Physical Unclonable Function Monitoring via Dynamic Challenge Signals
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Solution Overview
Problem
The predictability of channel impulse responses in security systems using electromagnetic waves is limited by the superposition principle, reducing the number of non-predictable independent challenge-response pairs, which complicates the use of physical unclonable functions (PUFs) for secure applications.
Innovation Solution
A method is introduced that assesses a physical unclonable function by providing an electromagnetic challenge signal with predetermined parameters, generating a modified challenge signal based on received signal data, and determining the channel impulse response, thereby reducing predictability through non-linear reactions and complex signal interactions with the local environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic challenge signals are used to assess physical unclonable functions, then security key generation is enabled, but the superposition principle reduces the number of non-predictable independent challenge-response pairs
Solution Approach 1:
The patent changes the parameters of the challenge signal by modifying signal characteristics such as frequency, amplitude, or phase before re-transmission. This parameter modification ensures that the superposition of signals does not follow predictable patterns, thereby increasing the number of non-predictable challenge-response pairs while maintaining security reliability
Solution Approach 2:
The system dynamically adjusts the challenge signal parameters based on previous responses and environmental conditions. By making the signal parameters dynamic rather than static, the system prevents attackers from predicting future responses even if they observe previous ones, thus resolving the contradiction between security reliability and response predictability
2Device complexity
If the number of reflections in the local environment is limited, then signal propagation is simpler, but the complexity of channel impulse response is reduced
Solution Approach 1:
The patent introduces signal processing intermediaries that artificially create complex reflection patterns without requiring physically complex environments. By using intermediate signal processing steps to simulate multiple reflections, the system achieves high channel impulse response complexity while maintaining simple physical environments that are easy to manufacture and deploy
3Reliability
If modified challenge signals with dependent parameters are generated, then unpredictability of responses increases, but system complexity increases
Solution Approach 1:
The patent replaces complex physical signal processing mechanisms with computational algorithms. Instead of using physically complex devices to generate modified challenge signals, the system uses software-based signal processing that achieves the same unpredictability enhancement with lower hardware complexity, thus resolving the contradiction between reliability and device complexity
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 enhances the security of PUF-based systems by increasing the unpredictability of channel impulse responses, making it more difficult to replicate or tamper with the security keys, thus providing a robust security mechanism.
Implementation Method 1
a transmitter providing, as a challenge, an electromagnetic challenge signal to the local environment
Implementation Method 2
a transceiver, in response to receiving the challenge signal and determining signal data of the received challenge signal
Implementation Method 3
The alteration of the environment causes a change in the response to the wireless signal that propagates through said environment
Implementation Method 4
The complexity of a channel impulse response is limited by the number of reflections in the local environment
Data Source
AI summary
The invention is directed to a method for assessing a physical unclonable function using a response of a fixed local environment to electromagnetic challenge signals. It comprises providing an electromagnetic challenge signal with a corresponding set of predetermined signal parameters to the local environment being in a reference state, in response to receiving the challenge signal and determining signal data of the received challenge signal, generating and transmitting a modified challenge signal with a respective set of modified signal parameters that depend on the signal data of the received challenge signal, determining the channel impulse response for the challenge signal using the received modified challenge signal; and storing the determined channel impulse response in pairwise association with the respective challenge signal, thereby increasing the unpredictability of the association between the challenge signal and the channel impulse response.