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- Information hiding and watermarking
- Uses of information hiding and
This Module details the practical applications of information hiding and watermarking audio as studied in the fall 2008 ELEC 301 class project.
Uses
Secure storage
Hiding security-sensitive information in music epitomizes the idea of
"security through obscurity" . Even if an intruder should gain access to the encrypted music files, there may not be any external indication that the files contain encrypted data, rather than simply music. Playing the files as they were intended produces regular, non-suspicious music that is nearly indistinguishable from the unmodified recording. Even if a would-be eavesdropper realizes that the music contains encoded bits, the issue still remains of finding the encoded bits within the signal and deciphering their meaning.
Covert communication
The same reasoning can be applied to music that is openly broadcast between parties wishing to communicate in secret. An unsuspecting listener just hears music, but the desired audience has the tools to extract the hidden message. This is not just for spies, of course. A system could be designed where a radio station broadcasts music encoded with information about the song that is currently playing. A special receiver interprets the hidden code and offers the listener the option to buy the current song or other songs by that artist. Regardless, listeners with or without the special receiver do not perceive any loss of sound quality compared to a regular radio broadcast.
Copy control
Individual copies of a piece of music could be labeled with imperceptible watermarks containing serial numbers. The watermarking algorithms designed in this project would have to be modified slightly, but they could be used to verify a signal's compliance with the following rule. A copy is only a legitimate copy if it includes the official watermark and/or a serial number that has already been sold. Furthermore, when each customer purchases a copy of the song, his or her purchase will be assigned a serial number. If multiple copies of a song bearing the same serial number are discovered where they should not be, then it is clear which user is responsible for breaking the rules.
Source:
OpenStax, Elec 301 projects fall 2008. OpenStax CNX. Jan 22, 2009 Download for free at http://cnx.org/content/col10633/1.1
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