Artemis- 14 Digit Lock

  Mulch’s door was key coded. A fourteen-number sequence. Nothing like a bit of paranoia to keep you out of prison.
...
  There was a human youth beside the rockery. In his apartment! The boy’s appearance was strange even by Mud Man standards. He was abnormally pale, raven-haired, slender, and dressed in a school suit that looked as though it had been dragged across two continents. The hairs on Mulch’s chin stiffened. This boy was trouble. Dwarf hair is never wrong.

  “Your alarm was amusing,” continued the boy. “It took me several seconds to bypass it.”

-The Arctic Incident, Chapter 11