Requirements for Designing Next-Generation IP Set-Top-Boxes

Exclusive to EE Times, By Jim Nguyen, Director of Marketing, WISchip International (ghost written by Mark Haas)

As the worldwide market for IP set-top boxes (IP-STBs) grows rapidly, engineers will play a critical role in making the right design choices when designing the next-generation of IP-STBs. As a dedicated entertainment device sitting at the nexus of high-definition TVs and a dizzying array of broadcast, satellite, broadband, home network and other free and premium content sources, IP–STBs will be required to play a central role in decoding, distributing and protecting this content.

Because of the wide variety of content sources – free-to-air broadcasts, cable and telco service providers, personal computers, network attached storage (NAS) devices and more -- IP-STBs need to support a wide variety of advanced codecs. Not only must STBs support legacy content playback, including MPEG-1, MPEG-2, MPEG-4 part 2, DivX, Real, WMV9, and Quicktime, but as service providers seek to deliver more high-definition channels and revenue-generating services over limited bandwidth, IP-STBs will need to support advanced codecs such as H.264 and VC-1.

The winning design for IP-STBs must also include seamless connectivity to any consumer device, PC and NAS to create a home entertainment network. This will require auto-device discovery protocol support, including uPnP, DLNA and PlaysForSure, as consumers should never have to enter a network address or subnet mask as part of the set up procedure.. Additionally, IP-STBs must feature seamless transmittal and receipt of encrypted digital content using IP streaming protocols.

Of all the requirements for next-generation IP-STBs, however, security is the cornerstone for premium content. Content protection comprises both content access – encryption and authorization – as well as digital rights management (DRM). But the security landscape is in flux and there are no clear winners or standards for either, making it necessary to be able to support not only a number of current content protection schemes but be prepared to support a variety of future technologies as well as needs evolve.

The situation is exacerbated by the many approaches to DRM. Besides popular DRM methodologies from NDS Irdeto, SecureMedia and Verimatrix, Microsoft is advocating the proven public key encryption approach, while other players such as Widevine are touting persistent encryption. Virtual smart cards further muddy the DRM waters.

Content providers will continue to use a multiplicity of security technologies to deliver premium content. Given this uncertainty, IP-STBs need the flexibility to be able to support multiple content access and DRM strategies today, and also be field-upgradeable to enable them to adapt to future standards.

To support these requirements, as well as maximize system performance, IP-STBs can employ an embedded security subsystem with a secure, dedicated processor for programmability and key and session management and hardware acceleration for critical cryptographic functions such as 3/DES, AES and Microsoft Block Cipher, among others. A number of single-chip content processors provide these security subsystems, but not all are created equal, and care must be taken to ensure they meet current and future application requirements. Beware of any security subsystems lacking programmability, hardwired for specific content protection methods, and unable to adapt to future needs.

Security also must be extended throughout the IP-STB design, however, ensuring that all signals on and off the chip are either encrypted or hidden to prevent access to clear content. Encryption can be used to protect content passing between ASICs or between the processor and memory, for example. If that is not possible, then care must be taken to bury leads and traces between board layers to make them inaccessible to probes and other methods used for capturing the unencrypted content.

Finally, designers need to keep their thumbs on the pulse of the industry, and be active in the various DRM working groups to ensure they are on top of changes. Designers should work closely with both content owners and chip vendors to maintain a good understanding of both the security needs of the content providers and the full capabilities these chips can provide to meet these security requirements.

By adhering to these guidelines, designers will be well on their way to developing next-generation IP-STBs.

About the Author

Jim Nguyen is a pioneer in the audio/video market with a record of defining leading-edge audio/video silicon and software solutions for IP-STBs, digital TVs, DVDs and other advanced consumer products. He currently heads marketing at WISchip International, a semiconductor solutions provider for the digital home. Jim also founded ViaNet Consulting, a developer of streaming audio video streaming applications, and has held key positions at MIPS, Sigma Designs and Chips & Technologies.

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