Security Module Multi-Key Chunk Encryption for Media Protection
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Solution Overview
Problem
Existing media content protection systems are vulnerable to attacks on local keys, allowing pirates to decrypt and redistribute content easily, as the security relies heavily on a single key for re-encryption, making it economically viable to hack despite the complexity.
Innovation Solution
Implementing a security module that decrypts and re-encrypts media content using multiple keys for small chunks, increasing the complexity and cost for pirates to decrypt the entire content by changing keys for each chunk, making it unprofitable to attempt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single local key is used for re-encrypting media content in the consumption device, then the device complexity is reduced and ease of operation is improved, but the security reliability deteriorates because attackers can focus their efforts on recovering this single key
Solution Approach 1:
The media content is divided into multiple chunks, and each chunk is encrypted with a different local key. Instead of using a single local key for the entire content, the system segments the content and applies multiple keys (K1, K2, K3, ..., Kn) to different portions, thereby increasing security while managing complexity through structured segmentation.
Solution Approach 2:
The system dynamically generates and changes local keys for each chunk of media content. Rather than using a static single key, the encryption keys are dynamically varied across different segments, making it much harder for attackers to compromise the entire content by recovering just one key.
2Reliability
If a single local key is stored in the consumption device, then the ease of operation is improved and device complexity is reduced, but the security reliability worsens because the attack cost is low and incentive is high for pirates
Solution Approach 1:
The system segments the media content into multiple chunks and assigns a different local key to each chunk. This segmentation approach increases the effort required for attackers to compromise the content, as they would need to recover multiple keys rather than a single key, thereby improving security while maintaining manageable key distribution through the set-top box.
3Reliability
If multiple keys are used to encrypt different chunks of media content, then the security reliability is improved and attack incentive is eliminated, but the device complexity and key management complexity increase
Solution Approach 1:
The media content is divided into discrete chunks (C1, C2, C3, ..., Cn), and each chunk is encrypted with a unique local key. This segmentation strategy enhances security by requiring attackers to compromise multiple independently encrypted segments, thereby significantly increasing the complexity and cost of successful attacks while maintaining structured key management.
Solution Approach 2:
The system employs dynamic key assignment where each chunk of media content is encrypted with a different local key that is generated and managed dynamically. This dynamic approach to key management enhances security by preventing single-point compromise while the set-top box coordinates the distribution and management of these dynamic keys to the consumption devices.
Data Source
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AI summary
The present application refers to the protection of conditional-access media content received and processed by a decoder. The decoder is in charge of receiving the protected media content and removing the protection in order to give access to a user to the media content. More specifically, the invention concerns a method to protect a media content (MC) encrypted by a media content key (MK), said method being carried out by a security module (SM) embedded into a reception device and in connection with a decoder, said method comprising the steps of : a. receiving an encrypted media content (MC)MK, said media content being encrypted by a media content key (MK), b. receiving a secure message containing the media content key (MK), said message being encrypted by a personal key (PK) of the security module (SM), c. decrypting the secure message by the personal key (PK) to retrieve the media content key (MK), d. decrypting the encrypted media content by the media content key, e. generating a current local key (K1, K2, K3... Kn), f. encrypting a portion of the media content (MC) by the current local key, said portion defining a chunk, g. securely transmitting the current local key to the decoder, h. transmitting the encrypted chunk ((CHn)Kn) to the decoder, i. repeating the steps e) to h) for each chunk of the media content and modifying the current local key for each different chunk. The invention further concerns a security module (SM) in which the method of the invention is carried out.