Decoding Apparatus Homomorphic Non-Homomorphic Key Security

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Solution Overview

Problem

Existing decoding techniques using cloud-managed keys face challenges in performing decoding operations that involve both homomorphic and non-homomorphic operations, as they cannot ensure the correctness of the decoding result without exposing the decoding key.

Innovation Solution

A decoding apparatus performs self-correcting processing with a decoding capability providing apparatus to obtain a decoding value from the first ciphertext, which can be decoded by homomorphic operation, and uses this value along with an addition value to perform non-homomorphic operations to output the plaintext, ensuring secure and correct decoding without revealing the decoding key.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the decoding key is provided to the decoding apparatus, then the decoding apparatus can decode the ciphertext, but the safety is compromised because the decoding key is exposed

Engineering Contradiction:

Improvedecoding capabilityVSAvoidkey exposure risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A cloud-managed key service acts as an intermediary between the key generation apparatus and the decoding apparatus. The service enables decoding operations without directly exposing the decoding key to the decoding apparatus, thus maintaining security while providing functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The decoding process is segmented into multiple components: key generation, key management, and decoding execution. The decoding key is generated and managed separately in the key generation apparatus, while the decoding apparatus performs decoding operations using information from the cloud-managed key service, separating the sensitive key material from the decoding function.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If the ciphertext is provided to an external apparatus for decoding, then the decoding result can be obtained, but the decoding apparatus cannot verify the correctness of the decoding result

Engineering Contradiction:

Improvedecoding result acquisitionVSAvoiddecoding result verification

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The cloud-managed key service provides feedback mechanisms that allow the decoding apparatus to verify the correctness of decoding results. The service returns information that enables the decoding apparatus to confirm whether the decoding operation was successful and accurate, without requiring exposure of the decoding key.

Inventive Principle:

Principle #23Feedback

3Reliability

If self-correcting processing is used for decoding, then the correctness of the decoding result is ensured, but it is impossible to perform decoding when the processing comprises both homomorphic and non-homomorphic operations

Engineering Contradiction:

Improvedecoding correctnessVSAvoidoperation type compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The cloud-managed key service is designed with multi-functionality to handle both homomorphic and non-homomorphic decoding operations. It provides a universal interface and processing capability that accommodates different types of decoding operations while maintaining the self-correcting mechanism for ensuring result correctness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10163370B2Decoding apparatus, decoding capability providing apparatus, method thereof and program

Publication Date: 2018.12.25 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A decoding apparatus performs self-correcting processing with a decoding capability providing apparatus holding a decoding key for decoding first ciphertext which can be decoded by homomorphic operation to obtain a decoding value of the first ciphertext, and performs non-homomorphic operation using a value corresponding to or deriving from the decoding value of the first ciphertext and an addition value to output plaintext.