Smart card.

Abstract

The invention relates to a smart card (100), for transaction with a reader (200) or a server (300), comprising: • a first chip (110), for establishing a transaction, • a second chip (120), muted by default, configured to perform a calculation from the transaction data, and emit a signal whose value is representative of the result. It is essentially characterized in that: The second chip (120) is configured to be able to exit its mute mode and issue a tamper request, which is: • either recognized as such by the reader (200) or the server (300), • or unexpected by the reader (200) or the server (300), the reception of all at least one tamper request by the reader (200) or the server (300) sabotaging the transaction between the first chip (110) and the reader (200) or the server (300).

Description

Title of the invention: Smart card.

[0001] A smart card comprises a communication antenna, which allows the exchange of data and energy between the chip of the card and a server, via a reader. Typically, the exchange of data and energy takes place either offline between the smart card and a reader, or online between the smart card and a server, via a reader.

[0002] A smart card is used for example for banking applications, identity applications, or security applications, in particular single-use passwords, known as “OTP” for “One Time Password”.

[0003] The present invention relates to all types of smart card, that is to say whatever the application thereof. However, for the sake of brevity, only the case of a smart card for banking applications will be described here, and hereinafter referred to as "the card", and each use of the card is called a "transaction" whatever the application.

[0004] By "transaction" is meant an exchange of data and energy corresponding to a pre-programmed interactive operation, in "question-answer" form and which includes the search, introduction or modification of information in a file or in a database.

[0005] Also, the present invention is limited to the types of smart card which comprise a first chip, called a transaction chip, which makes it possible to establish a transaction with the reader or with the server according to a pre-established communication standard, and a second chip, called a calculation chip, mounted in parallel with the transaction chip.

[0006] The transaction chip is configured to be able to establish communication with a reader according to a transaction standard with the server.

[0007] For example, in the banking sector, this first chip is called a payment chip and allows banking transactions to be carried out according to a standard, typically the EMV standard (Europay MasterCard Visa, registered trademarks).

[0008] The calculation chip is silent by default. It is configured to be able to access the analog or digital data of the transaction emitted by the reader to the smart card, typically to the transaction chip. The calculation chip is also configured to be able to perform a calculation from at least one of the data of the transaction emitted by the reader, and to emit a signal whose value is representative of the result of said calculation.

[0009] For example, in the banking sector, the calculation chip makes it possible to calculate and display a dynamic code, or dynamic cryptogram, called DCVV for Dynamic Card Validation Code on a display screen of the chip card.

[0010] For displaying the DCVV, these smart cards include a display screen, or electronic paper, which is electrically connected to the computing chip.

[0011] The second bullet is mute by default, that is to say: - it does not communicate with the first chip; - it “understands” the server commands issued by the reader, that is to say it can be activated according to one or more commands issued by the server, via the reader.

[0012] The server is configured to only exchange with the first chip, the exchanges typically comprising a set of questions / answers.

[0013] As the reader transfers information from the server to the card and from the card to the server, for simplification, the terms "reader" and "server" are used here without distinction.

[0014] Currently, in order for the exchanges between the server and the smart card to be secure, the server is configured to communicate only with the first chip, and the second chip is configured for example to calculate and display a dynamic DCVV code upon receipt of an instruction from the server, and it is limited to this use.

[0015] To secure exchanges between the card and the server, the server includes, for a given smart card, a list of pre-established dynamic DCVV codes.

[0016] Normally, this dynamic code changes with each transaction.

[0017] For a transaction to be validated by the server, in particular for a so-called "card absent" or "card not present" transaction, better known by the English acronym CNP for "card not present", for example for an Internet banking transaction, the card user must enter in particular the DCVV displayed on the card of which he is the holder.

[0018] Normally, the DCVV displayed on the map should be equal to the DCVV of the server.

[0019] However, it may happen that the value of the DCVV displayed on the smart card does not change not from one transaction to another. However, the value of the DCVV on the server changes with each transaction.

[0020] In this case, the server's DCVV value is ahead of the DCVV value displayed on the smart card.

[0021] It also happens that the DCVV value displayed on the smart card is incremented but the transaction does not complete. In this case, the server's DCVV value is behind the DCVV value displayed on the smart card.

