Transaction device with noise signal encryption

• US 7,392,396 B2
• Filed: 03/07/2003
• Issued: 06/24/2008
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Soysa, G.F.R. Sulak, Fernando, Llavanya, Wang, Nathan C.
• Primary Examiner(s): REVAK, CHRISTOPHER A
• Application Number:
  US10/384,010
• Publication Number:
  US 20040064711A1
• Time in Patent Office: 1,936 Days
• Field of Search: 726/2, 726/26, 713/182, 713/183, 713/189
• US Class Current: 713/184
• CPC Class Codes: G06F 21/83 input devices, e.g. keyboards, mice or controllers thereof
• CPC Class Codes: G06Q 20/20 Point-of-sale [POS] network systems

Abstract

A transaction device adds or injects a random noise component into signals representing (x,y) coordinate signals associated with user interface with an input screen associated with the device. The noise component can be generated by converting to analog the output of a random number generator, and then adding the noise component to the x-axis and/or y-axis component of the (x,y) coordinate signal. Alternatively the noise component can be injected into the x-axis and/or y-axis operating potential for the input screen. The result is a masking of the original (x,y) positional information. The randomly generated number is only available internal to the device. The device can use this number to de-crypt the true (x,y) signals, which signals can then be re-encrypted before transmitting from the device.

Claims

1. A transaction device for receiving a user input, the transaction device comprising:

a user-interfaceable surface, coupled to at least one source of electrical potential so as to generate an x-axis signal and a y-axis signal as a function of the at least one source of electrical potential and a location of the user input;

a signal generating unit generating a random signal; and

an arithmetic unit generating an encrypted output signal by adding the random signal to at least one of the x-axis signal and the y-axis signal, wherein the adding comprises at least one of (i) combining the random signal with the at least one source of electrical potential and (ii) combining the random signal with the at least one signal, and wherein the signal generating unit comprises;

a random digital signal generator; and

a digital-to-analog converter coupled to receive output from the random digital signal generator, wherein an output from the digital-to-analog converter is the random signal.

2. The transaction device of claim 1, wherein the signal generating unit and the arithmetic unit comprise electronic components housed within the transaction device.

3. The transaction device of claim 1, further including:

a processor;

a screen controller coupled to the processor and to the user-interfaceable surface;

wherein the processor reproduces the x-axis signal and the y-axis signal by decrypting the encrypted output signal using the random signal.

4. The transaction device of claim 3, further including:

an encryption unit encrypting the x-axis signal and the y-axis signal after the processor performs the decryption; and

a communication interface outputting the encrypted x-axis signal and the encrypted y-axis signal.

5. The transaction device of claim 1, wherein the arithmetic unit directly sums the random signal with the at least one of the x-axis signal and the y-axis signal.

6. The transaction device of claim 1, wherein the arithmetic unit supplements the at least one source of electrical potential by injecting the random signal.

7. The transaction device of claim 1, wherein the user-interfaceable surface is a display-input screen that can output information from the transaction device and can respond to the user input.

8. The transaction device of claim 1, wherein the user-interfaceable surface comprises a material responsive to a change in pressure exerted against the user-interfaceable surface.

9. The transaction device of claim 1, wherein the user-interfaceable surface is responsive to heat transferred to the user-interfaceable surface.

10. The transaction device of claim 1, wherein the user-interfaceable surface is responsive to changes in light incident upon the user-interfaceable surface.

11. The transaction device of claim 1, wherein the user-interfaceable surface is responsive to infrared energy incident upon the user-interfaceable surface.

12. A method of encrypting signals corresponding to locations on a user-interfaceable surface of a transaction device, the method comprising:

receiving an x-axis signal and a y-axis signal generated as a function of a location of a user input on the user-interfaceable surface;

generating a random signal; and

generating an encrypted output signal by adding the random signal to at least one of the x-axis signal and the y-axis signal, wherein the adding comprises at least one of(i) combining the random signal with a source of electrical potential from which the x-axis and y-axis signals are generated and (ii) combining the random signal with the at least one signal, wherein generating the random signal comprises;

generating a random number; and

converting the random number to an analog signal used as the random signal.

13. The method of claim 12, wherein the user-interfaceable surface is a display-input screen that can output information from the transaction device and can respond to the user input.

14. The method of claim 12, wherein the method is carried out by electronics disposed within a housing of the transaction device.

15. The method of claim 12, further comprising:

disposing within a housing of the transaction device electronics carrying out the method;

the electronics including at least a screen controller and a processor;

the processor coupled to the screen controller, and the screen controller coupled to the user-interfaceable surface; and

coupling the encrypted output signal to the processor;

wherein the processor can decrypt the encrypted output signal.