Secure contactless payment method and device with active electronic circuitry

Abstract

A contactless payment device including a wireless communication device; a power source; a processor coupled to the power source; an accelerometer communicatively coupled to the processor and the power source; and an actuator communicatively coupled to the wireless communication device and the processor. The actuator is configured to activate the wireless communication device when the actuator is set in a closed state, and deactivate the wireless communication device when the actuator is set in an open state. The processor is configured to receive an incoming signal from the accelerometer; determine whether the incoming signal corresponds to a pre-programmed signal corresponding to an enabling gesture; and set the actuator in the closed state for a time interval, when the incoming signal corresponds to the enabling gesture.

1 - 20 . (canceled) 
     
     
         21 . A contactless payment device comprising:
 an antenna having a resonant frequency;   a sensor coupled to the antenna; and   a communication circuit;   wherein:
 the resonant frequency is an operating frequency when a finger is pressed against the sensor; 
 the resonant frequency is a detuned frequency when a finger is not pressed again the sensor; 
 the communication circuit communicates with a payment terminal when the resonant frequency is the operating frequency; and 
 the communication circuit is inhibited from communication with the payment terminal when the resonant frequency is the detuned frequency. 
   
     
     
         22 . The contactless payment device of  claim 21 , further comprising
 a power source; and   a cryptographic coprocessor coupled to the communication circuit and the power source, the cryptographic coprocessor being configured to verify signals received from the antenna when the resonant frequency is the operating frequency.   
     
     
         23 . The contactless payment device of  claim 21 , wherein the operating frequency is higher than the detuned frequency. 
     
     
         24 . The contactless payment device of  claim 21 , wherein the operating frequency is lower than the detuned frequency. 
     
     
         25 . The contactless payment device of  claim 21 , wherein the sensor is a capacitive sensor comprising at least one of copper, indium tin oxide, or printed ink. 
     
     
         26 . The contactless payment device of  claim 21  further comprising a ground plane connected to the sensor. 
     
     
         27 . The contactless payment device of  claim 26  wherein:
 the contactless payment device has a shape of a key fob; and 
 the ground plane comprises a key fob ring. 
 
     
     
         28 . The contactless payment device of  claim 21  further comprising a thermal resistive sensor that modifies the resonant frequency based on temperature. 
     
     
         29 . The contactless payment device of  claim 21  wherein the sensor comprises an LC resonator constructed with a fixed inductor. 
     
     
         30 . The contactless payment device of  claim 22  further comprising an LED which is turned on when a finger on the sensor, and is turned off when the no finger is on the sensor. 
     
     
         31 . The contactless payment device of  claim 21 , wherein the sensor is connected in series with the antenna. 
     
     
         32 . The contactless payment device of  claim 21 , wherein:
 the communication circuit comprises an NFC circuit; and   the communication circuit is connected in series with the antenna and the sensor.   
     
     
         33 . The contactless payment device of  claim 21 , wherein the antenna comprises two types of antennas calibrated for changes between the operating and detuned frequencies. 
     
     
         34 . The contactless payment device of  claim 21 , wherein the antenna comprises at least one of a tag antenna, a patch antenna, a planar inverted-F antenna, or a folded inverted conformal antenna. 
     
     
         35 . The contactless payment device of  claim 21 , wherein:
 the sensor comprises two capacitive sensors;   the resonant frequency is the operating frequency when two fingers are pressed against the capacitive sensors; and   the resonant frequency is the detuned frequency when two fingers are not pressed against the capacitive sensors.   
     
     
         36 . The contactless payment device of  claim 21  further comprising an actuator coupled to the communication circuit, wherein
 the actuator is set in a closed state when a finger is pressed against the sensor; and 
 the actuator is set in an open state when a finger is not pressed against the sensor. 
 
     
     
         37 . The contactless payment device of  claim 21 , further comprising a baseline tracking estimator that monitors the resonant frequency,
 wherein:
 a difference between the operating frequency and the detuned frequency is a function of an estimated resonant frequency. 
   
     
     
         38 . The contactless payment device of  claim 22 , wherein the cryptographic coprocessor is configured to:
 generate a first random number that is transmitted to the payment terminal when the antenna resonates at the operating frequency;   receive a second random number from the terminal; and   determine whether the second random number matches the first random number.   
     
     
         39 . A system for performing a transaction with a contactless payment device comprising:
 an antenna having a resonant frequency;   a sensor coupled to the antenna;   a communication circuit; and   a cryptographic coprocessor,   wherein
 the resonant frequency is an operating frequency when a finger is pressed against the sensor; 
 the resonant frequency is a detuned frequency when a finger is not pressed again the sensor; 
 the communication circuit communicates with a payment terminal when the resonant frequency is the operating frequency; 
 the communication circuit is inhibited from communication with the payment terminal when the resonant frequency is the detuned frequency; and 
 the cryptographic coprocessor is configured to verify signals received from the antenna when the antenna resonates at the operating frequency. 
   
     
     
         40 . A method for performing a transaction with a contactless payment device comprising:
 receiving a gesture signal from a sensor that a finger is being pressed against a sensor;   configuring an antenna to resonate at an operating frequency when the finger is being pressed against the sensor, the antenna being coupled to the sensor;   communicating, by a communication circuit, with a payment terminal when the antenna resonates at the operating frequency;   verifying, by a cryptographic processor, signals received by the communication circuit;   receiving a gesture signal from a sensor that a finger is not being pressed against a sensor;   configuring an antenna to resonate at a detuned frequency when the finger is not being pressed against the sensor; and   inhibiting communication between the payment terminal and the communication circuit when the antenna resonates at the detuned frequency.