Encryption Device Block Tagging for Tampering Location

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Solution Overview

Problem

Existing authentication encryption techniques cannot detect the location of tampering in encrypted data, only whether tampering has occurred.

Innovation Solution

An encryption device and decryption device that divide data into fixed-length blocks, encrypt each block using a block cipher, and generate tags for each block set to detect tampering and locate it within the encrypted data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If authentication encryption techniques are used to detect tampering with encrypted data, then the presence of tampering can be detected, but the location of the tampering cannot be detected

Engineering Contradiction:

Improvetampering detection capabilityVSAvoidtampering location information

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent divides the encrypted data into multiple blocks and generates separate authentication tags for each block. When tampering occurs, the verification process can identify which specific block's tag does not match, thereby locating the tampering position. This segmentation approach transforms a single authentication mechanism into multiple localized authentication units, enabling both detection and location of tampering.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If block-by-block encryption is performed with tag generation for each block set, then tampering location can be detected, but the device complexity increases

Engineering Contradiction:

Improvetampering location precisionVSAvoidencryption device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a block cipher that serves dual functions: encrypting data blocks and generating authentication tags. By using the same cryptographic primitive for both encryption and authentication purposes, the system achieves precise tampering location detection without requiring separate dedicated hardware or algorithms, thus limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of information

If tags are generated for each block set to enable tampering location detection, then the location information is preserved, but the processing time increases

Engineering Contradiction:

Improvetampering location informationVSAvoidencryption and decryption processing time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The patent combines the encryption and authentication tag generation processes into a unified workflow. The block cipher operations perform both encryption and tag generation in sequence without requiring separate processing stages, which reduces the overall processing time compared to using independent encryption and authentication algorithms, while still preserving tampering location information through block-specific tags.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250038951A1Encryption device, decryption device, cryptographic system, encryption method, and decryption method

Publication Date: 2025.01.30 NEC CORP

AI summary

An encryption device generates a sequence of blocks by dividing data to be encrypted into blocks of fixed length, performs encryption using a block cipher for each block in the sequence of blocks into which the data to be encrypted is divided, and concatenates the encrypted blocks to generate encrypted data, and generates a tag for each block set, which is a combination of blocks included in the sequence of blocks into which the data to be encrypted is divided, and concatenates the tags for each block set to generate a tag for the encrypted data.