VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.
Axcrypt - AxCrypt - Password Protect Files With Strong Encryption. AxCrypt is the leading open source file encryption software for Windows.
Easy File Locker - Easy File Locker is a pretty small file at 224KB and will do exactly what it says.
iGPMail - iPGMail: OpenPGP Email security for iPhone and iPad
jCardSim - jCardSim is an open source simulator implements Java Card, v.2.2.1: - javacard.framework.*
Windows BitLocker - This topic provides a high-level overview of BitLocker, including a list of system requirements, practical applications, and deprecated features.