Set on a generation ship, there is a unique teleporter room located just adjacent to the bridge where the captain works. This teleporter room has 26 telephone box-like chambers for personnel to be transported to one of 26 similar chambers spread out across the ship. The design is to prevent unauthorized entry into the bridge without permission from the captain, i call this system the “Bombe Gate System”.

Purpose of Bombe gate:

  • prevent any unauthorized entry into the bridge area or the engine room

Parts of Bombe gate system:

  • Consist of 26 chambers (all located in teleporter room) along with another 26 corresponding chambers (spread out throughout the ship)
  • 3 ROTORs (a set of 3 supercomputers located on the bridge, the name is an acronym)
  • 26 Reflector cards (held by key members of the crew including the captain)

Concept of Bombe gate system:

Imagine the captain wants to teleport to the canteen from the no.3 chamber in the teleporter room, she knows all the settings on the 3 ROTORs and on each Reflector card. Therefore she can immediately tell that no.3 chamber definitely leads to the canteen area. The captain and the key members must reset the settings on the 3 ROTORs regularly using their reflector cards simultaneously otherwise it won’t change anything.

One significant flaw of the Bombe Gate system is that the chamber with a certain number cannot be teleported to their corresponding chamber for example no.8 chamber in the teleporter room cannot be teleported to another no.8 chamber which is located in the storage room.


  • there are over 12,000 lookalike chambers on the ship and they can be used to teleport to any of these chambers by any person.
  • all the chambers including the Bombe Gate system used the designated area and function for naming instead of number or alphabet.


Does this Bombe Gate System really hold up as an anti trespass system for this generation ship?

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  • 4
    $\begingroup$ (a) Can anybody use the system? If so, how are they able to determine where they're going? (b) It appears that the path to the bridge is open to anyone but otherwise hidden by obfuscation. Would the reflector cards not be a better solution for control, or are there more than 26 people who belong on the bridge? (c) This appears to be a technology dichotomy, you have the tech for teleportation but not for a rational biometric/card/pin combo for security? $\endgroup$
    – JBH
    Dec 12, 2023 at 4:15
  • 2
    $\begingroup$ I must confess I find this description bewildering. The "basic concept" is not explained clearly, and I think this is because some key rules of the system are unstated. I suspect there are rules about "correspondence" that you've simply omitted from this post. My hat's off to JBH for recognizing there is some security-by-obscurity in here -- and I'll note that's a fatal flaw in any system that must stand for generations. $\endgroup$
    – Tom
    Dec 12, 2023 at 4:21
  • 1
    $\begingroup$ I'll be honest with you, I'm not much more enlightened. Now it appears that only those with reflector cards can get to the bridge teleporter room - so what's the point of all the obfuscation? To be honest, the average user must depend on predictability for the system to work for them at all... so I'm having trouble understanding the need for the ROTORs. $\endgroup$
    – JBH
    Dec 12, 2023 at 5:33
  • 1
    $\begingroup$ What I glean: there are thousands of rooms scattered across the ship that each contain a couple dozen teleportation booths. Each booth has a fixed destination, assigned in a deliberately confusing way such that the bridge can only be reached by people who know the (secret) correct route, but other non-restricted areas are easily reached by anybody. Booth destinations can be re-assigned by the captain and lieutenants acting in concert. I believe all the rest of the details in the post are unimportant flavor. It is a virtual, programmable maze. $\endgroup$
    – Tom
    Dec 12, 2023 at 5:53
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    $\begingroup$ @user6760 I understand what you're trying to do. I'm frankly having trouble getting past why a system would be designed this way. What sabotage are you trying to avoid that wouldn't be stopped with a good biometric deterrent system? This is what I mean by "technology dichotomy." You have teleport technology, which means you must have the ability to scan the body... but you aren't using a DNA scan to restrict access to the bridge. Instead you're using this really complex shuffle system that would be easily resolvable by the computers of the day. Weird. $\endgroup$
    – JBH
    Dec 12, 2023 at 7:54

2 Answers 2


Wait a minute....

