Abstract:
A method for determining the presence of a human being, comprising:
       measuring (S 6 ) a movement (MOV) of a first device ( 4 ) by a sensor ( 44 ) of said first device ( 4 ),   determining the presence of a human being on the basis of the measured movement (MOV).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of transactions involving a communication between the terminal of a user and a server. 
       BACKGROUND OF THE INVENTION 
       [0002]    When a transaction is performed between the terminal of a user and a server, it is generally desirable for the server to authenticate the user. Common techniques for to authenticating a user are the use of a login and a password, a cryptographic signature calculated by a secure element such as a SIM card, etc. 
         [0003]    Furthermore, considering the possibility that a malicious computer program commonly known as a malware may run on the user&#39;s terminal, it is also desirable for the server to verify that the transaction is performed under control of the user. 
         [0004]    A common technique for verifying that a transaction is performed under the control of a user (a human being) is a challenge-response test known as CAPTCHA. Typically, the server sends an image to the terminal which comprises alphanumeric characters that are difficult to recognize for an OCR program, but visible to a human, The terminal displays the image and the user enters the alphanumeric characters. The server checks that the entered characters correspond to the image. 
         [0005]    However, an attack is still possible and indeed, some character recognition software have been developed to recognise the information in a CAPTCHA image. 
         [0006]    Thus, it is desirable to improve the techniques for verifying that a transaction is performed under the control of a user. 
       SUMMARY AND OBJECT OF THE INVENTION 
       [0007]    The invention provides a method for determining the presence of a human being, comprising:
       measuring a movement of a first device by a sensor of said first device,   determining the presence of a human being on the basis of the measured movement.       
 
         [0010]    In an embodiment, the method comprises outputting a stimuli on a user interface, wherein the stimuli comprises instructions for performing a predetermined movement, 
         [0000]    wherein determining the presence of a human being on the basis of the measured movement comprises determining the presence of a human being on the basis of the measured movement and of the predetermined movement. 
         [0011]    The method may comprise:
       transmitting the stimuli from a server to said user interface,   determining, by said first device, a signature on the basis of the measured movement,   transmitting said signature from the first device to the server.       
 
         [0015]    The method may comprise:
       transmitting first data from a server to said first device,   determining, by said first device, said stimuli on the basis of said first data,   determining, by said first device, whether the measured movement and the predetermined movement match,   if the measured movement and the predetermined movement match, determining, by said first device, a signature on the basis of the first data,   transmitting said signature from the first device to the server.       
 
         [0021]    Said first data may comprise an amount of a payment transaction. 
         [0022]    Said first device may be a secure element. 
         [0023]    Outputting the stimuli on the user interface may comprise outputting the stimuli on the user interface of a second device different from said first device. 
         [0024]    In an embodiment, the method comprises:
       determining transaction data on the basis of the measured movement,   determining, by said first device, a signature on the basis of said transaction data,   transmitting said signature from the first device to a server.       
 
         [0028]    Said transaction data may comprise an amount of a payment transaction. 
         [0029]    In an embodiment, the first device is configured for authorising the execution of a function protected by authentication upon reception of identification or authentication data entered by a user, the method comprising determining said identification or authentication data on the basis of the measured movement. 
         [0030]    The first device may have a first state wherein it accepts identification or authentication data entered on a user interface of a second device and a second state wherein it does not accept identification or authentication data entered on said user interface, the method comprising a step of commuting from said first state to said second state in response to a detection that the second device performs a predetermined transaction. 
         [0031]    The invention also provides a system for determining the presence of a human being, comprising:
       a first device comprising a sensor for measuring a movement of said first device,   means for determining the presence of a human being on the basis of the measured movement.       
 
         [0034]    The system may comprise a second device having a user interface for outputting a stimuli, wherein the stimuli comprises instructions for performing a predetermined movement, wherein the means for determining the presence of a human being are configured for determining the presence of a human being on the basis of the to measured movement and of the predetermined movement. 
