[Bug 24027] Define a generic Initialization Data solution for ISO Base Media File Format and/or Common Encryption (will be used by Clear Key)

https://www.w3.org/Bugs/Public/show_bug.cgi?id=24027

--- Comment #8 from David Dorwin <ddorwin@google.com> ---
(In reply to Mark Watson from comment #6)
> My proposal, in outline, would be that the PSSH box contain
> - one or more 16-byte Key Ids
> - for each Key Id, optionally, a 16-byte MAC of the Key Id, calculated as
> the HMAC-SHA256 of the Key Id using the Content Key as the key for the HMAC
> calculation

This sounds fine. The question is how do we specify the count (easier) and
whether to expect the MAC.

> I would
> expect, though, that the PSSH is usually constructed when the file is
> encrypted - since the form of the encryption is very ISO BMFF-specific - and
> s the encryption key(s) would be available.

To clarify, the first paragraph of comment #5 was referring to also being able
to generate the PSSH to provide to createSession(). I agree that the encryption
key should always be available during packaging.


(In reply to Joe Steele from comment #7)
> This looks like a good format. And many (most?) OTT providers should be able
> to generate this either at packaging time or at license generation time
> without trouble.

Yes, but it's not needed at license generation time - the license contains the
key but not the Initialization Data. On the other hand, an application might
want to generate valid Initalization Data at license request generation time
(createSession()).

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Received on Wednesday, 19 February 2014 22:47:28 UTC