Decryption Engine Key Synchronization via Dual-Key Detection
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Solution Overview
Problem
In High-Bandwidth Digital Content Protection (HDCP) 2.2 encryption/decryption systems, synchronization failures due to incorrect control signals from the transmitting terminal lead to user experience issues, requiring a method to independently verify frame encryption status without relying on control signals.
Innovation Solution
A decryption engine comprising an update circuit, a key generator, and a detection circuit that generates and uses both encrypted and non-encrypted keys to decrypt frames, employing image processing to determine the correct frame and update keys accordingly, thereby bypassing control signal errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiving terminal relies on control signals from the transmitting terminal to determine frame encryption status, then the decryption process follows the standard authentication flow, but synchronization failures occur when control signals are incorrect, requiring lengthy re-authentication
Solution Approach 1:
The patent performs preliminary actions by generating both encrypted and non-encrypted keys in advance before decryption is needed. The system prepares multiple key possibilities ahead of time, so when a frame arrives, it can immediately attempt decryption with pre-generated keys without waiting for authentication confirmation or control signals, thereby avoiding synchronization failures and re-authentication delays
Solution Approach 2:
The patent implements feedback by detecting whether decryption was successful and using this information to determine the actual encryption status of frames. The system continuously monitors decryption results and adjusts its key selection and generation strategy based on this feedback, allowing it to adapt to control signal errors and maintain synchronization without re-authentication
2Ease of operation
If the system uses control signals to determine encryption status, then the decryption process is straightforward, but it becomes vulnerable to control signal errors causing synchronization failure
Solution Approach 1:
The patent applies self-service by enabling the receiving terminal to independently verify frame encryption status through decryption attempts and result detection, rather than relying on external control signals from the transmitting terminal. The system uses its own resources (multiple key generators and decryption circuits) to self-determine encryption status, making the process both simple and reliable simultaneously
Solution Approach 2:
The system generates multiple possible keys (encrypted and non-encrypted versions) in advance before needing to process frames. This preliminary key preparation allows the system to immediately attempt decryption without waiting for control signals, maintaining ease of operation while ensuring reliability through independent verification
Data Source
AI summary
A decryption engine includes an update circuit, a key generator, a decryption circuit and a detection circuit. The update circuit generates a first updating information based on a premise of that a currently received frame is encrypted, and generates a second updating information based on a premise of that the currently received frame is non-encrypted. The key generator produces a first key according to the first updating information, and produces a second key according to the second updating information. The decryption circuit generates a first decrypted frame according to the first key and the currently received frame, and generates a second decrypted frame according to the second key and the currently received frame. The detection circuit detects whether the currently received frame is decrypted according to the first decrypted frame and the second decrypted frame, to generate an encryption detection result.