AUTHENTICATION OF A TERMINAL BY AN ELECTROMAGNETIC TRANSPONDER

• US 20100328046A1
• Filed: 06/15/2010
• Published: 12/30/2010
• Est. Priority Date: 06/25/2009
• Status: Active Grant

• Current Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Wuidart, Luc
• Granted Patent: US 8,482,388 B2
• Time in Patent Office: Days
• US Class Current: 340/10.4
• CPC Class Codes: G05B 1/01 electric
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07336 Active means, e.g. jamming or scrambling of the electromagnetic field
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G08B 21/0275 Electronic Article Surveillance [EAS] tag technology used for parent or child unit, e.g. same transmission technology, magnetic tag, RF tag, RFID

Abstract

A method of authentication of a terminal generating a magnetic field by a transponder including an oscillating circuit from which a D.C. voltage is generated, wherein at least one quantity depending on the coupling between the transponder and the terminal is compared with at least one reference value.

Claims

1. A method of authentication of a terminal generating a magnetic field by a transponder comprising an oscillating circuit from which a D.C. voltage is generated, wherein at least one quantity depending on the coupling between the transponder and the terminal is compared with at least one reference value.

2. The method of claim 1, wherein a quantity corresponding to the level of said D.C. voltage is measured and compared with a reference value depending on this same voltage in a condition of optimum coupling between the transponder and the terminal.

3. The method of claim 2, wherein said value in the optimum coupling condition is deduced from a training phase.

4. The method of claim 1, wherein:

a first quantity corresponding to the level of said D.C. voltage is measured and stored for a first value of the resistive load formed by circuits of the transponder on the oscillating circuit;

a second quantity corresponding to the level of said D.C. voltage are measured and stored for a second value of the resistive load on the oscillating circuit; and

a ratio between the two quantities is compared with one or several reference values.

5. The method of claim 4, wherein said reference value depends on the respective resistive load values.

6. The method of claim 4, wherein a variation of the resistive load between the first and second values is obtained by modifying the consumption of processing circuits comprised by the transponder.

7. The method of claim 4, wherein a variation of the resistive load between the first and second values is obtained by switching a resistive retromodulation element comprised by the transponder.

8. The method of claim 1, wherein in the absence of an authentication, the transponder sends intentionally incorrect data.

9. An electromagnetic transponder comprising:

an oscillating circuit upstream of a rectifying circuit capable of providing a D.C. voltage when the transponder is present in the magnetic field of a terminal; and

at least one processing unit capable of implementing the method of claim 1.