Le decadi 10 fructidor, an CCXXIII, Thomas Schmitt a écrit : > the reason why i am insisiting in getting facts is that > i want to know whether drive firmware can get altered > by just inserting and reading a commercial Blu-ray disc. > > I sincerely doubt that the drive firmware will do this, > but rather believe it is about software on the level > of operating system and application software. > (Both of kinds which i would not touch with fire tongs.)
IIUC and IIRC, the DRM on Video Blu Ray disks work as follows. You can probably ask for confirmation from the authors of libaacs, who are much more likely to have reliable information than anyone on this list (including me). The video data on a Video Blu Ray disk is encrypted using AES and a random unique session key. (Or more probably it is a key per title or something, it does not matter much but may be used to identify leaks.) Then the session key is encrypted using all the keys currently recognized by the Video Blu Ray cartel. Publishers of video players, either as computer applications or embedded in dedicated hardware, have to buy keys from the cartel. With these keys, the players can decode and play Blu Ray discs, but they have contractual obligation to refuse anything that would allow duplicating them. If a key becomes compromised, the cartel revokes it simply by stopping using it for new discs. Therefore, new discs can no longer be decoded with that key. Older discs are already leaked anyway. (I suspect the purpose of this system is not to really prevent copy than to delay it, in fact.) The publisher that used that key can buy another one from the cartel, possibly after proving that they have increased the obfuscation of their software (using the word security in this case would be absurd) tu prevent further leaks. Happy owners of players that used that key can possibly download an update from the publisher with new keys. If the publisher has gone out of business, or simply got bored with that model and wants to push for new buys, no updates will be available, and the aforementioned happy owners will soon become unhappy owners of a useless lump of metal and plastic, they will probably realize that if the industry really wanted people to respect copyright they would make it more comfortable and easy than not, and eventually install a BitTorrent client. I believe that is all there is in general. Of course, it does not exclude isolated initiatives by overzealous publishers. The Sony rootkit was mentioned, but it was on CDs, not Blu Rays. There were the DVD drives by Matsushita, usually found on laptops, that did refuse to return the encrypted contents if the region did not match. I do not know of any specific case for Blu Rays. Regards, -- Nicolas George
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