[Bug 25269] Add a container-independent initialization data type for providing a list of key IDs to createSession()

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25269

--- Comment #6 from Joe Steele <steele@adobe.com> ---
(In reply to David Dorwin from comment #5)
> (In reply to Joe Steele from comment #4)
> > (In reply to David Dorwin from comment #3)
> > > (In reply to Joe Steele from comment #2)
> > > > This assumes that the list of key IDs would be meaningful to the underlying
> > > > DRM without any accompanying metadata (i.e. PSSHs). This is not generally
> > > > true.
> > > 
> > > Maybe not in legacy implementations, but why couldn't such a DRM system add
> > > support for this?
> > 
> > At least in the Primetime case, this is not possible. The metadata contains
> > information about the license server(s) and how to communicate with them. So
> > lacking this information, the list of key IDs could only be used to
> > reference existing keys not to request new ones.
> 
> Do you mean URLs, etc.? Since the application handles the communication with
> the license server, couldn't it know the URLs, etc.?

Yes and other information. The application may know some of the information,
but it may not be able to use the information to create a valid key request. 

When talking about CENC, the key ID referred to in the TrackEncryptionBox
(tenc) or the SampleGroupDescriptionBox (sgpd) is just a reference. The
information about how to use the key ID to decrypt content is contained within
the PSSH. If the PSSH is not present, in general the DRM does not have enough
information to retrieve the key needed to decrypt the content.

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Received on Monday, 7 April 2014 18:44:17 UTC