VeraCrypt
Open source disk encryption with strong security for the Paranoid
.... This is acceptable to the legitimate owner but it makes it much harder for an attacker to gain access to the encrypted data.
All released files are PGP signed with key ID=0x680D16DE, available on key servers and downloadable at https://www.idrix.fr/VeraCrypt/VeraCrypt_PGP_public_key.asc
VeraCrypt can mount TrueCrypt volumes. It also can convert them to VeraCrypt format.
Documentation: https://www.veracrypt.fr/en/Documentation.html
FAQ : https://www.veracrypt.fr/en/FAQ.html