[0022] For example, [Fig. 2] illustrates a set of three-dimensional measurement positions for which the efficiency of the first chip and the second chip of a smart card according to the prior art is measured. The result of at least some of these measurements is illustrated in [Fig. 3].

[0023] In [Fig.3], the first column corresponds to the position of the chip card in [Fig.2], the second column includes the OK / NOK response of the first chip, and the third column includes the OK / NOK response of the second chip.

[0024] If the response of the first chip is OK (transaction OK) and the response of the second chip is OK (transaction OK), then the database code and the DCVV code of the smart card are the same.

[0025] If the response of the first chip is NOK (transaction not OK) and the response of the second chip is OK (transaction OK), then the database code is behind the DCVV code of the smart card.

[0026] If the response of the first chip is OK (transaction OK) but the response of the second chip is NOK (transaction not OK), then the database code is ahead of the DCVV code of the smart card.

[0027] There is therefore sometimes a problem of desynchronization between the value of the DCVV displayed on the map and the value of the corresponding DCVV of the server.

[0028] To overcome this problem, it is known to implement a code window, comprising a predetermined number of possible DCVV codes expected by the server.

[0029] Typically, in the pre-established list of codes, if the expected code is the code of rank N, then the server can nevertheless accept, i.e. consider as valid, the code of rank N1, N-2 or N-3 or the code of rank N+1, N+2 or N+3, in the pre-established list of codes, and thus authorize the transaction. The size of the window [NM; N+M] with M a configurable natural integer. In the banking sector, the bank itself determines the value of M on its server.

[0030] However, the larger the value of M, the more vulnerable the transaction is to attacks.

[0031] The present invention makes it possible to remedy this problem.

[0032] For this purpose, the present invention relates to a smart card (100), for transaction offline with a reader (200), or online transaction with a server (300) via a reader (200), the smart card (100) comprising:

[0033] • a card body,

[0034] • a first chip (110), called a transaction chip, configured to be able to establish a transaction with the reader (200) or with the server (300) according to a pre-established communication standard,

[0035] • a second chip (120), called calculation chip, and which is silent by default, which is configured to be able to access the analog or digital data of the transaction emitted by the reader (200) or the server (300), and configured to be able to perform a calculation from at least one of the data of the transaction emitted by the reader (200) or the server (300), and emit a signal whose value is representative of the result;

[0036] • a communication device configured to be able to transmit said signal emitted by the second chip (120).

[0037] It is essentially characterized in that:

[0038] The second chip (120) is configured to be able to exit its mute mode and transmit a set of at least one sabotage request to the server (300) or to the reader (200), a sabotage request being a predetermined request transmitted by the second chip (120) and which is:

[0039] • is recognized as such by the reader (200) or the server (300),

[0040] • either unexpected by the reader (200) or the server (300),

[0041] receiving all of at least one tampering request by the reader (200) or the server (300) tampering with the transaction between the first chip (110) and the reader (200) or the server (300).

[0042] Thanks to the invention, a sabotage request can be sent possibly indistinctly from the communication device.

[0043] A single module (140) may be provided, said module (140) comprising the first chip (110) and the second chip (120).

[0044] It can be provided that the second chip (120) is configured to:

[0045] • Measure the value of the current or voltage at its terminals,

[0046] • Compare the measured current or voltage value to a pre-set threshold value recorded in a memory, and

[0047] • If the measured current or voltage value is lower than the threshold value,

[0048] • Then send a set of at least one sabotage request to the server (300).

[0049] Thanks to this feature, it is possible to sabotage a transaction if the communication device is not sufficiently supplied with electrical energy.

[0050] It can be provided that the second chip (120) is configured to inhibit the emission of the signal whose value is representative of the result calculated by the second chip (120).

[0051] It can be provided that the second chip (120) is configured to:

[0052] • Detect a predetermined response from the server (300),

[0053] • Count the number of successive predetermined responses, and

[0054] • At each predetermined response or if the number of predetermined responses is greater than a threshold value pre-recorded in a memory,

[0055] • Then send a set of at least one sabotage request to the server (300).

