- From: David Singer <singer@apple.com>
- Date: Fri, 10 Jan 2014 08:56:01 -0800
- To: "public-restrictedmedia@w3.org" <public-restrictedmedia@w3.org>
On Jan 10, 2014, at 6:26 , Jeff Jaffe <jeff@w3.org> wrote: >> We can start a new group and make a fresh start exploring alternative approaches such as water marking, or using web intents to redirect DRM content to an alternative device, > > I doubt that anyone would object to exploring these alternatives in the current group. I, for one, have been asking for that for a long time. In a desperate attempt to discuss something actually technical… I am only aware of two uses of watermarking in copy protection: 1) Define the system such that all players must detect watermarks and refuse to play unlicensed content. Since such a system can’t be implemented open-source (or one could trivially defeat the refusal to play), it doesn’t meet your goals. Also, since now everyone has a watermark-detector, you have given the world the tool needed to detect when they have successfully *stripped* the watermark. So, this approach neither meets your goals nor works well. (There was a famous attempt to do copy protection this way about a decade ago, and a competition to see if it was breakable — which it was.) 2) Use watermarks for forensics. Every copy delivered is watermarked in some way (minimally, so you can tell who sold it). If repeated unlicensed copies are found, then start dividing the possible population into successively smaller parts, focusing in slowly on the miscreant. Eventually, if they are prolific, you find the original sale that leads to the unlicensed distribution. Needless to say, this is a lot of work, and only worth it for the most egregious cases, and so doesn’t serve to introduce ‘friction’ into the copying, and so doesn’t really serve as copy-protection, but rather enforcement assistance. True, the fear that you are catchable and may be caught is a (small) deterrent. Are there other uses of watermarking that anyone thinks work better? David Singer Multimedia and Software Standards, Apple Inc.
Received on Friday, 10 January 2014 16:56:30 UTC