Protection of communication between an electromagnetic transponder and a terminal

• US 9,507,975 B2
• Filed: 04/18/2012
• Issued: 11/29/2016
• Est. Priority Date: 06/03/2011
• Status: Active Grant

• Current Assignee: Stmicroelectronics Rousset SAS (STMicroelectronics NV)
• Original Assignee: Stmicroelectronics Rousset SAS (STMicroelectronics NV)
• Inventors: Wuidart, Luc
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): BLACK-CHILDRESS, RAJSHEED O
• Application Number:
  US14/123,751
• Publication Number:
  US 20140118115A1
• Time in Patent Office: 1,686 Days
• Field of Search: None
• US Class Current: 1/1
• 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 19/07309 Means for preventing undesired reading or writing from or onto record carriers
• CPC Class Codes: G06K 19/07318 by hindering electromagnetic reading or writing jamming of communication, counter-measures H04K3/00; secret communication H04K1/00
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08
• CPC Class Codes: G06K 7/10128 the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag
• CPC Class Codes: G06K 7/10386 the interrogation device being of the portable or hand-handheld type, e.g. incorporated in ubiquitous hand-held devices such as PDA or mobile phone, or in the form of a portable dedicated RFID reader
• CPC Class Codes: H04B 5/45 Transponders

Abstract

A method for protecting communication between an electromagnetic transponder and a terminal, wherein the transmission of a polling request by the terminal is only allowed when the transponder is in mechanical contact or in quasi-mechanical contact with the terminal.

Claims

1. A method to protect communication between an electromagnetic transponder and a terminal, comprising:

attempting to transmit a polling request by the terminal; and

allowing transmission of the polling request only when the electromagnetic transponder is in mechanical contact or in quasi-mechanical contact with a terminal package, the package including a communication antenna wherein the allowing includes;

storing a no-load value of current in an oscillating circuit of the terminal when no transponder is in a field of the terminal;

periodically measuring a first value of current in the oscillating circuit of the terminal;

based on a first comparison, while the first value is determined to equal the no-load value, repeating the periodically measuring;

based on the first comparison, when the first value is determined not to equal the no-load value;

calculating a ratio between the no-load value of current and the first value of current;

storing the calculated ratio in a second value;

performing a second comparison between said second value to a third value of said calculated ratio, said third value calculated in a previous iteration; and

when the second value is determined to be different from the third value, repeating the periodically measuring, the calculating the ratio, the storing the calculated ratio, and the performing the second comparison.

2. The method of claim 1, wherein, when the second value and the third value are determined to be equal:

performing a third comparison between the second value and a threshold;

based on the third comparison, allowing transmission of the polling request when it is determined the threshold has not been reached; and

based on the third comparison, disallowing transmission of the polling request when it is determined the threshold has been exceeded.

3. The method of claim 2, wherein when it is determined said threshold has been reached, preceding transmission of the polling request by an increase in a value of a resistive element of the oscillating circuit if the second value is greater than 2.

4. The method of claim 1, comprising,

blocking transmission of the polling request when the second value is smaller than the third value.

5. A terminal to communicate with an electromagnetic transponder, comprising:

a processor;

an oscillating circuit;

a current measuring circuit;

a controllable inductive circuit coupled to the processor, the oscillating circuit, and the current measuring circuit; and

at least one storage element, wherein the processor is arranged to determine when the electromagnetic transponder is in mechanical contact or in quasi-mechanical contact with a terminal package of the terminal, the determination made by;

determining a no-load value of current in the oscillating circuit corresponding to a value of current in the oscillating circuit when no electromagnetic transponder is in a field of the terminal;

periodically measuring a first value of current in the oscillating circuit until the first value of current in the oscillating circuit is determined to be different from the no-load value of current in the oscillating circuit;

after it determined that the first value of current in the oscillating circuit is different from the no-load value of current in the oscillating circuit, calculating a ratio between the no-load value of current and the first value of current;

comparing the calculated ratio to a second value, the second value being an earlier calculated ratio stored after a previous iteration of calculating the ratio;

permitting a transmission from the terminal via the controllable inductive circuit only when the calculated ratio is determined to be different from the second value; and

storing the calculated ratio as the second value in the at least one storage element.

6. The terminal of claim 5, wherein the terminal is arranged within a cell phone.

7. The terminal of claim 5, wherein the determination is further made by:

when the calculated ratio is determined not to be different from the second value, comparing the calculated ratio to a threshold;

based on comparing the calculated ratio to the threshold, permitting the transmission when it is determined the threshold has not been reached; and

further based on comparing the calculated ratio to the threshold, not permitting the transmission when it is determined the threshold has been exceeded.

8. The terminal of claim 7, wherein when it is determined the threshold has been reached, preceding the transmission by an increase in a value of a resistive element of the oscillating circuit if the calculated ratio is greater than 2.

9. The terminal of claim 7, wherein the determination is further made by:

blocking the transmission when the calculated ratio is smaller than the second value.

10. The terminal of claim 5, wherein the transmission includes a polling request.

11. The terminal of claim 5, wherein the processing circuit drives a modulator, wherein the modulator generates a high-frequency transmission signal and passes the high-frequency transmission signal to the controllable inductive circuit, and wherein the current measuring circuit is arranged to measure current of the controllable inductive circuit.

12. A device, comprising:

a processing means;

an oscillating circuit means;

a current measuring means;

an inductive means controllable by the processing means and coupled to the oscillating circuit means and the current measuring means; and

a storage means, wherein the processing means is arranged to make a determination, the determination indicating when an electromagnetic transponder is in mechanical contact or in quasi-mechanical contact with a terminal package of the inductive means, the determination made by;

determining a no-load value of current in the oscillating circuit representative of a value of current in the oscillating circuit when no electromagnetic transponder is in a field of the terminal package of the inductive means;

measuring with the current measuring means a first value of current in the oscillating circuit;

repeating the measuring iteratively until the first value of current is determined to be different from the no-load value of current in the oscillating circuit;

after it determined that the first value of current is different from the no-load value of current, calculating with the processing means a ratio between the no-load value of current and the first value of current;

comparing the calculated ratio to a second value, the second value being an earlier calculated ratio stored after a previous iteration of calculating the ratio;

allowing the inductive means controllable by the processing means to transmit data from the device only when the calculated ratio is determined to be different from the second value; and

after each iteration, storing the calculated ratio as the second value in the storage means.

13. The device of claim 12, wherein the device is a mobile device.

14. The device of claim 12, further comprising:

a comparison means, wherein when the calculated ratio is determined not to be different from the second value, comparing the calculated ratio to a threshold using the comparison means, and based on comparing the calculated ratio to the threshold, allowing the controllable inductive means to transmit when it is determined the threshold has been reached.

15. The device of claim 14, wherein when it is determined the threshold has not been reached, preceding a transmission by increasing a value of a resistive element means if the calculated ratio is greater than 2.

16. The device of claim 12, further comprising:

a blocking means, the blocking means arranged to block a transmission when the calculated ratio is smaller than the second value.

17. The device of claim 12, wherein a transmission using the inductive means includes a polling request.

18. The device of claim 12, wherein the processing means drives a modulator means, wherein the modulator means generates a high-frequency transmission signal and passes the high-frequency transmission signal to the inductive means, and wherein the current measuring means is arranged to measure current in the inductive means.