Process for enrolling a smart card in a smartphone.

Abstract

The invention relates to a method for enrolling a smart card in a smartphone equipped with a camera device, the method comprising steps consisting of: - recording information relating to the smart card and to the bearer of the smart card in the secure element of the smartphone; It is essentially characterized in that it further comprises, before or after the recording step, steps consisting of: - recording an audio / video stream with a device of the smartphone, - detecting at least one audio or gesture sequence in the audio / video stream, - comparing the sequence detected in the video stream with a previously recorded sequence, and - enrolling the smart card only if the detected sequence corresponds to the previously recorded sequence.

Description

Title of the invention: Method for enrolling a smart card in a smartphone.

[0001] The present invention relates to the field of dematerialization of smart cards.

[0002] Today, smart cards have a wide use, especially in the field of identification or payment.

[0003] For brevity, only the field of payment, or banking, will be described here. This field being among the most restrictive in terms of security, the person skilled in the art will easily adapt the present invention to other fields, for example transport cards, subscription cards, etc.

[0004] In this context, the invention can be implemented in the field of dematerialized payment, that is to say without physical support such as a bank card, but with a specific application stored in a communicating object, typically an electronic wallet stored in a smartphone.

[0005] Today, it is possible for a cardholder to save their bank card in their smartphone.

[0006] By "bank card" we mean any individual means of payment by chip card. The bank card may be a card issued by a bank or any other credit institution, a debit or credit card, for immediate payment or for deferred or staggered payment.

[0007] By “bank” or “banking establishment” is meant any credit organization or establishment.

[0008] To pay with such applications, it is appropriate, in a prior enrollment phase, to record data relating to a means of payment in a secure memory of the smartphone, the means of payment generally being a bank card of the smartphone holder.

[0009] Typically, a smartphone comprises a chip which comprises a secure element. Said secure element comprises a secure memory in which certain data of the holder of the payment card are recorded, for example at least one of the following information: - the bank card number, - the expiration date, - the name and first name of the bank card holder, or the account holder, - the bank card security code, - the name of the credit institution, - the encryption protocol of the payment method.

[0010] By payment means encryption protocol, we mean for example protocols such as Visa, Carte Bleue (registered trademarks), etc.

[0011] For example, the bank card holder saves a front / back photograph of their bank card in the memory of their smartphone.

[0012] The information extracted from the bank card is exchanged via the smartphone with the credit institution from which the bank card originates, and when this information is verified by the credit institution, this information is enrolled, stored in the secure element of the smartphone chip.

[0013] At the same time, the credit institution contacts the bank card holder on their smartphone to verify their identity and their willingness to register the bank card in the smartphone.

[0014] Typically, the bank contacts the bank card holder via SMS, sending them a one-time secret code. The bank card holder, who owns the smartphone, must enter this secret code to be able to enroll their bank card in the payment application on their smartphone.

[0015] This dematerialization of the means of payment then allows the smartphone holder and bank card holder to make payment orders with their smartphone without the physical support of their bank card.

[0016] During a dematerialized payment, the information relating to the payment is tokenized. Tokenization, called as such by Anglicism, is a process allowing sensitive data to be replaced by an equivalent element, called a token, which will have no meaning outside of its operating system. Tokenization therefore consists of generating a token, or "token", randomly, which can no longer change once in place. In the system in which the token is used, the data at the origin of the token does not appear and is not readable. The tokenized data can only be used in the system that created it. Each transaction generates a unique token, which secures the transaction since if the token is intercepted by someone malicious, the token is unreadable and unusable.

[0017] As a general rule, to make a dematerialized payment using a smartphone, there is a biometric recognition step prior to payment which allows the smartphone holder to be authenticated.

[0018] For each payment method there is a fraud rate. See for example the document https: / / www.banque-france.fr / sites / default / files / medias / documents / rapport_osmp_2021 .pdf.

[0019] Dematerialized payment is no exception to fraud and the present invention aims to reduce this risk. The amount of smartphone payment fraud in France is currently estimated at around EUR 100 million per year.

[0020] In this context, according to a first of its objects, the present invention relates to a method for enrolling a smart card in a smartphone equipped with an electronic chip comprising a secure element and a shooting device, the method comprising steps consisting of:

[0021] - record information relating to the smart card and the cardholder chip in the secure element of the smartphone chip.

