Monitoring of a local environment using a physical unclonable function
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.
1 . A method for assessing a physical unclonable function using a response of a local environment to electromagnetic challenge signals, the method comprising
a transmitter providing, as a challenge, an electromagnetic challenge signal to the local environment, the challenge signal being provided with a corresponding set of predetermined signal parameters, and the local environment being in a reference state;
a transceiver, 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;
a receiver receiving the modified challenge signal;
a signal processor determining, for association with the challenge signal, a channel impulse response using the received modified challenge signal; and
the signal processor storing the determined channel impulse response in pairwise association with the respective challenge signal.
2 . The method of claim 1 , wherein the step of receiving the modified challenge signal includes receiving a direct line-of-sight component of the transmitted modified challenge signal and/or receiving a reflected component of the transmitted modified challenge signal.
3 . The method of claim 1 , wherein the signal parameters of the set of predetermined signal parameters according to which the challenge signals and the modified challenge signals are transmitted include one or more of a transmission power, a transmission frequency, a transmission direction, a directivity, a polarization and a phase, of the challenge signal.
4 . The method of claim 1 , wherein the channel impulse response is indicative of the electromagnetic field at the receiver, which is generated by at least the modified challenge signal.
5 . The method of claim 1 , wherein the step of providing challenges include transmitting two or more challenge signals simultaneously as a single challenge, and wherein the method comprises determining a single channel impulse response for the two or more challenge signals transmitted simultaneously.
6 . The method of claim 5 , comprising generating and transmitting the modified challenge signal with a respective set of modified signal parameters that further depend on the signal parameters of the two or more challenge signals provided simultaneously.
7 . The method of claim 1 , further comprising providing parameter data to the transceiver, the parameter data being indicative of the signal parameters of the set of predetermined signal parameters used for providing the challenge.
8 . A method for monitoring unwanted changes to a local environment, the method comprising:
assessing a physical unclonable function using a response of the local environment to electromagnetic challenge signals by performing the method of claim 1 ; and
performing a monitoring step, including:
selecting a set of predetermined signal parameters and the transmitter providing the corresponding challenge to the local environment, the local environment being in a surveillance state;
the transceiver, in response to receiving the challenge signal and determining the signal data of the received challenge signal, generating and transmitting the modified challenge signal with the respective set of modified signal parameters that depend on the signal data of the received challenge signal;
the receiver receiving the modified challenge signal;
the signal processor determining the channel impulse response for a given challenge signal using the received modified challenge signal; and
the signal processor comparing the determined channel impulse response with that channel impulse response stored during the assessment of the physical unclonable function, and
upon determining a deviation beyond a predetermined threshold amount between the stored channel impulse response and the currently determined channel impulse response, both associated to an identical challenge, providing a modification signal indicative of a modification of the local environment between the reference state and the surveillance state.
9 . A local environment monitoring arrangement, comprising:
one or more transmitters configured to provide as a challenge, an electromagnetic challenge signal to the local environment, the challenge signal having a corresponding set of predetermined signal parameters, and the local environment being in a reference state or a surveillance state, which induces a channel impulse response to be determined for the given challenge signal;
one or more transceivers configured to, in response to a reception of the challenge signal, to determine signal data of the received challenge signal, and to generate and transmit a modified challenge signal with a respective set of modified signal parameters that depend on the signal data of the received challenge signal;
one or more receivers configured to receive the modified challenge signal;
a signal processor connected at least to the one or more transmitters and to the one or more receivers and configured:
to determine the channel impulse response for the challenge signal using the received modified challenge signal
to store the determined channel impulse response in pairwise association with the respective challenge signal;
to compare a currently determined channel impulse response with that channel impulse response stored, both obtained using an identical challenge; and
upon determining a deviation beyond a predetermined threshold amount between the stored channel impulse response and the currently determined channel impulse response, both associated to an identical challenge, to provide a modification signal indicative of a modification of the local environment between the reference state and the surveillance state.
10 . The local environment monitoring arrangement of claim 9 , wherein the one or more transmitters and/or the one or more receivers are transceivers, and wherein each of the transceivers is configured to act as any of a transmitter, a transceiver or a receiver for performing the steps of a method comprising:
providing, as a challenge, an electromagnetic challenge signal to the local environment, the challenge signal being provided with a corresponding set of predetermined signal parameters, and 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; and
receiving the modified challenge signal.
11 . The local environment monitoring arrangement of claim 9 , wherein the one or more transmitters and/or the one or more transceivers comprise an antenna array for providing the challenge signals and/or the modified challenge signals with a predetermined transmission direction and/or a predetermined directivity.
12 . The local environment monitoring arrangement of claim 9 , further including one or more passive reflectors having a structured reflective surface, the one or more passive reflectors arranged within the local environment for reflecting at least the modified challenge signal provided by the transceiver.
13 . The local environment monitoring arrangement of claim 12 , wherein an area of the one or more passive reflectors is larger than an impinge-area of the modified challenge signal on the one or more passive reflectors.
14 . The local environment arrangement of claim 12 , wherein each of the one or more passive reflectors has a structured reflective surface having a linear structure, a circular structure, or a helical structure.
15 . A computer program comprising computer-executable instructions stored on a non-transitory computer-readable medium that, when executed by a processor of a local environment monitoring arrangement, cause the processor of the local environment monitoring arrangement to carry out a method for assessing a physical unclonable function using a response of a local environment to electromagnetic challenge signals, the method comprising:
a transmitter providing, as a challenge, an electromagnetic challenge signal to the local environment, the challenge signal being provided with a corresponding set of predetermined signal parameters, and the local environment being in a reference state;
a transceiver, 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;
a receiver receiving the modified challenge signal;
a signal processor determining, for association with the challenge signal, a channel impulse response using the received modified challenge signal; and
the signal processor storing the determined channel impulse response in pairwise association with the respective challenge signal.