Wireless Receiver Detuning via Cryptographic Authentication
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Solution Overview
Problem
The rapid growth of IoT devices necessitates secure wireless charging systems to protect against harsh transient signals from counterfeit wireless chargers, which can cause overvoltage or overcurrent conditions, and existing authentication protocols become unsustainable with multiple receivers and chargers due to the need for pre-programmed keys or shared master keys.
Innovation Solution
A method and apparatus for detuning a resonant wireless power transfer system using cryptography, where an authentication challenge is emitted from a wireless receiver to a charger, and the response is validated to adjust the resonant frequency of the main inductive element, allowing for secure authentication and impedance adjustment in the auxiliary inductive element to ensure valid or invalid responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resonant wireless power transfer is used to enable wireless charging, then power transfer efficiency is improved, but the system becomes vulnerable to harsh transients from counterfeit chargers causing overvoltage or overcurrent conditions
Solution Approach 1:
The system performs preliminary authentication through challenge-response protocols before enabling power transfer. The receiver sends an authentication challenge to the charger, validates the response using cryptographic verification, and only then tunes the resonant frequency to enable power transfer. This preliminary security check prevents counterfeit chargers from causing harmful transients while maintaining efficient resonant power transfer with authorized chargers.
2Reliability
If symmetric key authentication is used for charger authentication, then security is improved, but scalability deteriorates when multiple receivers and chargers are involved
Solution Approach 1:
The system replaces symmetric key authentication with public key infrastructure (PKI). Instead of requiring pre-shared secrets between all devices, each charger has a unique public-private key pair. The receiver stores multiple charger public keys and verifies charger responses using these public keys. This substitution enables scalable authentication where any receiver can authenticate with any authorized charger without requiring pre-programmed shared secrets, while maintaining strong security through cryptographic verification.
3Reliability
If the receiver is open circuited during authentication to prevent power transfer, then security is improved, but power delivery is delayed until authentication completes
Solution Approach 1:
The system performs authentication actions in advance before power transfer begins. The receiver opens the circuit switch during the authentication phase to prevent power transfer, completes the challenge-response authentication protocol, and only then closes the switch to enable power transfer. This preliminary authentication ensures security is established before any power is delivered, while the delay is minimized by efficiently executing the authentication protocol before the switching action.
4Reliability
If multiple auxiliary inductive elements are used for detuning, then authentication security is improved, but device complexity increases
Solution Approach 1:
The system segments the authentication function into two independent inductive elements: a main inductive element for normal power transfer and auxiliary inductive elements for authentication and detuning. During authentication, the controller activates the auxiliary inductive element to detune the resonant frequency, preventing power transfer even if the main element is coupled to a charger. This segmentation provides enhanced security through physical isolation of authentication and power transfer functions, while the modular design keeps complexity manageable by reusing the main inductive element for both power transfer and authentication when appropriate.
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 solution effectively secures the wireless power transfer by ensuring only authorized chargers can provide power, preventing damage from transient signals and maintaining scalability with multiple receivers and chargers through public key authentication and impedance control.
Implementation Method 1
a first inductive coil coupled to a digital authentication engine
Implementation Method 2
adjusting a resonant frequency of the main inductive element
Implementation Method 3
a second inductive coil coupled to an auxiliary rectifier
Data Source
AI summary
A method and apparatus for achieving detuning for a resonant wireless power transfer system including cryptography is described. Detuning for a resonant wireless power transfer system including cryptography allows for detuning a wireless receiver based upon authentication between the wireless receiver and a wireless charger.