FR3073062A1 - METHOD OF MANAGING, WITH A PORTABLE OBJECT, COMMUNICATION WITHOUT CONTACT WITH AN EXTERNAL READER - Google Patents

Abstract

The invention relates to a portable object (OP) capable of communicating in the near field with an external reader (BRN) capable of supplying a magnetic field (H), the object (OP) comprising a first antenna (AN1) connected to a microcontroller (CLF) capable of managing the near-field communication with the external reader (BRN) equipped with a second antenna (AN2) whose coupling with the first antenna (A1) generates a current induced in the first antenna (AN1) thanks to the magnetic field (H), the microcontroller (CLF) being connected to the first antenna (AN1) via an electrical connection and a link for the transport of data, characterized in that the object further includes a switch located on a link, the switch being able to validate or not, depending on its state, a communication with the reader.

Description

The invention relates generally to telecommunications, and more specifically to contactless communications using short-range radio technologies, in particular of the NFC (Near Field - NF Communications) type.

It applies more particularly to a method of managing, by a portable object, a contactless communication with an external reader.

The portable object targets any equipment equipped with physical and software resources including a passive type near-field communication module, capable of communicating with external reading terminals.

State of the art

"NFC" communications, based primarily on ISO (International Standard Organization) 14443, use wireless technologies to allow information to be exchanged between two devices that are a short distance apart, typically less than ten centimeters.

These contactless applications can be, for example, relating to electronic transactions in the field of public transport, or also identification applications, access control, etc. An NFC communication is established between two contactless entities, called NFC entities, one operating as a contactless card and the other operating as a contactless card reader. Such an NFC entity is composed of a near-field communication device and an associated antenna which enables it to set up contactless communication with another NFC entity. The NFC entity which operates as a contactless card can for example correspond to a radio tag, in English "NFC tag". An NFC entity that operates as a card reader can correspond, for example, to an electronic payment terminal or equipment to validate electronic transport tickets, etc.

The functionality of such a contactless entity can be provided by a complex device, for example a mobile telephone terminal, a computer, an electronic tablet, etc. However, these mobile terminals are expensive and bulky, and are therefore reserved for a certain category of people, notably excluding children. It is desirable in this context to be able to benefit from very simple and very compact objects which can offer such capacities. In order not to be lost by the user while remaining practical to use, such an object can advantageously be in the form of an electronic bracelet or any other portable object to be worn on the body of a user.

However, a security analysis on these objects reveals a lack of consent. Indeed, current solutions do not ensure the identification of the carrier of the issuer. By identification is meant here the fact of recognizing the bearer of the object. We can imagine that a second user, for example malicious, uses the transaction to his own advantage: he can jostle the bearer as he approaches the reader and take advantage of the reception of the fortuitous signal by the reader to pass the door in place of the wearer, validate a purchase, etc.

The invention offers a solution which does not have the drawbacks of the state of the art.

The invention

To this end, according to a material aspect, the invention relates to a portable object capable of communicating in the near field with an external reader capable of providing a magnetic field, the portable object comprising a first antenna connected to a microcontroller capable of managing near field communication with the external reader, the external reader being equipped with a second antenna whose coupling with the first antenna generates an induced current in the first antenna thanks to the magnetic field, the microcontroller being connected to the first antenna via a electrical link and a link for data transport, characterized in that the object also includes a switch located on a link, the switch being able to validate or not, depending on its state, a communication with the reader.

The presence of the switch allows to validate or not a communication between the portable object and the reader. Thanks to the invention, a user of the object controls the communications between the object and the reader; even if a malicious third party tries to shake up the legitimate bearer, communication with the reader will not take place until the switch is pressed.

Note that, in the present text, by switch is meant any device intended to interrupt a communication between the portable object and the reader, such as an electric current, data, etc.

According to a first embodiment, the switch is placed on the electrical connection; in this configuration, validation of a communication between the portable object and the reader consists in closing the switch on this electrical connection so as to allow the induced current to pass and supply the microcontroller. This first mode makes it possible to supply the microcontroller only if a communication is validated; the microcontroller is therefore not powered unnecessarily.

According to a second particular embodiment of the invention, which can be implemented alternately or cumulatively with the previous one, the switch is placed on the link for the transport of data. This second mode has the advantage of speeding up the transmission of data from the object to the external reader; Indeed, the microcontroller having received the data from the reader because it is supplied by the induced current; and having processed this data, is ready, when the switch is closed, to send data to the reader.

