Open-source apps must maintain accountability when it comes to security. They have an active community of developers and users who help discover vulnerabilities, peer-review code, and perform routine audits on a mass scale. Security holes are patched at a rate that discourages programmers from placing back-door malicious codes. Though not every open-source app is secure, the ones that are benefit from the community in a way that closed-source programs and applications can rarely duplicate.
Many of the apps listed here have been so widely distributed and scrutinized that even RSA Conference attendees trust and recommend them.
Gpg4Win is a Windows build of GNU Privacy Guard (GPG). GPG is a command-line tool that allows you to sign your data and communication with encryption. It features key and signature expiration settings, as well as a filter program and wide compatibility with a variety of applications.
Though primarily known for voice communication during gaming, Mumble's main advantage over many other clients is that it encrypts your communication by default, using public-/private-key authentication.
OpenVAS stands for Open Vulnerability Assessment System. It's a set of tools and services that scans and provides a feed of network vulnerability tests to manage any system vulnerabilities.
OpenSSH and PuTTY
OpenSSH is a traffic encryption tool that helps prevent online eavesdropping and hijacked connections, and it provides secure tunneling capabilities for increased privacy. PuTTY offers free SH1+SSH2 implementation for Windows.
KeePass helps you manage your passwords and secure them in a single database that's encrypted with AES and Twofish algorithms.