TECHNICAL FIELD The present invention relates to a dual interface smartcard for loading a number of prepaid credits into a prepayment meter.

BACKGROUND OF THE INVENTION

In this description, a smart card or smartcard refer to a plastic card having at least an embedded integrated circuit. The integrated circuit corresponds to a processing system comprising a central processing unit associated to a memory such as a random access memory (RAM), a read-only memory (ROM) and/or an electrically-erasable programmable read-only memory (EEPROM).

A prepayment meter refers to an apparatus that passes a fixed amount of fluid and/or energy for each credit prepaid by a user also called subscriber. Prepayment meters can be used for example for distributing electricity, gas or water.

Some existing prepayment meters comprise a slot adapted to connect a smartcard. The user can buy credits and store them temporarily on his smartcard. For that purpose, a refilling terminal can be used and such terminals can be deployed, for example, in different shops or post offices. This kind of terminal is widely used as it allows on the one hand the users to better control their consumption and on the other hand the suppliers to secure their income.

There are many already deployed prepayment meters for which the only communication capability is a contact interface used to connect the smartcard, via for example a build-in ISO/IEC 781 6 reader. Therefore, the user has to refill its smartcard via a terminal which can be far from its home and not available (for example, a terminal may be available only during the opening hours of a given shop). SUMMARY OF THE INVENTION

The object of the invention is to provide a dual interface smartcard for loading a number of prepaid credits into a prepayment meter comprising:

- at least one electrical contact adapted to electrically connect the smartcard to a prepayment meter;

- a wireless communication module configured to connect the smartcard to a remote server through a wireless access network;

- a non-volatile memory adapted to memorize a prepayment variable representative of a number of prepaid credits; - a processing system configured to control the wireless communication module in order to download on the smartcard from a remote server at least one prepaid credit by updating the memorized prepayment variable, said processing system being further configured to transfer the memorized prepaid credits to a prepayment meter via the electrical contacts.

In one aspect of the invention, the wireless communication module, the nonvolatile memory and the processing system are powered by the prepayment meter when connected via the electrical contacts.

The dual interface smartcard may also comprise an embedded battery adapted to power the wireless communication module, the non-volatile memory and the processing system.

In one embodiment, the electrical contacts are adapted to comply with the ISO/I EC 781 6 standard.

As an example, the wireless communication module is adapted support Wi- Fi technology.

Alternatively or in complement, the wireless communication module is adapted to support ZigBee technology and/or NFC (Near Field Contact) technology. As an example, the non-volatile memory which is adapted to memorize a prepayment variable representative of a number of prepaid credits is of EEPROM type.

The non-volatile memory which is adapted to memorize a prepayment variable representative of a number of prepaid credits and the processing system can be implemented in a secure element.

The secure element and the wireless communication module are implemented, for example, in a single integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS Additional features and advantages of the invention will be more clearly understandable after reading a detailed description of one preferred embodiment of the invention, given as an indicative and non-limitative example, in conjunction with the following drawings:

- Figure 1 illustrates a first embodiment of a dual interface smartcard according to the invention;

- Figure 2 illustrates a second embodiment of a dual interface smartcard according to the invention;

- Figure 3A and 3B illustrate a third embodiment of the dual interface smart card according to the invention;

- Figure 4 gives an example of scenario where prepaid credits are loaded on a dual interface smartcard for being later transferred to a prepayment meter;

- Figure 5 is an example of a system in which several dual interface smartcards are used to refill prepayment meters with prepayment credits. DETAILED DESCRIPTION

Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention as defined by the appended claims.

Figure 1 illustrates a first embodiment of a dual interface smartcard according to the invention.

A dual interface smartcard is a smartcard provided with a contact interface and a contactless communication interface. Electrical contacts 101 are implemented in order to connect the card to the prepayment meter via its smartcard slot are implemented.

As an example, if the contact interface is of ISO/IEC 7816 type, the electrical contacts can be implemented according to the ISO/IEC 781 6 part 2 specifications which define the dimensions and location of the contacts. In this embodiment, the side of the dual interface smartcard which has to be plugged into the prepayment meter into the reader has to fit the criteria thinness of the ISO/IEC781 6 standard. This makes possible to insert the dual interface smartcard into the slot of the prepayment meter.

