What is the difference between “plain” and LUKS format?
Plain format is just that: It has no metadata on disk, reads all paramters from the commandline (or the defaults), derives a master-key from the passphrase and then uses that to de-/encrypt the sectors of the device, with a direct 1:1 mapping between encrypted and decrypted sectors. Primary advantage is high resilience to damage, as one damaged encrypted sector results in exactly one damaged decrypted sector. Also, it is not readily apparent that there even is encrypted data on the device, as an overwrite with crypto-grade randomness (e.g. from /dev/urandom) looks exactly the same on disk. Side-note: That has limited value against the authorities. In civilized countries, they cannot force you to give up a crypto-key anyways. In the US, the UK and dictatorships around the world, they can force you to give up the keys (using imprisonment or worse to pressure you), and in the worst case, they only need a nebulous “suspicion” about the presence of encrypted data. My advice is to either be
