VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.
M3 Bitlocker Loader - Read/write Bitlocker encrypted drive in macOS/Mac OS X and Linux
Axcrypt - AxCrypt - Password Protect Files With Strong Encryption. AxCrypt is the leading open source file encryption software for Windows.
OpenPuff - OpenPuff is a professional steganography tool: HW seeded random number generator (CSPRNG)
Windows BitLocker - This topic provides a high-level overview of BitLocker, including a list of system requirements, practical applications, and deprecated features.
SilentEye - SilentEye is a cross-platform application design for an easy use of steganography, in this case hiding messages into pictures and sounds.