         [0035]    The first device may be a secure element inserted in said second device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    These and other objects and features of the present invention will become dear from the following description of the preferred embodiments given with reference to the accompanying drawings, in which: 
           [0037]      FIG. 1  shows a system according to an embodiment of the invention, 
           [0038]      FIG. 2  is a flow diagram of a transaction in the system of  FIG. 1 , according to a first embodiment of the invention, 
           [0039]      FIG. 3  is a flow diagram of a transaction in the system of  FIG. 1 , according to a second embodiment of the invention, 
           [0040]      FIG. 4  is a flow diagram of a transaction in the system of  FIG. 1 , according to a third embodiment of the invention, 
           [0041]      FIG. 5  is a flow diagram of a transaction in the system of  FIG. 1 , according to a fourth embodiment of the invention, 
           [0042]      FIG. 6  is a flow diagram of a transaction in the system of  FIG. 1 , according to a fifth embodiment of the invention, 
           [0043]      FIG. 7  is a flow diagram of a transaction in the system of  FIG. 1 , according to a sixth embodiment of the invention, and 
           [0044]      FIG. 8  illustrate a method for entering a PIN in the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0045]      FIG. 1  shows a system  1  which comprises a terminal  2 , a server  3 , and a secure element  4 . In an example embodiment, the terminal  2  is the mobile phone of a user (a human being), the server  3  is a point-of-sale payment terminal and the secure element  2  is a smart card inserted in the terminal, for example a SIM card. However, the invention is not limited to this embodiment. For example, the terminal  2  may be a personal computer, a portable electronic device, etc. The server  3  may be an ATM or a web server. The secure element  4  may be a USB key connected to terminal  2  or a separate device which communicates with the terminal  2  by a wireless or wire connection. Also, the terminal  2  and the server  3  may be the same device. 
         [0046]    The terminal  2  presents the general architecture of a computer. It comprises a user interface  21  which include for example a screen  22  and a keyboard  23  or a touchscreen, a processor  24 , a non-volatile memory  25 , a volatile memory  26 , a communication interface  27  and a communication interface  28 . The processor  21  allows executing computer programs stored in non-volatile memory  25 , by using volatile memory  26 . The functioning of the terminal  2  described hereafter corresponds to the execution of such computer programs. The communication interface  27  allows communication between the terminal  2  and the server  3  through a link L 1 . For example, communication interface  27  is a short range radio communication interface, for example a Near Field Communication (NEC) interface which includes a Frontend NEC and a NEC antenna. In other embodiments, the communication interface  27  is configured for communication with the server  3  through a wire or wireless network, for example through the Internet and/or through a mobile phone network. 
         [0047]    The communication interface  28  allows communication between the terminal  2  and the secure element  4  through a link L 2 . in the example of a smart card inserted in the terminal  3 , the link L 2  is for example a standardised ISO 7816 link. 
         [0048]    The secure element  4  presents the general architecture of a computer. It comprises a processor  11 , a non-volatile memory  12 , a volatile memory  43 , a sensor  44  and a communication interface  45 . The processor  41  allows executing computer programs stored in non-volatile memory  42 , by using volatile memory  43 . The functioning of the secure element  4  described hereafter corresponds to the execution of such computer programs. The communication interface  45  allows communication between the terminal  2  and the secure element  4  through link L 2 . The non-volatile memory  42  stores a PIN code and a cryptographic key K of the user. The sensor  44  is for example a MEMS sensor, an accelerometer, a compass, etc. configured for measuring a movement, an orientation or a position of the secure element  2 . 
         [0049]    Links L 1  and L 2  allow communication between the secure element  4  and the server  2  through a link L 3 , which is based for example on SWP protocols and which enables communication between an NFC frontend and the secure element  4 . 
         [0050]    The server  3  presents the general architecture of a computer. It comprises a processor  31 , a non-volatile memory  32 , a volatile memory  33  and a communication interface  34 . The processor  31  allows executing computer programs stored in non-volatile memory  32 , by using volatile memory  33 . The functioning of the server  3  described hereafter corresponds to the execution of such computer programs. The communication interface  34  allows communication between the terminal  2  and the server  3  through link L 1 . 
         [0051]    In the system of  FIG. 1 , the secure element  4  is considered a more secure environment than the terminal  2 . Indeed, installing new applications by loading computer programs in the non-volatile memory  25  of the terminal  2  is a usual task which can be performed by the user of the terminal  2 . Installing of a new application in the terminal  2  may involve, without knowledge of the user, the installation of a malware. Thus, a malware may by running on the terminal  2 . In contrast, loading a computer program in the non-volatile memory  42  of the secure element  4  can only be performed after authentication by an authorised party, for example the manufacturer or the issuer of the secure element or a trusted third party. In other words, the secure element  4  comprises means for authorising the loading of a computer program in its non-volatile memory  42  only after authentication by an authorised party. Thus, normally there is no malware running on the secure element  4 . 
