Contributions from free and open software makers can be found throughout the tech world. From your data centre to the desktop and everywhere in between; there's an open solution to your computing needs.
This is no less true in information security. My focus in this article is the several outstanding information security desktop tools that personify the innovation and ingenuity of the FOSS (Free and Open Source Software) world. Please keep in mind that all of these applications (except one) are cross platform so you can find appropriate versions on whatever you run (BSD, Mac OSX, Linux or Windows). The examples herein, however, will be catered to the largest install base (statistically): Microsoft Windows.
GnuPG & Gpg4win
GNU Privacy is a free software encryption application that is a product of the Free Software Foundation's GNU Software project. GnuPG provides a complete free software implementation of the OpenPGP standard RFC4880, making it interoperable with other OpenPGP complaint systems.
Out of the box GnuPG provides a command line interface (CLI) with numerous optional graphical add-ons available for nearly all platforms. On Windows, there is Gpg4win, which is a unified set of graphical tools on top of GnuPG (command-line based). Featured packed, it offers all the options of GnuPG plus integration into Explorer for file encryption, a certificate manager application, a plug-in for Microsoft Outlook, and even a full-blown version of Clawsmail with the plug-in for GnuPG installed.
ClamAV & ClamWin
ClamWin is a lightweight and simple open source software antivirus program for Windows. It features automatic updates, a schedule scanner, integration into context menu of Windows Explorer and even a Microsoft Outlook add-on. ClamWin is based on the ClamAV engine, which is an open source anti-virus package catered to e-mail gateways on Unix/Linux. This scanner is very light on system resources and can be run in conjunction with other malware detection suites, as I often do. No anti-malware suite is perfect but this light and stable protection helps in a world of ever present and evolving malware.