Bombes, Rotors, Reflectors, the number 26?

This is just an Enigma Machine Puzzle!

In which case - the short answer: No.

Why? Modern computers using just a Brute-force attack can crack this system in a few minutes. It's nowhere near sophisticated enough for a security system in a futuristic setting.

First solution would be a much simpler access list - restricting access to only listed personnel.

Secondly would be that each person has a PIN/Unique password that is stored in non-reversible encryption and this is what controls access to the Bridge.

Unlisted personnel can attempt to access the bridge, and this will generate an approval request to the Captain.

  • 2
    $\begingroup$ Sharp eye! I also found this on Wikipedia: "The bombe was an electro-mechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted secret messages during World War II." $\endgroup$
    – Tom
    Dec 12, 2023 at 4:41
  • $\begingroup$ hi i just edited to add some diagrams but no worry nothing changes ;D $\endgroup$
    – user6760
    Dec 12, 2023 at 5:13

Not secure

I believe you've got a virtual, programmable maze. As JBH perceptively notes, this is essentially security by obscurity.

Security by obscurity generally gets a bad rap among security professionals, but we should not underestimate it -- passwords are security by obscurity, and they were adequate for decades. So, let's consider what it would take to defeat your obscurity.

Since there is no penalty for guessing wrong in the teleporter booth, a villain can study the current layout of the maze by exploring it and taking notes. Given enough attempts, they'll reach the bridge.

Your system has a precaution against this: the captain and their lieutenants can change the layout of the maze whenever they like, which will reset the villain's progress to zero. This requires that they (1) use their Reflector cards (2) simultaneously.

Villains have three obvious ways to circumvent this precaution:

1. The villain could happen to guess the right answer right away

It can happen! On a long-enough timeline, it will happen.

2. Many villains acting in concert can explore the solution space faster than the crew expects

If the captain & crew are unaware that the villain has collaborators, they won't scramble the layout frequently enough to prevent the conspiracy from discovering the solution. And, of course, many villains are that much more likely to guess the correct route right out of the gate.

3. The villain can lock the maze into its current configuration by interfering with the reset mechanism

This is a truly fatal weakness. Since scrambling the maze requires the captain and all 26 lieutenants to use their reflector cards at the same time, all the villain has to do to completely incapacitate the system's defenses is contrive to prevent just one lieutenant from participating in a scramble. One obvious way is to steal, destroy, or damage somebody's reflector card.

The more insidious possibility, which I consider far more likely, is that the villain could persuade one or more lieutenants to refuse to help scramble the maze. You're maybe thinking this is absurd, but I assure you that it's inevitable on a generation ship.

The central challenge on every generation ship is that the people on board will eventually drift away from their original purpose. When the human element deteriorates, it always becomes clear that the interlocking technological systems are inadequate to restore them or to protect the ship's original mission.

After all, where do you suppose your villains come from?

The villain does not have to persuade a lieutenant to explicitly help them overthrow the captain. Here are some ideas:

  • They might convince a lieutenant that it's a hassle for everybody on the ship to learn new routes to their everyday destinations. "I'm getting really sick of dashing to the teleporter because I need to visit the restroom urgently, only to discover that the system has been reset and I'm in the chapel or the women's locker room!"

  • They could cultivate a populist social movement that results in one or more lieutenants finding it distasteful to actually wield their security powers to reset the system.

  • They could start a spiritual movement that forbids performing certain "work-like" tasks during periods of special significance.

