Forensic Watermarking for Secure Multimedia Distribution
The Internet was established as a medium for communication, to facilitate the distribution of information in electronic format, which is contrary to the desire of some parties to control the distribution and use of their intellection property. The problem of infringement was a minor issue for many years, but given the recent growth in the use of computer technology as a delivery method for multimedia (audio, image, video) content, the illegal copying and distribution of certain works has been a growing concern.
This chapter presents a method for forensic tracking through digital watermarking - in effect, the inclusion, in a media file, of data that will identify the owner and verify the authorized user of protected content.
MULTIMEDIA DISTRIBUTION AND DIGITAL WATERMARKING
There are three primary concerns for IP owners:
- The ability to identify the rightful owner of any given piece of content
- The ability of the owner to determine where the content has been distributed
- The ability of the owner to detect any illegal attempts to redistribute or alter the content
The focus of this chapter is forensics - the detection of actions taken by individuals. Methods to prevent unauthorized actions, or to react to them after they have occurred, are separate matters.
There are some details about the act of redistributing content - how the network facilitates the creation of "perfect" copies of digitized content, and how an individual who has received, by legitimate means, a copy of the content can then redistribute it to others freely. Attempts to prevent the redistribution of digital files have been attempted, and have been thwarted.
The author's suggestion is to include a watermark in the data file, which identifies the owner and the legal recipient of a file, such that any copies made of that file could be traced back to that individual. This addresses the three primary concerns above, or at least provides a marking that can be used to address them.
A NEW ICA-BASED WATERMARKING SCHEME
The author gets into the nuts-and-bolts of watermarking - mathematical equations of visual examples of watermarked images. Some key points:
- Watermarking can be invisible to the user, and should not interfere with the quality of the media.
- Watermarking should be embedded in the data itself, in a way that makes it difficult to be removed
- Visible indication of ownership should still be provided as an explicit indication of ownership
- The digital watermark should be easily read by comparing the watermarked file with an original, unmarked file - differences between the two files constitute the watermark.
- The watermark should be repeated throughout the file, such that editing the file (cropping, scaling, distorting, down sampling) will not prevent it from being detected.
SUMMARY
EN: The chapter went way too far into the granular details and seemed to be more about a heads-down implementation than principles that could be more broadly applied. Didn't get anything out of it, really.