Protecting HTML Video with Encrypted Media Extensions

In the digital age, Broadcast, Media, & Entertainment companies have undergone significant evolution. On the web, the industry has moved away from proprietary plug-in based solutions (flash/silverlight) and opted for universal open-source and plug-in free video systems based on the HTML5 specifications and industry requirements for things such as adaptive packaging and content encryption. Browsers had their own built-in plug-ins such as ActiveX in Internet Explorer, and they are now using solutions that are more secure, more stable, and more extensible. This is much easier for viewers as well, since everything uses open standards built into the browsers, the viewer does not have any plug-ins to install or update.

Historically web video was primarily protected using a handful of DRM schemes. Google Widevine, Adobe PrimeTime, and Microsoft PlayReady are a few of the leading DRM Schemes. While these worked very well, and they were very effective for protecting content, the were siloed technologies. This means that they were proprietary and locked customers into one way of doing things. The next generation of DRM schemes solved this problem. A few API based standards have emerged as clear leaders, Media Source Extensions, and Encrypted Media Extensions. These are open platforms that allow customers to bring their own scheme and easily change between schemes. The first major tech giant to adopt EME/MSE is Apple, Inc., with their FairPlay, which protects content served by AppleTV.

Media Source Extensions (MSE)

MSE is an API standard for JavaScript that generates video streams for playback over HTML5 using standard media tags. JavaScript acts as the intermediary for the streams which can be either live or on-demand. Because of this, video players can operate without the use of a plug-in, and enables leading streaming standards like HTTP-Live-Streaming, time shifting, and alternate audio tracks. MSE is not specific to any codec, conainer, or DRM scheme, so it can work with any format the browsers supports, creating the opportunity for seamless cross-platform playback.

The MSE uses the HTMLMediaElement via JavaScript to provide detailed controls of the standard HTML5 video tag. All of the properties for this JavaScript element can be found on the Mozilla Developer page. By leveraging an open framework, MSE allows developers to completely customize the components of an application. They are not limited to a specific DRM scheme of method of adaptive playback. The possibilities are endless.

Encrypted Media Extensions (EME)

This is a JavaScript API that is part of a larger content protection and delivery system for HTML5. EME uses Content Decryption Modules (CDM) which are built into the browser, but function independently of the browser. This was a requirement from the media and entertainment industry since the browser is viewed as insecure and untrusted. The CDM is the trusted component that content owners rely on for copyright protection.

For DRM, EME uses a Key System instead of what is traditionally referred to as a DRM scheme. The Key System is the component of the CDM that handles encryption and decryption of content. In the case of the web browser, each browser would have it's own unique key system, which ensures cross browser compatibility.

What makes EME unique is that it is not tied to any specific DRM scheme. The CDM can accommodate whatever scheme the content distributor prefers. This encourages both cross-platform compatibility and improved playback experience. Whether decrypting and serving, encrypting & decrypting, or bypass the CPU by using the GPU, the more the CDM handles the more secure the content remains in the end-to-end workflow. Essentially the more the CDM manages the content-protection process, the less the user can interfere and potentially violate content copyrights. In some cases the copyright holders will place stricter controls on HD vs. SD content. CDM is compatible with the following container formats: MP4/H.264 & WebM/VP8. Encryption can happen both within and without the container, but generally happens within the container. However the beauty of the CDM being abstracted means the container/codec combos can work with any number of encryption schemes.

Ultimately the EME provides several benefits to both content creators, content consumers, and the engineers building content solutions. Creators enjoy a standardized means for securely delivering audio and video, standardization often results in decreased delivery costs. For developers, a streamlined structure means easier cross-platforms implementations because of the use of existing web technologies and an open API. Consumers enjoy the ability to view a broader range of content on a broader range of devices. Because the EME API is so lightweight, all parties enjoy a vastly improved user experience.

LINK:	http://www.encoding.com/blog/2015/08/21/protecting-html-video-with-enc...
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