Server-Mediated Public Key Exchange for Stable Device Communication

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Solution Overview

Problem

Existing communication key exchange methods face challenges in ensuring secure and stable communication between devices, particularly in asymmetric key systems where public keys need direct local connections, which are unstable and limited to close proximity, and in symmetric key systems where a compromised key affects all devices, leading to significant security risks.

Innovation Solution

A method for exchanging public keys through a server, allowing devices to establish encrypted communication based on their own private keys and each other's public keys, ensuring secure communication without direct key exchange, and enabling long-distance key exchange with high flexibility and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If direct local connection is used for public key exchange in asymmetric key systems, then key exchange can be performed, but connection stability is poor and it is limited to close proximity

Engineering Contradiction:
Improvekey exchange capabilityVSAvoidconnection stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces a server as an intermediary to facilitate public key exchange between devices. Instead of requiring direct local connections between devices, the server acts as a mediator that receives public keys from one device and distributes them to authorized devices. This resolves the contradiction by maintaining key exchange capability while eliminating the need for unstable direct connections, allowing long-distance communication through the server infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If symmetric key system is used to simplify communication, then communication is simplified, but a compromised key affects all devices leading to significant security risks

Engineering Contradiction:
Improvecommunication complexityVSAvoidsecurity risk from key compromise
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the communication security into device-specific key pairs rather than using a single shared symmetric key. Each device generates its own public-private key pair, and the server manages these segmented keys individually. This resolves the contradiction by maintaining simplified server-mediated communication while eliminating the cascading security risk, as compromise of one device's key does not affect other devices' security.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If public keys are exchanged directly between devices, then key exchange is possible, but it is limited to close proximity and lacks flexibility for long-distance communication

Engineering Contradiction:
Improvekey exchange flexibilityVSAvoidcommunication distance
Core Design Contradiction:
Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The server acts as an intermediary that removes the distance limitation from public key exchange. Devices can send their public keys to the server over any distance, and the server distributes them to authorized devices without requiring direct connection between the communicating devices. This resolves the contradiction by maintaining key exchange flexibility while enabling long-distance communication through the server's network infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4701125A1Key exchange method, apparatus, device, and storage medium
Publication Date: 2026.02.25 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4701125A1 patent drawingFigure 1a~2
  • EP4701125A1 patent drawingFigure 3~6
  • EP4701125A1 patent drawingFigure 7~8

AI summary

The present disclosure provides a key exchange method, an apparatus, a device, and a storage medium. The method comprises: generating a first key pair, wherein the first key pair comprises a first public key and a first private key; sending the first public key to a server; and receiving a first public key CA sent by the server, wherein the first public key CA comprises a second public key in a second key pair, the second key pair is generated by a second device, the second key pair further comprises a second private key, and the second device is a device requiring communication with a first device. The method of the present disclosure is high in communication security, low in application limitation, high in flexibility and high in stability, improves the user experience, expands the application range, and is low in operation complexity.