[0022] It is essentially characterized in that it further comprises, before or after the step of recording the information relating to the smart card and to the holder of the smart card, steps consisting of:

[0023] - record an audio or audio-video stream with an audio device respectively or audio-video from the smartphone,

[0024] - detect at least one candidate audio or gesture sequence in the audio stream or audio-video respectively,

[0025] - compare the candidate sequence detected in the video stream with a sequence of previously recorded reference, and

[0026] - enroll the smart card in the smartphone only if the candidate sequence detected corresponds to the previously recorded reference sequence.

[0027] It can be provided that the step of detecting a candidate audio or gesture sequence comprises the detection of movements of predetermined parts of the body of an individual in the video stream by steps of:

[0028] - activate a pattern recognition computer program configured to:

[0029] - detect at least one stable position of an individual in the video stream, and for each stable position detected,

[0030] - detecting the absolute position or the relative position of at least one upper limb or lower of said individual, the candidate sequence corresponding to the sequence of absolute positions or relative positions of at least one upper or lower member of said individual, and

[0031] - optionally associate an alphanumeric character corresponding to the position of said at least one detected upper or lower limb.

[0032] It can be provided that the step of detecting an audio or gesture sequence comprises the detection of movements of predetermined parts of the body of an individual in the video stream by steps of:

[0033] - activate a pattern recognition computer program configured to:

[0034] - detect at least one stable position of an individual in the video stream, and for each stable position detected,

[0035] - detecting the absolute position or the relative position of the unfolded fingers of at least one hand of said individual, the candidate sequence corresponding to the sequence of absolute positions or relative positions of unfolded fingers of at least one hand of said individual, and

[0036] - optionally associate an alphanumeric character with the position or number of unfolded fingers.

[0037] It can be provided that the step of detecting an audio or gesture sequence comprises the detection of movements of predetermined parts of the body of an individual in the video stream by steps of:

[0038] - activate a pattern recognition computer program configured to:

[0039] - detect at least one stable position of an individual in the video stream, and for each stable position detected,

[0040] - detect the number of eyelids open or closed, the candidate sequence cor responding to the sequence of open or closed eyelids.

[0041] It can be provided that the step of detecting an audio or gesture sequence comprises the detection of movements of predetermined parts of the body of an individual in the video stream by steps of: - activating a facial recognition computer program configured to detect at least one facial expression, the candidate sequence corresponding to the sequence of detected facial expressions.

[0042] It can be provided that the step consisting of detecting an audio or gesture sequence comprises the detection of movements of the smartphone in the video stream by steps consisting of:

[0043] - activate a computer program for tracking horizontal and vertical position of the smartphone, thanks to a three-dimensional position sensor integrated into the smartphone, the candidate sequence corresponding to the series of horizontal and vertical positions of the smartphone.

[0044] It can be provided that the step of detecting an audio or gestural sequence comprises the detection of movements of determined or indeterminate parts of the body of an individual in the audio or audio video stream by steps of:

[0045] - activate a computer program for analyzing the intensity of the audio signal of the stream audio or audiovideo, and within a predetermined time window,

[0046] - determine at least one of:

[0047] * the number of peaks in the audio signal, each peak corresponding to a time range continuous during which the audio signal has an intensity greater than a predetermined threshold value,

[0048] * the duration of each peak, the candidate sequence corresponding to the peak sequence determined.

[0049] It is also possible to provide a biometric identification step, comprising steps consisting of:

[0050] - from the video stream, activate a computer program for recognition of shape configured to detect an individual's hand,

[0051] - performing palm biometric measurements on an image of said hand, and

[0052] - compare palm biometric measurements to reference measurements,

[0053] the step of enrolling the smart card in the smartphone being further controlled by the biometric identification step.

[0054] A step of identification by spectral recognition can be provided, comprising steps consisting of:

[0055] - record a voice sequence on the smartphone,

[0056] - activate a computer program for spectral analysis of the voice sequence in registered, and

[0057] - compare the recorded spectrum to a reference spectrum,

[0058] the step of enrolling the smart card in the smartphone being further controlled by the spectral recognition step.

[0059] According to another of its objects, the invention relates to a computer program comprising program code instructions for implementing the method according to the invention when said program is executed on a computer.

[0060] Finally, the invention also relates to a smartphone equipped with a computer program according to the invention.

