FractalCrypt
FractalCrypt is a free cross-platform deniable encryption cryptoarchiver.
FractalCrypt permits an encrypted file with an arbitrary number of keys. If any set of men ask you for a password, and you say that there is no information in the encrypted container or you have forgotten the password, it is far more likely that they will not believe you. Whereas, using FractalCrypt you can safely give away the keys to unclassified volumes, and there is no way to prove that there are actually more volumes than you have disclosed.
Technical details
AES-256 is used for encryption in XTS mode. PBKDF2 is used to generate a key (10k iterations) and an initialization vector (25k iterations).
Each layer, when decrypted, has the following header:
8 bytes - "fractal" c-string signature (null-terminated)
8 bytes - the length of the subsequent zip archive in big endian, aligned to 16 bytes