Triple Wrap Encryption for Secure Program Data
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Solution Overview
Problem
Existing copy protection systems for pay-per-view systems are vulnerable to unauthorized copying and reverse-engineering, leading to substantial revenue losses for content providers.
Innovation Solution
A triple wrap encryption method is employed, where program data is encrypted using dynamic keys, and these keys are further encrypted using message segment keys, with a modifier message and checksum ensuring secure key synchronization between the transmitter and receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If encryption keys are transmitted to enable decryption of program data, then authorized users can access the content, but unauthorised users may also obtain and use the keys to bypass protection
Solution Approach 1:
The encryption key is divided into two separate components: a program key used for encrypting program data and a modification key used for encrypting modifier messages that contain synchronization information. This segmentation ensures that even if one key is compromised, the other remains protected, maintaining the reliability of the copy protection system while still enabling authorized decryption.
Solution Approach 2:
Modifier messages act as an intermediary mechanism between the transmitter and receiver, carrying synchronization information that enables the receiver to independently determine when to switch program keys without directly transmitting the keys themselves. This intermediary approach maintains security by avoiding direct key transmission while ensuring authorized users can access content.
2Reliability
If program keys are frequently changed to enhance security, then unauthorized copying is thwarted, but synchronization between transmitter and receiver becomes more difficult to maintain
Solution Approach 1:
The system transmits modification keys in advance through encrypted modifier messages before they are needed for program key changes. This preliminary action allows the receiver to prepare for upcoming key switches without complexity, as the synchronization information is provided ahead of time rather than requiring complex real-time coordination.
Solution Approach 2:
The modifier messages contain checksums that provide feedback verification to ensure successful reception and interpretation of synchronization information. This feedback mechanism simplifies the synchronization process by enabling automatic verification of key switching timing between transmitter and receiver, maintaining reliability without increasing complexity.
3Reliability
If encryption is applied to all data including PSI data, then comprehensive security is achieved, but authorized users cannot access program information needed for decryption
Solution Approach 1:
The encryption system applies different security levels to different types of data: program data and modifier messages are encrypted with dynamic keys, while PSI data is either left unencrypted or encrypted with static keys that do not change. This local differentiation of encryption quality ensures that authorized users can always access necessary program information while maintaining high security for the actual program content.
Data Source
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AI summary
A receiver receives a data key from a transmitter. The data key is generated by a random number generator seeded with a seed derived from data to be encrypted in the transmitter. The receiver also receives a synchronizing signal in place of a null packet in an MPEG transport stream, receives encrypted data in the MPEG transport stream, and synchronizes, in response to the received synchronization signal, use of the data key to decrypt the received encrypted data. Additionally or alternatively, an encrypted message having sequential first, second, third, and fourth encrypted portions is decrypted into sequential first, second, third, and fourth decrypted data portions by use of a triple wrap decrypting technique.