I am a Linux user and was unhappy to discover that HDCP protection on websites such as vhx.tv is preventing me from viewing the content in perfectly legitimate contexts because all Linux browsers lack HDCP support. Since HDCP was "broken" years ago, in terms of master key leaking, any device could theoretically authorize itself against an HDCP check.
Hypothetically, what is preventing someone from either writing a browser extension or creating a custom firefox build that overrides the DRM API in this way?
Why is there no such project, is it just a lack of interest or is there a hard technical barrier that is preventing this? How can anyone say that HDCP was "broken" if not even legitimate users can circumvent it when they wish to do so (eg. to watch DRM content on Linux)?
DRM systems are not within the browsers control usually, they are self-contained blobs, and the only way to get licenses (and therefore the content keys) is by using the DRM module to do a license acquisition operation.
Getting the license and decrypting and displaying the content happens within the DRM component (outside the purview of the browser) and can therefore not be accessing from a browser extension. The only way to get around that, would be to create an unauthorised version of the DRM module, get that loaded in the browser, and not have the server side code discover that the DRM module has been altered. This is generally very hard, and that is really what makes the DRM module work.