         [0052]      FIG. 2  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a first embodiment of the invention. 
         [0053]    Initially, the user U initiates a transaction with the server  3  (step S 1 ). This may involve bi-directional communication between the terminal  2  and the server  3 . In another embodiment, the user U uses another device than the terminal  2  for communication with the server  3 , and specifies the how the server  3  can contact the terminal  2 . For example, the user U uses a personal computer to initiate the transaction with a web server, and specifies his phone number. 
         [0054]    Then, when the transaction needs to be validated by confirming that it is performed under the control of the user U, the server  3  determines an image IMG (step S 2 ) and sends a message M 1  containing the image IMG to the terminal  2  (step S 3 ). The image IMG contains instructions for the user to perform a specific movement MOV. An example of a relation between the instructions contained in the image IMG and the movement MOV will be described hereafter. 
         [0055]    In response to the reception of the message M 1 , the terminal  2  displays the image IMG on the screen  22  (step  54 ). Then, the user U performs the movement MOV instructed by the image IMG (step S 5 ) while the sensor  44  measures the movement MOV and the secure element  4  determines data D on the basis of the measured movement MOV (step S 6 ). 
         [0056]    Then, the secure element  2  determines a signature S by signing data D with the cryptographic key K (step S 7 ) and sends a message M 2  containing the signature S to the server  3  (step  58 ), In an alternative, the message M 2  is first sent from the secure element  2  to a secure device (not shown) and then from the secure device to the server  3 . This also applies to the embodiments describes hereafter. 
         [0057]    Finally, the server  3  checks whether the signature S corresponds to the image IMG of step  52  (step  59 ). For example, the server  3  check whether the signature S is a signature by user U of data D′ corresponding to the instructions of image IMG, He, data D′ represent data that should be determined at step S 6  if the user U performs the correct movement. The transaction is validated only if the signature S corresponds to the image IMG of step S 2 . 
         [0058]    The method of  FIG. 2  allows checking that the transaction is performed under the control of the user U. Indeed, a malware which would run on the terminal  2  would have access to the image IMG, but not to the movement MOV which is measured on the secure element  4  nor to the cryptographic key K which is stored on the secure element  2 . Thus, the malware would be incapable of generating a signature S corresponding to the image IMG without knowledge of the user U. 
         [0059]      FIG. 3  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a second embodiment of the invention. 
         [0060]    Initially, the user U initiates a transaction with the server  3  (step S 11 ). As in  FIG. 2 , this may involve bi-directional communication between the terminal  2  and the server  3 , or the user U may uses another device than the terminal  2  for communication with the server  3 , and specifies the how the server  3  can contact the terminal  2 . 
         [0061]    Then, when the transaction needs to be validated by confirming that it is performed under the control of the user U, the server  3  determines a challenge CHAL (step S 12 ) and sends a message M 3  containing the challenge CHAL to the secure element  1  (step S 13 ). The challenge CHAL is for example a number determined in a pseudo-random manner and/or on the basis of transaction data. 
         [0062]    In response to the reception of the message M 3 , the secure element determines an image IMG (step S 14 ) on the basis of the challenge CHAL, As in  FIG. 2 , the image IMG contains instructions for the user to perform a specific movement MOV. Then, the secure element  4  sends a message M 4  containing the image IMG to the terminal  2  (step S 15 ). 
         [0063]    In response to the reception of the message M 4 , the terminal  2  displays the image IMG on the screen  22  (step S 16 ). Then, the user U performs the movement MOV instructed by the image IMG (step S 17 ) while the sensor  44  measures the movement 
         [0064]    MOV and the secure element  1  determines data D on the basis of the measured movement MOV (step S 18 ). 
         [0065]    Then, the secure element  4  determines whether data D correspond to the movement MOV instructed by the image IMG (step S 19 ). For example, the secure element  4  compares data D with data D′ representing data that should be determined at step S 18  if the user U performs the correct movement. 
         [0066]    If it is determined in step S 19  that the data D correspond to the movement MOV instructed by the image IMG, the secure element  4  determines a signature S by signing the challenge CHAL with the cryptographic key K (step S 20 ) and sends a message M 5  containing the signature S to the server  3  (step S 21 ). 
         [0067]    Finally, the server  3  checks whether the signature S corresponds to the challenge CHAL of step S 12  (step S 22 ). The transaction is validated only if the signature S corresponds to the challenge CHAL of step S 12 . 
