Right, that's also possible, but I like the new key every boot as it gives forward security. Even if the key for the whole image is cracked (which is easier to

Right, that's also possible, but I like the new key every boot as it gives forward security. Even if the key for the whole image is cracked (which is easier to bruteforce than a completely random key as it is usually human-memorizable), it will not be possible to access the swapfile/temp contents.