US 12,035,133 B2
Secure key generation using a chaotic oscillator
Jan-Peter Schat, Hamburg (DE)
Assigned to NXP B.V., Eindhoven (NL)
Filed by NXP B.V., Eindhoven (NL)
Filed on Apr. 1, 2021, as Appl. No. 17/301,387.
Prior Publication US 2022/0322082 A1, Oct. 6, 2022
Int. Cl. H04W 12/041 (2021.01); H04B 1/04 (2006.01); H04B 1/16 (2006.01)
CPC H04W 12/041 (2021.01) [H04B 1/04 (2013.01); H04B 1/16 (2013.01)] 17 Claims
OG exemplary drawing
 
9. A communications device, comprising:
a radio frequency (RF) receiver coupled to a receive antenna to receive an RF input signal corresponding to bits of a first cryptographic key from another communication device;
an oscillator portion having an input for receiving the RF input signal, and an output for providing an output signal;
an inverter having an input coupled to receive the output signal and an output for providing an inverted output signal;
a non-inverting buffer coupled in parallel with the inverter and having an output for providing the output signal;
a switch for coupling either the output of the inverter or the output of the non-inverting buffer to an input of a RF transmitter, the RF transmitter coupled to a transmit antenna for transmitting an RF output signal comprising bits of a second cryptographic key to the another communication device, wherein the second cryptographic key is different from the first cryptographic key;
a control circuit coupled to control the switch in response to detecting a characteristic of the input signal received from the another communication device; and
a key creation circuit for combining the first cryptographic key with the second cryptographic key to create a common key for use in authentication of the communication device with the another device in a data transfer between the communication device and the another communication device,
wherein the transmit antenna and the receive antenna of the communications device are spaced apart from each other by a first distance, and the another communications includes a transmit antenna and a receive antenna spaced apart from each other by the first distance, wherein during the receipt of the RF input signal, the receive antenna of the communications device is spaced apart from the transmit antenna of the another communications device by a second distance, and wherein the second distance is less than one wavelength of a frequency of the RF input signal, and the first distance is greater than the second distance.