R. Star wrote:
This movie was made in the early 80's so dated security measures can be forgiven. At the time that seemed like a highly advanced security precaution. Really the only thing that surprised me is, what's the point of having these security prefix codes if any ship can look them up?
Well, Starfleet never planned on any of their vessels being hijacked. The prefix codes were probably intended for use in an emergency. It worked out that Kirk used the code to save the Enterprise
, but that's probably not why they existed in the first place.