Last week, Verance announced that the US Patent and Trademark Office has issued them a new patent intended to prevent the disabling of a watermark on recorded content. The patent is entitled "Method and Apparatus for Preventing Removal of Embedded Information in Cover Signals." The company has recently drawn the ire of audiophiles, who claim that its watermarking methods are audible in high resolution media such as DVD-Audio recordings (see previous report).

The company says that the patented technology involves a new method of protecting "transactional" watermarks. Verance explains that "transactional watermarks permit unique information to be embedded into individual copies of recorded material. These watermarks are potentially subject to collusion attacks, in which multiple recipients combine copies in an attempt to erase or obscure the marks in the combined copy."

The company is claiming that the recently developed method represents a fundamental advance in the security of transactional watermarking technology. Verance's Joseph Winograd states that "as we continue to make advancements in the applications of watermarking technology, it is imperative that we continue to develop new methods for protecting the integrity of watermarks. With this new patent, we make an important breakthrough in watermark security."