A jargon message is much like a substitution cipher but instead of replacing individual letters the words are changed. In this author's younger days, I used a sort of jargon code to talk about pretty girls without them realizing it. My friends and I would replace the girl's name with a similar boy's name, usually trying to replace as few letters as possible to keep the real name clear. If, for example, we wanted to talk about 'Jen' we'd refer to her as 'Ken'. Changing the girl's names to a boy's added the mystery of our conversations (especially since there wasn't a Ken in our class). I doubt, though, that Jen didn't realize we were talking about it.

The Jargon code relies, like the Cardano Grille, on the sender's imagination and ingenuity to prevent from raising any eyebrows about the contents. In the case of this author's childhood mischief, the senders did a very bad job of masking the meaning of the jargon. But, the author feels a little better about his foolishness when he reads about adult diplomats whose jargon codes were just as obvious.

In a telephone exchange between Japanese diplomats during WWII, it's painfully clear what each of the jargon terms mean. With sentences like, "", it's difficult not to realize what they're talking about.

So far, we've only seen bad examples of jargon code. However, it can be very powerful if used correctly. One Russian spy, for example, sent the following message in a letter that was intercepted by the American Black Chamber (a mail interception and monitoring facility).

Plaintext…

In the very innocuous looking text above, the speeds of several American fighter jets are hidden. The only reason that the message was correctly identified as a jargon code was because the swim times seemed impossible (which they were). If not for the quick eye of a mail reader, this jargon message would have passed easily. Jargon codes were so difficult to differentiate from normal mail that soon after Pearl Harbor the U.S. Postal service placed censorship bans on types of messages that could easily be carrying dangerous information. Games of chess via the mail were banned, as were messages ordering flowers, children's drawings - even the XOX's at the bottom of lover's letters were removed for fear of a secret code. A censor once found instructions for knitting a sweater and actually knit the sweater to make sure that secret messages weren't hidden in the sweater.

So, just remember to make your jargon code look like a normal message, and if you're like me, this will come in handy during school when you want to refer to a girl without her knowing it.