S the first mode and the second mode are implemented cumulatively, in this case, the object comprises at least two switches located on respective links; a first switch located on the link for data transport and a second switch located on the electrical link. These switches can be actuated in isolation by means of two respective control means; they can also be actuated by means of the same control means capable of controlling the two switches simultaneously. We will see below that the control means targeted is arbitrary; the example chosen to illustrate this control means in the following description will be a push button to simplify the description of the invention.

According to a variant of this second mode, when the microcontroller is powered, the microcontroller checks the open / closed state of the switch on the link for the transport of data; then, data is transmitted from the microcontroller to the reader via the data bus only when the switch is closed; the microcontroller therefore checks the state of the switch before transmitting data. This variant prevents the microcontroller from transmitting data unnecessarily on the data bus while the switch, located on the link dedicated to data transport, is open.

According to a third embodiment, which can be implemented alternately or cumulatively with the previous ones, the switch is actuated by means of a control means such as a push button.

According to a variant of this third mode, the control means also comprises a means of authenticating the user of the object. Indeed, even if a malicious third party steals the object and actuates the switch, this third party will not be authenticated; the switch would then remain open preventing any communication between the object and the reader. This variant improves security.

Finally, according to another embodiment, which can be implemented alternately or cumulatively with the previous ones, the microcontroller, when powered by the induced current, emits a notification signal perceptible by a user. In this way, the user is warned that communication is possible with the external reader; and that effective communication requires closing the switch.

The invention will be better understood on reading the description which follows, given by way of example and made with reference to the appended drawings in which:

- Figure 1 shows the general context of using a portable object immersed in an electromagnetic field, capable of providing NFC services to its wearer.

- Figure 2 shows a schematic view of the main components of a portable object.

- Figure 3 shows a schematic view of the object of the antenna and the location of the switch according to one embodiment.

- Figure 4a is another schematic view of the first embodiment; Figure 4b shows another schematic view of a second embodiment.

- Figure 5a is a schematic view of bidirectional exchanges between the object and the reader according to the first mode; FIG. 5b illustrates a variant of this first mode.

- Figure 6 is a schematic view of bidirectional exchanges between the object and the reader according to the second mode.

Detailed description of embodiments illustrating the invention

FIG. 1 represents the general context of using a device, or portable object OP, capable of providing NFC services to its bearer (not shown), according to the state of the art. Such an NFC service is for example a service for purchasing and consuming transport tickets, materialized by a reader included in a BRN terminal. In the present text, the term reader or terminal will be used interchangeably to designate the NFC reader.

Once the applications and data necessary for the proper functioning of the service are loaded into the portable device, the latter behaves like a contactless smart card.

The object, or portable device OP includes at least NFC type near field communication means conventionally including an NFC antenna (AN1) and an NFC component, called a CLF microcontroller (ContactLess Frontend), capable of ensuring field communications. close to NFC type, with an external reader;

Referring to Figure 2, The CLF microcontroller includes:

o a processing unit "CPU" (for "Central Processing Unit"), intended to load instructions in memory, to execute them, to carry out operations;

o a set of memories, including a volatile memory RAM (for Random Access Memory) used to execute code instructions, store variables, etc. ;

o a non-volatile ROM type memory (from English "Read Only Memory >>), or" EEPROM >> (for "Electronically Erasable Programmable Read Only Memory >>), or equivalent, intended to contain persistent information. In the case of a ticketing service, this memory can be used to store the balance of tickets;

o a MOD modulator intended to adapt if necessary a digital signal produced by the microprocessor CPU into a modulated electrical signal, intended to be transmitted via the antenna AN1. In the exemplary embodiment described here, the modulation operation carried out by the modulator MOD is an amplitude modulation by all or nothing, also called modulation "OOK" (from English "On-Off Keying") . Thus, for example, the signal is a signal at 13.56 MHz modulated in amplitude all or nothing. The invention is not however limited to this type of modulation. In another exemplary embodiment, the modulation is a frequency modulation, less sensitive to interference. Note that this realization is however more expensive because it requires more components. In another exemplary embodiment, phase modulation is performed. The MOD modulator is arranged to implement the modulation step of the communication method described below;

o a DMOD demodulator, intended to receive via the antenna AN1 a second modulated electrical signal and to transform it into a second digital signal intended to be transmitted to the processing unit CPU. The DMOD demodulator is arranged to implement the demodulation step of the method described below;

o a SWT switch adapted to connect the MOD modulator to the AN1 antenna and the DMOD demodulator to the AN1 antenna alternately. In the first position, the portable device 1 is in reception mode, the SWT switch connects the antenna AN1 to the DMOD demodulator. Upon detection of the first modulated electrical signal received via the antenna AN1, the detection being an analog level detection, the switch switches and connects the antenna AN1 to the MOD modulator. Then the SWT switch switches again to connect the antenna AN1 to the DMOD demodulator. The portable device is then in reception mode until it detects and receives a new modulated electrical signal.

o an optional TM clock intended to cooperate with the SWT switch to alternate, for example, predetermined periods of time in transmission and reception during a two-way communication.

