[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 #6 from Mark Watson <watsonm@netflix.com> ---
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

The purpose of the MAC is to enable the CDM to validate the key that it
receives for a given Key Id immediately that it receives it, before using it
for decryption.

The MAC can be optional, so that service providers can decide whether providing
it (with the consequence that the content keys must be available to the
packaging system that generated this box) is worthwhile. 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.

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Received on Tuesday, 18 February 2014 16:24:55 UTC