Key Sharing Device Asymmetric SIDH Authentication

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The Diffie-Hellman (DH) key sharing scheme is not quantum-resistant, and there is no known method to convert the supersingular isogeny DH (SIDH) key sharing scheme, which has asymmetricity, into a key sharing scheme with an authentication function.

Innovation Solution

A key sharing device that selects one static key out of two static keys and generates a shared key using the selected static key, enabling conversion of an asymmetric key sharing scheme into a scheme with an authentication function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the SIDH key sharing scheme is used, then quantum resistance is achieved, but authentication function is lost due to asymmetricity

Engineering Contradiction:

Improvequantum resistanceVSAvoidauthentication function

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The scheme segments the key sharing process into two distinct phases: key generation using asymmetric SIDH for quantum resistance, and key selection using symmetric NAXOS technique for authentication. This segmentation allows each phase to optimize for its specific function while combining to achieve both quantum resistance and authentication capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges the asymmetric SIDH key sharing scheme with the symmetric NAXOS authentication technique. By combining these two previously separate approaches, the system achieves both quantum resistance (from SIDH) and authentication functionality (from NAXOS), resolving the contradiction between these two features.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If traditional DH key sharing is used, then simplicity is maintained, but quantum resistance is lost

Engineering Contradiction:

Improvescheme simplicityVSAvoidquantum resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The invention changes the mathematical parameters and structures used in key sharing from traditional DH to SIDH-based isogeny calculations. This parameter change enables quantum resistance while maintaining a relatively simple two-stage process structure that builds upon familiar key sharing concepts.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If authentication function is added to key sharing, then security is improved, but reciprocal communication is required

Engineering Contradiction:

Improveauthentication capabilityVSAvoidcommunication rounds

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The NAXOS authentication components are prepared and configured in advance during the key generation phase. This preliminary action allows authentication to be embedded in the initial key exchange without requiring additional reciprocal communication rounds, as the authentication capability is pre-established through the key selection mechanism.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11171778B2Key sharing device, key sharing method, and computer readable medium

Publication Date: 2021.11.09 MITSUBISHI ELECTRIC CORP

AI summary

An objective is to enable conversion of a key sharing scheme having asymmetricity into a key sharing scheme with an authentication function. In a key sharing device, a key selection unit selects, out of two static keys of different classifications, one static key being different from a static key of a key-sharing counterpart. A temporary key generation unit generates a temporary key of the same classification as the static key selected by the key selection unit. A shared key generation unit generates a shared key using the static key selected by the key selection unit and a temporary key generated by the counterpart.