In Star Trek II: The Wrath of Khan, there is a scene in which the Enterprise finds itself

Under attack from the USS Reliant, which has been commandeered by Khan.

Right at the most critical moment of the battle however,

Kirk transmits some sort of code to the Reliant, shutting down the hostile ship's shields and allowing the Enterprise to damage the Reliant and escape.

What exactly did Kirk transmit, and how did it manage to affect the Reliant so dramatically?

In addition, could any Starfleet officer with a transmitter and knowledge of the proper code do this? And if so, why isn't it ever seen again?

  • 7
    It was a cyber attack!!!
    – Stone True
    Jun 13, 2016 at 0:32
  • 1
    I don't remember where I saw it, but I'm pretty sure there's another 'Star Trek' sequence where an attempt is made to assume control of another star ship. The whole idea struck me as logical in TWOK, but I'd think it would be something a star ship commander would change regularly. It's a bit like being able to hack someone's WiFi because their password is "Password". Jun 13, 2016 at 0:57
  • 8
    If you're going to spoiler a detail in question, don't immediately hint at what happened and then explicitly say it after that!
    – Nij
    Jun 13, 2016 at 5:41
  • A similar real-life scenario which may or may not have happened: skeptics.stackexchange.com/questions/11152/…
    – pjc50
    Jun 13, 2016 at 16:17
  • 2
    It's been 34 years. I think it's safe to get rid of the spoilers.
    – user40790
    Jun 14, 2016 at 17:03

4 Answers 4


The transcript explains it:

SPOCK: Reliant's prefix number is one six three zero nine.
SAAVIK: I don't understand.
KIRK: You have to learn why things work on a starship.
SPOCK: Each ship has its combination code.
KIRK: To prevent an enemy do what we're attempting. Using our console to order Reliant to lower her shields.
SPOCK: Assuming he hasn't changed the combination. He's quite intelligent.


  • Kirk transmitted orders to lower shields, prefixed with Reliant's code
  • Any officer with a transmitter and knowledge of the proper code AND ship's code could do this.
  • 11
    Khan was quite intelligent, but he was using a technology he had not had time to familiarize himself with. Give him 6 weeks, he could probably have the Reliant flying upside down and backwards. Jun 13, 2016 at 0:59
  • 16
    @Ajasja - A five digit password can only be hacked on your mobile phone if you can run all the possible options through your mobile phone and find the right one. Fine if you've got physical access to the hashed password file, but not fine if you're trying to guess your way into a system. The system could be programmed to lock you out after X number of failed attempts, or to only respond to any request after five seconds, either of which would make it extremely unlikely that you'd gain access without knowledge of the code. Same reason you haven't hacked my 4-digit bank card PIN yet.
    – Simba
    Jun 13, 2016 at 10:45
  • 12
    @Ajasja: the term “prefix code” suggests that this is only the ship-specific prefix to another, more complex code.
    – Holger
    Jun 13, 2016 at 12:58
  • 4
    "Hehe, a five digit password could be hacked from my mobile phone" that's ridiculous, BTW. You cannot "hack" a four digit password using either "your phone" or a supercomputer. Note that if you mean you're trying to "guess" the password, you don't need "a phone" nor "a supercomputer" to do that - you just guess. You only get two or three guesses when entering a password.
    – Fattie
    Jun 13, 2016 at 16:11
  • 4
    And the Enterprise's shield modulation frequency in Generations was only 4 significant figures. Isn't it odd that security in the 24th century was only as advanced as a bicycle padlock in the 1990's? Jun 13, 2016 at 21:21

Kirk gained remote control of the Reliant

He set quickly to work. Saavik watched the prefix code thread its way through the schematics and dissolve Reliant's defenses. She understood suddenly what Kirk intended to do: transfer control of Reliant to the Enterprise and lower its shields.

The Wrath of Khan (novelization)

Kirk was able to look up the command codes in the database of the Enterprise:

Kirk spoke softly and out of range of the highly directional transmitter mike. "At least we know he hasn't got it. Just keep nodding as though I'm giving orders. Lieutenant Saavik, punch up the data charts on Reliant's command console. Hurry."

The Wrath of Khan (novelization)

It seems likely that anyone with knowledge of the prefix code could indeed take control of the ship. However, most of the time Kirk (or other captains) is not contending with another Starfleet vessel. As such, there would be no way to shut down the ship's shields. Starfleet databases presumably do not contain Klingon command codes, for example. It is also possible that non-Starfleet ships might use an entirely different (and unknown) transmission frequency.

  • 2
    I like this answer better than mine :) +1 Jun 13, 2016 at 0:39
  • 2
    Really, Klingons might not have the same remote control system. The star fleet remote control might be a legacy of a 20th century software firm enforcing update abilities on all computers. ;)
    – Yakk
    Jun 13, 2016 at 18:17

The codes are meant to limit a ship's commands to its own ship. The implication is that the command to lower shields is transmitted from the console (rather than across a physical wire). There are a number of reasons why that would be - (1) you don't want damage to the ship to break the communication to the shields (effectively leaving the ship without shields the first time it got hit unawares), and (2) there are likely multiple sources of the shields scattered around the surface of the ship (complete assumption on my part, please confirm or refute if you have definite knowledge).

What Kirk did was to switch his command transmission to use the Reliant's code... rather than lowering his own shields, the command to lower shields was picked up by the Reliant as a command issued from its own console.

  • 3
    re: multiple sources of shielding scattered around the ship. When announcing damage to the shields, they'll regularly mention different parts being damaged, e.g. "aft shields down to 47%". They'll also apply more power to different parts of the shield to reinforce it directionally, e.g. "Transfer all auxiliary power to forward shields".
    – Mar
    Jun 13, 2016 at 18:07
  • Duh. Of course. #sheepish
    – James King
    Jun 13, 2016 at 19:09

It is seen again, sort of...

In TNG: Peak Performance, Commander Riker captains the 80 year old starship USS Hathaway in a wargames simulation against the Enterprise.

The Hathaway hacks the Enterprise's sensors to fool them into believing a Romulan warbird is near.


The Hathaway uses the same technique against a Ferengi vessel that was threatening both ships.

It's not exactly the same, but it is still hacking another starship's computer.

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