Time-Based Roving HDCP Architecture for Fast HDMI Authentication

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Solution Overview

Problem

Existing HDMI authentication methods are time-consuming and unreliable, leading to delays and visual distortions due to the need for frequent re-authentication and slow integrity checks, especially in systems with multiple ports.

Innovation Solution

A time-based roving HDCP architecture with a main pipe for the selected port and a roving pipe for background ports, performing pre-authentication and maintaining authentication in the background to reduce re-authentication time and improve reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If authentication is performed every time a Source is connected to a Sink, then authentication reliability is improved, but authentication time increases causing delays

Engineering Contradiction:

Improveauthentication reliabilityVSAvoidauthentication time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The Sink performs pre-authentication by monitoring the Ri counter values from multiple Sources in advance before actual content transmission begins. This preliminary authentication action allows the system to establish secure connections faster when content playback is needed, as the authentication state is already prepared.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors Ri counter values from Sources and uses this feedback to determine when authentication has been successfully established. The Sink compares the Ri counter values to track authentication state changes and triggers re-authentication only when necessary, optimizing the balance between security and speed.

Inventive Principle:

Principle #23Feedback

2Reliability

If periodic integrity checks are performed by Sources, then authentication monitoring is improved, but detection speed decreases due to up to 2 second intervals

Engineering Contradiction:

Improveauthentication monitoringVSAvoiderror detection speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The Sink continuously monitors authentication status by tracking Ri counter values without interruption, rather than relying on periodic checks. This continuous monitoring enables immediate detection of authentication failures or key desynchronization, eliminating the 2 second delay inherent in periodic checking schemes.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The Sink independently performs authentication monitoring and integrity checking without requiring Source intervention or periodic signaling. The Sink autonomously tracks Ri counter values and detects authentication issues, making the system self-sufficient in maintaining secure connections.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If authentication is performed in the foreground for selected ports, then user experience is improved, but system complexity and power consumption increase

Engineering Contradiction:

Improveuser experienceVSAvoidsystem complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system divides authentication processing into separate foreground and background pipelines. The foreground pipeline handles authentication for the currently selected port with full user experience, while background pipelines perform authentication monitoring for other ports asynchronously. This segmentation reduces the complexity burden on any single pipeline.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Background authentication monitoring operates periodically by sampling Ri counter values at appropriate intervals rather than continuously. This periodic action maintains security for unselected ports while significantly reducing power consumption and processing complexity compared to continuous monitoring.

Inventive Principle:

Principle #19Periodic action

4Reliability

If re-authentication is performed frequently, then authentication security is improved, but link downtime increases

Engineering Contradiction:

Improveauthentication securityVSAvoidlink downtime

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The system performs pre-authentication and authentication state maintenance in advance for multiple ports before they are needed. By preparing authentication states beforehand and continuously monitoring Ri counter values, the system can quickly resume secure connections without requiring full re-authentication sequences, thereby reducing link downtime.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the authentication parameter from requiring complete re-authentication sequences to monitoring and validating Ri counter values. This parameter change allows the system to maintain security by tracking authentication state changes rather than repeatedly performing full authentication, significantly reducing the time required to restore secure connections.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12445421B2Apparatus, methods, and systems for pre-authentication, keep-authentication, and regain-authentication

Publication Date: 2025.10.14 ANALOG DEVICES INC

AI summary

Authentication is a key element for content protection. This invention makes the authentication fast and reliable by hiding the authentication, keeping the authentication, and regaining the lost authentication. The embodiments in this invention reduce the complexity and power consumption of the operation significantly.