The future for CAMs

When I wrote about Sky Sports on Freeview a couple of weeks ago, I mentioned that one possible outcome may be the ability to use a CI Plus module with some receivers. Before people get too excited, it’s worth saying that that’s my theory, not an official comment. TopUpTV would obviously like it to be available to everyone via standard CAMs, and Sky would like it restricted only to receivers with embedded encryption. A CI+ system would, I think, be a reasonable compromise.

And that has raised the issue of what is CI+ and why is it more secure than a standard CAM solution. I answered this question on a well known forum, but for reasons best known to them, all the messages have mysteriously disappeared. So, I though I’d explain here what the difference is between embedded encryption, CI+ and standard CAMs, and why it affects what you’ll be able to use to watch Sky Sports.

Embedded solutions

What I mean by embedded encryption is a solution that is, essentially, akin to what you have with a Sky box. There’s a slot in the receiver that takes a viewing card directly; these are credit card sized, with a small chip. The receiver has the chips necessary to handle the encryption system built in; they can’t be replaced with another system, but they can often be updated to a newer version, and sometimes newer versions of the smart cards are handed out too.

Often, these systems allow for things like configuring the box only to work with a specific card, so you can’t take your card from your home, pop round to a friend’s place and put it in their receiver to watch the match on their fancy TV. It’s considered the most secure system, because there’s essentially nothing you can tamper with.

What’s wrong with a CAM?

The CI (common interface) slot appears on many digital TVs and lots of receivers, including PVRs. It looks just like the PC card slots that used to be on notebooks, and uses the same connectors. A CAM (conditional access module) fits in the CI slot, and the smartcard slides into the CAM.

A receiver that works like this sends the encrypted information to the CAM, and then receives an unencrypted stream back, which can be displayed on screen, or in the case of a PVR saved to the hard disk.

The advantage is that the consumer can pick the equipment they want, then they buy a CAM that supports the encryption used by the programmes they want to watch, subscribe, and put smartcard in CAM, then CAM in CI slot, and tune it.  Some equipment supports two CI slots, so you could have two different pay TV providers on one box – much more convenient than having a separate box for each one.

So, on the face of it, a great idea, and there are more clever things you can do with CAMs and the CI system; for example, I’ve seen a CI module that fits in the slot, and has an Ethernet connector, and is designed to stream media from your home network, passing it into the set top box via the CI slot. A neat solution, though hard to make it work.

One of the reasons for that was that the CI system is limited in functionality. It’s designed to do one thing, really – take an encrypted signal and turn it into an unencrypted one. There’s a built in system that allows modules to display menus via the TV interface, but it’s very basic – a simple text based system. And when you want to do other things, it’s tricky; the Ethernet module I mentioned worked with some TVs; with others, you just couldn’t get the TV to display a picture from the module, because it wasn’t programmed to do that, unless it was tuned to a channel with an encrypted transmission.

But what about Sky Sports?

The CI/CAM system has worked pretty well in the past, so why would Sky have problems with it? One of the issues is the way that the CAM decrypts the broadcast and transfers it back into the receiver in the clear. When you’re just using a TV that’s not so much of a problem, but these days many people use recorders (PVRs), and the last thing the owner of rights wants is the ability of people to save unencrypted, unprotected copies of their broadcasts.

Some people have said “But it’s only sports, which is ephemeral” and there may be a degree of truth in that, but if other content were to follow later, like movies, that might be of more concern, and so no one’s going to settle for anything less than the strongest protection they can agree on.

There are already a few recorders out that that will save programmes unencrypted on the hard disk and have easy ways of transferring those to PCs. It doesn’t take much imagination to realise that with premium content, some people won’t be happy with CAMs for that reason.

They can also cause issues for users too; with live TV, a CAM is straightforward. With recorded TV, it’s less so. For example, if you’re watching one encrypted channel while recording another, what can happen is that the CAM is used for live TV, and the recording is saved to disk in encrypted form, then decrypted on playback (and which point some recorders let you save a decrypted version too). But if you don’t watch for a while, and the encryption keys are updated (for example with your  monthly subscription data), you can find that a recording on the hard drive won’t play any more. That’s obviously very annoying for users, too.

Step forward CI Plus

The CI Plus system is designed to solve, or help solve, lots of these problems. Physically it looks just the same, and a CAM will fit into a CI Plus slot and work just the same. But for the broadcasters – and the user – it brings some useful advantages.

Since I started this piece by talking about Sky Sports, let’s look first at the broadcaster’s point of view. Where a standard CAM has a straightforward unencrypted link back into the receiver, in CI Plus that’s replaced by a secure encrypted link. Think of it as a bit like a secure connection between your web browser and an online shop. This allows for the module to pass information back to the receiver, including details of ‘entitlement,’ which is the jargon for saying what you can do with the material.

The decrypted programmes can be stored on the hard drive using a different encryption system, like AES, so that they can’t simply be copied (or uploaded to the internet), but without the potential problems caused by things like monthly updates to the smartcard. So the programme remains protected, even though it’s been decrypted, which is obviously appealing to companies like Sky, or anyone else with premium content.

From the user’s point of view, that’s probably not an overwhelming reason to embrace CI Plus. But it does also improve on the interface between the CI system and the equipment. Where CI allowed only basic text menus, CI Plus allows for a much richer, browser-based sort of system. That means that it can display graphics, and be much more interactive and – potentially – show you menus within your TV or PVR interface with options for buying pay per view content, and other fancy things like that.

And, to go back to the beginning, with the ability to ensure content is protected on the hard disk of recorders, to all intents and purposes, CI Plus will allow broadcasters like Sky the same control over their content as they get with embedded encryption systems, while giving customers the benefits of being able to choose their own equipment – albeit from the more limited range of CI Plus kit, though that already includes some TVs and recorders, including the new Humax HDR Fox T2 Freeview HD recorder.