I'm curious about how does Ubuntu's full disk encryption works under the hood. Here's an example:
Considering the following string as all the disk's content:
After applying some kind of encryption method it would look something like this:
(I've used Caesar cipher with an shift of +1 for this example, e. g. A → B; B→C…)
As I understand, when the computer is turned off, the drive's content would be the string above. But when it's turned back on, Ubuntu needs its content to be back again
hello world in order to successfully boot.
What I don't really get is that in the real world the disk's content is way much more, and the encryption algorithm way more complex, and I find it difficult for the computer to completely encrypt/decrypt all of it in just a few seconds (it doesn't take longer to boot or to shut down).
How is this possible?