Let's say you're about to meet a friend in public, and you need to communicate an extremely important message. However, you can't say a word, write down anything, or make any visible gestures. How would you communicate your message?
This is a dilemma that was faced by government operatives during the height of the Cold War, since they never knew when they were being watched or listened to, and they couldn't leave behind any evidence of their true intentions. These days, it may sound like something out of a spy movie, but there were undoubtedly many real situations when lives depended on sending a message in public without alerting passersby.
The need for silent and covert communication led CIA operatives to develop creative solutions. One of these solutions involved subtle variations to an often overlooked piece of apparel: shoelaces. The Cold War Spy Pocket Manual explains:
“Because shoelaces are inserted in shoes in three standard ways, any deviation in these ways becomes useful for signaling. There are… several standard ways of lacing shoes and several ways in which shoes could be laced but never are. None of these alternate ways will attract attention, yet each is obvious to one looking for such a signal.”
See above for an illustration of a few potential shoelace code variations. These were found in The Official CIA Manual of Trickery and Deception, a declassified version of an actual CIA field agent training manual from the 1950s.
So, what did these codes mean? There wasn't a standardized language — these patterns are believed to serve as a visual cue for identification, but they could also be used to send messages which had been previously agreed-upon between operatives. The Cold War Spy Pocket Manual continues, “Because there are several such patterns, added information could be given by the choice of pattern used. “I have information for you.” “I'll follow your instruction.” “I have brought another person.” What need be said is not for this writer to suggest — merely the means to say it.”
As you might imagine, shoelaces were only one of many secret visual cues. The manual also suggests subtle variations in shirt button shape or color, pen or pencil placement in a pocket, or even sticking a thumbtack in a specific location on the heel of a shoe. If you'd like to learn more, check out The Cold War Spy Pocket Manual by Philip Parker, and The Official CIA Manual of Trickery and Deception by H. Keith Melton and Robert Wallace.
For a documented example of covert communication saving lives, watch this video of U.S. naval aviator Jeremiah Denton blinking “T-O-R-T-U-R-E” in morse code during his time as a POW in North Vietnam.