An encryption scheme for mass storage devices employing a tweakable encryption scheme to add variability to the encrypted data to resist attacks by traffic analysis. Explicit tweak and implicit tweak may be used to add variability to plaintext prior to encryption and eventual storage. The tweak information is either stored on the storage device along with the encrypted data as in the case of an explicit tweak, or it is derived from another source when needed as in the case of an implicit tweak. The ciphertext is decrypted using either the stored explicit tweak value or derive the implicit tweak value to "de-tweak" the decrypted data prior to usage. The data may be deleted by destroying the cipher key(s) to render the ciphertext useless. The tweak information alone is useless for decryption, as the ciphertext needs to be decrypted with the cipher key(s).