RF Power Measurement for Cryptography Key Generation
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Solution Overview
Problem
Current cryptography methods require exchanging key information between devices, which can be intercepted or compromised, posing security risks, and often necessitate complex network security deployments for key distribution.
Innovation Solution
The system generates identical encryption keys in two communicating devices based on reciprocal channel characteristics determined through setup signals, without exchanging key information, utilizing channel reciprocity to ensure secure communication without prior key knowledge or storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If key information is exchanged between devices for cryptography, then secure communication is enabled, but the key information may be intercepted during exchange
Solution Approach 1:
The patent extracts the key generation process from the communication channel entirely. Instead of exchanging key information over the channel, each device independently generates identical keys by measuring channel characteristics (such as RF power) locally. This removes the vulnerable key exchange step while maintaining secure communication capability.
Solution Approach 2:
The channel characteristics (RF power measurements, impulse response) serve as an intermediary that both devices can measure independently yet derive identical keys from. This intermediary enables key agreement without direct key exchange, preventing interception while ensuring both parties arrive at the same cryptographic key.
2Reliability
If keys are stored in devices for encryption, then communication security is maintained, but the stored keys may be compromised by theft
Solution Approach 1:
The patent implements dynamic key generation where cryptographic keys are recreated fresh for each communication session based on current channel measurements. Keys are not stored statically in devices but generated dynamically from changing channel characteristics (RF power, impulse response), making stolen or cached keys obsolete.
Solution Approach 2:
Each device independently generates its own cryptographic keys by measuring channel characteristics locally without receiving keys from the other device. This self-service key generation eliminates the need to store or transfer keys, preventing both theft and interception vulnerabilities.
3Reliability
If complex network security deployment is used for key distribution, then key security is improved, but system complexity and cost increase
Solution Approach 1:
The patent removes the complex network security infrastructure (certificate authorities, key distribution centers, PKI systems) by extracting key generation from centralized security deployments. Instead, key generation is distributed to individual devices that independently create keys using local channel measurements, eliminating the need for complex network-wide security management.
Solution Approach 2:
Each device autonomously generates cryptographic keys without requiring enrollment in complex key distribution systems. The devices self-configure security by measuring channel characteristics and deriving keys locally, replacing centralized security management with decentralized self-service key generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents key interception and compromise, enabling secure communication without pre-shared keys, while maintaining security through dynamic key updates based on changing channel conditions, suitable for various network standards including Wi-Fi implementations.
Implementation Method 1
a channel comprising communication links that are on the same frequency and opposite in direction between two devices shows reciprocity by exhibiting the same channel characteristics at each device
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The embodiments provide a cryptography key for two communicating devices that is based on information known only to the devices. The information may only be determined by the devices. Each device determines the information without communicating key information related to the encryption key with the other. Channel characteristic reciprocity between the devices allows creation of identical keys in each device. Each device sends a signal to the other device at the same power level based on the distance between the devices. The power level may be set to result in a target receive power level at the other device. Each device samples the received signal, generates sampling results, creates a key based on the sampling results and a threshold power level, and utilizes the key. The threshold power level may be based on the target receive power level, or a median power determined from the sampling results.