Proxy Reencryption for End-to-End DRM Content Key Protection
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Solution Overview
Problem
Existing DRM protocols expose content keys in the clear, creating a potential attack surface and reducing the willingness of content creators and providers to share these keys, and they introduce high latency in the license provisioning process.
Innovation Solution
Implementing proxy reencryption techniques using RSA-OAEP encryption, indistinguishability obfuscation, and functional encryption to protect content keys end-to-end from origin to user devices, while maintaining ciphertexts in a standardized format for devices and reducing message exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If content keys are transmitted in clear to DRM service, then DRM service can process licenses, but security is compromised and content creators are less willing to share keys
Solution Approach 1:
The system segments the key distribution process into two independent phases: (1) content key encryption by the content service using the device's public key, and (2) license decryption by the device using its private key. The DRM service operates independently on license data without accessing content keys, eliminating the security risk of key exposure while maintaining license provisioning functionality.
Solution Approach 2:
The device itself acts as an intermediary that performs the key transformation function. Instead of requiring the DRM service to handle content keys, the device uses its private key to decrypt the content key ciphertext received from the content service, thereby eliminating the need for the DRM service to access plaintext content keys while still enabling license delivery.
2Productivity
If traditional DRM license provisioning is used, then licenses can be delivered, but high latency is introduced due to multiple message exchanges
Solution Approach 1:
The content service performs preliminary encryption of the content key using the device's public key before transmitting it to the device. This preliminary action eliminates the need for subsequent decryption requests and key exchange messages between the device and DRM service, reducing the number of message exchanges and latency in the license provisioning process.
3Reliability
If content keys are protected end-to-end, then security is improved, but device compatibility and standardized formats may be compromised
Solution Approach 1:
The system extracts the content key from the license data and transmits it separately as encrypted ciphertext to the device. The license data contains only the decryption information needed to recover the content key, while the actual content key ciphertext is delivered independently through a separate channel, allowing both security and compatibility to be maintained.
Solution Approach 2:
The device's private key serves multiple functions: it decrypts the content key ciphertext to obtain the content key, and it also verifies the license signature. This multi-functionality eliminates the need for separate key exchange protocols and maintains compatibility with existing device architectures while achieving end-to-end protection.
Data Source
AI summary
This disclosure relates to systems and methods for managing protected electronic content using proxy reencryption techniques. Rights management architectures are described that may, among other things, provide end-to-end protection of content keys from their point of origination at a content creator and/or content service to end user devices. Proxy reencryption techniques consistent with aspects of the disclosed embodiments may enable transformation of a ciphertext under one public key to a ciphertext containing the same plaintext under another public key. Consistent with embodiments disclosed herein, proxy reencryption processes may be implemented using indistinguishability obfuscation and puncturable public-key encryption schemes, functional encryption, and/or white box obfuscation techniques.