Updateable encryption in self encrypting drives

A method of updating a key in a self-encrypting drive (SED) storing encrypted data MEK(data), comprising:

• deriving, in the SED, a master key (MK) from a user password (PIN);
• decrypting, in the SED, wrapping keys comprising a media encryption key (MEK) and a media encryption key encryption key (MEKEK) from stored ciphertext MEKEK(MEK) and MK(MEKEK) using the MK;
• generating, in the SED, new wrapping keys MEK′ and MEKEK′;
• re-encrypting, in the SED, the already-encrypted data MEK(data) in the SED with MEK′ without decrypting the MEK(data) to obtain ciphertext MEK′(MEK(data));
• encrypting, in the SED, MEKEK′ with MK to obtain new ciphertext MK(MEKEK′);
• encrypting, in the SED, a concatenation of MEK and MEK′ with MEKEK′ in a MEK string to obtain new ciphertext MEKEK′(MEK′, MEK);
• and
• storing, in the SED, ciphertext MEK′(MEK(data)), ciphertext MK(MEKEK′), and ciphertext MEKEK′(MEK′, MEK) in the SED such that MEK(data) is overwritten with MEK′(MEK(data)) and MEKEK′(MEK′, MEK) replaces MEKEK(MEK).

A method of refreshing a nested concatenation of a plurality of media encryption key (MEK) iterations and a current media encryption key encryption key (MEKEK) stored in encrypted form, the media encryption key iterations used for nested encryption and re-encryption of user data without decryption in a self-encrypting drive (SED) in which previously-encrypted used data is overwritten wither-encrypted user data, the method comprising:

• decrypting the plurality of media encryption key iterations to a MEK string;
• generating a new media encryption key and a new media encryption key encryption key;
• determining, in the SED in which the previously-encrypted used data is overwritten with the re-encrypted user data a number of re-encryptions of the user data using a number of non-null MEK entries in the decrypted MEK string;
• and
• refreshing the stored MEK string in the SED when a predetermined number N of re-encryptions of the encrypted data has previously occurred, as indicated by a number of non-null MEK iterations in the MEK string.