Stream Cipher Multimedia Encoding Switching Coding Conventions

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Solution Overview

Problem

Existing multimedia encryption techniques are vulnerable to chosen-plaintext and chosen-ciphertext attacks, particularly when using universal codes like Exp-Golomb coding, as they fail to securely handle codewords and lead to decoding failures or attacks that can recover symbols from ciphertext-only access.

Innovation Solution

A data encoding method using a stream cipher to control switching between two universal coding conventions, ensuring high security with low computational complexity, where the key stream generated by the stream cipher determines the coding convention for each symbol, thereby preventing attacks and minimizing decoding errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional encryption methods (AES, DES) are used to encrypt entire multimedia data, then security is improved, but computational burden and power consumption increase excessively

Engineering Contradiction:

ImprovesecurityVSAvoidcomputational burden and power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies segmentation by dividing the multimedia data into individual symbols and processing them through a stream cipher on a symbol-by-symbol basis rather than encrypting entire blocks of data. This reduces computational burden while maintaining security, as the encryption is performed incrementally on smaller units during the natural compression process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges encryption and compression into a single integrated process. The stream cipher is applied within the arithmetic coding framework, combining the security function of encryption with the efficiency of compression in one unified operation, thereby avoiding the excessive computational burden of separate encryption passes on already-compressed data.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If encryption is applied to compressed multimedia files, then security is improved, but the hierarchical structures (scalability, transcoding, rate shaping) become unrecognizable

Engineering Contradiction:

ImprovesecurityVSAvoidhierarchical structure recognition

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by performing encryption during the compression process itself, before the final compressed bitstream is generated. The stream cipher is integrated into the arithmetic coding steps, ensuring that encryption and compression occur simultaneously in the correct sequence, preserving the structured nature of the output.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the arithmetic coding process as an intermediary that bridges compression and encryption. The arithmetic coder naturally produces structured bitstreams with preserved hierarchical information, and the stream cipher operates within this framework, allowing the intermediary compression process to maintain structure while applying security.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If multiple Huffman trees are used for encryption, then encryption and compression are achieved in one step, but the system becomes vulnerable to chosen-plaintext attacks

Engineering Contradiction:

Improveintegrated encryption-compression efficiencyVSAvoidsecurity against chosen-plaintext attacks

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent substitutes the mechanical Huffman coding system with an arithmetic coding system enhanced by a stream cipher. Arithmetic coding provides better compression efficiency and, when combined with the cryptographic stream cipher, achieves both integrated encryption-compression and resistance to chosen-plaintext attacks, replacing the vulnerable multiple Huffman tree approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If arithmetic coding is used for higher compression efficiency, then productivity is improved, but existing encryption schemes become subject to chosen-ciphertext attacks

Engineering Contradiction:

Improvecompression efficiencyVSAvoidsecurity against chosen-ciphertext attacks

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a composite encryption-compression system by combining arithmetic coding with a stream cipher. This composite approach leverages the compression efficiency of arithmetic coding while the integrated stream cipher provides security against chosen-ciphertext attacks, achieving both high productivity and reliability through the synergistic combination of two different technical approaches.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8189776B2Method and system for encoding multimedia content based on secure coding schemes using stream cipher

Publication Date: 2012.05.29 THE HONG KONG UNIV OF SCI & TECH

AI summary

Described herein are various embodiments of a coding technique that utilize a stream cipher for switching between first and second coding conventions for encoding a symbol sequence. The first coding convention specifies a first mapping between a symbol and a first codeword and the second coding convention specified a second mapping between the symbol and a second codeword. According to the invention, a key generated by the stream cipher is used to selected one of the first and second coding convention and the mapping of the selected coding convention is then utilized for encoding the symbol.