[0061] 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 examples. Detailed description

[0062] In the field of dematerialized payment, it has been observed by the applicant that the risk of fraud lies essentially in the phase of enrolling the bank card in a smartphone.

[0063] Despite the double level of authentication by which a banking establishment sends a single-use secret code to the bank card holder, such a system is not infallible, for example by phishing.

[0064] Fraud involving electronic bank cards is therefore a problem for the user, for the merchant and for the banking establishment which guarantees payment.

[0065] To overcome this drawback, the present invention cleverly uses a means embedded in any smartphone: the shooting device, as explained later.

[0066] Thanks to the present invention, it is possible to implement strong authentication.

[0067] Strong authentication can be defined as the combination of at least two different authentication factors from among the following: - what I know, generally intangible (password, PIN code, etc.); - what I own, generally hardware (smart card, smartphone, etc.); - what I am, generally in the form of biometrics (fingerprint, face, vocal frequencies, etc.).

[0068] It is sometimes considered that "what I do", i.e., a behavior, is another authentication factor. However, for the purposes of the present invention, the "what I do" factor is considered a mode of the "what I know" authentication factor.

[0069] Typically, a user is the owner of the smartphone, the owner of a bank account and a chip bank card associated with said bank account, and wishes to enroll the chip card in his smartphone.

[0070] For this purpose, as explained below, according to the invention, the user performs at least one sequence of movements of predetermined parts of his body.

[0071] By conciseness, we mean by “the sequence” the set of at least one sequence of movements.

[0072] This sequence is performed in front of the smartphone's shooting device and defines a "what I do" gesture code, corresponding to a "what I know" authentication factor.

[0073] Alternatively, the sequence can be recorded by another shooting device and sent to the smartphone.

[0074] The gesture code is known only to the user, the smartphone holder, and to the banking establishment.

[0075] It is therefore possible to compare the sequence of movements, i.e. the gesture code, detected in the video stream with a previously recorded sequence, and only enroll the bank card in the smartphone if the detected sequence corresponds to the previously recorded sequence.

[0076] The comparison can be implemented on the smartphone or, preferably, on a remote server. In this case, the smartphone is configured to send the recorded sequence to the server, and configured to receive from said server a binary instruction to enroll the card if the recorded sequence corresponds to the pre-recorded sequence; or to inhibit the enrollment of the card if the recorded sequence does not correspond to the pre-recorded sequence.

[0077] As explained below, the sequence of movements may correspond to a code, in particular alphanumeric. For simplification, the terms “sequence” and “code” or “gesture code” are therefore understood indistinctly.

[0078] The user's gesture code is detected using a pattern recognition computer program.

[0079] The embodiments below may, where appropriate, be combined.

[0080] In a first embodiment, the gesture code is a succession of positions of the individual's limbs.

[0081] Preferably, only the upper limbs (arms, forearms, possibly hands and fingers) are taken into consideration, which facilitates the taking of the picture by the smartphone, and may correspond to a form of bodily expression.

[0082] In a first variant, the video stream comprises a succession of stable positions of the individual.

[0083] In a stable position, the individual's limbs are substantially immobile, so that their position can be detected by a shape recognition computer program.

[0084] Provision may be made to associate an alphanumeric character with the position of said at least one detected member, in which case the position of the members is significant, for example according to the semaphore alphabet or another alphabet. The members of the individual's body may themselves define letters, for example as according to the choreography of the YMCA song.

[0085] It can also be provided that the position of the members is not significant and that the gesture code is a succession of predetermined positions of the individual's members, without each position itself defining an alphanumeric character.

[0086] For example, we can predict that the gestural code corresponds to the succession of the following stable positions: the individual spreads his arms, then folds the right arm, then folds the left arm, etc.

[0087] In a second variant, the video stream comprises a continuous succession of positions of the individual's limbs, without necessarily passing through stable positions.

[0088] In this case, the position of the limbs may be insignificant, arbitrary, like dance movements for example.

[0089] For example, we can predict that the gesture code corresponds to the succession without pause of the following movements: the individual raises the left arm, rotates this outstretched arm in one direction then in another, etc.

[0090] It is possible to combine the first variant and the second variant, so that the gestural code comprises a part corresponding to a succession of stable positions and a part corresponding to a continuous succession of positions of the individual's limbs.

