HDCP Audio Return Channel Encryption via Sink Device Preamble Codes
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Solution Overview
Problem
High-quality audio data transmitted over the Audio Return Channel (ARC) in HDCP configurations is vulnerable to illegal copying as it is not encrypted, lacking protection.
Innovation Solution
A sink device inserts a first preamble code into sub-frames of encrypted audio data to indicate rekeying and encryption status, ensuring that audio data transmitted to the source device over the ARC is encrypted using the HDCP protocol, thereby protecting it from unauthorized copying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If audio data is transmitted over the Audio Return Channel (ARC) without encryption, then ease of operation is improved, but security is worsened making audio data vulnerable to illegal copying
Solution Approach 1:
The patent changes the encryption parameter by inserting a first preamble code into sub-frames of audio data to indicate that rekeying should be performed at the source device. This transforms the audio data transmission from unencrypted to encrypted state while maintaining compatibility with the existing ARC infrastructure, thereby improving security without completely redesigning the system.
2Reliability
If encryption is implemented for audio data over ARC, then security is improved, but device complexity is worsened due to additional encryption and authentication requirements
Solution Approach 1:
The patent makes the sink device perform multiple functions: it acts as both an audio receiver and an encryption initiator by inserting the first preamble code into audio sub-frames. This multi-functionality allows the system to achieve encryption without adding separate dedicated encryption hardware, thereby improving security while limiting the increase in device complexity.
3Reliability
If rekeying is performed at the source device, then security is improved through enhanced encryption protection, but productivity is worsened due to additional processing time
Solution Approach 1:
The patent implements preliminary action by having the sink device insert the first preamble code into the audio data before transmission. This prepares the source device in advance to perform rekeying operations, ensuring that encryption key changes are already scheduled and executed smoothly without causing delays during actual audio playback, thus improving security while minimizing impact on productivity.
Data Source
AI summary
Embodiments relate to inserting a preamble code as a preamble of a sub-frame of encrypted data to indicate rekeying is to be performed at a source device and to indicate data of the sub-frame and subsequent sub-frames is encrypted. A sink device authenticates a source device using an authentication and encryption protocol. The sink device receives a data stream including audio data. At least a portion of the received audio data is encrypted and the encrypted audio data is packetized into sub-frames. The sink device inserts a first preamble code as a preamble of a sub-frame to indicate rekeying is to be performed at the source device according to the authentication and encryption protocol, and to indicate that the audio data in a payload of the sub-frame and payloads of subsequent sub-frames is encrypted. The sink device transmits the packet to the source device via a first data link.