         [0068]    The method of  FIG. 3  allows checking that the transaction is performed under the control of the user U. Indeed, a malware which would run on the terminal  2  would have access to the image IMG, but not to the movement MOV which is measured on the secure element  4  nor to the cryptographic key K which is stored on the secure element  2 , nor to the challenge CHAL which is not transmitted to the terminal  2 . Thus, the malware would be incapable of generating a signature S corresponding to the challenge CHAL without knowledge of the user U. 
         [0069]    In a variation of the method of  FIG. 3 , at step S 17 , the user U perform a movement MOV 1  which correspond to the image IMG, and a movement MOV 2  which correspond to his PIN, A technique for performing a movement which correspond to a PIN will be described hereafter. At step S 18 , both movements MOV 1  and MOV 2  are measured, data D are determined on the basis of MOV 1  and an entered PIN, noted PIN′ is determined on the basis of MOV 2 . Then, data D and PIN′ are checked at step S 19 . 
         [0070]      FIG. 4  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a third embodiment of the invention. 
         [0071]    Initially, the user U initiates a transaction with the server  3  (step S 31 ). In this example, the transaction is a payment transaction of an amount A determined by the server  3  (step  32 ) and involves bi-directional communication between the terminal  2  and the server  3 . 
         [0072]    Then, when the transaction needs to be validated by confirming that it is performed under the control of the user U, the server  3  sends a message M 6  containing the amount A to the secure element  4  (step S 33 ). 
         [0073]    In response to the reception of the message M 6 , the secure element  4  determines an image IMG (step S 34 ) on the basis of the amount A. The image IMG contains instructions for the user to perform a specific movement MOV and the amount A. Then, the secure element  4  sends a message M 7  containing the image IMG to the terminal  2  (step S 35 ). 
         [0074]    In response to the reception of the message M 7 , the terminal  2  displays the image IMG on the screen  22  (step S 36 ). Then, if the user U agrees with the amount A displayed in the image IMG, he performs the movement MOV instructed by the image IMG (step S 37 ) while the sensor  44  measures the movement MOV and the secure element  4  determines data D on the basis of the measured movement MOV (step S 38 ). 
         [0075]    Then, the secure element  2  determines whether the data D correspond to the movement MOV instructed by the image IMG (step S 39 ). 
         [0076]    If it is determined in step S 39  that data D correspond to the movement MOV instructed by the image IMG, the secure element  4  determines a signature S by signing the amount A with the cryptographic key K (step S 40 ) and sends a message M 41  containing the signature S to the server  3  (step S 41 ). 
         [0077]    Here, the message M 6  which includes the amount A and the message M 8  which include the signature of the amount A may be messages conforming to payment standards, for example to the EMV standards. 
         [0078]    Finally, the server  3  checks whether the signature  5  corresponds to the amount A of step S 32  (step S 42 ). The transaction is validated only if the signature corresponds to the amount A of step S 32 . 
         [0079]    The method of  FIG. 4  allows checking that the transaction is performed under the control of the user U and that the user agrees on the amount A. Indeed, a malware which would run on the terminal  2  would have access to the image IMG, but not to the movement MOV which is measured on the secure element  4  nor to the cryptographic key K which is stored on the secure element  2 . Thus, the malware would be incapable of generating a signature S corresponding to the amount A without knowledge of the user U. Furthermore, in case the malware tries to modify the amount indicated in the displayed image, this would also, by side effect, modify the instruction related to the movement to be performed. The movement performed by the user U would not be recognized by the secure element  4  at step S 39  and therefore the secure element  4  would not determine the signature  5 . 
         [0080]      FIG. 5  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a fourth embodiment of the invention. 
         [0081]    Initially, the user U initiates a transaction with the server  3  (step S 51 ). In this example, the transaction is a payment transaction of an amount A determined by the server  3  (step S 52 ) and involves bi-directional communication between the terminal  2  and the server  3 . 
         [0082]    Then, when the transaction needs to be validated by confirming that it is performed under the control of the user U, the server  2  sends a message M 9  containing the amount A to the secure element  4  (step S 53 ). Furthermore, the terminal  2  prompts the user to enter the amount A′ agreed for the transaction (step S 54 ). 