[0056] For example in a banking transaction, the predetermined response is an R(NAK) or S(WTX) request.

[0057] It can be provided that the second chip (120) is configured to:

[0058] • Measure the value of the current or voltage at its terminals,

[0059] • Compare the measured current or voltage value to a pre-set threshold value. recorded in a memory, and

[0060] • If the measured current or voltage value is greater than the threshold value,

[0061] So:

[0062] • Trigger a stopwatch or counter if a predetermined response from the server (300) is detected, and

[0063] • If the transaction between the first chip (110) and the server (300) or the reader (200) is still running when the stopwatch or counter reaches a threshold value pre-recorded in a memory,

[0064] • Then send a set of at least one sabotage request to the server (300).

[0065] For example, for a transaction in the banking domain, the predetermined response from the server 300 is a GENERATE AC or GPO request.

[0066] It can be provided that the second chip (120) is configured to store in memory the value of the calculated signal, and display this value during the next transaction.

[0067] It can be provided that the number of successive predetermined responses is greater than or equal to 2.

[0068] It can be provided that the first chip (110) and the second chip (120) are configured for so-called “card not present” (CNP) transactions.

[0069] It can be provided that the set of at least one request to sabotage the transaction comprises a predetermined sequence of bytes.

[0070] The predetermined sequence of bytes may optionally not conform to a predetermined standard.

[0071] Other characteristics and advantages of the present invention will appear more clearly on reading the following description given by way of illustrative and non-limiting example and made with reference to the appended figures.

[0072] [Fig. 1] illustrates a basic electrical diagram for a transaction between a reader and a smart card according to the prior art or according to the invention,

[0073] [Fig.2] illustrates a set of positions in space, for which the efficiency of the first chip and the second chip of a smart card according to the prior art is measured,

[0074] [Fig.3] illustrates the result of transaction efficiency measurements for positions of [Fig.2],

[0075] [Fig.4] illustrates a simplified timeline of a successful transaction in the banking field,

[0076] [Fig.5] illustrates a simplified timeline of a sabotaged transaction in the banking sector. Detailed description

[0077] [Fig.l] illustrates a basic electrical diagram for a transaction between a smart card 100 according to the invention and a server 300, via a reader 200.

[0078] The smart card 100 comprises a card body, a first chip 110 and a second chip 120, independent of each other.

[0079] Preferably, the first chip 110 and the second chip 120 are configured for so-called “card not present” transactions.

[0080] The first chip 110 is called a transaction chip. It is configured to be able to establish a transaction according to a pre-established communication standard. For example, in the banking sector, the standard is the so-called EMV standard. The transaction can be offline with a reader 200, or online with a server 300 via a reader.

[0081] The second chip 120 is mounted in parallel with the first chip 110. In a known manner, the second chip 120 is mute by default. It is configured to be able to access the analog or digital data of the transaction emitted by the reader 200 or the server 300, and configured to be able to perform a calculation from at least one of the transaction data, and emit a signal whose value is representative of the result of the calculation. The second chip 120 “listens” to the requests from the reader 200 and the responses from the first chip 110 to see where the transaction is.

[0082] Preferably, the first chip 110 and the second chip 120 are included in a module 140.

[0083] The smart card 100 also comprises a communication device configured to be able to transmit said signal calculated and emitted by the second chip 120.

[0084] For example, the communication device may be, as explained at the beginning of the description, a display screen, or electronic paper, which makes it possible to display a dynamic code (DCVV) calculated by the second chip 120, or even a one-time password (OTP), the dynamic code DCVV or the one-time password OTP being the result of the calculation.

[0085] The chip card 100 may also comprise as a communication device a set of at least one LED, or a sound device, for example of the buzzer type, and the second chip 120 may emit a signal corresponding to the selective activation of the corresponding communication device.

[0086] For example, if the smart card 100 is a subscription card, then the second chip 120 can emit a signal for activating a communication device, the signal corresponding for example to the number of journeys / entries remaining to the credit of the holder of the smart card 100 or to a payment tranche, etc. Preferably, the smart card 100 also comprises a concentrator 130, which makes it possible to concentrate the energy from the reader 200 towards the module 140 of the smart card. 100.