[0091] In a second embodiment, the gesture code is a succession of positions of the individual's fingers.

[0092] In a first variant, the video stream comprises a succession of stable positions of the individual.

[0093] In a stable position, a set of at least one finger of the individual is sens possibly immobile, so that the position of said at least one finger can be detected by a shape recognition computer program.

[0094] It is possible to provide for associating an alphanumeric character with the position of said at least one detected, in which case the position of the fingers may be significant, for example according to the alphabet of sign language or another alphabet.

[0095] It can also be provided that the position of the fingers is not significant and that the gesture code is a succession of predetermined positions of the individual's fingers, without each position itself defining an alphanumeric character.

[0096] For example, we can predict that the gestural code corresponds to the succession of stable positions of particular finger positions, like the "signatures" of football players or rappers.

[0097] In a second variant, the gesture code corresponds to the absolute position of the unfolded fingers of at least one hand of said individual.

[0098] For example, an index pointing in one direction does not necessarily have the same encoding as the same index pointing in another direction.

[0099] Provision may be made to distinguish, to identify, the unfolded finger or fingers, so that for example an unfolded index finger does not necessarily have the same coding as an unfolded middle finger.

[0100] In a third variant, the gesture code corresponds to the relative position of the unfolded fingers of at least one hand of said individual.

[0101] For example, an index finger pointing in the forearm direction does not necessarily have the same coding as the same index finger pointing in another direction.

[0102] For example, the index and middle fingers unfolded in a V shape may correspond to a different coding than the code corresponding to the index and middle fingers unfolded and joined.

[0103] Provision may be made to distinguish, to identify, the unfolded finger or fingers, so that for example an unfolded and joined index finger and middle finger do not necessarily have the same coding as an unfolded and joined middle finger and ring finger.

[0104] In a fourth variant, the gesture code corresponds to the absolute number of unfolded fingers of at least one hand of said individual.

[0105] A digital code corresponding to the absolute number of unfolded fingers can be associated.

[0106] For example, the unfolded index finger and the unfolded middle finger may correspond to the same coding, in this case two unfolded fingers, as the unfolded thumb and little finger.

[0107] In this case, the step of comparing the sequence detected in the video stream with a previously recorded sequence can be replaced by a step of comparing the digital code detected in the video stream with a previously recorded digital code.

[0108] In a fifth variant, the gesture code corresponds to the relative number of outstretched fingers of at least one hand of said individual.

[0109] A code corresponding to the relative number of unfolded fingers can be associated.

[0110] For example, the unfolded index finger and the unfolded middle finger may correspond to a coding different from the code corresponding to the thumb and little finger unfolded, although both positions each have two fingers unfolded.

[0111] It is possible to combine all or part of the variants of the second embodiment, so that the gesture code corresponds to at least one of: the absolute position of the unfolded fingers, the relative position of the unfolded fingers, the absolute number of unfolded fingers, the relative number of unfolded fingers.

[0112] In a third embodiment, the gesture code corresponds to a sequence of open or closed eyelids.

[0113] It is therefore planned to detect at least one stable position of an individual in the video stream, and for each stable position detected it is planned to detect the number of eyelids open or closed, or a sequence of eyelid blinks.

[0114] In a fourth embodiment, the gesture code corresponds to a sequence of at least one facial expression. For this purpose, it is planned to activate a facial recognition computer program configured to detect at least one facial expression, the candidate sequence corresponding to the sequence of detected facial expressions. For example, a facial expression recognition algorithm such as DLIB can be implemented.

[0115] In a fifth embodiment, the gesture code is a succession of positions of the smartphone, in this case moved by the individual carrying said smartphone.

[0116] The horizontal and vertical position of the smartphone can be tracked using a three-dimensional position sensor integrated into the smartphone, generally a GPS sensor or a three-dimensional accelerometer.

[0117] In a sixth embodiment, the gesture code is detected using the smartphone's microphone.

[0118] In this case, a signal processing step is implemented consisting of analyzing the intensity of the audio signal of the audio or audio video stream.

[0119] Typically, if the user carrying the smartphone taps on the smartphone's microphone, this generates an intensity peak. An intensity peak corresponds to a continuous time range during which the audio signal has an intensity greater than a predetermined threshold value, possibly up to saturation of the audio signal. The present invention cleverly uses this characteristic, by determining, for example, in a predetermined time window:

[0120] * the number of peaks of the audio signal,

[0121] * the duration of each peak,

[0122] * the sequence of peaks.

