If you are meeting your friend or colleague in public but can’t let anyone know about the meeting, how would you do it? The message is extremely important, it is a matter of security and lives depend on it being conveyed – but if you are seen talking, writing things down or making visible gestures then it could all be for nothing. This is the goal the CIA wanted to solve when they created their shoelace code.
The dilemma came about during the height of the Cold War since they could never know if they were being watched or listened to by other government operatives. These days it sounds like something that would only happen in a spy novel or James Bond movie but during the Cold War, this was an everyday ordeal that operatives had to deal with. Lives would depend on an agents ability to send a message to a passerby without alerting anyone in public. Therefore, the CIA developed a shoelace code.
Because shoelaces are generally inserted into a shoe in three standard ways, any deviation from these ways becomes an opportunity to send a signal. You can do this, therefore, and use them as a way to send coded messages to a passerby, also because having shoelaces on a bit differently will probably not arouse any suspicion in public.
These coded CIA shoelace messages were published in a declassified version of a real CIA field manual from the 1950s. There was not however a standardized language, the patterns were normally to be used as a way to make an identification. But of course, if two operatives had met beforehand, then they could agree on a pattern to mean a different message.
As you can imagine the CIA used many ways to covert secret messages during the Cold War including things like button shapes or type of pen. It could even be as simple as having a pencil in one pocket, covert communication was a way to save lives.