Easy Message - Easy Message app comes up with features to help users in effortlessly sending text messages to a phone number, which is not in the contact list.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
Message Peeping Tom - Message Peeping Tom is an app by HSTAR, offers features that let you read your messages without giving the read report to the sender.
Kleopatra - Kleopatra is a certificate manager and GUI for GnuPG.
WhatsRemoved+ - WhatsRemoved+ is a mobile tool developed and published by Development Color for Android devices only.
PGP Tool - PGPTool allows you to encrypt and decrypt files. It's free and easy to use.