There is a long and melodious history of hiding secret messages in song—so-called musical steganography—that dates back at least 500 years. But now a cybersecurity expert from Poland has revealed a new way to send messages that are otherwise undetectable through song: tiny adjustments in tempo. To test this, Krzysztof Szczypiorski turned to club music for its trance-like repetition and happily packed his bags for Ibiza off the coast of Spain, arguably the dance-club capital of the world, reports Vice. (Hey, somebody's gotta do it.) Szczypiorski reports in the open journal arXiv (it has not yet been peer reviewed) that in experiments DJing for dancers, he was able to adjust a song's tempo up or down by as much as 2% without anyone noticing any change.
By having a faster tempo represent a dash and a slower one a dot, he used Apple's Logic Pro X digital audio workstation to manipulate the speeds of songs like "Rhythm Is a Dancer" by Snap (normally 130 beats per minute) and randomly encode the message "Steganography is a dancer" in Morse code, reports MIT Technology Review. So long as the change in tempo was subtle enough, nobody was the wiser. (Listen here.) His conclusion: It would be pretty simple to develop software that automatically encodes or decodes messages sent this way. An algorithm could be used to decode the message, though it's possible that some very careful listeners could do so on their own. (Music might also help your beer taste better.)