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Subject: Monkey in the Middle: Cracking the Code rss

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Gary Boyd
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I have given some thought to designing a game based on WWII cryptography but have been stuck on the problem for awhile now and thought greater minds might prevail.

I'm calling the problem the monkey in the middle because it's been a monkey on my back and it focuses on the problem of the middle player in a game of passing notes. Here is the problem as I see it:

Player A passes a message(preferably in card form) to Player C. Player B may or may not know the contents of that message based on events which have taken place earlier in the game. The fact that Player C knows the contents should be completely hidden from Players A & B because this knowledge will have a huge impact on the outcome of the game.

How does Player C discover the contents of a message between Player A and Player B without Players A & B knowing that Player C has intercepted the message?

Idea(perhaps convoluted and ill conceived):

A deck of crypto cards is comprised of 10 sets of 3 cards each. Each set is placed into a sleeve and then shuffled with the rest of the sets. A set of 3 crypto cards are then chosen at random and dealt out to our 3 players. These cards only have a symbol on them(say 1 of 10 unique symbols).

Players A & C look at the crypto card while Player B's card is shuffled into a deck. Message cards have 10 unique messages on them with each corresponding to 1 of the 10 unique crypto symbols. Each player draws a hand of 7 cards. Player A passes a message card to Player B who may look at the message card but must pass it to Player C. Players A & C reference their crypto card to discover which of the 10 messages on the message card is being passed.

Player B somehow accesses his deck each turn and has a chance of cracking the code. If the crypto card comes up he would then know which message was being passed. This could happen early in the game (like it did for Enigma) or it could not happen at all (like with Native American Code Talkers).

I wanted players to have the option of changing crypto but having a great disincentive to doing so. If players felt they were compromised they could switch crypto but this could create chaos among the ranks or cause armies to stall because orders are not forthcoming.

One of the problems I foresee with this solution is that a keen player could potentially deduce the crypto in very few turns thereby knowing very quickly what messages are being passed back and forth between the other players. This could potentially work out well as a feature of the game as players attempt to deduce the crypto representing the struggle to crack the other sides codes. Players without the desire to do so could rely on the luck of the draw and other elements of gameplay.

Another problem is that if you were to add Player D to the equation you now have 2 sets of cryptography which reduces the difficulty of deduction present in the 3 player scenario. It also adds the confusion of players passing cards through other players on a frequent basis. Maybe this would work out well by keeping players minds on too many things to always remember what the crypto of the message was that was passed. The idea of 4 players each with the potential of cracking the opponents code at any time by drawing the card seems to cheapen the whole idea to me.

If this system does work, which I'm not convinced it will, would the number of possible crypto systems have to be much greater? Would 12 be enough to provide obfuscation without making deduction impossible? Is this a question to be answered by playtesting? And is there anything inherently broken in this system that would make playtesting futile?

I appreciate any feedback and/or brainstorming as this particular question has burning at my brain for months now.

As I was proofreading this I had an idea. What if instead of having 1 unique symbol on it, a crypto card has 2 symbols: 1 for sending and 1 for receiving. This makes deduction much more difficult and the potential based on a limited number of crypto icons and card space much greater.

 
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Brian Fong
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debiant wrote:
I have given some thought to designing a game based on WWII cryptography but have been stuck on the problem for awhile now and thought greater minds might prevail.

I'm calling the problem the monkey in the middle because it's been a monkey on my back and it focuses on the problem of the middle player in a game of passing notes. Here is the problem as I see it:

Player A passes a message(preferably in card form) to Player C. Player B may or may not know the contents of that message based on events which have taken place earlier in the game. The fact that Player C knows the contents should be completely hidden from Players A & B because this knowledge will have a huge impact on the outcome of the game.

How does Player C discover the contents of a message between Player A and Player B without Players A & B knowing that Player C has intercepted the message?

Idea(perhaps convoluted and ill conceived):

A deck of crypto cards is comprised of 10 sets of 3 cards each. Each set is placed into a sleeve and then shuffled with the rest of the sets. A set of 3 crypto cards are then chosen at random and dealt out to our 3 players. These cards only have a symbol on them(say 1 of 10 unique symbols).

