Re: Old typewriter
For example, a program to broadcast a specific piece of music to indicate where to plant bombs.
That's code, not encryption, and depends on the receiver(s) having been given a set of pre-defined actions corresponding to the messages that are going to be sent, the most famous ones likely being the two that announced the Allied invasion of France, one a day ahead, the second at the actual start. Getting such a list of actions to, in that case, the French Resistance may well have employed cryptography, but the messaging mechanism itself is code.
Biting the hand that feeds IT