[0087] It can be provided that the smart card 100 comprises a single module 140, which comprises the transaction chip 110 and the calculation chip 120.

[0088] The second chip 120 is configured to be able to exit its mute mode, that is to say that it comprises an algorithm which, as a function of certain sabotage parameters exposed later, commands the calculation chip 120 to emit a set of at least one predetermined request, called sabotage, exposed later.

[0089] The set of at least one sabotage request is sent to the server 300 or to the reader 200.

[0090] A sabotage request is a predetermined request, issued by the second chip 120, and which is recognized as such by the reader 200 or the server 300.

[0091] For example, a sabotage request is a sequence of bytes whose value is predetermined, and for example always the same, recognized in the communication protocol between the smart card 100 and the reader 200 or the server 300 as a sabotage request.

[0092] A sabotage request can also be an unexpected request by the reader 200 or the server 300. For example, a request recognized as valid in the communication protocol but which is not sent at the appropriate time.

[0093] Upon receipt of at least one sabotage request by the reader 200 or the server 300, the latter sabotages the transaction with the first chip 110, for example by stopping the transaction. Sabotage Settings

[0094] In one embodiment, it can be provided that the second chip 120 is configured to measure the value of the current or voltage at its terminals.

[0095] It then compares the value of the measured current or voltage to a threshold value pre-recorded in a memory, and depending on the result of the comparison, it remains silent or emits a set of at least one sabotage request.

[0096] For example, if the value of the measured current or voltage is lower than the threshold value, then it can be provided that the calculation chip 120 comes out of its mute mode and sends a set of at least one sabotage request to the server 300 or to the reader 200, advantageously independently of the successful or unsuccessful exchanges between the first chip 110 and the reader 200 or the server 300.

[0097] Typically, this means that the computing chip 120 does not have enough power to power the communication device.

[0098] If the calculation chip 120 does not have enough energy to power the communication device, it can also be provided that it is configured to inhibit the transmission of the signal whose value is representative of the result calculated by the second chip 120.

[0099] In this case, the second chip 120, which is in mute mode by default, wakes up and sends a response to the reader 200. The transmission of data by the second chip 120 sabotages the transaction because the reader 200 or the server 300 thus receives unexpected instructions.

[0100] In this case, the second chip 120 prevents the increment of the DCVV value, and the displayed DCVV value is retained.

[0101] In a non-limiting example, the communication device is a DCVV display screen. If the electrical energy is not sufficient for the DCVV code to be displayed, then the display of the DCVV code on the display screen of the smart card 100 may be inhibited, or the transaction may be sabotaged, which avoids desynchronizing the DCVV code of the smart card 100 and the DCVV code of the server 300.

[0102] In another embodiment, it can be provided that the second chip 120 is configured to detect a predetermined response from the server 300, and count the number of successive predetermined responses.

[0103] It can then be provided that for each predetermined response or if the number of predetermined responses is greater than a threshold value pre-recorded in a memory, then the calculation chip 120 sends a set of at least one sabotage request to the server 300 or the reader 200.

[0104] For example, in the field of banking transactions, the predetermined response from the server 300 may be an R(NAK) or S(WTX) response. For example, beyond 2 successive R(NAK) responses, issued by the server 300 or the reader 200, the calculation chip 120 issues a set of at least one sabotage request.

[0105] In another embodiment, when the second chip 120 is configured to measure the value of the current or voltage at its terminals and the value of the measured current or voltage is greater than the threshold value, then the second chip 120 is configured to trigger a timer or a counter if a predetermined response from the server 300 or the reader 200 is detected by it.

[0106] Then, if the transaction between the first chip 110 and the server 300 is still in progress when the stopwatch or the counter reaches a threshold value pre-recorded in a memory, then the second chip 120 sends a set of at least one sabotage request to the server 300 or the reader 200.

[0107] For example, in the banking field, a predetermined response from the server 300 or the reader 200 may be a GENERATE AC request, or GPO.

