GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
PGP Everywhere - PGP Everywhere is an iPhone / iPad app that allows you to utilize the security of PGP encryption anywhere you type, in almost any app!
Kleopatra - Kleopatra is a certificate manager and GUI for GnuPG.
Homomorphic encryption - Homomorphic encryption by IBM allows you to perform computations on its encrypted data without first decrypting it.
PGP Tool - PGPTool allows you to encrypt and decrypt files. It's free and easy to use.
KETS Quantum Key Distribution - KETS Quantum Key Distribution service is a utility that allows future-proof, quantum-safe communications at ultra-low power in a low-cost Quantum Key Distribution chip.