ATSC 3.0: DRM and Encryption

A bit more than a year ago I headed over to a former client’s headquarters to discuss a potential ATSC 3.0 project. The moment I stepped into the office I was swarmed by a group of engineers and managers with one primary question : are 3.0 broadcasts really going to be encrypted, and if so what DRM is going to be employed?

There’s been a lot of chatter about encryption of ATSC 3.0 broadcasts and what it means for free over-the-air TV. A lot of that discussion conflates encryption, content protection, and content rights management. This post will hopefully help in untangling things a bit while providing some context, and also some discussion around the unintended consequences that encryption may have on innovation in the consumer electronics space.

At the end of the day encryption is a tool, and with any tool it’s really what employment the tool is put to that deserves more scrutiny than the tool itself. There’s been a lot of speculation, some  more reasonable than others, about why ATSC 3.0 services will or should be encrypted.

Perhaps the most obvious is the use of encryption as part of rights management. Rights management is an integral part of video and can be found in the DVD/BluRay formats, paid TV services, and streaming services. (It should be noted however that not all paid TV services and streaming services are encrypted. A surprising number, including some large players in the streaming space, are not employing encryption at this time.)

In the context of broadcast television, rights management may involve restricting whether a broadcast can be recorded, and if it can be recorded, whether it can be transferred or streamed off of the DVR. Content has value, and content owners wish to preserve their ability to continue to monetize that content in the future.

Another argument for encryption is that it protects against hacking of a 3.0 service. I’ve heard this a few times and find it a bit of a head-scratcher. One is exactly how the hacking might occur. There is some concern that a broadcaster’s infrastructure might be hacked before the transmitter. However integrity at this level can (and arguably must) be accomplished via a combination of physical security and encryption of the studio-transmitter link. Malware on the viewer end is of greater concern, particularly if a gateway distributes a 3.0 service over a home network and given 3.0’s applications for interactivity (A/344) . However what is required here is authentication of the service – some proof that the bits being received are in fact the ones that the broadcaster sent out. Authentication can be accomplished via digital signatures, where a sender signs a message with a private key and a receiver verifies the message with a public key. The primary difference between encryption and signing is how the key used in each is treated. Encryption keys need to be carefully guarded. The public keys required to verify a signature on the other hand are intended to be distributed widely.

The broadcast industry has long had a tenuous relationship with companies seeking to innovate in how viewers consume television. When the VCR was first introduced broadcasters sued Sony to prevent sales of its Betamax VCRs. While the Betamax format itself didn’t survive the VCR wards, Sony’s victory established a doctrine of fair use – that indeed viewers do have the right to record television signals and watch them later, as long as its for their own personal use.

Fast-forward a couple decades and in 2001 ReplayTV, one of the pioneers in DVRs, was sued by Viacom, Disney and NBC who asserted that Replay was “arming their customers with and continuously assisting them in using unprecedented new tools for violating copyright interests in the programming they supply to various TV distribution services.” The copyright infringement aspect included the Replay DVR’s “commercial advance” and “send show” features. This case was never resolved as ReplayTV went bankrupt, in part due to the costs involved in defending itself.

ReplayTV competitor TiVo, wanting to avoid similar legal entanglements, walked a cautious line between innovating in TV viewing and the concerns of broadcasters. Early TiVo software did not allow a 30-second commercial skip, for example, which was one of the complaints brought against ReplayTV. TiVo users could fast-forward through commercials, which led to some counter-innovation among ad agencies to create commercials that were appealing enough when fast-forwarded through that users would stop fast-forwarding and watch them. TiVo also started encrypting recordings with its 3.0 software release in part to assuage concerns that TiVo DVRs were a glorified pirating device. This eventually evolved into TiVo’s DRM scheme TiVoGuard, which played a role in ensuring later innovations such as Multi-room Streaming, streaming to mobile devices, and out-of-home streaming were done within the restrictions of fair use and not for public performance.

Later in the 2000s broadcasters raised the spectre of the “broadcast flag”. Content broadcast with this flag could only be displayed via protected outputs (e.g. HDMI with HDCP encryption), or the image had to be degraded before display on an unprotected output. This in itself wasn’t particularly troublesome and would affect very few users. However there were also restrictions on recording, and in theory the flag could be used prevent recording altogether, restricting viewing to live TV (or at best through a live TV cache).  Fortunately for viewers the courts determined that the FCC did not have the authority to force CE manufacturers to implement the broadcast flag in receivers. The FCC eventually withdrew the broadcast flag rules in 2011.

As for the client mentioned at the beginning of this post – why were they so riled up? They were well-versed in dealing with DRM and had a number of cable and satellite receivers from various providers in their portfolio. But DRM is a thorn in any project’s side, and with new players there would inevitably be the legal wrangling over whether and how product features worked with the DRM. This was enough to give considerable pause to pursuing a project in the fledgling 3.0 space..

Wishlist 3.0

At the end of the day broadcasters, CE manufacturers and TV technology enthusiasts all live in an ecosystem where it serves to consider each others  interests, concerns, and aspirations. With this in mind, here’s a wishlist for 3.0 broadcasts:

    • Keep at least the base layer of free 3.0 services unencrypted. 3.0 has a provision allowing a service to provide a base and an enhancement layer. An example would be to provide a 1080p/60 base layer (somewhat analogous to ATSC 1.0 1080i) and a 4k/60 enhancement layer. Viewers content with the reduced resolution can watch the base service freely, while those desiring an enhanced experience can help to cover its additional production and delivery costs.
    • Keep the base layer visual quality comparable to better than ATSC 1.0 broadcasts (circa 2019, before any ATSC 1.0 lighthousing). Viewers should expect 720p or 1080p resolution with a level of compression artifacts comparable to 2019 ATSC 1.0 emissions.

This will create two classes of 3.0 receivers: those which, from a casual user’s perspective, are similar to what is available with ATSC 1.0, and a second class providing superior visual quality, and potentially access to expanded content.

It would not prevent the creation of paid audiovisual services (e.g. ESPN) using ATSC 3.0 as a distribution mechanism. Nor would it affect how new classes of services such as data delivery are managed.