Social Source Commons

OpenPGP for Android. It's open source and its goal is to provide a similar OpenPGP implementation as GnuPG.
Changes:
* more secure random number
* fix multi-select in recipient list
* manage secret/public keys (eg. GPG/PGP)
* encrypt/sign/decrypt/verify emails and files
* some integration into GMail accounts on the phone
* integration with K9
* HKP Keyserver support
* basic key creation and editing possible (beta)
* Intent API for other apps

Data encryption software.

An email encryption tool that is easy to use.

This is a free and open-source file encryption solution based on the original EncFS code. Cryptonite is fully compatible with all EncFS features. Cryptonite brings EncFS and TrueCrypt to Android. You can browse, export and open EncFS-encrypted directories and files on your Dropbox and on your phone. On rooted phones that support FUSE (e.g. CyanogenMod) you can also mount EncFS and TrueCrypt volumes.

Cryptorganizer is a free tool to manage your information in a secure way, thus all the data is encoded

dm-crypt is such a device-mapper target that provides transparent encryption of block devices using the new Linux 2.6 cryptoapi. The user can basically specify one of the symmetric ciphers, a key (of any allowed size), an iv generation mode and then he can create a new block device in /dev. Writes to this device will be encrypted and reads decrypted. You can mount your filesystem on it as usual

Enigmail is an extension to the mail client of Mozilla / Netscape and Mozilla Thunderbird which allows users to access the authentication and encryption features provided by GnuPG

Firefox addon which maximizes the number of sites you visit which are served via HTTPS. This helps secure you from accidentally negotiating an insecure session with certain sites.

freenigma adds privacy technology (with strong e-mail encryption) to your favourite webmail service.

GPG Suite includes GPG for Mail, GPG Keychain, GPG Services, and MacGPG

GPG for Mail is an open source plugin for Apple Mail. Encrypt, decrypt, sign and verify mails using OpenPGP with a few simple clicks.

GPG Keychain is an open source application for Mac OS X. It allows you to manage your OpenPGP keys. Create and modify your keys and import the keys of your friends from a key server.

GPG Services is a plugin that brings GPG power to almost any application.
It allows you to encrypt/decrypt, sign/verify and import keys from text selections, files, folders and much more.

MacGPG is the underlying power engine of our GPG Suite. If you're familiar with the command line use the raw power of it.
Based on GnuPG 2.0.20.

The Gpg4win project aims at updating the Gpg4win Windows installation package with GnuPG encryption tool, associated applications and documentation on a regular basis.

Secure Android ROM

XDA-Developers Thread: http://forum.xda-developers.com/showthread.php?t=2317794

Guardian ROM is a custom android ROM for Galaxy Nexus and Nexus 4 devices. The ROM is completely Open Source and based off of the Android Open Source Project. The ROM aims to due the following:

Secure/Harden the android kernel with GRSecurity
Remove uneeded/Insecure binaries (Similar to SecDroid)
Replace insecure Text Messaging app with TextSecure
Include apps from the Guardian Project Installer (Optional add-on)
Include support for SQLCipher
Change Android Full Disk Encryption from AES-128 to AES-256 for more security
Allow for seperate Login and boot passwords
All of these have been completed except the final three which are underway but will take much more time.

KeePass is a free/open-source password manager or safe which helps you to manage your passwords in a secure way

A FUSE-Compliant File System Implementation Mechanism for Mac OS X

This is a simple open-source notepad app which demonstrates the capability of the SQLCipher for Android encrypted database library. All notes created and stored by this app are saved fully secured using industry standard 256-bit AES encryption. They are never stored in an unencrypted state on the disk, only in memory.

OTR allows you to have private (not just encrypted) conversations over instant messaging by providing: Encryption, Authentication, Deniability, and Perfect forward secrecy.

The Pdf995 suite of products provides a broad spectrum of PDF functionality, including creation, editing, merging, and security.

PGPi is the international variant of PGP (Pretty Good Privacy), a public key encryption program originally written by Phil Zimmermann in 1991.

Email encryption software

Revelation is a password manager for the GNOME desktop

Shinkuro is a small software program that enables teams to securely share files, exchange instant messages, and do simple screen sharing.

Encrypted internet chat protocol

Stunnel is a program that allows you to encrypt arbitrary TCP connections inside SSL (Secure Sockets Layer) available on both Unix and Windows. Stunnel can allow you to secure non-SSL aware daemons and protocols (like POP, IMAP, LDAP, etc) by having Stunnel provide the encryption, requiring no changes to the daemon's code.

TextSecure encrypts your text messages over the air and on your phone. It's almost identical to the normal text messaging application, and is just as easy to use.

TrueCrypt is a free open source on-the-fly encryption (OTFE) program for Microsoft Windows XP/2000/2003 and Linux. It allows one to create a virtual encrypted disk within a file and then mount it as a real disk

VaultletSuite 2 Go is privacy protecting software that installs on your hard drive or your thumb/USB drive. It uses Open Source 2048 bit RSA public key and 256 AES encryption, and provides easy-to-use (transparent) encrypted and controllable email and password protects important files.

WinSCP (Windows Secure CoPY) is an open source SFTP and FTP client for Microsoft Windows. Its main function is secure file transfer between a local and a remote computer. WinSCP offers basic file manager functionality for uploading and downloading files from a server.