Cryptography in Gaming

This is a post from an much older version of this blog, circa 2009, that I have reposted here without rewritting for archival purposes

You know what the worst obstacle to gaming is? Work. So now that work is starting to slow down a bit for me I decided it was time to start posting some of the stuff I've been thinking about since I last posted, which up until last week was also the last time I did any gaming.

First up, Crypto. I am fascinated by cryptography and have for some time now been looking for a way to integrate it into a roleplaying campaign. The biggest problem with the way cryptography is traditionally handled in gaming is that it's glossed over with a few dice rolls, after which the character either understands the message right, understands it wrong, or has no idea what it means. What if you want have your players more involved in deciphering the message. Well you could give them the sheet of cipher-text and hope they know some cryptanalysis techniques, or you could give them a Ceaser cipher and watch them break it with ease (especially if they have computers with them), but neither of those have any relation to the character's actual skill in cryptography so you've removed all incentive for players to spend anything getting or upgrading those skills.

What we really need is some sort of system that is based on the characters' skill but still has some involvement of the players solving the puzzle, and since I'm posting this I've obviously got a suggestion for use which I'm calling Cryto Cards.

The idea of Crypto Cards is that all coded messages the players find will be given to them in English but instead of the Latin alphabet a constructed alphabet (probably of at least 100 characters) will be used to write the handout. This means that when the players first find or receive the message it will appear totally alien and unreadable to them. Now the GM will of course have a translation key for the alphabet (having likely been the one who created it) and from this key they will create a set of Crypto Cards. Each of these cards will contain the English translation of one character from the constructed language, for example the character depicted by '#' means 'th' in English.

Everytime a character gets a new coded message they will make a skill roll against whatever deciphering skill they would use, this roll should be modified by a penalty based on the GM assigned complexity of the overall code and a bonus based on the information content of the messaged being worked on (a repetitive standardized message will give better clues for decoding). Based on the success of the roll the player will receive a number of random Crypto Cards for characters in the message, ie the player scored 3 over the target number for the skill test and recieves 3 Crypto Cards.

Armed with the Crypto Cards and the raw coded message the player(s) then can work on their own to decode the message. Depending on how you are running the campaign the players may need to find more messages or make more decryption tests on the same message till they have all of the Crypto Cards or enough that they can solve the message on their own. This give the players some involvement in decrypting the messages but characters with higher decryption skills to be of more use in the task. Of course this system is of no use if your players have no interest in cryptography or working out puzzles themselves, but that's your job as GM to judge that.

As an option to increase complexity of the system you could add False and Complex Crypto Cards. False cards would look identical to regular cards but have a incorrect translation on them ('#' means 'ch', when it actually means 'th') and would be received by players when their character makes a major failure on their decrypting roll, to simulate false leads in decoding the message. Complex cards would contain more information than normal cards; either several translated characters, or translations of the most complex characters, or root forms used to create certain sets of characters, or even a complete sentance translated. Players would recieve Complex cards if their characters had a major success of their skill roll, to represent a major breakthrough in decoding.

If you want to know the convoluted thought process that lead to the idea of Crypto Cards you can read below. Or you can just go off and try them in your game and see how it goes, that was I plan to do in an up coming campaign I am currently developing, but more on that in a future post.

Like most ideas (or at least mine) this one came from a bizarre connection of ideas, in this case it was the Voynich manuscript, Japanese, and Nordic runes.

It all started by wondering if someone could create a work as cryptic as the Voynich manuscript by just writing in English but using a constructed alphabet instead of the standard Latin character set. A standard monoalphabetic replacement with just 26 characters would not be enough of course so what if one did something like written Japanese does where characters can represent consonant-vowel parings (ha, me, so, ...), then you've now got an alphabet with over 150 characters. If you then expanded it out to include common English consonant-consonant and vowel-vowel pairings (ea, ie, ch, gh, ...) and some three letter groupings (ght, tch, eat, ...) you would probably be well over 200 characters in the alphabet. To increase the complexity even further you could have seperate characters for capitalized letters (T vs t, Ha vs ha, ...) and have no commonality between grouped letters and their root letters (th has no common form to t or h or Th), this would probably allow you to easily approach 500 visually unique characters in your alphabet.

Now while this is a fascinating idea is doesn't have a whole lot of practical use for anything other than confusing cryptographers and archaeologists of the future, so I just had is kicking around in the back of my head for a while till something else triggered it. The trigger to move the idea of a constructed alphabet on actually came from a small blurb at the bottom of a Wikipedia article. While reading an entry on Nordic runes I came across mention of use of the runic language in fantasy literature as a representation of the Dwarven language, this got me thinking that I could use my idea of a constructed alphabet in gaming somehow.

Now the next step in this chain of ideas gets a little fuzzy, but I think it had something to do with the constructed alphabet actually being used to write English text and the idea of handing players messages written in the alphabet, but somehow this lead to a jump to the idea of Crypto Cards.