Players A & C look at the crypto card while Player B's card is shuffled into a deck. Message cards have 10 unique messages on them with each corresponding to 1 of the 10 unique crypto symbols. Each player draws a hand of 7 cards. Player A passes a message card to Player B who may look at the message card but must pass it to Player C. Players A & C reference their crypto card to discover which of the 10 messages on the message card is being passed.

Player B somehow accesses his deck each turn and has a chance of cracking the code. If the crypto card comes up he would then know which message was being passed. This could happen early in the game (like it did for Enigma) or it could not happen at all (like with Native American Code Talkers).

I wanted players to have the option of changing crypto but having a great disincentive to doing so. If players felt they were compromised they could switch crypto but this could create chaos among the ranks or cause armies to stall because orders are not forthcoming.

One of the problems I foresee with this solution is that a keen player could potentially deduce the crypto in very few turns thereby knowing very quickly what messages are being passed back and forth between the other players. This could potentially work out well as a feature of the game as players attempt to deduce the crypto representing the struggle to crack the other sides codes. Players without the desire to do so could rely on the luck of the draw and other elements of gameplay.

Another problem is that if you were to add Player D to the equation you now have 2 sets of cryptography which reduces the difficulty of deduction present in the 3 player scenario. It also adds the confusion of players passing cards through other players on a frequent basis. Maybe this would work out well by keeping players minds on too many things to always remember what the crypto of the message was that was passed. The idea of 4 players each with the potential of cracking the opponents code at any time by drawing the card seems to cheapen the whole idea to me.

If this system does work, which I'm not convinced it will, would the number of possible crypto systems have to be much greater? Would 12 be enough to provide obfuscation without making deduction impossible? Is this a question to be answered by playtesting? And is there anything inherently broken in this system that would make playtesting futile?

I appreciate any feedback and/or brainstorming as this particular question has burning at my brain for months now.

As I was proofreading this I had an idea. What if instead of having 1 unique symbol on it, a crypto card has 2 symbols: 1 for sending and 1 for receiving. This makes deduction much more difficult and the potential based on a limited number of crypto icons and card space much greater.



Cryptography is not quite something that can be fully explained in an A to B Process. Some cyphers have multiple key phrases that determine that determine the actual cryptex used.

If you're paying face to face, you'll know if somebody has intercepted the message by the "aha" moment on his or her face.

You could do a code breaking game where they co-op to break a code, but then that diminishes replay value.
 
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Graham Muller
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Am thinking of a couple of methods, but depends on what is the more important aspect.

Is the deduction of the crypto mechanic important or the chance of messages being intercepted important.

If its the chance side, then I would suggest having a deck of blank cards, player A shuffles the instruction card with 2 blank cards and hands the set of 3 to player C, player C can then pick one card to view, place it back and shuffle the cards giving it to player B. This means each turn player C has 1/3rd chance of understanding the message. You can increase number of blank cards per message.

A second option for the decryption algorithm is to have 3 colours and 6 sets of instruction cards with colour A on top and B on the bottom.

Player A and B know the first colour lets say red. A sends Instruction 1 with red on the top and blue on the bottom as well as 2 decoy cards. Player B then knows that the next message must have blue on the top.
Player C can view the cards but will only know the instruction if they can figure out the pattern and remember the colour. This way the encryption breakdown can occur.
 
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Gary Boyd
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EBWonder wrote:

Cryptography is not quite something that can be fully explained in an A to B Process. Some cyphers have multiple key phrases that determine that determine the actual cryptex used.

If you're paying face to face, you'll know if somebody has intercepted the message by the "aha" moment on his or her face.

You could do a code breaking game where they co-op to break a code, but then that diminishes replay value.


Brian,

I completely understand that cryptography is not A to B translation at anything but the most fundamental levels. My idea was to evoke the them in a broad sense where the crypto icons represent particular types of cryptography. So the game is more about the feel of breaking a code then actual code breaking.