         [0083]    Thus in response to step S 54 , the user U performs a movement MOV representative of the amount A′. For example, the user U uses the terminal  2  which include the secure element  4  as a pen to write the amount A′. In a variation, the amount A′ is entered in a similar manner to the entering of a PIN described hereafter. Meanwhile, the sensor  44  of the secure element  4  measures the movement MOV and the secure element  4  determines an amount A′ from the movement MOV measured by the sensor  44  (step S 56 ). Then, the secure element  4  compares the amount A′ with the amount A of message M 9  (step S 57 ). 
         [0084]    If A′=A, the secure element  4  determines a signature S by signing the amount A with the cryptographic key K (step S 58 ) and sends a message M 10  containing the signature S to the server  3  (step S 59 ). 
         [0085]    Here, the message M 9  which includes the amount A and the message M 10  which include the signature of the amount A may be messages conforming to payment standards, for example to the EMV standards. 
         [0086]    Finally, the server  3  checks whether the signature S corresponds to the amount A of step S 52  (step S 60 ). The transaction is validated only if the signature corresponds to the amount A of step S 52 . 
         [0087]    The method of  FIG. 5  allows checking that the transaction is performed under the control of the user U and that the user agrees on the amount A. Indeed, a malware which would run on the terminal  2  would not have access to the movement MOV or to the amount A nor to the cryptographic key K. Thus, the malware would be incapable of generating a signature S corresponding to the amount A without knowledge of the user U. 
         [0088]      FIG. 6  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a fifth embodiment of the invention. 
         [0089]    Initially, the user U initiates a transaction with the server  3  (step S 71 ). In this example, the transaction is a payment transaction of an amount A. 
         [0090]    Then, the terminal  2  prompts the user to enter the amount A agreed for the transaction (step S 72 ). 
         [0091]    Thus in response to step S 72 , the user U performs a movement MOV representative of the amount A (step S 73 ). Meanwhile, the sensor  44  of the secure element  4  measures the movement MOV and the secure element  4  determines the amount A from the movement MOV measured by the sensor  44  (step S 74 ). Then, the secure element  4  determines a signature  5  by signing the amount A with the cryptographic key K (step S 75 ) and sends a message M 11  containing the signature  5  and the amount A to the server  3  (step S 76 ). 
         [0092]    Finally, the server  3  checks whether the signature S corresponds to the amount A of message M 11  (step S 77 ), The transaction is validated only if the signature S corresponds to the amount A of message M 11 . 
         [0093]    The method of  FIG. 6  allows checking that the transaction is performed under the control of the user U and that the user agrees on the amount A. Indeed, a malware which would run on the terminal  2  would not have access to the movement MOV or to the amount A nor to the cryptographic key K. Thus, the malware would be incapable of generating a signature S corresponding to the amount A without knowledge of the user U. 
         [0094]      FIG. 7  is a flow diagram of a transaction in the system  1  of  FIG. 1 , according to a sixth embodiment of the invention. 
         [0095]    In this embodiment, the secure dement  4  controls the execution of functions protected by authentication. The secure element  4  is configured for comparing identification or authentication data entered by a user with identification or authentication data stored therein, and authorises the execution of a protected function only if the entered and stored data match. In this example, the identification or authentication data comprise a PIN. Furthermore, a first type of protected function can by authorised by entering the PIN on the user interface  21  of the terminal  2 , while a second type of protected function can only be authorised by entering the PIN as described hereafter. In this example, a protected function of the first type comprises authentication with mobile telephone network, and a protected function of the second type comprises validating a transaction, for example a payment transaction. 
         [0096]    Initially, the secure embodiment  4  is in a state ST 1  wherein it accepts a PIN entered by the user U on the user interface  21 . For example, when the terminal  2  is turned on, the secure element  4  enters state ST 1  (step S 90 ). Then, the user U enters his PIN on the keyboard  23  (steps S 91  and S 92 ) and the PIN is transmitted to the secure element  4  (step S 93 ), for example in an ADPU command of the ISO 7816 standard. If the transmitted PIN matches the PIN stored in non-volatile memory  42 , the secure element  4  allows authentication with the mobile telephone network (step S 94 ). In other words, authentication with the mobile telephone network is a protected function of the first type mentioned above. 
         [0097]    Later, the user U initiates a transaction with the server  3  (step S 95 ), This may involve a bi-directional communication between the terminal  2  and the server  3 . 
         [0098]    At step S 96 , the secure element  4  detects the initiation of the transaction and switches in a state S 2  wherein it does not accept a PIN entered on the user interface  21 . 
