Pairwise Key Generation Using Time-Domain Channel Reciprocity
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Solution Overview
Problem
Ensuring the security and efficiency of pairwise key generation in contactless data transmission between zero-power devices is a challenge due to the unsecure nature of communication channels.
Innovation Solution
A method involving a first device sending multiple messages occupying different time domain ranges to enable a second device to generate a key, with the first device verifying the key using a target model and sending an acknowledgement upon consistency, and the second device confirming key verification upon receiving the acknowledgement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple messages are exchanged between devices for key generation, then key security and randomness are improved, but communication time and processing complexity increase
Solution Approach 1:
The patent applies preliminary action by having devices pre-process and extract channel characteristics from multiple messages before final key generation. The first device extracts first channel characteristics from multiple first messages, and the second device extracts second channel characteristics from multiple second messages, preparing the randomness material in advance to accelerate the final key generation process
Solution Approach 2:
The patent uses channel characteristics as an intermediary between the exchanged messages and the final cryptographic key. Instead of directly using message content, the devices extract channel characteristics (such as signal strength, phase, or timing information) from the messages, which serve as a mediator to generate the key while preserving security and reducing direct communication overhead
2Reliability
If multiple messages are exchanged between devices for key generation, then key randomness is improved, but device complexity increases
Solution Approach 1:
The patent segments the key generation process into distinct phases: message exchange phase, channel characteristic extraction phase, and key generation phase. The first device sends multiple first messages and extracts first channel characteristics separately from how the second device sends second messages and extracts second channel characteristics. This segmentation divides the complex task into manageable parts that can be processed independently
Solution Approach 2:
Channel characteristics serve as an intermediary that simplifies the processing complexity. Instead of devices directly processing and comparing entire message contents to generate keys, they extract compact channel characteristics (such as signal strength indicators, phase differences, or timing information) from messages, which then serve as the basis for key generation, reducing the computational burden
3Manufacturing precision
If channel reciprocity is leveraged for key generation, then key consistency between devices is improved, but communication overhead increases
Solution Approach 1:
The patent implements feedback by having the second device send second messages back to the first device in response to the first messages. The second device extracts second channel characteristics from these second messages and uses them to generate a key. The first device then verifies the key consistency by comparing its own generated key with the key derived from the second device's channel characteristics, creating a feedback loop that ensures key consistency
Data Source
AI summary
A key generation method and a device are provided. The method includes: a first device sends a plurality of first messages to a second device. Different first messages among the plurality of first messages occupy different time domain ranges. The first messages are used for the second device to generate a key. The first device receives a plurality of second messages sent by the second device. Different second messages among the plurality of second messages are related to different first messages. The last second message among the plurality of second messages carries the key of the second device. The first device generates a verification key of the second device on the basis of the plurality of second messages and a target model.