Activation cylinder

An activation cylinder was a device required to allow a spaceship to fly in hyperdrive. It was often colloquially referred to as a security key. However, presumably, any activation cylinder whatsoever could be used instead of another to the same effect, making the cylinders unlike keys, which operate on one specific lock only. An activation cylinder, a large, opal tube, had to put into an extensive hole in a navicomputer of a ship.

Purpose
One of the uses of activation cylinders was to prevent any troops from using ships to desert battlefields; such was a preventive tactic applied by the Sith Lord Daiman to have a better grip on his forces. Flight crews of the Daimanite Heavy-Lift Starcrossers were entrusted to carry the keys instead of Sith warriors as the former were believed to be more loyal. Amongst this organization, a special flight-crew-issue case with an activation cylinder inside was known as a dispatch case.

Storage
Replacement navicomputers were kept in hangars with activation cylinders inside them as there was "no reason to hide the keys" when there were "no ships attached."

Appearances
Star Wars: Knight Errant: Influx