         [0099]    Then, the server  3  sends a message M 12  to the secure element  4 , containing data T related to the transaction (step S 97 ). For example, in a similar manner to the message M 6  of  FIG. 4 , data T contain an amount A. 
         [0100]    The secure element  4  is configured for approving the transaction by signing the data T only if the user U enters his PIN. However, in state ST 2 , the user cannot transmit his PIN to the secure element  4  by entering it on the user interface  21 . In other words, approving the transaction is a protected function of the second type mentioned above. 
         [0101]    Thus, in step S 98 , the user U perform a movement MOV corresponding to his PIN. The movement MOV is measured by the sensor  44  and the secure element  4  determines an entered PIN, noted PIN′, on the basis of the measured movement MOV (step S 99 ), The, the secure element  4  determines whether PIN′ and the PIN stored in nonvolatile memory  42  match (step S 100 ). 
         [0102]    In case the PIFs matches, the secure element  4  determines a signature S by signing the data T with the cryptographic key K (step S 101 ) and sends a message M 13  containing the signature S to the server  4  (step S 102 ). 
         [0103]    Here, the message M 12  which includes data T and the message M 13  which includes the signature of the data T may be messages conforming to payment standards, for example to the EMV standards. 
         [0104]    Finally, the server  3  checks whether the signature S corresponds to the data T of message M 12  (step S 103 ). The transaction is validated only if the signature S corresponds to the data T of message M 12 . 
         [0105]    The method of  FIG. 7  allows checking that the transaction is performed under the control of the user U and that the user agrees on the data T. Indeed, a malware which would run on the terminal  2  would not have access to data T, the movement MOV or the cryptographic key K. Thus, the malware would be incapable of generating a signature S corresponding to the data T. Furthermore, in case the malware tries to send a PIN from the terminal  2  to the secure element  4 , this PIN would not be accepted by the secure element  4  because it would have entered state ST 2  upon detection of the beginning of the transaction. Thus, even if a malware intercepts the PIN of the user (for example at step S 92 ), the transaction cannot be validated by the malware without the knowledge of the user. In other words, a protected function of the second type is more secure. 
         [0106]      FIG. 8  represents an example of how a user can perform a movement MOV corresponding to instructions displayed in an image IMG (for example at steps S 5 , S 17 , S 37 ) to an amount A or A′ (for example at steps S 55 , S 73 ) or to his PIN (for example at steps S 37  of the variation mentioned above or step S 98 ) and how the secure element  4  can determines data D, amount A or A′ or PIN′ (for example at step S 6 , S 18 , S 38 , S 56 , S 74 , S 99 ) on the basis of the measured movement. 
         [0107]    In this example, the sensor  44  is a compass capable of measuring an orientation of the secure element  4  and therefore of the terminal  2 . The secure element  4  periodically transmits the orientation measured by the sensor  44  to the terminal  2 . 
         [0108]    The terminal  2  display an image on the screen  22  comprising a dial  210  and an arrow  211 . The dial  210  comprises alphanumeric characters, in this example numbers 0 to 9. The arrow  211  is displayed at a fixed position while the terminal  2  controls the display of the dial based on the orientation measured by sensor  44 . Thus, as show in  FIG. 8 , when the user performs a movement which changes the orientation of the terminal  2 , the number of the dial  210  indicated by the arrow  211  changes. 
         [0109]    When the user rotates the terminal  2  so that the arrow  211  indicates a specific number of the dial  210  and stops in this position, the secure element  4  considers that this specific number has been entered. By repeating this, the user can perform a movement MOV comprising a plurality of rotations and stops and which corresponds, for the secure element  4 , to a succession of numbers. This succession of numbers represents data determined on the basis of the movement MOV, within the meaning of the present invention. 
         [0110]    In the example of  FIG. 8 , the dial  210  is a predetermined image wherein the numbers 0 to 9 are displayed in order. However, the dial  210  may be an image determined by the secure element  4  wherein alphanumeric characters are displayed in a random order. in this case, it is not possible for a malware running on the terminal to determine the data D, amount A/A′ or PIN′ from the orientation transmitted from the secure element  4  in order to control the display of the dial. 
         [0111]    In some of the embodiment above, an image comprise information for instructing the user to perform a specific movement and is displayed by the terminal. In a variation, information for instructing the user to perform the movement is comprised in another type of stimuli, for example a sound or a vibration, which is output by the terminal.