Apparatus and mthod for encrypting data in a magnetic stripe reader

Abstract

A magnetic stripe reader assembly for a point of sale terminal is provided. The magnetic stripe reader reads the account data from a card and may encrypt it within the magnetic head. An encrypted representation of the account data may be provided to a host processor in the terminal for carrying out a financial transaction, such as a payment for goods or services. The account data is typically recorded on the magnetic stripe on the card in a magnetic flux pattern that is sensed and then converted to an analog signal. Such sensing and conversion and other processing of the account data to produce the encrypted representation of the account data typically involves one or more parameters, and may include at least one parameter that is adjustable.

1 . A payment terminal for receiving a payment for a retail transaction via a card encoded with account data in a magnetic flux pattern on a magnetic stripe, the terminal comprising:
 a magnetic head for reading the account data on the magnetic stripe, the magnetic head including a sensing element and a microcontroller, wherein the microcontroller includes an analog-to-digital converter, a signal processor coupled to the analog-to-digital converter, and an encryption unit coupled to the signal processor, the encryption unit including an output,   wherein the sensing element is configured to respond to the magnetic flux pattern on the magnetic stripe and to produce an analog signal representing the magnetic flux pattern, the sensing element communicating the analog signal to the analog-to-digital converter,   and further wherein the analog-to-digital converter in the microcontroller converts the analog signal to a digital signal, and the signal processor converts the digital signal to a representation of the account data, and further wherein the encryption unit encrypts the representation of the account data and provides the representation of the account data at the output of the encryption unit, and further wherein at least one of the signal processor and the encryption unit includes at least one adjustable parameter and the microcontroller includes an interface for changing the at least one adjustable parameter.   
     
     
         2 . The payment terminal of  claim 1 , further including a host processor in the terminal coupled to the output of the encryption unit, the host processor configured to receive the representation of the account data and to carry out processing of the retail transaction. 
     
     
         3 . The payment terminal of  claim 1 , further wherein one adjustable parameter is a sensitivity setting for the conversion by the signal processor of the digital signal to the representation of the account data. 
     
     
         4 . The payment terminal of  claim 1  further including a conductive grid arranged to respond to an attempt to tamper with the magnetic head. 
     
     
         5 . The payment terminal of  claim 1  wherein the magnetic head further includes a filter coupled between the sensing element and the microcontroller to remove noise. 
     
     
         6 . The payment terminal of  claim 1  wherein the encryption unit includes random data with the account data at the output of the encryption unit. 
     
     
         7 . The payment terminal of  claim 1  wherein the encryption unit uses a symmetric encryption scheme. 
     
     
         8 . The payment terminal of  claim 1  wherein the encryption unit uses an asymmetric encryption scheme. 
     
     
         9 . The payment terminal of  claim 1  wherein the magnetic head is encased to prevent monitoring signals within the head. 
     
     
         10 . The payment terminal of  claim 1  wherein the magnetic head further includes a second sensing element and a third sensing element, and further wherein the second and third sensing elements are coupled to the microcontroller. 
     
     
         11 . The payment terminal of  claim 1  wherein the microcontroller selectively provides the representation of the account data in an unencrypted format. 
     
     
         12 . The payment terminal of  claim 1  further comprising a connection port for the interface for changing the at least one adjustable parameter, wherein the port provides for a remote initiation of an adjustment to the at least one adjustable parameter. 
     
     
         13 . A payment terminal for receiving a payment for a retail transaction via a card encoded with account data in a magnetic flux pattern on a magnetic stripe, the terminal comprising:
 a magnetic head for reading the magnetic stripe, the magnetic head including a sensing element and a microcontroller, wherein the microcontroller includes an analog-to-digital converter, a signal processor coupled to the analog-to-digital converter, and an encryption unit coupled to the signal processor, the encryption unit including an output,   wherein the sensing element is configured to respond to the magnetic flux pattern on the magnetic stripe and to produce an analog signal representing the magnetic flux pattern, the sensing element communicating the analog signal to the analog-to-digital converter,   and further wherein the analog-to-digital converter in the microcontroller converts the analog signal to a digital signal, and the signal processor determines a series of times representing minimum values and maximum values of the digital signal, and further wherein the encryption unit encrypts the minimum value times and maximum value times and provides the encrypted minimum value times and maximum value times at the output of the encryption unit.   
     
     
         14 . The payment terminal of  claim 13 , further including a host processor in the terminal coupled to the output of the encryption unit, the host processor configured to receive the encrypted minimum value times and maximum value times and to carry out processing of the retail transaction. 
     
     
         15 . The payment terminal of  claim 14  wherein the output of the encryption unit is coupled by radio frequency to the host processor. 
     
     
         16 . The payment terminal of  claim 13  wherein the signal processor and the encryption unit are software modules programmed to run on the microcontroller, and further wherein at least one of the signal processor and the encryption unit includes at least one adjustable parameter. 
     
     
         17 . The payment terminal of  claim 16  wherein the microcontroller includes an interface for changing the at least one adjustable parameter. 
     
     
         18 . The payment terminal of  claim 17  further comprising a connection port for the interface for changing the at least one adjustable parameter, wherein the port provides for a remote initiation of an adjustment to the at least one adjustable parameter. 
     
     
         19 . The payment terminal of  claim 16 , further wherein one adjustable parameter is a sensitivity setting relating to the determination of the series of times representing minimum values and maximum values of the digital signal. 
     
