DRM Key Package Segmentation for Offline Authorization
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Solution Overview
Problem
Current Digital Rights Management (DRM) systems are vulnerable to key management and handling issues, leading to exposure of cryptographic keys during playback, sharing, and dictionary attacks, which compromise security and allow unauthorized access to digital content.
Innovation Solution
Implementing a method where a key package contains multiple representations of an asset key, allowing a DRM module to switch to a new key generation formula or sequence without network connectivity, ensuring continued authorization and security by replacing compromised key-related functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the content key is published and made available to the public after being discovered by hackers, then unauthorized users can access and decrypt the content, but the security of the system is substantially reduced
Solution Approach 1:
The key management system is segmented into multiple key bags, each containing different content keys. When a key is compromised, only the affected key bag needs to be updated or replaced, rather than the entire key management system. This segmentation limits the impact of key publication and maintains security for other content.
Solution Approach 2:
The system performs preliminary actions by pre-distributing multiple key bags with different content keys before any compromise occurs. When a key is discovered to be compromised, the system can immediately switch to using alternative keys from previously distributed key bags, preventing unauthorized access without needing to republish or re-distribute all keys.
2Ease of operation
If the receiving party's computer decrypts the entire key bag to retrieve a key for content playback, then the content can be decrypted, but the keys are exposed to potential attack
Solution Approach 1:
The patent extracts only the specific content key needed for playback from the key bag, rather than decrypting the entire key bag. The DRM module is enhanced to selectively retrieve and use individual keys, minimizing the exposure window and reducing the amount of sensitive data in memory at any given time.
Solution Approach 2:
Different portions of the key bag are encrypted with different encryption methods or have different access controls. The system applies local quality by ensuring that only the specific key needed for current playback is decrypted and made available, while other keys remain encrypted and protected, reducing overall exposure risk.
3Adaptability or versatility
If different devices use different formats for their key bags, then each device can store keys according to its own requirements, but the keys are further exposed to penetration when content is transferred between devices
Solution Approach 1:
The patent implements a universal key bag format that can be used across different devices and platforms. This standardized format allows keys to be securely stored and transferred between devices without format conversion, eliminating the security vulnerabilities associated with multiple device-specific formats while maintaining adaptability through software implementation.
Solution Approach 2:
The system uses parameter changes by implementing a standardized key bag format with configurable parameters that can be adapted to different device requirements. This allows the same fundamental format to serve multiple devices while maintaining security consistency, avoiding the need for device-specific formats that create transfer vulnerabilities.
4Ease of operation
If the content key remains available in the memory of the playback device during play or when the user pauses, then the content can be accessed, but the key is vulnerable to pause attacks
Solution Approach 1:
The system implements periodic re-encryption or re-authentication of the content key during playback sessions. Instead of keeping the key continuously available in memory, the DRM module periodically validates authorization and re-encrypts the key, limiting the window of opportunity for pause attacks while maintaining continuous playback capability.
Solution Approach 2:
The key availability in memory is made dynamic rather than static. The system adjusts key retention in memory based on playback state, automatically evicting or re-encrypting keys when playback pauses or transitions between states. This dynamic management reduces the time keys are vulnerable to extraction attacks while maintaining ease of playback access.
Data Source
AI summary
In a Digital Rights Management (DRM) system, cryptographic keys for decrypting distributed assets (such as audio or video media) are distributed using an offline (e.g., non-Internet) method for distribution of the key generation process, with an implicit authorization to use the distributed key generation process. This is used to update an asset key for use by a client such as a media player when a key formula for generating the key for decrypting an asset has been compromised, such as by hackers.