Group Key Generation for Multi-Device Zero-Power Communication

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Solution Overview

Problem

Existing non-contact data transmission systems with zero-power devices lack efficient and secure methods for sharing secret information among multiple devices, as existing solutions only consider security between a single zero-power device and a target device.

Innovation Solution

A method involving a first device sending multiple messages to multiple second devices, each occupying different time domains, for key generation, and exchanging messages to determine a group key, ensuring secure and efficient information sharing among the devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single pairwise key is used for data transmission between a zero-power device and a target device, then security is ensured, but efficiency of sharing secret information among multiple devices deteriorates

Engineering Contradiction:
ImprovesecurityVSAvoidefficiency of sharing secret information
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the key management system into two distinct key types: pairwise keys for individual device communication and a group key for multi-device secret sharing. This segmentation allows each key type to serve its specific function optimally, resolving the contradiction between security and efficiency in multi-device scenarios

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a group key as an intermediary that enables efficient secret sharing among multiple zero-power devices. The group key acts as a mediator that allows devices to share secrets without requiring multiple pairwise key exchanges, thereby improving efficiency while maintaining security through the established key hierarchy

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If pairwise keys are established between target device and multiple zero-power devices, then security is ensured, but complexity of key management increases

Engineering Contradiction:
ImprovesecurityVSAvoidcomplexity of key management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the key management complexity into two manageable segments: pairwise keys for individual device authentication and a group key for collective secret sharing. This segmentation simplifies the overall key management structure compared to establishing and maintaining multiple pairwise keys for all device combinations

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The group key serves multiple functions simultaneously: it enables secret sharing among all group members, provides a basis for group authentication, and reduces the number of key management operations needed. This multi-functionality reduces key management complexity while maintaining security

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If multiple messages are exchanged for key generation, then security of key establishment is improved, but time consumption increases

Engineering Contradiction:
Improvesecurity of key establishmentVSAvoidtime consumption
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary key generation actions by establishing pairwise keys and generating the group key in advance through structured message exchanges. This preliminary action ensures security is built into the key establishment process before actual data transmission begins, reducing time consumption during operational phases

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4679764A1Key generation methods, and devices
Publication Date: 2026.01.14 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP4679764A1 patent drawingFigure 1~2
  • EP4679764A1 patent drawingFigure 3~4
  • EP4679764A1 patent drawingFigure 5~6

AI summary

The present disclosure relates to a key generation method, a device, a computer-readable storage medium, a computer program product, and a computer program. The method includes the following. A first device sends multiple first messages to multiple second devices, where a different first message among the multiple first messages occupies a different time domain range, and the multiple first messages are used for the multiple second devices to generate keys. The first device receives multiple second messages sent by the multiple second devices, where a different second message among the multiple second messages is related to a key of a different second device. The first device sends multiple third messages to the multiple second devices, where a different third message among the multiple third messages is used for a different second device to determine a group key.