https://en.m.wikipedia.org/wiki/Gabriele_Gast

> After agreeing to help, Gast very soon found herself sent on an intensive spycraft course, including hands-on training with the latest in covert communications equipment. She was given a Stasi code name, "Gisela", which came with a false passport and a new handbag, incorporating a well concealed secret compartment. Back home in Aachen, every Tuesday evening at the same time she tuned into a shortwave radio station from East Germany and carefully wrote down a long line of numbers, read out in a monotone, without further elaboration, by a "radio presenter". When she decrypted the messages from Schmidt she found some were instructions while others were simply encouraging love messages.