Conditional Access Archives – The Broadcast Knowledge

Content protection needs to evolve not only to new attacks but also to the technology landscape around it. While the PCMCIA form factor has been successfully used now for CAMs, it is an old technology that takes up a lot of space. This video looks at the move to USB interfaces and feature updates to the DVB CI standards,

To lead us through, TP Vision’s Nicholas Frame joins DVB’s Emily Dubs ad starts by explaining how all the different specifications and standards connect to provide the decryption ecosystem. This video centres on CI Plus 1.4 and CI Plus 2.0 which are standardised as ETSI TS 103 205 and ETSI TS 103 605 respectively.

CI Plus 1.4, Nicholas continues, introduces two main features. The first is the introduction of a negotiation mechanism to get a list and choose to use optional features in much the same way as a browser and server negotiate when they set up a secure HTTPS connection using TLS. Nicholas walks us through the negotiation process and explains that the first of these optional features is Overt Watermarking.

Watermarking is the practice of embedding data within a media stream which helps in tracking the source for use in copyright protection. This can be done with hidden data or overtly and works by defining a layer that is composited on top of the base video layer. This is not unlike the way that the decoder would also show the application GUI however the watermark layer is controlled by the CAM which says when to show or hide the watermark. The protocol is kept simple with the watermark itself comprising just ASCII text of a chosen colour at a defined position. Naturally, communication between the CAM and decoder is encrypted and the decoder provides confirmation back to the CAM when the watermark is shown which allows the CAM to take action if it believes the watermark isn’t being respected.

Moving on to CI Plus 2.0, Nicholas explains that it’s an evolution, not a new standard. It’s based on the previous mature, trusted work in the CI Plus standard and adds additional functionality with a modern interface. There’s no loss of features nor change in signalling. It does change the interface, however, which brings with it a whole raft of improvements and possibilities.

USB A is probably the most universally used physical interface which means it’s well known by the public and is a tried and tested, robust connector. It avoids being inserted the wrong way round and has no possibility of bent pins. In terms of manufacturing, space will be saved on circuit boards and manufacturing with USB components is very well understood. Nicholas sees this as opening up new possibilities such as decoders with different form factors or a move to virtualisation.

Although the lower layers defined by USB will change, the upper layers which are specific to CI and DVB won’t change. Nicholas finishes the video explaining how the USB interface (either 2.0 or 3.x) can use bulk transfer and will group MPEG TS packets into fragments for onwards transmission.

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Speakers

	Nicholas Frame Standardisation Manager, TP Vision
	Moderator: Emily Dubs Head of Technology, DVB Project

With video piracy estimated to cost the US economy $29M a year and programming rights costing 100s of millions of dollars or more, there’s plenty of reason to look to technology to protect your content. There is a long history of copy protection for broadcast/linear content which is continually changing.

Graham Turner, who has worked extensively in copy protection for many years, gives us an overview of how pay TV works, a look at the different types of protection and a look back at the history to see what we can learn from the mistakes made since the late 1980s.

After explaining the many reasons different types of channels have to protect their content, Graham explains the fundamentals of content protection, encryption and decryption being central to protection discussing symmetric and asymmetric cryptography. He then discusses key length which is something we hear a lot of, but can be non-trivial to understand. After all, AES talks of 128 and 256-bit keys, whereas in other areas we hear 1024, 2048 and more. Graham shows how these relate to the different keys in symmetric and asymmetric cryptography.

Pay TV is the area of focus for this video whereby live decryption keys need to be available at the set top box (STB) in the home. For DVD copy protection, the key is already in the DVD player and revocation of the rights of that DVD player are difficult. For TV there is a path from the broadcaster to the receiver which allows for more reactive rights management. ECM, Entitlement Checking Messages and EMM, Entitlement Management Messages, are the ways in which these permissions are spread so we look at how these work.

The architecture of the STB comes in focus next as Graham explains how the decryption and describing fit together along with hardware security and software security. Naturally after the STB has decoded the video, there’s interest in making sure the delivery to the TV is also secure which is where HDMI’s HDCP comes in with HDCP 2.2 protecting UHD content. HDCP is a method of ensuring that recording devices don’t get to record protected video whereas TVs or display devices can. Fingerprinting and watermarking are two technologies which are also examined showing how they are useful, to an extent, in identification of footage though not directly useful in preventing piracy itself.

The video ends with a very interesting look at the various high profile hacks from the last 30 or so years examining what was broken and how – in particular whether the cryptography itself was broken or whether the attack succeeded due to a weak link in the chain of another part of the system.

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