Selective Multimedia Data Encryption for Conditional Access
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Solution Overview
Problem
Conditional access systems for multimedia data face high hardware performance demands due to the need for real-time processing of MPEG streams, which is challenging for conventional hardware, especially in providing adequate security for multimedia commerce.
Innovation Solution
A selectively encrypted transport stream is created by encrypting specific data packets within a base transport stream using an event encryption key, reducing processing requirements and allowing decryption with low-performance hardware, such as smart cards, while maintaining high security levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional scrambling is used for all data packets in a transport stream, then security is provided, but hardware performance requirements become excessively high
Solution Approach 1:
The patent divides the transport stream into individual data packets and applies encryption selectively to only those packets containing essential information (such as P-frames and I-frames in MPEG streams). This segmentation approach reduces the total volume of encrypted data from 100% to approximately 10-20% of the stream, thereby reducing hardware processing requirements while maintaining security
Solution Approach 2:
The patent applies different treatment to different parts of the data stream: critical packets are encrypted with strong encryption algorithms while non-critical packets (such as B-frames or redundant data) are either encrypted with simpler methods or left unencrypted. This local differentiation optimizes the balance between security and processing load
2Power
If selective encryption of particular data packets is implemented, then hardware performance requirements are reduced, but system complexity increases due to packet detection and reinsertion
Solution Approach 1:
The patent performs preliminary detection and identification of packets requiring encryption before the actual encryption process. By pre-marking or pre-identifying critical packets (such as those containing key frames or essential data), the system avoids the need for complex real-time analysis during the encryption phase, thereby reducing overall system complexity
Solution Approach 2:
The patent extracts only the necessary control information and packet identification data from the full transport stream for processing. By separating the essential metadata (packet types, sequence numbers, timing information) from the full data stream, the system reduces processing complexity while maintaining the ability to correctly reinsert encrypted packets
3Reliability
If decryption is performed in real-time with low-performance hardware, then security is enhanced through smart card implementation, but processing speed may be insufficient
Solution Approach 1:
The patent applies partial encryption by selecting only the most critical packets for encryption rather than encrypting the entire stream. This partial action approach ensures that the minimum necessary security is provided while keeping processing speeds within the capabilities of smart card hardware, which can handle the reduced workload in real-time
Data Source
AI summary
A conditional access system for multimedia data is disclosed that offers acceptable security at drastically reduced requirements on hardware performance. A selectively encrypted transport stream is formed from a clear transport stream by detecting particular data packets within the clear transport stream, removing and encrypting the particular data packets with an event encryption key, and inserting the encrypted data packets into the remaining clear transport stream at insertion positions corresponding to the original positions of the particular data packets in the clear transport stream. For specific embodiments that include decryption circuitry inside a user smart card, the level of security of such system is even higher than that of conventional ones.