Whitebox Device Binding for DRM Security
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Solution Overview
Problem
Existing methods for white-box cryptography do not effectively prevent malicious users from copying and distributing DRM applications, as they can perform code-lifting attacks and share decryption keys, leading to unauthorized access and piracy.
Innovation Solution
The implementation of whitebox device binding, which involves a method where a user device receives an encrypted message, signs it, and then uses a whitebox to recover and decrypt the message using a master secret key, ensuring that the application is bound to a specific device and cannot be easily copied or shared.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If white-box cryptography is used to allow users to decrypt content, then content accessibility is improved, but security against code-lifting attacks deteriorates
Solution Approach 1:
The system segments the decryption functionality by separating the master secret key storage from the white-box program. The master secret key is stored in a secure element, while the white-box program contains only the public key and encryption logic. This segmentation prevents code-lifting attacks because the critical secret key material cannot be extracted from the white-box program alone.
Solution Approach 2:
The patent introduces a secure element as an intermediary component between the user device and the content delivery system. This secure element acts as a trusted mediator that stores the master secret key and performs cryptographic operations, preventing direct access to secret keys while enabling secure content decryption. The secure element mediates between the need for key accessibility and security protection.
2Adaptability or versatility
If decryption keys are distributed to multiple users, then content distribution capability is improved, but vulnerability to key extraction deteriorates
Solution Approach 1:
The system applies local quality by making each user's decryption capability unique and device-specific. Each user device has its own secure element with unique key material, and the white-box program is bound to that specific device. This means that while content can be distributed to multiple users, each user's decryption capability is locally optimized and isolated to their specific device, preventing key extraction and sharing.
Solution Approach 2:
The patent implements asymmetry in the key distribution model by using public-key cryptography where the public key can be freely distributed in the white-box program, but the private master secret key remains asymmetrically secured in the secure element. This asymmetric structure allows broad content distribution capability while protecting the critical private key from extraction.
3Difficulty of detecting and measuring
If the white-box program is made traceable through watermarking, then piracy tracking is improved, but prevention of code copying deteriorates
Solution Approach 1:
The system performs preliminary action by binding the white-box program to the user's device identifier and secure element during the initial setup and enrollment process. This pre-binding occurs before any content distribution or potential piracy activities, creating device-specific decryption capabilities that cannot be transferred. The preliminary binding action prevents code copying effectiveness rather than relying on post-detection watermarking.
Data Source
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AI summary
A method is disclosed. The method includes receiving, by a user device, an encrypted message from a server computer. The encrypted message is a message encrypted with a master secret key or a key derived from the master secret key. The user device signs the encrypted message with a secure element private key. The user device, using a whitebox, cryptographically recovers a secure element public key from a certified key using a server computer public key. The certified key is certified by the server computer and based on at least the secure element public key. The user device, using the whitebox, cryptographically recovers the encrypted message from the signed encrypted message using the secure element public key. The user device, using the whitebox, decrypts the encrypted message using the master secret key or the key derived from the master secret key in the whitebox to obtain the message.