DRM as a Service: What Makes It Tick? (Part 3: Licenses)

We continue our short series on the basics of video security and how it's of critical importance to any thriving video service business. Today's installment is on the topic of the mysterious DRM license. Remember that we have wrapped all this information up in our published book on DRMaaS - download today and register your T-shirt size!

Digital Rights Management (DRM) is actually an essential component of the video business, and it has server/cloud side components as well as components that must be implemented as a part of each and every video client device. The link between these two components - and the core of the security implementation - is the DRM license.

In the body of our FAQ document, we try and explain the general technical nature of a DRM license, although the actual format is a highly proprietary secret in each of the major DRM systems in use. At the highest level, the process described above separates out the distinct concerns of delivering the video content itself from the communication and rights checks that simultaneously delivers the necessary decryption keys and the rules about playback constraints. The large and continuous stream of video content is delivered from one cloud resource, while the license that permits playback is requested and delivered by a separate, almost instant one-time transaction with the secure DRM service. To deliver service efficiency, the video content streamed to all devices is essentially identical, while the license required to view that content is created in real-time to be unique to each playback request and the device that made it.

The security of the encryption keys used to protect video content would be easily compromised, if the communication between the DRM client on a consumer device and the secure DRM key service was not itself heavily protected. This protection required goes way beyond the typical communication security of a web protocol such as SSL. To address the specific needs of DRM, the decryption keys are delivered to client devices in the form of a communications object known as a DRM license, that incorporates key management that is specific to the video service and, at the highest level, to the hardware of the playback device itself.

The overall goal is to ensure that the video encryption cannot be compromised by interception of the license communication or the process of unwrapping that license to actually decrypt the video content during playback. It is also convenient to include, wrapped up in this same protected license object, all of the information about restrictions on use of the license keys - such as the time period over which the license is valid, the constraints on protecting video outputs and so on.

In fact, the concept of a DRM license in the form of a file is pretty anachronistic and dates from the early days of Internet digital audio and video distribution where the objective of a DRM system was to protect downloaded files in an almost wholly offline consumption model. With today’s near continuous online streaming model, it might be a lot more straightforward to check user rights in real time during any given section of the playback of content. This historical precedent leads to a number of undesirable effects in media systems, such as the inability to rescind the issue of a license. It does, however, provide a way to distinguish between transient and persistent rights for content consumption.

Visit our Frequently Asked Questions page for the full story - or download the full DRMaaS - What Makes it Tick? reference document. When you request this document, you'll also get in in line to receive our latest cool T-shirt swag! Something that shouldn't be missed in this time of virtual "no gift available" trade shows :)

Thanks for reading.

The Team at EZDRM
Digital Rights Management. Simplified.