Ciphering Compressed Audio Video Streams with Error Tolerance
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Solution Overview
Problem
Current methods for ciphering compressed video data streams are inadequate as they compromise compression efficiency, require excessive computing resources, and are not compatible with variable bandwidth and error-resistant standards, while also failing to maintain compliance with coding standards and transparency in data transport.
Innovation Solution
A method using a pseudo-random stream cipher that maintains bit positions and compatibility with variable-length codewords, employing a unique pseudo-random stream for each packet and hashing for enhanced security, allowing for secure and efficient transmission without reducing compression efficiency or increasing computing power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a codeword in a table of codewords of different lengths is entirely ciphered, then security is improved, but the syntax compliance is degraded and decoder recognition fails
Solution Approach 1:
The patent applies different ciphering strategies to different parts of the data stream. Specifically, it preserves the syntax elements (headers, motion vectors, quantization parameters) in plain text while applying ciphering only to the transform coefficients. This local differentiation maintains syntax compliance for decoder recognition while providing security for the actual image data.
Solution Approach 2:
The patent segments the compressed video stream into distinct components: syntax elements (headers, motion data, quantization parameters) and transform coefficients. By separating these elements and applying different treatments (plain text for syntax, ciphered for coefficients), the system resolves the contradiction between maintaining syntax compliance and providing security.
2Productivity
If compression efficiency is maintained, then data rate is reduced, but security requirements cannot be met
Solution Approach 1:
The patent applies security measures selectively only to the transform coefficients while leaving the compression-optimized syntax elements unchanged. This approach maintains the high compression efficiency achieved by the MPEG encoder while providing adequate security for the actual image content, avoiding the need to re-compress or alter the highly optimized syntax portions.
3Reliability
If proprietary cipher systems are used, then security is provided, but adaptability to various standards and applications is limited
Solution Approach 1:
The patent creates a universal ciphering method that works with any MPEG-compressed video stream regardless of the specific MPEG version (MPEG-2, MPEG-4, H.264) or application (broadcast, storage, streaming). By operating at the generic level of transform coefficients and syntax elements, the system provides standard-compatible security that can be applied across multiple standards and use cases.
4Reliability
If computing power is increased to meet security requirements, then security is improved, but compatibility with embedded terminals is degraded
Solution Approach 1:
The patent reduces computing requirements by applying ciphering only to the transform coefficients rather than the entire bitstream. This localized approach significantly reduces the computational burden compared to full-stream encryption, making the security solution feasible for embedded terminals and resource-constrained devices while still providing adequate security.
Data Source
AI summary
A method ciphers a standardized stream of compressed audio or video data, wherein at least one part of the bits of data packets delimited by two consecutive synchronization markers is ciphered by pseudo-random stream.