Server environments have needed secure communications for almost as long as computers have been around. But authentication and encryption often aren’t even discussion points when it comes to consumer devices. Take the lowly IR television remote. At last month’s International Consumer Electronics Show (CES) in Las Vegas, a blogger used a small remote called TV-B-Gone to wreak havoc on a host of HDTVs (Fig. 1).
Essentially, the remote can blast all of the power-off sequences for all of the TVs that it knows about with a single press of a button. This denial of service (DOS) attack shut down displays during some of the show’s presentations, much to the chagrin and confusion of the presenters. The blogger won’t be attending CES anymore.
Cell-phone jammers take a slightly different approach and simply disrupt reception to block it within a localized area. But the end result is similar—denial of service. The big difference between cell-phone jammers and TV-B-Gone is that cell phones use a bidirectional, authenticated link between the phone and the cell tower. Jammers can block service, but they can’t mimic a phone.
On the other hand, infrared (IR) receivers for most TVs lack the security support found in cell phones. The simplistic IR interface allows universal remotes like Logitech’s Harmony 1000 (Fig. 2) to control a range of devices (see “Components Converge For HDTV Everywhere” at www.electronicdesign.com, ED Online 17566). But the controller does not know whether there is one TV or a dozen because the interface is unidirectional and not secure.
A Possible Solution
Sony was showing off its new Bravia HDTV displays, which utilize the RF-based Synkro entertainment control platform (ECP) introduced by Freescale at the Freescale Technology Forum last year (Fig. 3). This bidirectional technology is based on 802.15.4. Freescale decided that ZigBee, while a great standard, had too much overhead for a low-cost remote control. ECP uses a star network instead of ZigBee’s mesh.
Communication between controllers and devices uses authentication, thereby preventing the type of DOS attack used at this year’s CES. The system is still susceptible to jammers, but at least attackers don’t gain control of the device. Near-field communication (NFC) links controllers and devices. The remote must be close to the device’s RF transceiver when the controller and device are paired. The controller can still turn multiple devices on and off at approximately the same time, but only if they are paired.
The approach has some interesting features, such as the ability to pair devices via the controller so a Blu-ray player could turn on a TV. Wired HDMI, another hot technology at CES, can do this now as long as devices are linked via HDMI. But this assumes a homogeneous environment.
I prefer the ECP approach since it is more amenable to a mixed environment like my home entertainment system, since I don’t plan on tossing out my DVD player just yet. It also has the advantage of potentially eliminating the need for device-specific remotes. In a few years, devices may come with a coupon to buy a universal remote.
As designers, we need to keep security in mind, even if we don’t think our creations will need it. This may mean thinking outside of the box, but that’s what we get paid the big bucks for doing. It’s also in an engineer’s nature to want a more robust solution.
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