Elliptic-Curve Key Exchange Using Isomorphic Mapping Against Quantum Attacks

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Solution Overview

Problem

Current asymmetric cryptography methods, such as Elliptic-Curve-Diffie-Hellman key exchange, are vulnerable to quantum computer attacks and lack standardized, secure post-quantum cryptography solutions.

Innovation Solution

A method for arranging a shared cryptographic key using isomorphic and inverse mappings between elliptic curves, where points on a first elliptic curve are exchanged via a public channel after point compression, and the key is determined through a non-trivial inverse mapping, ensuring security against quantum computer attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard ECDH key exchange is used, then implementation is simple and well-established, but security is vulnerable to quantum computer attacks

Engineering Contradiction:
Improvesecurity against quantum attacksVSAvoidcryptographic protocol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary isomorphic mapping function Φ that transforms points between two elliptic curves E and E'. This mapping acts as a mediator that allows the key exchange to occur on curve E' (which is secure against quantum attacks) while maintaining the mathematical structure needed for Diffie-Hellman key exchange. The mapping function bridges the gap between standard ECDH implementation and post-quantum security requirements without requiring completely new protocols.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameters of the elliptic curve system by introducing a second elliptic curve E' that is isomorphic to the original curve E through mapping Φ. By performing key exchange operations on the transformed curve E' and then mapping results back to E, the system achieves post-quantum security while maintaining compatibility with existing ECDH infrastructure. This parameter transformation allows the same mathematical operations to provide enhanced security.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If point compression is applied to reduce transmission data, then communication efficiency improves, but key reconstruction difficulty must be maintained

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidkey reconstruction difficulty
Core Design Contradiction:
ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies asymmetric treatment to point compression by compressing points on curve E' differently than points on curve E. The isomorphic mapping Φ transforms uncompressed points from E to compressed points on E' for transmission. This asymmetric compression approach allows efficient communication while the non-trivial nature of the isomorphic mapping ensures that compressed points cannot be easily reversed to reconstruct the original key material, maintaining security against reconstruction attacks.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentUS12489609B2Method for arranging a shared cryptographic key and method for encrypted communication, computer program product and device
Publication Date: 2025.12.02 SIEMENS AG
  • US12489609B2 patent drawing
  • US12489609B2 patent drawing
  • US12489609B2 patent drawing

AI summary

Various embodiments of the teachings herein include a method for arranging a shared cryptographic key with a communication partner. The method may include: selecting a first point of a first elliptic curve; sending the first point to the communication partner using a public channel; receiving a second point of the first elliptic curve from the communication partner; and determining the shared key using a non-trivial, inverse shared mapping of the second point with respect to a shared isomorphic mapping of a second elliptic curve onto the first elliptic curve.