[0123] We can therefore easily compare the sequence of peaks to a reference code, or even associate a code with the sequence of peaks, like a Morse code.

[0124] Thus, according to the different embodiments of the invention, the sequence is:

[0125] - a sequence of movements of indeterminate parts of an individual's body, or

[0126] - a sequence of movements of predetermined parts of an individual's body, or

[0127] - a sequence of smartphone movements.

[0128] Thus, the gesture code can be a succession of movements of different parts of the body, for example translational or rotational movements of the hand, forearm, arm, etc.

[0129] Preferably, for practical reasons, the gesture code is a succession of movements of the upper limbs of the wearer's body.

[0130] The gesture code is recorded by the smartphone's camera device and sent, for example, to the credit institution for code verification.

[0131] The verification consists of comparing the gesture code sent with a reference gesture code previously recorded in a secure memory accessible to said credit institution.

[0132] It is possible to provide a gesture code recorded exclusively by video, without necessarily an audio recording.

[0133] However, as an alternative or in combination, it is advantageous to implement an audio recording step, consisting of recording a voice sequence on the smartphone.

[0134] In this case, a voice analysis step is provided, typically a spectral analysis step, making it possible to identify the smartphone carrier. For this purpose, a computer program is provided for example for spectral analysis of the recorded voice sequence, and a step for comparing the recorded spectrum to a reference spectrum.

[0135] It is also possible to provide that the audio recording step consists of recording a voice code, the voice analysis step consisting of analyzing this voice code and comparing this voice code with a reference voice code. For example, the smartphone holder has as code the sequence of numbers "1234" to pronounce. In the audio-video recording, the smartphone holder states each number, possibly at the same time as he does so with a part of his body. We can thus have a triple level of security: the gesture code, the voice code and the spectral analysis.

[0136] As an alternative or in combination, it is also possible to provide a step of biometric analysis of the smartphone holder, using the photographing means.

[0137] For example, on the images of the video stream sent, it is possible to plan to carry out a set of biometric measurements, and to compare them to reference measurements.

[0138] The biometric measurements can be carried out in particular on images of the face of the smartphone wearer, i.e. facial biometrics; and / or on images of his hand, for example the distance between the phalanges, the spacing of the fingers, the shape of the palm of the hand, fingerprints, etc. i.e. palm biometrics.

[0139] Such biometric data corresponds to the “what I am” authentication factor.

[0140] It is possible to enroll a plurality of smart cards on the same smartphone. In this case, it is preferably provided that each smart card corresponds to a respective previously recorded code.

[0141] Provision may be made to record in a memory of the smartphone an image of the front or a front / back image of the smart card. The image of the smart card may then be displayed on a display screen of the smartphone when said smart card enrolled via said smartphone is used. For example, in the case of a plurality of smart cards enrolled, selecting the image of a smart card makes it possible to activate said smart card for the intended transaction.

[0142] To record certain data of the holder of the smart card in the secure element, for example at least one of the following information: - the bank card number, - the expiration date, - the name and first name of the bank card holder, or the account holder, - the bank card security code, - the name of the credit institution, - the encryption protocol of the payment method,

[0143] It is possible to implement an optical character recognition step to extract from the image of the smart card said information relating to the smart card and to the holder of the smart card.

[0144] It is also possible to further provide steps consisting of:

[0145] - recording an image of the front or back of the smart card, said image able to be displayed on a display screen of the smartphone when using said smart card enrolled via said smartphone;

[0146] and, prior to enrollment:

[0147] - activate optical character recognition software to extract from the image from the smart card the said information relating to the smart card and the smart card holder.

[0148] It can also be provided that, if the detected sequence differs from the previously recorded sequence, the method comprises at least one of the steps consisting of:

[0149] - inhibit the enrollment of the smart card in the smartphone, and

[0150] - emit an alarm signal.