     
         20 . The payment terminal of  claim 13  further including a conductive grid arranged to respond to an attempt to tamper with the magnetic head. 
     
     
         21 . The payment terminal of  claim 13  wherein the magnetic head further includes a filter coupled between the sensing element and the microcontroller to remove noise. 
     
     
         22 . The payment terminal of  claim 13  wherein the signal processor interpolates in determining the series of times representing minimum values and maximum values of the digital signal. 
     
     
         23 . The payment terminal of  claim 13  wherein the encryption unit includes random data with the encrypted minimum value times and maximum value times at the output of the encryption unit. 
     
     
         24 . The payment terminal of  claim 13  wherein the encryption unit uses a symmetric encryption scheme. 
     
     
         25 . The payment terminal of  claim 13  wherein the encryption unit uses an asymmetric encryption scheme. 
     
     
         26 . The payment terminal of  claim 13  wherein the magnetic head is encased to prevent monitoring signals within the head. 
     
     
         27 . The payment terminal of  claim 13  wherein the magnetic head further includes a second sensing element and a third sensing element, and further wherein the second and third sensing elements are coupled to the microcontroller. 
     
     
         28 . The payment terminal of  claim 13  wherein the microcontroller selectively provides the minimum value times and maximum value times in an unencrypted format. 
     
     
         29 . A magnetic head for detecting a magnetic flux pattern on a magnetic stripe, the magnetic head comprising:
 a sensing element configured to respond to the magnetic flux pattern on the magnetic stripe and to produce an analog signal representing the magnetic flux pattern; and   a microcontroller including an analog-to-digital converter coupled to receive the analog signal from the sensing element, a signal processor coupled to the analog-to-digital converter, and an encryption unit coupled to the signal processor, the encryption unit including an output,   wherein the analog-to-digital converter in the microcontroller converts the analog signal to a digital signal, and the signal processor determines a series of selected data points of the digital signal, and further wherein the encryption unit encrypts the selected data points and provides the encrypted selected data points at the output of the encryption unit.   
     
     
         30 . The magnetic head of  claim 29  wherein the selected data points are the times representing minimum values and maximum values of the digital signal. 
     
     
         31 . The magnetic head of  claim 29  wherein the output of the encryption unit is provided by radio frequency. 
     
     
         32 . The magnetic head of  claim 29  wherein the signal processor and the encryption unit are software modules programmed to run on the microcontroller, and further wherein at least one of the signal processor and the encryption unit includes at least one adjustable parameter. 
     
     
         33 . The magnetic head of  claim 32  wherein the microcontroller includes an interface for changing the at least one adjustable parameter. 
     
     
         34 . The payment terminal of  claim 32  further comprising a connection port for the interface for changing the at least one adjustable parameter, wherein the port provides for a remote initiation of an adjustment to the at least one adjustable parameter. 
     
     
         35 . The payment terminal of  claim 32  further comprising a connection port providing for a remote replacement of at least one of the software modules. 
     
     
         36 . The magnetic head of  claim 32 , further wherein one adjustable parameter is a sensitivity setting relating to the determination of the selected data points. 
     
     
         37 . The magnetic head of  claim 29  further including a second sensing element and a third sensing element, and further wherein the second and third sensing elements are coupled to the microcontroller. 
     
     
         38 . The magnetic head of  claim 29  further wherein the microcontroller selectively provides the selected data points in an unencrypted format. 
     
     
         39 . A magnetic head for reading account data encoded in a magnetic flux pattern on a magnetic stripe, the magnetic head comprising:
 a sensing element configured to respond to the magnetic flux pattern on the magnetic stripe and to produce an analog signal representing the magnetic flux pattern; and   a microcontroller including an analog-to-digital converter coupled to receive the analog signal from the sensing element, a signal processor coupled to the analog-to-digital converter, and an encryption unit coupled to the signal processor, the encryption unit including an output,   wherein the analog-to-digital converter in the microcontroller converts the analog signal to a digital signal, and the signal processor converts the digital signal to a representation of the account data, and further wherein the encryption unit encrypts the representation of the account data and provides the representation of the account data at the output of the encryption unit, and further wherein at least one of the signal processor and the encryption unit includes at least one adjustable parameter and the microcontroller includes an interface for changing the at least one adjustable parameter.   
     
     
         40 . The magnetic head of  claim 39 , further wherein one adjustable parameter is a sensitivity setting used by the signal processor in determining a series of times representing minimum values and maximum values of the digital signal. 
     
     
         41 . The magnetic head of  claim 39  further including a second sensing element and a third sensing element, and further wherein the second and third sensing elements are coupled to the microcontroller. 
     
     
         42 . The magnetic head of  claim 39  further wherein the microcontroller selectively provides the minimum value times and maximum value times in an unencrypted format. 
     
     
         43 . The magnetic head of  claim 39  further comprising a connection port for the interface for changing the at least one adjustable parameter, wherein the port provides for a remote initiation of an adjustment to the at least one adjustable parameter. 
     
     
         44 . A method for processing data encoded in a magnetic flux pattern on a magnetic stripe, the method comprising the steps of:
 providing a magnetic head with a sensing element and a programmable microcontroller with an output;   detecting the magnetic flux pattern on the magnetic stripe;   producing an analog signal representing the magnetic flux pattern;   converting the analog signal to a digital signal;   determining a series of times representing minimum values and maximum values of the digital signal;   encrypting the minimum value times and maximum value times; and   providing the encrypted minimum value times and maximum value times at the output of the microcontroller.