[0108] Typically, with reference to [Fig.4], if the transaction between the first chip 110 and the server 300 is still in progress, i.e. the request S(DESELECT) has not yet been sent when the stopwatch or the counter reaches a threshold value pre-recorded in a memory, then the second chip 120 sends a set of at least one sabotage request to the server 300 or the reader 200. Examples

[0109] The following non-limiting example is given by way of illustration for a transaction in the banking field. In this case, the communication device of the chip card 100 is a display screen configured to be able to display a dynamic DCVV code. The value of the DCVV calculated and displayed by the second chip 120 is not transmitted to the reader 200 or to the first chip 110, but only to the display screen.

[0110] Typically, an EMV transaction between a reader 200 and such a chip card 100 operates as follows.

[0111] For brevity, “reader 200” is understood throughout this description to mean “reader 200 or server 300”.

[0112] From the start of a transaction, there is an exchange of data between the reader 200 and the smart card 100. This exchange is standardized.

[0113] As illustrated in [Fig.4], the data exchanges between the reader 200 and the smart card 100 are represented by the INIT requests and the INIT_R responses.

[0114] At this stage (step A), the voltage or current value is measured across the second chip 120.

[0115] If this value is lower than the threshold value, then it can be expected that the second chip 120 comes out of its mute mode and sends a set of at least one sabotage request to the reader 200 (not shown).

[0116] If this value is greater than the threshold value, then the transaction continues.

[0117] During this standardized exchange, the reader 200 sends to the smart card 100 a predetermined command, called GPO for Gate Processing Option, which is a standardized cryptographic command, and which is issued even for smart cards which do not include a DCVV display screen, and which makes it possible to encrypt the rest of the exchanges between the smart card 100 and the reader 200. In general the GPO command is issued at approximately 28 ms from the start of the EMV transaction. The GPO_R response is issued by the first chip 110.

[0118] The GPO command is a trigger for the second chip 120. Upon receipt of this GPO command by the second chip 120, illustrated by step B in [Fig.4], the second chip 120 begins its calculation of the DCVV value to be displayed on the display screen using a value contained in this GPO command, by cryptographic diversification. Preferably, the counter or stopwatch is also triggered.

[0119] After a certain time, in this case approximately 200 ms after the second chip 120 receives the GPO command, the second chip 120 has completed its calculation of the value and displays this new DCVV value on the display screen.

[0120] While the second chip 120 calculates the value of the DCVV to be displayed on the screen display, the exchanges continue between the reader 200 and the first chip 110.

[0121] The last step of the EMV transaction consists of issuing a predetermined command “Generate AC” by the reader 200, to which the first chip 110 must respond.

[0122] There may be a number of requests and responses between the GPO_R response and the Generate AC request, they have been deliberately not referenced in [Fig.4] to simplify reading.

[0123] The response to this Generate AC request by the smart card 100 involves a heavy cryptographic calculation, which consumes power and takes time.

[0124] If the transaction proceeds normally, then the value of the DCVV is displayed on the display screen, illustrated by step C in [Fig.4].

[0125] If the response from the smart card 100 is correct, then the transaction is approved, and completed by the reader 200.

[0126] The end of the EMV transaction ends with a sound, generally a beep, emitted by the reader 200, following an exchange between a request S(DESELECT) and the corresponding response S(DESELECT)_R by the first chip 110. The duration is generally at least 300 ms from the start of the EMV transaction.

[0127] If the calculation of the first chip 110 to the command "Generate AC" is too long, that is to say beyond a predetermined duration, then the first chip 110 can emit a set of at least one predetermined command "S(WTX)", which declares to the reader 200 that it needs an additional period of time, the duration of which is predetermined. The first chip 110 can emit a succession of commands "S(WTX)_R". And the reader 200 responds S(WTX)_A to each command "S(WTX)", as illustrated in [Fig.5].

[0128] Depending on the number of successive predetermined responses, in this case S(WTX) or R(NAK), and comparison of this number of successive responses with a threshold value, it is possible to provide for sending a set of at least one sabotage request to the reader 200, as illustrated by step D in [Fig.5].

[0129] It is possible that the value of the DCVV to be displayed on the display screen is different from that expected by the banking server 300.

[0130] The present invention makes it possible to limit, or even eliminate, such desynchronization.

