I have qualms about key being used for the npub.


Key Etymology: “

> instrument for opening locks," Middle English keie, from Old English cæg "metal piece that works a lock, key" literal and figurative ("solution, explanation, one who or that which opens the way or explains"), a word of unknown origin, abnormal evolution, and no sure cognates other than Old Frisian kei.”

Key makes perfect sense for nsec. 

 I agree. IDs and Keys.
npub = Nostr Public ID
nsec = Nostr Secret Key