Lab Notes

A year ago (I'm a little behind in my reading!), the New Yorker covered efforts to quell prison violence by reining in the Aryan Brotherhood. Mixed in with a harrowing account of prison life is a description of how inmates used cryptography to communicate murder plans in plain view of the guards.

The prisoners employed multiple layers of security to conceal their messages. First, they used urine as poorman's invisible ink — when the paper containing the message is heated, the "ink" becomes visible. Next, the message was written using seemingly innocuous phrases that were really coded instructions — "eight pound seven ounce baby boy" meant "the murder is approved". Finally, the shape of the alphabet letters in the messages concealed a secondary message containing a sequence of A's and B's (the initials of the Aryan Brotherhood). By breaking this sequence into clusters of five characters, the secondary message could be translated, provided the recipient had the cheat sheet for mapping each cluster to a single letter.