Claims

Claims

1. Method for enrolling a smart card in a smartphone equipped with an electronic chip comprising a secure element and a camera device, the method comprising steps consisting of: - recording information relating to the smart card and to the holder of the smart card in the secure element of the chip of the smartphone; - recording an audio or audio-video stream with a respectively audio or audio-video peripheral of the smartphone, - detecting at least one candidate audio or gesture sequence in the audio or audio-video stream respectively, - comparing the candidate sequence detected in the video stream with a previously recorded reference sequence, and - enrolling the smart card in the smartphone only if the detected candidate sequence corresponds to the previously recorded reference sequence;characterized in that the step of detecting an audio or gesture sequence comprises detecting movements of predetermined parts of the body of an individual in the video stream by steps of: - activating a shape recognition computer program configured to: - detect at least one stable position of an individual in the video stream, and for each stable position detected, - detect the absolute position or the relative position of the unfolded fingers of at least one hand of said individual, the candidate sequence corresponding to the series of absolute positions or relative positions of unfolded fingers of at least one hand of said individual, and - optionally associating an alphanumeric character with the position or the number of unfolded fingers.;

2. The method of claim 1, wherein the step of detecting a candidate audio or gesture sequence comprises detecting movements of predetermined parts of an individual's body in the video stream by steps of: - activating a shape recognition computer program configured to: - detect at least one stable position of an individual in the video stream, and for each stable position detected, - detect the absolute position or the relative position of at least one upper or lower limb of said individual, the candidate sequence corresponding to the series of absolute positions or relative positions of at least one upper or lower limb of said individual, and - optionally associate an alphanumeric character corresponding to the position of said at least one detected upper or lower limb.

3. A method according to any preceding claim, wherein the step of detecting an audio or gesture sequence comprises detecting movements of predetermined parts of an individual's body in the video stream by steps of: - activating a pattern recognition computer program configured to: - detect at least one stable position of an individual in the video stream, and for each stable position detected, - detect the number of open or closed eyelids, the candidate sequence corresponding to the series of open or closed eyelids.

4. A method according to any preceding claim, wherein the step of detecting an audio or gesture sequence comprises detecting movements of predetermined parts of an individual's body in the video stream by steps of: - activating a facial recognition computer program configured to detect at least one facial expression, the candidate sequence corresponding to the sequence of detected facial expressions.

5. Method for enrolling a smart card in a smartphone equipped with an electronic chip comprising a secure element and a camera device, the method comprising steps consisting of - recording information relating to the smart card and to the bearer of the smart card in the secure element of the chip of the smartphone; - recording an audio or audio-video stream with a respectively audio or audio-video peripheral of the smartphone, - detecting at least one candidate audio or gesture sequence in the audio or audio-video stream respectively, - comparing the candidate sequence detected in the video stream with a previously recorded reference sequence, and - enrolling the smart card in the smartphone only if the detected candidate sequence corresponds to the previously recorded reference sequence recorded; characterized in that the step of detecting an audio or gesture sequence comprises detecting movements of the smartphone in the video stream by steps of: - activate a computer program for tracking the horizontal and vertical position of the smartphone, using a three-dimensional position sensor integrated into the smartphone, the candidate sequence corresponding to the series of horizontal and vertical positions of the smartphone.

6. A method according to any preceding claim, wherein the step of detecting an audio or gesture sequence comprises detecting movements of determined or indeterminate parts of an individual's body in the audio or audio video stream by steps of: - activate a computer program for analyzing the intensity of the audio signal of the audio or audio-video stream, and within a predetermined time window, - determine at least one of: * the number of peaks in the audio signal, each peak corresponding to a continuous time range during which the audio signal has an intensity greater than a predetermined threshold value, * the duration of each peak, - the candidate sequence corresponding to the sequence of determined peaks.

7. A method according to any preceding claim, further comprising at least one of the steps of: * a biometric identification step, comprising steps consisting of: - from the video stream, activate a pattern recognition computer program configured to detect an individual's hand, - perform palm biometric measurements on an image of said hand, and - compare palm biometric measurements to reference measurements, the step of enrolling the smart card in the smartphone being further controlled by the biometric identification step; and * a step of identification by spectral recognition, comprising steps consisting of: - record a voice sequence on the smartphone, - activate a computer program for spectral analysis of the recorded voice sequence, and - compare the recorded spectrum to a reference spectrum, the step of enrolling the smart card in the smartphone being further controlled by the spectral recognition step.

8. A computer program comprising program code instructions for implementing the method according to any one of the preceding claims when said program is executed on a computer.

9. Smartphone equipped with a computer program according to claim 8.