F2008-05-055
DTCP on MOST - The Key for High Quality DVD Applications in Automotive Infotainment Systems
New automotive infotainment applications require the distribution of digital contents, such as DVD-Audio and DVD-Video, in a car. A rear seat entertainment application for example requires that DVD-Video content be distributed from a DVD-Player in the dashboard to the display in the back of the car. Also high-end audio systems need that the DVD-Audio contents are distributed from the player to the respective amplifiers.
The realizations of such application become a challenge for the developer of such systems or solutions since the owners of the digital contents have a high interest to protect them. DTCP (Digital Transmission Content Protection) is the technology driven by several organizations and that the developers of automotive infotainment solutions have to adapt when the distribution of digital contents via a network is needed in such a system.
The Digital transmission of non-protected audio data from DVD is allowed up to an audio resolution of 16 bit, but above-mentioned applications need higher resolution and even video content distribution from a DVD. This higher resolution and/or multi-channel audio have to be encrypted before transport. Also audio with a sampling rate of more than 48 kHz needs to be protected. Copyrighted digital video data has to be encrypted anytime. Therefore DVD data in most cases has to be content protected with DTCP before it is transmitted over a network.
DTCP requires source and sink devices to authenticate each other. In addition, multimedia streaming data must be encrypted before it is sent over a digital network. A sink device, therefore, must also be able to decrypt protected digital content.
DTCP addresses four fundamental layers of copy protection: · Authentication and key exchange (AKE) · Content encryption/ decryption · Copy control information · System renewability
Using MOST, the digital integration of DVD applications into vehicles is no longer an issue - even when streaming media at the full-quality bandwidth. Application developers can now take advantage of a secure infrastructure for transferring DVD audio and video content. MOST was the first network to be fully approved by the DVD Copy Control Association (DVD-CCA) to carry DVD content provided it is DTCP protected. This was made possible by adapting DTCP to the MOST standard.
In order to implement transport of high-end DVD audio and DVD video over MOST, a DTCP encryption/decryption engine, as well as an Authentication Key Exchange (AKE) engine, is needed in each node that handles such signals. Before data can be transmitted through a digital output, the source and sink must perform a joint authentication procedure. This procedure consists of a sequence of data swaps and key calculations that validate the licenses of both devices. Once two compliant devices have authenticated each other´s right to perform protected transfers, they assemble the appropriate encryption/ decryption keys and set up a secure path. Content is then encrypted (ciphered) using one or more authorized cryptographic ciphers. DTCP solutions for MOST are available in hardware as well as in software from various suppliers. SMSC provides turnkey solutions for DTCP. One example is shown below in more detail.
As mentioned above, MOST has been approved to transmit DVD content, provided the content is protected with DTCP. This approval was the pre-condition to enable fully digital video solutions over MOST. Hybrid solutions with partially analog and partially digital transmission of video simply do not make economic sense. Although it takes some time in the automotive industry for new architectures to find their way into platforms, the process of designing-in MOST for DTCP applications is gaining speed with a number of customers.
DTCP increases the complexity of MOST nodes and this results in the challenge for the developer to get the device and the system running. The debugging such applications is a major task on the way to get the system working properly.
This speech describes the basics and mechanism in detail and shows how a real example of such an application might look like. It also addresses and describes the obstacles and difficulties facing all, the system architects and the device developer, the carmaker and the supplier. It also gives some valuable hints how to overcome the obstacles and how efficient debugging of DTCP systems and devices can be done.
The speech is arranged in four main chapters:
1. Basic explanation of DTCP 2. Detail explanation of the encryption/decryption mechanisms 3. Real application example 4. Analysis Tool support for DTCP based applications and how to use them most efficiently 5. Conclusion and outlook
Session: System Architecture