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Re: Encrypted Media proposal: Summary of counter-proposals

From: Charles Pritchard <chuck@jumis.com>
Date: Thu, 08 Mar 2012 14:46:28 -0800
Message-ID: <4F5936C4.10206@jumis.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
CC: Mark Watson <watsonm@netflix.com>, Henri Sivonen <hsivonen@iki.fi>, "Tab Atkins Jr." <jackalmage@gmail.com>, Christian Kaiser <kaiserc@google.com>, "<public-html@w3.org>" <public-html@w3.org>
Regarding: document.getElementById("video") 
.getContext('experimental-ecmd').generateKeyRequest("org.w3.clearkey", 
null);

On 3/8/2012 1:19 PM, Silvia Pfeiffer wrote:
> I like this idea a lot. It introduces a generic way to plug extensions into the video and image (and presumably the audio) element with functionality that is chosen through extra mime type parameters. I would, however, suggest not to use "audio/mpeg+keysystem" as the mime type, but rather mime type "audio/mpeg; keysystem=xxx".

I agree, that is a better use of mime type.


Here's how I see it playing out across uri, css, dom and xml:


On the Hixie uri prefix proposal, I'd see: 
"enc:<keysystem>;key=<optional key>,iv=<optional initialization key>:<url>"
Hixie's proposal serves different needs than the Encrypted Context.

For the first keysystem, "http".
The http keySystem processes the Content-Type of the url and uses that 
as the key system attribute.

For the second keysystem, "aes".
Hixie's AES block cipher proposal with multiple key lengths.

For the third keysystem, "chacha",
 From the ChaCha20/20  variant of eSTREAM Salsa20; the basis of the 
BLAKE entry to SHA3.

The fourth keysystem, "org.w3.clearkey",
 From the Encrypted Media Extension proposal.

The fifth keysystem, "org.w3.securekey",
Pass it off to the OS client certificate system to figure things out.
For example, OSX has keychain.

The sixth keysystem, "com.netflix.honorarymention",
 From the Encrypted Media Extension proposal, with actual CDM negotiation.

The enc prefix helps with shorthand static content, like CSS:
     url(enc:org.w3.securekey:http://cdn.example/encryptedfile.png),
     url(http://cdn.example/unencryptedfile.png),

As an example of CSS use, the author could swipe a card and the CSS 
would swap over to encryptedfile.png.

For DOM, it'll save unneeded requests:
var a = new Image(); a.src = 
"enc:org.w3.securekey:http://cdn.example/encryptedfile.png"

For HTML,
<video><source src="http://site.com/cdmprotected.file" type="video/mpeg; 
keysystem=com.netflix.honorarymention"><source src="loading.mp4" 
type="video/mpeg" /></video>
<script>video.getContext('experimental-ecmd')...</script>


On 09/03/2012, at 7:45 AM, Charles Pritchard <chuck@jumis.com> wrote:
>> >  TL;DR: This document includes my TL;DR recommendation, a summary of three proposals, and ends with a longer recommendation.
>> >  
>> >  We are here, and it's contentious:
>> >      var video = document.getElementById("video");
>> >      video.generateKeyRequest("org.w3.clearkey", null);
>> >  Let's go here:
>> >      var video = document.getElementById("video");
>> >      video.getContext('experimental-ecmd').generateKeyRequest("org.w3.clearkey", null);
Received on Thursday, 8 March 2012 22:46:54 UTC

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