[0131] The first chip 110 consumes a different current at the beginning of the transaction and at the end of the transaction. At the end of the transaction, the current consumption of the first chip 110 is maximum because of the heavy cryptographic calculation, following the “Generate AC” command.

[0132] It can be predicted that if the first chip 110 is at the limit, it does not authorize the transaction. However, at this stage, the second chip 120 has modified the value of the displayed DCVV on the display screen of the smart card 100. In this case, the value of the DCVV of the banking server 300 is late compared to the value of the DCVV displayed on the smart card 100.

[0133] To resynchronize, the second chip 120 detects that the previous transaction was not successful and in this case during the next transaction, the second chip 120 blocks the incrementation of the value of the DCVV to be displayed.

[0134] Advantageously, when a transaction is sabotaged, the calculated value of the DCVV is not recorded. It is therefore recalculated during the next transaction.

[0135]

[0136]

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[0142]

[0143] Advantageously according to the invention, the smart card 100 can be battery-free. Nomenclature 100 smart card 110 first chip 120 second chip 130 hub 140 module 200 reader 300 Server / database

Claims

Claims

1. Smart card (100), for offline transaction with a reader (200), or online transaction with a server (300) via a reader (200), the smart card (100) comprising: • a card body, • a first chip (110), called a transaction chip, configured to be able to establish a transaction with the reader (200) or with the server (300) according to a pre-established communication standard, • a second chip (120), called a calculation chip, and which is mute by default, which is configured to be able to access the analog or digital data of the transaction emitted by the reader (200) or the server (300), and configured to be able to perform a calculation from at least one of the data of the transaction emitted by the reader (200) or the server (300), and emit a signal whose value is representative of the result;• a communication device configured to be able to transmit said signal emitted by the second chip (120), Characterized in that: The second chip (120) is configured to be able to exit its mute mode and emit a set of at least one sabotage request to the server (300) or to the reader (200), a sabotage request being a predetermined request emitted by the second chip (120) and which is: • either recognized as such by the reader (200) or the server (300), • or unexpected by the reader (200) or the server (300), the reception of the set of at least one sabotage request by the reader (200) or the server (300) sabotaging the transaction between the first chip (110) and the reader (200) or the server (300).;

2. A smart card (100) according to claim 1, comprising a single module (140), said module (140) comprising the first chip (110) and the second chip (120).

3. Smart card (100) according to any one of the preceding claims, in which the second chip (120) is configured to: • Measure the value of the current or voltage at its terminals, • Compare the measured current or voltage value to a threshold value pre-recorded in a memory, and • If the measured current or voltage value is lower than the threshold value, • Then send a set of at least one sabotage request to the server (300).

4. A smart card (100) according to claim 3, wherein the second chip (120) is configured to inhibit the emission of the signal whose value is representative of the result calculated by the second chip (120).

5. Smart card (100) according to any one of the preceding claims, in which the second chip (120) is configured to: • Detect a predetermined response from the server (300), • Count the number of successive predetermined responses, and • At each predetermined response or if the number of predetermined responses is greater than a threshold value pre-recorded in a memory, • Then send a set of at least one sabotage request to the server (300).

6. A smart card (100) according to any one of the preceding claims, wherein the second chip (120) is configured to: • Measure the value of the current or voltage across its terminals, • Compare the measured current or voltage value to a threshold value pre-recorded in a memory, and • If the measured current or voltage value is greater than the threshold value, Then: • Trigger a timer or counter if a predetermined response from the server (300) is detected, and • If the transaction between the first chip (110) and the server (300) or the reader (200) is still in progress when the timer or counter reaches a threshold value pre-recorded in a memory, • Then issue a set of at least one transaction request. sabotage to the server (300).

7. A smart card (100) according to claim 5 or 6, wherein the second chip (120) is configured to store in memory the value of the calculated signal, and display this value during the next transaction.

8. A smart card (100) according to any one of claims 5 to 7, wherein the number of successive predetermined responses is greater than or equal to 2.

9. A smart card (100) according to any preceding claim, wherein the first chip (110) and the second chip (120) are configured for so-called card-not-present (CNP) transactions.

10. A smart card (100) according to any preceding claim, wherein the set of at least one transaction tampering request comprises a predetermined sequence of bytes.

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