IPTV boosts DRM

By Philip Hunter

In the IPTV era video is just another category of data file, capable of being stored, copied, pasted and redistributed. This has profound implications for tackling piracy and theft, because traditional conditional access (CA) mechanisms based on smart cards in the set top box do little to protect files once they have been downloaded. Now video can be shunted around a home network, transferred to a mobile device, and then uploaded again to a video-sharing site, and during all of this needs protecting against unauthorised copying.

There are only two practical ways this can be done. One is to keep the video encrypted throughout its distribution cycle, only decrypted at the point of display. The other recourse is digital watermarking, which does not prevent copying but does supposedly provide an indelible trace of the video’s origin. Then it should be possible to identify the source of stolen content. There are emerging techniques that insert digital watermarks on the fly at different stages of the video lifecycle, enabling the history of a movie or programme to be recovered subsequently even if it is transferred across different physical media – in other words providing an audit trail.

Both approaches could be combined to provide both copy protection and traceability, but at present the main focus is on encrypting content all the way to the final point of display. For this to happen, the decryption mechanism must be incorporated in the video processing chips in the receiver or handset, and there must be some standard for interoperability between communicating devices, within a home or mobile network. At present there are several competing or overlapping options. The SVP Alliance was established in an attempt to bring order to the home network environment including the set top box (STB) and TVs or devices decoding the video. This movement has gained ground recently within this home sector, with the SVP standard being implemented in video decoding chips from Broadcom, Conexant, Chips & Media, and STMicroelectronics, and in turn in STBs from PACE, Samsung and Thomson. SVP is ideally suited to the home network or situations where there is no security of the physical link, relying on the strength of the encryption algorithm, and the integrity of the on-chip implementation.

But IPTV also has a fast growing mobile dimension, and here different standards hold sway for enforcing digital rights. The implementation process is different for mobile handsets because the DRM usually has to be integrated into the SIM card, rather than a dedicated processor or smart card. This means that the vendor of DRM technology has to work closely with the handset vendor and so unlike with STBs does not have total control over the implementation. To complicate matters further, there are two groups of DRM standard for mobile handsets, one from the Open Mobile Alliance, and the other from Digital Video Broadcast (DVB) project. These respectively represent the mobile and broadcast camps, with the latter being supported by the traditional vendors of video content protection technology such as NDS, Nagravision, and Irdeto Access.

On the other hand the mobile handset vendors support the OMA standards. Both sides have pros and cons. The OMA standards are common to many handsets and are therefore more interoperable. On the other hand, the DVB DRM technology is more powerful, being capable of being upgraded in the event that the security is compromised. This is a crucial difference, according to Yossi Deutsch, VP of product marketing at NDS. “If NDS gets hacked, the operator can change either within that to get an upgrade, or replace with a completely new vendor,” said Deutsch.

Here Deutsch is referring to the most advanced OMA DRM, called OMA Bcast, which reflects the experience of traditional pay TV services, which have been riddled with regular hacks of smart card systems, leading to expensive replacements of the whole CA system. OMA Bcast incorporates a software container that can be replaced without affecting the rest of the system, allowing either the specific encryption keys or the whole DRM to be swapped out as Deutsch indicated.

However with OMA Bcast, or the DVB equivalent, only recently becoming available, some early mobile TV services have opted for Microsoft’s DRM. BT Movio has done this for example, highlighting the importance of the DRM because in this case it dictated the choice of Microsoft for other components of the mobile TV system, including the video codec.

But it is not clear how the DRM situation will resolve itself in the context of fixed/mobile convergence, and the likely trend towards transmission of video content between mobiles, PCs, and traditional set top boxes. This will either require consolidation around a single DRM, or more probably interoperability between multiple DRMs.

While SVP may facilitate secure transfer of video within a home network fed by an IPTV service, it is not being adopted elsewhere, for example on mobile handsets or consumer electronic devices. Another initiative called Marlin was set up by the consumer electronics industry by such luminaries as Sony, Samsung and Royal Dutch Philips, but also has not much ice in other device domains, even though this was promoted as a common non-proprietary DRM. Then there are the two big proprietary DRMs Apple’s Fairplay, and Microsoft’s Windows Media DRM, both gaining traction but unlikely to dominate either.

Indeed no single DRM is likely to span the whole distribution chain without being over-bloated with features, because requirements are very different at the stage where content is still within a secure network in the studio environment as compared with the consumer’s domain.

The future therefore could lie with the one major initiative to forge a DRM interoperability standard, from the Coral Consortium. Coral’s premise is that there cannot be a single standard for DRM and that by its nature security relies on diversity, avoiding dependence on a single solution with disastrous consequences when compromised. Coral therefore facilitates communication among multiple incompatible DRMs via interfaces designed to mitigate the differences, acting as an electronic broker or rights mediator.

It has become clear that IPTV services will have to address a wide variety of receiving devices, but that these will coalesce in coherent clusters, such as mobile handsets, big screen TVs, and consumer multimedia players. This is reflected in Coral’s design around the idea of ecosystems comprising devices within which video content can move more readily, with similar rights management rules applying. According to Coral’s president Jack Lacy, each ecosystem can have its own rules for viewing and using content.

Yet despite Coral’s appeal, it has been slow to gain market acceptance, and the so the future of DRM for IPTV remains uncertain. For this reason, Coral’s Lacy recently upped the ante with a public letter to Apple chairman Steve Jobs inviting the company to join the consortium. Until now Apple has resisted such overtures, but it may be that its hand is now forced by pressure from both device makers and content producers.