With regards to the contactless interface, it can be adapted to support one of the following technologies: Wi-Fi, Bluetooth Low Energy (BLE), ZigBee, General Packet Radio Service (GPRS) or enhanced GPRS (EGPRS). However, it is only for exemplifying purposes and it is not considered to reduce the scope of the present invention as other wireless technologies may also be considered.

On figure 1 , the smart card is provided with electrical contacts 101 used to connect a prepayment meter to a processing system implemented in an integrated circuit embedded into the smartcard. It is also provided with a second interface which is implemented thanks to a wireless communication module 102. The processing system 104 is configured to receive and send data through the two implemented interfaces, that is to say through the electrical contacts 101 and through the wireless communication module 102.

In a preferred embodiment, the processing system 104 is a secure element. Secure elements are small devices comprising at least a memory, a processor and an operating system for computing treatments. Such secure elements may comprise a plurality of memories of different types. They are called "secure" because they are able to control the access to the data they contain and to authorize or not the use of data by other machines. The secure elements may also provide computation services based on cryptographic components. The dual interface smartcard according to the invention is configured to be used to load prepaid credits onto a prepayment meter. For that purpose, the user may utilize a terminal such as a personal computer or a smart phone to conduct a transaction with a remote server and buy prepaid credits. A connection is established between the remote server and the smartcard through its contactless interface in order to update a prepayment variable representing a number of credits prepaid by the user. This prepayment variable is memorized in a secured memory of the smartcard. This secure memory is a non-volatile memory (NVM).

In one embodiment, the smartcard can be configured to conduct a transaction through its contactless interface when a contactless reader is located in near-field area. For that purpose, the wireless communication module may implement a technology such as Near Field Communication technology (NFC).

Smartcards are widely used to store sensitive information such as cryptographic keys or software routines that implement valuable algorithms or know-how. Therefore, the skilled person will appreciate that the prepayment variable representing the number of credits prepaid by the user can be stored securely on the smart card using state-of-the-art techniques. According to one aspect of the invention, the prepayment variable can be stored in an EEPROM memory integrated in the processing system 104.

Alternatively, a dedicated memory (not represented) separated from the integrated circuit 104 can be used. In this embodiment, a mechanism to secure the access to this memorized prepayment variable should be implemented. For example, the prepayment variable can be memorized ciphered, the processing system being capable of loading it into its internal memory and deciphering it when required. Further, a mechanism to check the integrity of the data stored in this external memory can be implemented in order to avoid an unauthorized user to modify the value of the prepayment variable.

In the example of figure 1 , the processing system 104 manages both interfaces. The electrical connections 101 are linked via a set of conductive lines 105-109 to the processing system 104. As already mentioned, the electrical connections may be compliant with the requirements of ISO/IEC 781 6 part 2. In that case, the connections associated to the conductive lines 105-107 correspond respectively to the supply voltage (Vcc), reset (RST) and clock (CLK) ISO/IEC 781 6 contacts. Contacts associated to conductive lines 108, 109 correspond respectively to the ground (GND) and Input/Output (IO) ISO/IEC 781 6 contacts. This processing system will be able to handle both the ISO/IEC 7816 Universal Asynchronous Receiver Transmitter (UART) and the communication from the wireless interface.

Figure 2 illustrates a second embodiment of a dual interface smartcard according to the invention. In this example, the contacts 201 are similar to the ones 101 of figure 1 . The difference of this embodiment is that the processing system and the wireless communication module are integrated into a single integrated circuit 102, for example a system on chip (SoC) comprising at least a secure element. In this embodiment, the secure element also comprises a wireless communication module.

The integrated circuit may comprise general purpose Inputs/outputs (GPIO) and the electrical contacts can be directly linked to the GPIO via the conductive lines 105-109.

In the examples of figures 1 and 2, it is supposed that the wireless communication module requires low power supply. Therefore, the power can be supplied directly by the prepaid meter when connected to the smartcard via the electrical contacts 101 , 201 (for example using the ISO/I EC 7816 Vcc contact). Figure 3A and 3B illustrate a third embodiment of the dual interface smart card according to the invention.

In this example, the smartcard includes a plurality of electrical contacts 301 , an integrated circuit 302, which can be a system on chip (SoC) comprising a secure element and a wireless communication module, a plurality of conductive lines linking the electrical contact to the integrated circuit and a battery 304. In this example, the integrated circuit 302 comprises a memory area 303 wherein the prepayment variable (PV) is stored.

