CRC Error Correction for Encrypted Bit Streams Using Retransmissions
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Solution Overview
Problem
Existing CRC-EC techniques are suboptimal for correcting bit errors in encrypted bit-streams, particularly in scenarios involving multiple retransmissions, and face challenges in computational complexity and availability of encrypted data for error correction.
Innovation Solution
A method for CRC-EC on encrypted bit-streams that involves generating and appending CRC parity bits to decrypted payloads, enabling error correction by comparing extended bit-streams from multiple transmissions, and utilizing CRC syndromes to identify and correct bit errors without direct access to encrypted payloads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing CRC-EC techniques are used on encrypted bit-streams, then error correction capability is provided, but computational complexity increases and performance becomes suboptimal for multiple retransmissions
Solution Approach 1:
The patent segments the error correction process into distinct phases: CRC remainder calculation on encrypted bit-streams, identification of candidate error positions through pattern matching, and verification through retransmission. This segmentation reduces computational complexity by avoiding exhaustive search while maintaining error correction capability across multiple retransmissions
Solution Approach 2:
The patent performs preliminary CRC remainder calculation on received encrypted bit-streams before attempting error correction. By pre-calculating remainders and comparing them against expected values, the system identifies candidate error positions without requiring full decryption or complex computational analysis, thus reducing overall computational complexity
2Reliability
If CRC-EC is applied to encrypted bit-streams, then bit error correction is enabled, but availability of encrypted data for error correction becomes limited
Solution Approach 1:
The patent introduces CRC remainders as an intermediary element that bridges encrypted bit-streams and error correction. By calculating and comparing CRC remainders on encrypted data without requiring full decryption, the system enables bit error correction while maintaining data confidentiality and working within the constraints of encrypted data availability
Solution Approach 2:
The patent applies partial decryption or selective processing only to the extent necessary for CRC calculation and error position identification. Rather than fully decrypting the bit-stream, the system performs minimal processing on encrypted data to extract error information, thus improving adaptability to encrypted data constraints while maintaining error correction capability
3Reliability
If multiple retransmissions are used for error correction, then error correction performance improves, but system complexity and processing overhead increase
Solution Approach 1:
The patent implements a feedback mechanism where CRC remainders from multiple retransmissions are collected, compared, and analyzed to identify consistent error patterns. This feedback loop enables the system to progressively refine error position identification across retransmissions, improving error correction performance while managing system complexity through structured comparison protocols
Solution Approach 2:
The patent employs periodic retransmission with structured CRC verification at each interval. By organizing error correction attempts into periodic cycles with clear start and end points, the system manages complexity through predictable processing patterns while accumulating error correction performance benefits across multiple transmission attempts
Data Source
AI summary
In some implementations, an apparatus may receive a first copy of payload data and a corresponding first cyclic redundancy check (CRC) code, and a second copy of the payload data and a corresponding second CRC code. Each of the first copy and the second copy may be encrypted with an identical keystream. The apparatus may decrypt, using the keystream, the first copy to obtain first decrypted data and the second copy to obtain second decrypted data, append the first CRC code to the first decrypted data to form first data, append the second CRC code to the second decrypted data to form second data, determine one or more bit positions, at each of which the first data and the second data have bit values different from each other, and correct, based on the one or more bit positions, an error contained in the first data.