  • They and some confederates could just conspire to keep at least one lieutenant busy at all hours so they are unavailable to perform a scramble. This is made vastly easier by having 26 lieutenants rather than, say, 2. Imagine chaining these together in sequence:

  1. LT1 can be kept at the bar for a couple hours by a friendly villain;
  2. then LT2 could be lured away from the office by a sexy playmate, which could go all day or even all weekend;
  3. LT3 could then be whisked away by a group of friends to go on some impromptu "road-trip" for funsies;
  4. LT4 can be invited to read some of their poetry aloud to a rapt audience who clamors for more;
  5. LT5 can be roofied;
  6. LT6 can be sent to the medical bay by an over-zealous athletic tackle in a friendly game of space-ball;
  7. LT7 can be stuck for hours in a high-stakes space-poker game;
  8. LT8 can be asked to speak at a public meeting of the Manly Mustache Society;
  9. LT9 can be taken bar-hopping and then spend the whole next day too hungover to get back to their own cabin;

... and so on -- I'm not even halfway through the set of LTs, and I've already paralyzed your security system for two or more weeks. And because there are so many targets, only one of which needs to be absented at any time, I've not raised anybody's suspicions -- nobody has been approached more than once, and none of these pretexts is subversive or mutinous. Hell, half the people on that list will be proud of their little adventure. And all the while, the only security system has been frozen in its tracks as the villains quietly search for its solution.

Overall, the Bomb Gate System is not secure: several avenues for defeating it are available to a villain who has allies, but even a single villain acting alone has a non-zero chance of getting lucky and stumbling onto the bridge. As it stands, a nice person could accidentally end up on the bridge just by walking into the wrong booth by mistake, or even by thinking they are going into the correct booth while being unaware of a recent scramble that invalidates their knowledge.

If it were impossible to simply guess the correct answer, I'd say it's somewhat secure against solo villains but vulnerable to groups.

You could make it somewhat more secure by making the reset operation more fault-tolerant by requiring fewer than all 26 lieutenants to participate in a reset, or even make the reset automatic.

You could make it vastly more secure by requiring the user to have a Reflector card to reach the bridge. Then you wouldn't need to build thousands of duplicate teleportation rooms, a scrambling mechanism, or three supercomputers.

It's probably a good design in a video game, as a challenge for the player. It is probably also a good narrative device in a story, although I will note that you'd need to be careful how you describe it in the narrative to avoid either confusing the reader or revealing how impractical it actually is.

  • $\begingroup$ Nice answer and immediately notice the Achilles heel, but the the possibility is 1 in 159 quintillion. $\endgroup$
    – user6760
    Dec 12, 2023 at 7:33
  • 1
    $\begingroup$ Great answer, but the Achilles heel possibility is far, far, far less than 1:159Q. Get the bored teenagers on the ship to make a Pokemon-GO! game out of running through the transporters and reporting where each one starts and ends. 12K transporter hubs and 6k+ people, approximately 13% of which are bored teens, means the job could be done in an hour or two. Plug results into a computer and the map is solved thereafter in seconds. And at least some of each new map must be revealed to the population or they won't get to their jobs on time. $\endgroup$
    – JBH
    Dec 12, 2023 at 8:10
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    $\begingroup$ And if I could up vote multiple times for your list of possible ways to disable the lieutenants... I would. $\endgroup$
    – JBH
    Dec 12, 2023 at 8:14
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    $\begingroup$ (+1) Though passwords are not security by obscurity. Every lock needs a key (this is the problem with this system: there's no lock), but physical keys can be stolen. A password is a key stolen in a brain, and since we haven't invented yet a mind reader, a brain is like the perfect wallet: you always carry it with you, and nobody but you can access to it. Since passwords can be guessed, now Multi-Factor Authentication schemes are used, which are based in something you know (password) and something you are (biometric) or own (phone). Nice answer, by the way. $\endgroup$
    – Rekesoft
    Dec 12, 2023 at 8:21
  • 1
    $\begingroup$ @TheDemonLord This is not a bug, is a feature: not even me can access to passwords stored in my brain most of the time. :D $\endgroup$
    – Rekesoft
    Dec 12, 2023 at 9:00

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