Dê uma olhada no TrueCrypt , parece que faria mais do que você está procurando. Você pode armazenar o sistema de arquivos criptografados em uma unidade USB facilmente e montá-lo como uma unidade (após o fornecimento da chave, é claro).
Main Features:
Creates a virtual encrypted disk within a file and mounts it as a real disk.
Encrypts an entire partition or storage device such as USB flash
drive or hard drive.Encrypts a partition or drive where Windows is installed (pre-boot
authentication).Encryption is automatic, real-time (on-the-fly) and transparent.
Parallelization and pipelining allow data to be read and written as fast as if the drive was not encrypted.
Provides plausible deniability, in case an adversary forces you to
reveal the password:Hidden volume (steganography) and hidden operating system.
Encryption algorithms: AES-256, Serpent, and Twofish. Mode of
operation: XTS.