The idea of making the game cooperative is very interesting. What would you propose? The game has to have replayability. How would we evoke the theme of players working on breaking a code without them actually having knowledge of cryptography?


gmuller wrote:

If its the chance side, then I would suggest having a deck of blank cards, player A shuffles the instruction card with 2 blank cards and hands the set of 3 to player C, player C can then pick one card to view, place it back and shuffle the cards giving it to player B. This means each turn player C has 1/3rd chance of understanding the message. You can increase number of blank cards per message.

A second option for the decryption algorithm is to have 3 colours and 6 sets of instruction cards with colour A on top and B on the bottom.

Player A and B know the first colour lets say red. A sends Instruction 1 with red on the top and blue on the bottom as well as 2 decoy cards. Player B then knows that the next message must have blue on the top.
Player C can view the cards but will only know the instruction if they can figure out the pattern and remember the colour. This way the encryption breakdown can occur.


Graham,

I definitely want to steer clear of your first idea as it is complete chance and I want players to feel as if they have actually cracked a code as opposed to just getting lucky and intercepting a message.

I'm having a hard time parsing your second option.

Thanks for the input both,
Gary
 
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Brian Fong
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debiant wrote:
EBWonder wrote:

Cryptography is not quite something that can be fully explained in an A to B Process. Some cyphers have multiple key phrases that determine that determine the actual cryptex used.

If you're paying face to face, you'll know if somebody has intercepted the message by the "aha" moment on his or her face.

You could do a code breaking game where they co-op to break a code, but then that diminishes replay value.


Brian,

I completely understand that cryptography is not A to B translation at anything but the most fundamental levels. My idea was to evoke the them in a broad sense where the crypto icons represent particular types of cryptography. So the game is more about the feel of breaking a code then actual code breaking.

The idea of making the game cooperative is very interesting. What would you propose? The game has to have replayability. How would we evoke the theme of players working on breaking a code without them actually having knowledge of cryptography?

For co-op, you'd have to have either a player entering the message into the cryptex or have the players have to deduce a predetermined message. You could make different levels of complexity with the easiest being a 1-1 replace while a super hard would be a polyalphabetic cypher with no capitalization.

http://en.wikipedia.org/wiki/Polyalphabetic_cipher (for reference)

my problem with code-breaking is that the game will probably feel like work. and they will probably have to do some level of code-breaking. You might want to check out Mad Gab or Mastermind. both games deal with code-breaking in some form.

To facilitate the learning of basic cryptography, you can have a beginner level where you can do a jumble or an easy puzzle together.

HAVEAGREATDAY = PRIORYFORMBRA (1-1)
SPOON = ONSOP (Jumble)

Just off the top of my head, there may be better examples and, probably, a better way to go about this.
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Graham Muller
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No worries I thought as much regarding the first idea.

So a message card will consist of 3 sections, the top which is the message colour, the middle containing the actual message, and the bottom which contains the next message colour (You could also use cryptography symbol).

Before the first turn player A (the sender) will choose a colour with player B (the receiver), let's say red. I would send my instruction to player B lets say (Watch your left flank) with red on the top of the card and green on the bottom. I would also send 2 other cards, one green on top and blue on the bottom, the other blue on top and red on the bottom.
Player C looks at all three cards and hands them to player B.

Now Green will become the message colour, so when player B responds or they will respond with a card green on top and whatever colour they decide the next message should be in.

The encryption then becomes a memory and deduction game based on the player actions. Also player A and B have to be careful to make sure the other two cards never mix colours with the main message.

To make the game even more encryption like. The cards could have colours on each corner, so player A and B can decide the message pattern will be top left to bottom right, or top left to top right, or cycling so first turn will be top left to bottom right, second turn top right to bottom left, third turn bottom right to top left etc. Or even A sends top left to bottom left and B sends bottom right to top right.

Hope that clarifies and presents some options?
 
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Gary Boyd
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gmuller wrote:

Before the first turn player A (the sender) will choose a colour with player B (the receiver), let's say red. I would send my instruction to player B lets say (Watch your left flank) with red on the top of the card and green on the bottom. I would also send 2 other cards, one green on top and blue on the bottom, the other blue on top and red on the bottom.
Player C looks at all three cards and hands them to player B...