In this embodiment, the wireless module requires a quantity of energy which cannot be provided through the electrical contacts 301 when connected to the prepayment meter. Therefore, a battery 304 is embedded in the smart card in order to supply the appropriate voltage.

An advantage of using an embedded battery is that it is not necessary to plug the card for a reader for being powered. Therefore, prepaid credits can be uploaded without plugging the card in a prepayment meter. According to one aspect of the invention, the integrated circuit 302 and the battery 304 are located on the side of the smartcard which is opposite to the one where is located the electrical contacts 301 . Further, as the smartcard may have to be inserted in a smartcard slot of a target prepayment meter, the side of the smartcard with the electrical contacts 301 has to be adapted for that purpose. As an example, the dimensions of the smart card can be selected as follow:

- Length 320: 85,725 millimeters;

- Width 330: 53,975 millimeters;

- Thickness 340 (side of the electrical contacts): 0,76 millimeters;

- Thickness 350 (opposite side of the electrical contacts): 6,50 millimeters.

Figure 4 gives an example of scenario where prepaid credits are loaded on a dual interface smartcard for being later transferred to a prepayment meter. In a first phase 410, the user buys prepaid credits which are transferred to the dual interface smartcard. For that propose, the user 400 sends an access request to a server 401 as well as an authenticate message via a user terminal, for example a smartphone, a personal computer or a tablet computer.

If the user is correctly authenticated, a positive authentication response is sent to the user 400 by the server 401 . The user 400 is then capable of buying credits. When it is done, a payment response is sent back to the client acknowledging the payment.

In a second phase 420, the smartcard is plugged by the user 400 into the prepayment meter 402. In this example, a smartcard without battery is used. The insertion will result into powering up the integrated circuit of the smartcard as it is now power via the supply voltage contact (Vcc).

Once powered up and thanks to its wireless communication module, the smartcard 402 will connect to the remote server 401 , for example using GSM, Wi-Fi, BLE or ZigBee technology. Once authenticated by the remote server 401 , the smartcard 402 will send a request to the server 401 for new prepaid credits. If prepaid credits are available because they have been previously bought by the user, they will be transferred by the server 401 to the smartcard 402 and the prepayment variable PV will be updated by adding the number of transferred prepaid credits to its current value. Further, the number of prepaid credits memorized for the user by the remote server 401 is reset.

In a third phase 430, the number of prepaid credits memorized into the smartcard is pushed towards the prepayment meter via the contact interface (ISO-7816 in this example) with the consequence of updating a balance of prepaid credits available for the user's consumption. Then, a confirmation message is sent by the prepayment meter 403 to the smartcard 402. After that, the smartcard can be removed from the prepayment meter. Figure 5 is an example of a system in which several dual interface smartcards are used to refill prepayment meters with prepayment credits.

In this example, four prepayment meters 513-515, 521 are deployed to provide services to four subscribers, for example for electricity distribution. Each subscriber has a dual interface smartcard 510-512, 520 adapted to refill its prepayment meter with prepaid credits allowing him to access to the provided service. The smartcards can be attributed exclusively to a subscriber. Alternatively, the same smartcard can be used by several subscribers to refill different prepayment meters.

A dual interface smartcard comprises a prepayment variable PV stored in a secure memory. This prepayment variable PV represents the number of prepaid credits that can be transferred to a prepayment meter, allowing the consumption of the provided service. In this example, the dual interface smartcards 510-512, 520 are powered autonomously as they are integrating an internal battery. A dual interface smartcard according to the invention comprises an access to a remote server 500 via a telecommunication network 501 such as an internet network. This network is accessed by the smartcards using a local wireless network allowing data transmission via the contactless interface of the smart card. For example, a set-top box 502 located in the housing of a subscriber or a Wi-Fi hotspot with a base station 503 located on a landing of a building may provide a Wi-Fi access to one or more dual interface smartcards 510-512, 520 having a Wi-Fi contactless interface. Prepaid credits can be bought by using a terminal (not represented) connected to the remote server. Said prepaid credits can then be transferred to the dual interface smartcards 510-512, 520 from the remote server 500 to update their prepayment variable PV. Then, the prepayment meters 510-512, 520 can be refilled with prepaid credits by connecting the smartcard vie their contact interface, compliant with the ISO/IEC 7816 part 2 for example.