A new watermarking technology could help track down people who make copies of copyrighted digital material. The technique works by concealing information about the identity of the offender inside the copy, according to the company developing the technique.
Amino Communications, based in the UK, is developing a specialised microchip and software for use with digital video recorders and future pay-per-view television systems that have digital recording capabilities. Amino’s system includes information from a user’s smart card in a watermark inserted into the copied file.
“Digital delivery of video is still in its infancy,” says Martin Neville-Smith, chief technology officer of Amino. “But the studios are already getting quite worried about things being ripped off.”
Current digital video recorders allow users to record and pause programmes they are watching by digitally storing information onto a hard drive. The next generation of players are expected to offer greater functionality, including incorporation into Pay TV, the capacity to send files over the internet and the ability to record files to a DVD.
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Watermarking involves hiding information inside a piece of data that cannot be removed without impairing the quality of its output. This can be used to protect audio and video files by telling hardware players and recorders whether a file can be copied or shared.
Electronic trail
Digital television broadcasters are developing other watermarking schemes designed to control copying in the first place. These would be added before a program is broadcast and would tell a receiving player not to record, or to only record something a limited number of times.
Neville-Smith says that the Amino watermarking scheme would take things a stage further. It would mean that even if someone manages to make pirate copies of a protected program, an electronic trail would lead straight back to them. Even if personal smart card data were unavailable, the watermark could include information about the hardware used to make the copy.
But although watermarking can protect content in practice, most schemes are fallible, say experts.
“So far nobody as come up with schemes that are really robust to attacks,” says Fabien Petitcolas of Microsoft’s research labs in Cambridge.
Privacy concerns
Jean-Paul Linnartz, a researcher at Phillips in the Netherlands says that this sort of watermarking might also raise some privacy concerns.
“The political issues of user identity in content is controversial,” Linnartz says. “I see these tools as an aid in tracing the source of the copies. Whether it can be a legal proof is doubtful.”
But Neville-Smith believes that users should not be concerned. “It is only relevant to content that belongs to someone else,” he says.