Hope that clarifies and presents some options?


That does clarify a great deal Graham, thank you. So, using your system players would meet in secret before hand in order to determine the color system, correct? That would actually be a much easier way to solve the problem. I was hoping to find a mechanical solution to determining the particular cryptography scheme, but it does make sense to do it this way.

One of the problems I'm facing is that if it is just one message at a time the deduction should be fairly easy based on your opponents actions. I think in order for the problem to become difficult there would have to be a plethora of information flying around and I don't know: A. what level of abstraction to use and B. how the hell to make it a fun game experience.

On my Facebook page one person suggested having the transmissions placed in the middle of the table. If there were a bunch of transmissions that could obfuscate things a bit, but once the players acted on them it would again become evident which system they were using.

With any course of action, having a revolving solution as you suggested would probably work best. Abstracting cryptography is proving very difficult to me.

 
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I have concerns with this concept and conversation. It sounds like the crypto will only be PART of a larger wargame... breaking crypto needs detailed notes or an astounding memory. You will either drive away everyone who does not have said memory, or slow the game down to the complete note taking level. Slow is bad.

The messages if too simple may not be useful, and if not simple, then they become much harder to crack in a short (game length) chunk of time. Saying Flank may not be sufficiently clear.

And, the crypto could simply be ignored. Pay attention to what the other players do, and not the garble of what they say, and beat them with as much coordination as they can squeeze through game crypto. In other words, it is a game and crypto is important in real life because lives depend on it. So 2 spend all their time and effort on crypto only to have it ignored by another player. Where was the fun in that? How is your game any different from a game of Diplomacy where players never know when they will be backstabbed anyway?

And then the damn KEY needs to be passed in whispers at the beginning of the game anyway, and probably changed at some point because if I see 3 messages, one of which is Flank, right before I'm flanked, I may not even need a very good memory to have broken the dummy code.

I have yet to hear here a quick crypto mechanic, that can handle non-simple messages, that does not require a machine, that can't be easily broken or has no chance of being broken, and that can be reset. Maybe: 8, color coded, 1 time pads, each filled with a page of wartime words in a different order than on the other pads. All any 2 players have to do is agree on a color, and then pass numbers indicating which word they choose. But, that is not really quick on coding and decoding, and it is subject to simple peaking to see which pad is being used, since every player will have a copy of all of the pads. And then, there is stil the problem of new keys. In fact, 2 smart players would change pads on every next message according to the original whispered key sequence so that there were no repeats. Will you force players to reveal all codes at the end of the game to show that there was no "cheating"? Grr.

Why not simply whisper the damn messages in another room? Why, in a game, give your opponent a chance at intercepting and decoding your plans?

And if your crypto mechanic is good, and your wargame is bad, your overall game will be bad. What is next? Will you make your players communicate by radio only, because that is authentic? If your wargame is okay to good, but your crypto mechanic kills the game, you will have a bad game. It would be better to seperate the crypto mechanic into the core of a different game entirely, at which time you are a lot closer to multiplayer Mastermind than a wargame. Just figure out a way to keep it fresh, and track score.
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Graham Muller
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Great.
As to deducing the code, this is where the 2 communicators have to be smart. They need to choose the red herring messages to add confusion.
For example if you know your partner will be doing x then may as well suggest a red herring x card.
You could also have encryption cards that player A and B share which tell them the pattern. If they have a set of 3 decided at the start of the game. When they believe their current pattern has been compromised. They can communicate a change cipher card.

Are you going to limit communication between player A and B to only the cards?

EDIT: Just thinking further the 4 corners with pattern means it wont be very easy to figure out the cipher pattern as you will need to remember all 4 colours for atleast 3 cards to get the pattern of movement.
 
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Gary Boyd
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ThroughTheDeckGlass wrote:
It would be better to seperate the crypto mechanic into the core of a different game entirely, at which time you are a lot closer to multiplayer Mastermind than a wargame. Just figure out a way to keep it fresh, and track score.


I have concerns with the concept, that's why I brought it to the forums. I think your concerns with the conversation are valid.

