VeraCrypt - data, disk and partition encryption
VeraCrypt allows you to create a virtual encrypted logical disk stored as a file and mount it as a real disk. You can also completely encrypt a partition of a hard disk or other storage media, such as a floppy disk or USB flash drive.
Encryption is performed automatically, in real time (on the fly), and transparently, allowing you to read and write data as quickly as if the drive were not encrypted.
Provides plausible deniability if an attacker forces you to reveal your password: hidden volume (steganography) and hidden operating system.