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(Note: This article originally appeared on EE Times Europe's Automotive site.)

The MOST networking technology enables carmakers to provide systems that easily integrate into a consumer's digital lifestyle. With increasing digital media content in cars, rights management becomes an issue. But MOST already contains mechanisms to protect the data.

Media Oriented Systems Transport (MOST) is the de-facto standard for high-bandwidth networking of audio and video in automobiles. This technology enables carmakers to provide systems that easily integrate into a consumer's digital lifestyle. MOST can efficiently move audio and video content from the location where it is stored (a memory card, a portable player, a hard disk) to where it is used (a video screen, headphones, stereo amplifier).

One challenge to doing this when distributing commercial content is to keep the data protected so it cannot easily be removed from the network. Digital Transport Content Protection (DTCP) has been widely adopted as the appropriate way to encrypt content before it is sent on to a digital output.

Content Protection Requirements
Copying analog data in the past resulted in quick deterioration of the quality when making a copy of a copy. However digital copies can be exact replicas of the original. Content owners want to make sure their property is not used without their authorization. The way they ensure that the data remains secure is by establishing strict guidelines for how the data can be used once it is removed from the medium on which it was originally stored.

There are many different technologies used to encrypt commercial data as it is stored on particular media. Each is managed by a different organization and includes an adopter's agreement that compels those using the technology to follow a certain set of rules.

For example, the Content Scrambling System (CSS) is required by the DVD Copy Control Association (DVD-CCA) to be used for DVD Video; the Advanced Access Control System (AACS) is required by the AACS Licensing Authority (AACS-LA) to store Blu-ray content; Content Protection for Recordable Media and Content Protection for Pre-recorded Media (CPRM and CPPM) are dictated by the 4C Entity to store DVD Audio. There are other agencies, such as the Open Mobile Alliance (OMA) that regulates some mobile content, that also restrict how content managed by their technology can be transmitted to digital outputs.

Although there are many different technologies involved for various kinds of content, there has fortunately been some industry-wide agreement on how that content needs to be protected once it is placed on a digital output, such as MOST. All the various organizations have gravitated to specifying that the content can be sent to a digital output if that output is protected by DTCP.

The DTCP specifications are managed by the Digital Transport Licensing Authority (DTLA). It uses cryptography to encrypt the content in such a way that it is very difficult to descramble. It relies on secret information shared between the components communicating with each other and uses complex math algorithms to encrypt the data.

The MOST Cooperation has long worked with the various agencies to ensure that it is allowed to transport commercial A/V content. As a matter of fact, back in 2003 it was the first networking technology to be fully enabled to transport DVD Video content protected with DTCP. Other technologies were mentioned as possibly being allowed if they used DTCP, but MOST was the first one to meet all the requirements.

Figure 1: Technologies used for different kinds of commercial content. For full resolution, click here.

Today the MOST Specifications include one for Stream Transmission that clearly define how to use DTCP.

Page 2: Digital Transmission Content Protection (DTCP)

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