The microcontroller CLF is also connected to an antenna AN1, called the first antenna, suitable for transmitting and receiving on the radio channel;

In the assembly formed by the CLF microcontroller and the antenna, the elements described above are conventionally connected to one another by means of data bus, address bus, control bus.

The object also includes a support, materialized here by a magnetic card support on which are fixed (posed, glued, etc.) the antenna AN1 and the CLF microcontroller formed by the NFC component.

The BRN terminal is also equipped with an AN2 antenna, called the second antenna, and with a microcontroller (not shown in the figures).

FIG. 3 illustrates an implementation in which the CLF component and the antenna AN1 are bonded to a CRT card. In this figure, for the sake of simplification of the description of the invention, only the CLF microcontroller and the first antenna AN1 are shown.

In this example, the microcontroller CLF and the antenna AN1 are connected by means of a link for the transport of data, typically a data bus referenced BD. In addition, the microcontroller CLF and the antenna AN1 are connected by means of an electrical connection LEC for the transport of an induced current I coming from the antenna AN1, this induced current being able to supply the microcontroller CLF as explained below. -Dessous.

As is well known to those skilled in the art, the antenna AN1 of the object OP operates in interaction with the antenna AN2 of the reader. This interaction takes the form of a magnetic coupling which allows the exchange of energy between the two antennas. Sle is based on the magnetic field H generated by the current flowing in the first antenna. Recall that the intensity of the magnetic field H is measured in Amperes per meter (A / m). The antenna generally consists of several turns constituting a winding. The magnetic field H generated by the reader is directed in a direction which depends on the direction of the current in the coil of the antenna. The direction of the magnetic field generated is orthogonal to the plane of the turns of the first antenna. According to the diagram, it is also perpendicular to the plane of the turns of the second antenna (that of the portable object) as presented to the reader. It conventionally generates an induced electric current in the NFC component of the portable object.

The antenna according to this example has no internal power supply to the portable object. The induced electric current alone enables communication between the BRN terminal and the OP object.

The main difficulty of such a portable device is that when the component is supplied by the induced current I, the CLF component is programmed to respond automatically; the user of the object therefore has no control over the communication between the object and the terminal when the object is in the magnetic field of the terminal.

The invention therefore proposes to introduce into the object a switch capable of, depending on its state (open / closed), authorize or not a data transmission from the object to the reader. This switch is used by the legitimate bearer to give his contentment for the completion of a transaction between the object and the terminal. This consent can be materialized by pressing a button, for example a push button, and closing the switch.

Note that the button (or actuator) can be located on the same support as the switch, or at a distance from the switch. Indeed, the microcontroller and antenna assembly can be located in a first piece of equipment, for example a telephone, a tablet or an equivalent device; the button can be located on a second device, or support such as a bracelet, a ring, etc. In this configuration, the remote communication between the object OP and the button is done by means of any network chosen according to the distance between the object and the button; the distance between the object and the button will often be short; in this case, a short range network such as a Bluetooth link, an RFiD link, etc. can be chosen.

This switch can be operated by a user. We will see below that to be sure that the person pressing the switch is the legitimate person, the object can include an authentication module capable of authenticating the user before deciding to close the switch. The method used to authenticate is arbitrary, it can be a code to enter, a method based on biometrics or any other equivalent methods known to those skilled in the art.

The object of the invention switch can be placed in different places in the object circuit. The switch can be located according to a first embodiment on the data bus between the microcontroller and the first antenna AN1 (fig. 4A), and / or according to a second embodiment on the electrical link which connects the first antenna AN1 and the microcontroller (fig. 4B).

We will describe these two embodiments; it is assumed that, by default, the INT switch is open.

The first mode is described with reference to Figure 5a. This first mode comprises several stages (E1, j = 1 to 7) described below.

In an initial step E11, the user equipped with the object approaches the BRN terminal and enters the magnetic field produced by the antenna AN2 of the BRN terminal.

In a second step E12, an induced current I is generated in the first antenna AN1.

In a third step E13, the microcontroller is supplied by the induced current. At this point, the SWT switch connects the AN1 antenna to the DMOD demodulator. the microcontroller goes into reception mode and can receive messages.

