Forensic digital watermarking technology, like the technology Microsoft has patented, doesn't encrypt files the way DRM technology does or prevent people from unauthorized use. However, it can be used to prove who owns the content of the digital file by encoding a file with a unique digital signature. That means illegally traded songs could be tracked back to the original purchaser, allowing authorities to identify illegal sharers and serving as a deterrent.
The technology could also be used to track files for royalty distribution.
In fact, Apple has been inserting simple watermarks into digital audio files that include personal information about the purchaser on some files sold over iTunes so those files can be traced back to their purchaser in the case of unauthorized distribution.
However, Microsoft's watermark is much more intrinsic to the file and cannot be stripped out easily by hackers, like Apple's can, said J. Alex Halderman, [cq] a computer science PhD candidate at Princeton University who specializes in DRM technology. "It's much harder for people to remove from the recording," he said.
The trick for these watermarks to be effective for digital music files, however, is that they must be inaudible and thus undetectable by those listening to the files, which has been difficult for those who have tried to create this technology in the past, Halderman said.
it works.