Steganography conceals information by hiding it in non-secret information.
Here we have a musical steganography -hiding information by varying the tempo of music (pdf)
StegIbiza: New Method for Information Hiding in Club Music
Krzysztof Szczypiorski 1,2
1 Cryptomage SA, Wrocław, Poland 2 Warsaw University of Technology, Warsaw
Abstract—In this paper a new method for information hiding in club music is introduced. The method called StegIbiza is based on using the music tempo as a carrier. The tempo is modulated by hidden messages with a 3-value coding scheme, which is an adoption of Morse code for StegIbiza. The evaluation of the system was performed for several music samples (with and without StegIbiza enabled) on a selected group of testers who had a music background. Finally, for the worst case scenario, none of them could identify any differences in the audio with a 1% margin of changed tempo.