Re: [gentoo-user] Re: DVD Movie backups

[Michael Mol]

On Sat, Dec 17, 2011 at 7:35 PM, Mark Knecht <markknecht@×××××.com> wrote:
> On Sat, Dec 17, 2011 at 3:03 PM, Neil Bothwick <neil@××××××××××.uk> wrote:
>> On Sat, 17 Dec 2011 20:13:43 +0000 (UTC), Grant Edwards wrote:
>>
>>> Yep.  I'm not aware of any Linux software that can create an encrypted
>>> DVD -- but I've never had a desire to do that, so my lack of knowlege
>>> of such a thing shouldn't be used as an indication of non-existence of
>>> such a thing. :)
>>
>> You also don't have the hardware to create them. CSS keys are stored on a
>> separate area of the disc, an area that is not available on DVD-Rs,
>> which is why yo cannot copy a CSS-encrypted DVD with dd, it copies the
>> encrypted data but not the decryption keys.
>>
>>
>> --
>> Neil Bothwick
>
> Interesting but still a little confusing. My DVD-RW drive can
> apparently _read_ the CSS keys because xine can play the DVD. I'm
> assuming here that the Linux DVD libraries need the keys but maybe
> they don't actually even need them to play a DVD if the encryption can
> be broken without the keys.
>
> I guess you are saying that either the CSS keys are completely
> unnecessary,

The CSS encryption scheme is incredibly poor. Where it's actually
applied, it can usually be cracked fast enough that you wouldn't
notice a stutter in playback.

> or that the DVD-RW drive can read but not write to the
> area where they are stored?

They may be read, but not written to. In order to read them, your
player software needs to present the DVD-reading devices with some
kind of credential. DVD playback devices are supposed to be licensed,
and this is the hardware means of enforcing that.

Consumer DVD burners aren't able to write to the portion of the disc
where keys are stored, either. This is part of the copy protection
mechanism of CSS.

-- 
:wq