, IP address, ports, alert classification, and sensor.
OpenPGP Webmail is a set of PHP scripts which allows anonymous Web users to send encrypted email to anyone with PGP or GPG keys. It is designed to run over SSL, and has a key search facility built in. GnuPG is required to do the encryption. The project is now abandonware. Anyone can take it over if they like.
SilkPHP TextPass system was initially created as a temporary solution, whilst testing other scripts that were not yet publicly available. This system allows you to quickly set up a protected area for testing, and then remove everything once testing is complete. The resulting scripts may also be useful to those just starting out learning PHP and cookies.
gencoder - Simple PHP encoder is a simple PHP encoder that uses the base64 function algorithm to encode and decode the script. Unlike the Zend Encoder, this script won't solve the problem of hiding the source code from advanced programmers, but at least you're one step closer to making your code tougher for people to steal.
phpSecureSite is a modular authentication, session handling and security system for Web applications that was built using PHP. It features a stripped-down core that takes care of basic session handling, and modules for other functionality like brute force protection, session variables, and access control lists.