Folder Lock - Folder Lock is a security software that helps you to password protect files, shred files, clean history, encrypt the personal documents and much more.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
Wise Folder Hider - Wise Folder Hider is a free file/folder hiding tool.
Kleopatra - Kleopatra is a certificate manager and GUI for GnuPG.
Vov Hide Files - Lock your files and folders from prying eyes.
PGP Tool - PGPTool allows you to encrypt and decrypt files. It's free and easy to use.