In a fourth step E14, while it is powered, the microcontroller receives an interrogation message Ml NT from the reader BRN.

During a fifth step E15, in our example, the microcontroller emits a response REPn several times in succession.

As the INT1 switch is open by default, the REP response is therefore not issued.

We now assume that, at time t1, the object holder presses a button to close the switch.

During a sixth step E16, the switch INT1 closes; Since the response is sent several times in succession, closing the switch results in the transmission of a REP response to the BRN reader. Several responses can also be transmitted until the INT1 switch is reopened when the user stops pressing the button.

In a sixth step E17, the response REP is received by the reader BRN.

At this stage, after having transmitted at least one response, the microcontroller stops transmitting REP responses. For this, the microcontroller is equipped with a means of knowing the state of the switch; for example, if the INT1 switch is open, the microcontroller stops transmitting data.

According to a variant of this first mode, with reference to FIG. 5b, the fifth step ΕΓ5 can be replaced by a step ET5b. In this variant, the microcontroller CLF checks the state of the switch INT1 before transmission of responses REPn; if it is open, during a fifth step ET5b, the microcontroller suspends the transmission of responses REPn at least until time t1, that is to say until the time of closing of the switch . The duration of the suspension may be limited in time. The response is transmitted only when the INT1 switch is closed.

The second mode is described with reference to FIG. 6. This second mode comprises several steps (E2k, k = 1 to 6) described below.

The first two steps E21 and E22 are the same as for the first mode.

As the INT2 switch is open, current cannot supply the CLF microcontroller. The latter cannot therefore receive data from the reader; the microcontroller cannot therefore a fortiori respond to the BRN reader.

We now assume that the object bearer presses a button at a time t2 to close the INT2 switch.

During a third step E23, the microcontroller is supplied by the induced current. At this stage, the microcontroller goes into reception mode and can receive messages; implying, the switch connects the antenna to the DMOD demodulator as explained above.

In a fourth step E24, while it is supplied with power, the object OP receives an interrogation message Ml NT from the reader BRN.

During a fifth step E25, the microcontroller CLF emits a REP response, or even several responses if necessary.

During a sixth step E26, the response REP is received by the reader BRN.

In the two modes described, when the object generates an induced current, a notification signal can be sent so that the user is informed that the OP object is indeed within the scope of the BRN terminal. The user, when he receives this notification signal, can then press the button used to close the switch if he wishes the portable object to communicate with the reader.

Note that the switch described in this text can take several forms; the switch can be a push button, a slide switch, a rotary switch, a magnetic switch, that is to say a switch which establishes or cuts an electrical connection according to the presence or not of a magnetic field, a thermal switch actuated by temperature, or any other switch known to those skilled in the art.

Finally, it should be noted that this invention can be implemented on contactless cards, in particular cards having as their object a bank transaction, for which a purchase below a predefined threshold (for example 20 euros) does not require entry. a PIN code. The presence of a switch on the contactless card allows you to approach the card of the reader while keeping the switch closed, for example by pressing the push button in our example. Other applications other than banking can of course be envisaged.

Claims (7)

1. Portable object (OP) capable of communicating in the near field with an external reader (BRN) capable of providing a magnetic field (H), the object (OP) comprising a first antenna (AN1) connected to a microcontroller (CLF) able to manage near field communication with the external reader (BRN), the external reader being equipped with a second antenna (AN2), the coupling of which with the first antenna (A1) generates an induced current (I) in the first antenna (AN1) thanks to the magnetic field (H), the microcontroller (CLF) being connected to the first antenna (AN1) via an electrical link (LEC) and a link for data transport (BUS), characterized in that the object also includes a switch (INT1JNT2) located on a link, the switch being able to validate or not, depending on its state, a communication with the reader (BRN). 2. Portable object according to claim 1, characterized in that the switch (INT1) is placed on the electrical connection (LEC). 3. Portable object according to claim 1 or 2, characterized in that the switch (INT2) is placed on the link for data transport (BUS). 4. Portable object according to claim 3, characterized in that when the microcontroller is supplied, the microcontroller checks the open / closed state of the switch on the data bus, and in that the data is transmitted from the microcontroller to destination of the reader (BRN) via the link for data transport (BUS) only when the switch (INT2) is closed. 5. Portable object according to claim 1, characterized in that the switch is actuated by means of a control means. 6. Portable object according to claim 5, characterized in that the control means further comprises a means of authenticating the user of the object. 7. Portable object according to claim 2, characterized in that the microcontroller, when powered by the induced current, emits a notification signal perceptible by a user.