Display Key Encryption via Code Signature Authentication
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Solution Overview
Problem
Existing digital rights management systems, such as High-Bandwidth Digital Content Protection (HDCP), face challenges in securely managing display keys to prevent unauthorized access and ensure that compromising one display key does not compromise all keys.
Innovation Solution
Implementing a method where the display key is encrypted using a signature of a first code, with restricted access to the encrypted secret, ensuring only authorized codes can decrypt it, and using a code-signing key for authentication to prevent malicious access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the display key is stored in an accessible location for use in re-encryption, then the re-encryption process can be performed, but the secret becomes vulnerable to compromise
Solution Approach 1:
The patent introduces an intermediary mechanism where the display key is encrypted and stored in a protected location. A code authentication system acts as a mediator between authorized code and the encrypted key, allowing the key to be accessed only when the code proves its authenticity through signature verification. This resolves the contradiction by enabling key access for legitimate operations while preventing unauthorized access.
Solution Approach 2:
The patent applies preliminary action by requiring code authentication before key access is granted. The system verifies the authenticity of code attempting to access the display key through signature comparison against an expected value. This preliminary verification ensures that only authenticated code can access the encrypted key, resolving the security accessibility contradiction before any potential compromise can occur.
2Adaptability or versatility
If multiple display keys are used to protect different content, then content protection coverage is improved, but the complexity of key management increases
Solution Approach 1:
The patent applies segmentation by implementing separate key management for different content types and devices. Each display key is independently encrypted and stored with its own authentication mechanism, allowing multiple keys to be managed without creating a single point of failure or excessive complexity. The modular approach enables scalable key management as content protection coverage expands.
3Reliability
If the display key is encrypted using a signature of a first code, then access to the secret is restricted to authorized code, but the complexity of the encryption process increases
Solution Approach 1:
The patent uses the code signature as an intermediary element that bridges the gap between authorized code and the encrypted display key. The signature verification process acts as a mediator that authenticates the code before allowing key decryption, providing reliable access restriction while using well-established cryptographic primitives to manage the complexity.
Solution Approach 2:
The patent applies preliminary action by performing code authentication and signature verification before the actual key decryption operation. This preliminary step establishes the authorized access condition, and subsequent key decryption occurs only under the verified authentication context, simplifying the overall process by separating authentication from access operations.
Data Source
AI summary
Methods, devices, and systems of protecting a secret are provided. Access to the secret is designed to be restricted to a code with a specific signature, or fingerprint. The signature of that code is used in the encryption of the secret, and other codes are prevented from using this signature to decrypt the secret. This restricted access to the secret prevents the secret from being easily compromised, for example, by preventing a change in the code.