Multimedia security: Does signal processing have a place in securing the digital world?

With the recent growth of networked multimedia systems, techniques are needed to prevent (or at least deter) the illegal copying, forgery and distribution of digital media elements such as audio, images and video. The problem is that a copy of a media element is identical to the original. It is also desirable to determine where and by how much a multimedia element has been changed from the original. One classical approach to the problem of protecting "digital content" has been the use of cryptographic methods such as encryption and authentication. Recently other methods have been proposed to improve one's claim of ownership over a digital media element by inserting a small amount of distortion directly into the media element. This distortion, known as a digital watermark, can be used to uniquely identify the owner of the content. Digital watermarking research is mainly the domain of the signal processing community that is very naive when considering real world security problems. Also the attitude of the academic community that it has the "right" to copy and reproduce any multimedia element is curious at best and perhaps conveys the wrong message to our students. The use of the "Lena" image is a good example of this. In this talk I will survey the current state of multimedia security and describe important research issues. I will also express some concern that perhaps we in the signal processing community might want to understand the "security scenario" before making grandiose claims about how our latest watermarking technique will save the world!