Digital Content Protection via Apparatus-Specific Key Encryption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital content protection systems face challenges in preventing illegitimate use of contents, particularly due to the risk of decryption key disclosure, which can lead to unauthorized reproduction and distribution of encrypted media.
Innovation Solution
A digital work protection system that includes a recording apparatus and reproduction apparatus, utilizing a recording medium with a read-only unrewritable area for storing a medium inherent number and a rewritable area for media key data, where encrypted media keys are generated and stored for unrevoked apparatuses, and detection information is encrypted for revoked apparatuses, ensuring only authorized decryption and reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If decryption keys are stored in reproduction apparatuses for content decryption, then authorized reproduction is enabled, but the risk of key disclosure and illegitimate use increases
Solution Approach 1:
The system performs preliminary actions by encrypting media keys with apparatus-specific keys before distribution. Each reproduction apparatus receives pre-encoded encrypted media keys that can only be decrypted by its specific apparatus key, preventing unauthorized use before any actual reproduction occurs.
Solution Approach 2:
The invention changes the parameter of key encryption by using different apparatus keys to encrypt the same media key for different reproduction apparatuses. This parameter change ensures that even if one apparatus key is compromised, other apparatuses remain secure, as each has a unique encryption parameter.
2Reliability
If key revocation is implemented by updating revocation information on recording media, then revoked apparatuses can be blocked, but the system complexity increases
Solution Approach 1:
The system uses copying by distributing identical revocation information across multiple recording media. Each disc contains the same revocation data, eliminating the need for centralized management systems and reducing overall system complexity while maintaining effective revocation across all apparatuses.
Solution Approach 2:
Revocation information is prepared in advance and embedded into recording media during manufacturing. This preliminary action ensures that when a disc is played, the reproduction apparatus automatically checks against pre-configured revocation data, eliminating the need for real-time communication or complex dynamic management.
3Reliability
If media bind technique is used to encrypt content based on medium identifier, then unauthorized duplication is prevented, but compatibility with standard optical drives is reduced
Solution Approach 1:
The invention introduces an intermediary layer of encrypted media keys that bridge the gap between standard optical drive compatibility and copyright protection. The encrypted media keys are stored on standard discs readable by any optical drive, but decryption requires the specific apparatus key, thus mediating between compatibility and protection.
Solution Approach 2:
The system changes the parameter of encryption from content-based to key-based encryption. Instead of encrypting content with the medium identifier directly, the system encrypts media keys with apparatus-specific keys, allowing standard drives to read the discs while preventing unauthorized decryption.
4Reliability
If multiple encrypted media keys are stored for different apparatuses, then selective access control is achieved, but the storage space and data management complexity increase
Solution Approach 1:
The invention changes the parameter of key storage by storing encrypted versions of the same media key rather than multiple different keys. Each apparatus-specific key encrypts the identical media key, reducing storage requirements while maintaining selective access control through the encryption process itself.
Data Source
AI summary
A recording and reproduction apparatus for preventing illegitimate use of contents. A recording medium stores an inherent number in an unrewritable area. The recording apparatus writes media key data and an encrypted content onto the recording medium. The media key data includes encrypted media keys generated by (i) for each of unrevoked reproduction apparatuses, encrypting a media key using a device key of the unrevoked reproduction apparatus respectively, and (ii) for each of revoked reproduction apparatuses, encrypting detection information using a device key of the revoked reproduction apparatus. The reproduction apparatus decrypts the encrypted media key using a device key to generate a decryption media key, judges whether the decryption media key is the detection information, and prohibits the encrypted content recorded on the recording medium from being decrypted when judged in the affirmative.