Watermarks have been around for more than a century, but the digital versions are just starting to help authenticate and identify content and secure IDs
Ryan Kline, Contributing Editor
Six-months ago there was a battle between high definition content providers of DVDs. At the end of the battle, it was determined that HD DVDs would no longer be sold or produced, and that the Blu-ray disc format would become the standard. The situation is reminiscent of another video battle that happened in the early 1980s between VHS and Betamax. History repeats itself, but this time, it may be a little more important to you. How so? Blu-ray supports digital rights management (DRM) and digital watermarking, something that may be used to help verify authenticity of the materials stored on the disc. This digital watermarking technology is something that has been used on government-issued IDs for some time and is just starting to make an impact in the digital world.
How the battle ended
In early 2008, Warner Brothers, the only major studio still releasing movies in both HD DVD and Blu-ray disc format, announced it would release only in Blu-ray disc after May 2008. This led to a chain reaction in the industry, including major U.S. retailers, such as Wal-Mart, dropping HD DVD from its stores. A major European retailer, Woolworths, dropped HD DVD from its inventory as well. Then Netflix, the major online DVD rental site, said it would no longer stock new HD DVDs. Following these new developments, on February 19, 2008, Toshiba announced it would be ending production of HD DVD devices, allowing Blu-ray disc to become the industry standard for high-density optical disks. As a result, all major Hollywood studios now support only Blu-ray.
Blu-ray discs use Advanced Access Content System (AACS), a standard for content distribution and digital rights management. A consortium with large players including The Walt Disney Company, Intel, Microsoft, Panasonic, Warner Brothers, IBM, Toshiba and Sony developed the AACS under the consortium name of Advanced Access Content System Licensing Administrator.
Delivery of high-definition content via an optical device, in this case the Blu-ray disc, is an example of how DRM can be used, but there is another technology called digital watermarking that can also help identify the content. Digital watermarking was first used to keep tabs on media such as digital images, but then the technology was applied to different identification schemes, including driver licenses and government-issued IDs.
Digital watermarks, though, are different than normal watermarks. These digital features are not visible at all, unlike normal watermarks on images. “Watermarks are built to be imperceptible,” according to Reed Stager, executive vice president of Digimarc. “They are things that you can not see and can not hear, but can be detected by computers or by other similar devices.”
“Digital Rights Management is the end-to-end process by which content such as audio and video are discovered, delivered to, and consumed by users in such as way that both the content users and the content producers benefit,” according to Gord Larose, senior application security engineer at Cloakware, a security solutions provider that makes security inseparable from the software it protects. “Copy protection for audio and video is the most common use of DRM, but in well-implemented products it is unobtrusive and usually part of a package that has other advantages such as excellent user interfaces, well-managed web stores, etc.”
Something so discreet but still powerful
“DRM has a long history of being used in a number of different formats. Many people are familiar with the form of it as far as conditional access for television: Pay-per-view and what they might get over their set-top boxes at home,” comments Stager. “This basically allows you to manage or control pieces of media content.”
But what is digital watermarking?
Stager continued, “Digital watermarking is actually something that is complimentary to DRM, and can be used for that, but is more the ability to consistently identify media content, or all forms of content from digital images to video and audio to even printed material such as security documents, driver licenses or other forms of ID.
“Both digital watermarking and DRM and can help protect media content, but they do so in much different ways,” Stager says. “Traditionally, DRM seeks to encrypt content at a point of origin and allows a device further down the distribution chain to decrypt it.” For example, television signals are encrypted by the content owner or the broadcaster and are then decrypted by a set-top box so that viewers can see it.
“A watermark does provide a persistent identity for the content and doesn’t necessarily lock it up. It just allows you to identify that particular instance of content by putting an identifier into the signal itself before it is being transmitted and then certain readers and devices could read that down stream.” Most of us have already seen digital watermarks first hand. Stager explained that most of the broadcast television that we watch has a watermark or even multiple watermarks in the content. They are placed either in the video stream or the audio stream enabling broadcast monitoring as well as audience measurement, like what is done by Nielsen for the TV ratings.
AACS uses a combination of DRM and digital watermarking, according to Stager. “There are other forms of watermarking that have been deployed in conjunction with DRM systems, such as what is being used with Blu-ray discs. They will use a form of content protection called AACS. That system also has the ability to detect watermarks that indicate protected content. All the watermark does is help identify the content that should be protected. If it is protected with the standard AACS systems still around it, no action would happen to the content and it would be handled normally.”
Digital watermarking has become a growing industry, as evidenced by the sale of part of Digimarc, whose larger business has been working with states to issue driver licenses and other IDs. Digimarc sold that business and is concentrating on the digital watermarking content business.
Digital watermarking is also used to protect digital images with copyright and ownership information. “People like Microsoft with their Virtual Earth service watermark the images that are provided there with the satellite imagery. Many of the major motion picture studios watermark their digital imagery so they can identify the copyrights on it and actually can enable searches of the web looking for their copyrighted images.”
Even though it is a widely used technology, digital watermarking is still not widely publicized. Regardless, digital watermarks are everywhere. For instance, Hollywood “screener” DVDs given out before the Academy Awards have individualized watermarks so that if a copy turns up on the Internet at a peer-to-peer site, the movie producers can tell which screener leaked it.
It is also utilized on online magazine Web sites like Playboy. “Playboy has used watermarks for images on their web site and successfully sued site operators who copied those images on the basis of watermark evidence,” commented Larose.
“Watermarking involves two components,” says Larose, “an injector, which inserts watermark data into the media in a way undetectable to a human observer, and a detector, which subsequently scans the media and detects the existence of a watermark, if one is present. Watermarking schemes vary in how much data they can encode, and also in whether they contain generic information, such as this image belongs to Playboy vs. individual information, this image was downloaded by Bob Smith.”
Digital watermarking will likely see widespread cross-media use. Some new uses of the technology are being developed in conjunction with cell phones. Users can capture digital watermarks in photos of special print advertisements and business cards and then access additional content right on their phone. But current uses of digital watermarking are sure to stay as well. For instance, Adobe PhotoShop has digital watermark readers built in to the application, preventing users to manipulate certain images.
Digital watermarks also have been deployed in driver licenses. Stager estimates that 85 million licenses have been deployed with digital watermarks, “and it will be in approximately one out of every two driver licenses issued this year.”
“That allows you to quickly and easily detect a watermark and determine if the license is authentic or not,” continued Stager, “or if someone is trying to buy restricted products, determine if that person is of age to by alcohol or something like that.”
When it comes down to it, digital watermarks can help authenticate almost anything. They can be used to authenticate most types of identification documents, as well as almost all forms of content. The key value of digital watermarking is that you can consistently identify content. So don’t be surprised when something you can’t even see makes its way into your secure credentials, ID cards or other personal authentication devices.