I didn't necessarily want a full fledged war game outside of the crypto, but I did want the crypto to have consequences outside of the code. I'm wanting to evoke the feel of cryptography within the context of WWII without necessarily having to have a serious slog through actual cryptography or a war game.

My initial concept for keys was not to pass the key at the beginning of the game in a whisper, but to pass the key out as cards to each player. The middle player would not initially have access to it.

Information could be broken down into chunks: coordinates and actions but this would require more complication. It's a problem I'm still working on, and a problem I'm not sure that I'm capable of solving. I still think it's an interesting problem.
 
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Steve Zagieboylo
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I like the idea of a game that gives the feel of breaking a code without actually forcing players to do the hard work of code-breaking. It's as if you're the general who is in charge of the code breakers.

Then, I agree, you have to make it as only part of a larger game, where there is still a chance for the code-breaker to win if he doesn't break the code, but it's pretty small. [Edit: and I have a suggestion below, which you might like. I got on a roll and couldn't stop.]

Possibly make the game more symmetric. There are two teams competing over some geographic resource. So both teams are simultaneously trying to communicate secretly AND are trying to break the codes of the other team. I could see a six-person variant where each team has a General, an Admiral, and a code-breaker.

Here's another idea that, I think, gives the feel of code breaking: Information is placed on a card that is put in a certain position in a stack of cards. Let's say the stack has 10 cards, and the teammates agree to put the message at position 4.

The code-breaker gets the entire stack and is allowed to pull out one card by position and look at it. He then puts it back in the same position and passes it to the player receiving the message. He also pulls out only one card, but he know the right position, so he gets the message.

Once the code-breaker has deduced the position they are using, he is able to break every message they send until the agree on a new position, which represents them creating a new code. They should have some cost to be allowed to do this, possibly losing an entire combat turn.

This whole technique depends a lot on the players honoring the system, because, of course, they could flash each other signals to change their code position, but almost anything you come up with is going to have this issue. It also requires them to pull a card by position and put it back correctly, without the opponents able to see them do so. So it lends itself a little to cheaters who "accidentally" see more than one note, and just "happen" to stumble upon the right position to intercept notes faster than expected.

However, I like this method better than the one using colors, because the code-breaker only gets to see one note. With the colors, if he has a good enough memory, he can remember what all the colored notes said and then, when he sees the action, reverse-engineer which color is the right one. Using position, you can just have all the incorrect positions be blank.

For the combat, you could have a fairly simple territory-taking game. The map has 8 islands and each island has 8 regions. The team has 5 armies and 2 bombs to place, but they place them by the Admiral chooses the island for each, and the General chooses the region. The Admiral sends a coded message to the General of the island selections, then the General sends another back of the region. Then the code-breaker places his two bombs. If he has broken both codes (different in different directions), then he will know exactly where to place the bombs. If he has only broken one direction's code, he might be able to guess the remaining bit of information from context and tactics.

In successive turns players can change roles, so everyone gets to be each.

Just some thoughts. Use what you like. Good luck!






 
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Gary Boyd
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Steve,

Thanks for the insight. I like this method and I could see an amalgamation of the two working pretty well. So, for instance we have a bunch of location cards and a bunch of command cards. The players on a team agree on a set position for the command card and the location card they will use. That means that even if the opponent is able to find the position of the command they have not found the position of the location. So for example: "Naval assault on Normandy." Would be represented by 2 separate cards (one for naval assault and one for Normandy.

This could lead to interesting situation where your opponent knows what you're going to do, but not where you're going to do it. The larger game I had envisioned was an abbreviation of full scale war. So it would involve moving supplies and making attacks. This system would be more abstracted so as not to take focus away from the cryptography element.

Using this card stack method, the player's would then pull their command and location from the stack face down and their opponents would attempt to deduce what they have done that turn. So if the opponent could deduce that they were making a naval assault on Normandy they would be forced to flip over the cards and the attack would be thwarted (similarly on supply runs). This is, of course, much easier to deduce if you know the location or what they will be doing each turn. But if you guess every time they will probably switch their code.

What do you think of that combination?
 
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