* Added sample code for encrypting some text to a single key.
* Basically I'm just lifting existing production code and changing the
  key IDs from mine to "0x12345678DEADBEEF" for these first few
  examples.
* I'll fill in the text description after.
* Note: due to my regional location, I might split some tasks into
  more commits in order to be sure no work gets lost in case of
  emergency (or to put it another way: I know Telstra too well to
  trust them).