Mutual authentication of user-controllable devices or systems containing sensitive or confidential data

Abstract

A method for mutual authentication of a controllable electronic device (DE) and a user (USER) capable of controlling the controllable electronic device (DE) so that the device obtains a service (DS) for the user, the device (DE) containing sensitive or confidential data (DA) and being configured to perform an operation (SO) in an operation phase (OP) including a preliminary authentication step (UAP) of the user in order to obtain the service (DS), the method further comprising a previous authentication phase (SDAP) of the device to verify the authenticity of the device (DE), so that if the device (DE) is confirmed to be authentic when completing the previous authentication phase (SDAP) of the device, the user (USER) can perform the operation phase (OP), and if the device (DE) is not confirmed to be authentic, the user (USER) can prevent the execution of the operation phase (OP).

Description

Technical Field

[0001] The present invention relates to the authentication of devices or systems containing sensitive or confidential data and their uses. More specifically, the present invention relates to a method for mutual authentication of devices or functional electronic systems (also computers and communication electronic systems) that can be controlled by users, a method for operating such a device or such a system, and a device or system specifically designed to implement the authentication method or the operating method. Background Art

[0002] In the context of the present invention, the expression "functional electronic device" is to be understood as, for example, a payment terminal, while the expression "functional electronic system" is to be understood as a functional component comprising several devices that can be functionally associated with each other, in particular as a functional chain, such as a payment terminal and a remote server.

[0003] When qualifying such a device or system, the term "functionality" should be broadly understood as its function during the operational phase to perform a specific operation (also referred to as a task, transaction, etc.), which is specific and is likely to ultimately provide a certain service to the user, such as an order, payment, etc.

[0004] The term "controllable" in connection with the user and in relation to a device or a system should be understood to mean that this device or system is arranged such that its operation is initiated by the user, in particular during an operation phase.

[0005] The terms "device" and "system" simply refer to a functional electronic device and a functional electronic system, respectively.

[0006] For the purposes of the present invention, the term "authentication" should be understood to refer to a process for verifying authenticity. The term "authenticity" should be understood to mean legitimacy, as expected, genuine, real and unquestionable or trustworthy. The term "mutual authentication" related to a device or functional electronic system that can be controlled by a user should be understood to be related to the user's verification of the authenticity of the device or system and in combination with the device or system's verification of the authenticity of the user. In this way, the authentication method that is the subject of the present invention first involves verifying that the device or system is indeed the correct device or system, and then verifying that the user is the correct user. Mutual authentication is thus intended to ensure the operations and services that are ultimately provided to the user (including for the user).

[0007] In the context of the present invention, the term "data" should be understood to refer to any information, code, etc. that is specific and regulates the operation of a device or system to perform specific operations to provide a specific service to a user.

[0008] The terms “sensitive” and “confidential” should be understood as qualified data that shall not be known, revealed or accessed except by the authentic device or system or the authentic user, as the case may be, otherwise the operations performed and ultimately the services provided to the user will be or may be unsafe.

[0009] This is the context of the present invention, and this is the explanation of the terms used throughout.

[0010] Those skilled in the art are familiar with the authentication process for computers and telecommunications systems. For example, the real user of a mobile phone equipped with a SIM (Subscriber Identity Module) card has a personal PIN (Personal Identification Number) code that protects the SIM card from unauthorized use. If necessary, a second code, a PUK (standing for PIN unlocking key) code, is provided, whose only function is to unlock the SIM card when it is blocked after a series (e.g., three) of incorrect inputs. Document US 3 905 461 describes, for example, an access control device using a coded token provided to the real user. The authenticity certificate activates the lock to ensure a secure connection, as is usually the case with financial transactions and data transmissions. EP 2 431 904 describes an authentication system called question / answer authentication, which uses a challenge question and verifies the answer provided to the challenge question. Document EP 3 035 640 describes a method for authenticating a first device performed by a second device using a question / answer authentication process. Simply identifying, for example, a user in order to determine his identity does not constitute authentication of the user (see EP 2 278 538). Likewise, the mere identification of a device or system by a user does not assure the user that the device or system is authentic. Thus, if, for example, an authentic device or system has been replaced by a virtual device or system, the user's operation of that device or system will cause the user to communicate secret codes or sensitive or confidential data, etc., to that device or system, which can then be retrieved by an attacker who can fraudulently use the code or data on behalf of the authentic user. Summary of the invention

[0011] Therefore, the problem solved by the present invention is to provide a device and a functional electronic system that can be controlled by a user to ensure mutual authentication (i.e., verify that the device or system is indeed the correct device or system and the user is indeed the correct user) so as to ensure that the operations performed by the device or system and the services ultimately provided to the user are secure, including safe for the user.

[0012] The present invention solves the problem by providing a preliminary step for authenticating a device or system, in which the user verifies the authenticity of the device or system, before performing an operation in which the device or system authenticates the user and during which sensitive or confidential data can be accessed, said operation phase being conditional, only if and only if a preliminary authentication has been performed on the device or system and the device or system has been correctly authenticated by the user during the preliminary device or system authentication phase. Thus, a double authentication is performed and the operation performed by the device or system and ultimately the service provided to the user is ensured.

[0013] The following is a description of the present invention.

[0014] According to a first aspect, the invention relates to a method for mutual authentication of a controllable function electronic device and its user, said method comprising a preliminary configuration phase (SDCP) of said device (DE) defining methods for verifying its authenticity, said user then being able to control said device so that it provides a determined service for said user, said device containing sensitive or confidential data and being configured

[0015] - causes specific operations suitable for providing said service to be performed during an operating phase initiated by said user and comprising a preliminary step of authenticating said user through said device, said method also comprising a pre-authentication phase of said device verifying the authenticity of said device prior to any operating phase, so that:

[0016] - if at the end of the preliminary device authentication phase the device is proven to be authentic, the user may perform the operation phase,

[0017] - if at the end of said preliminary device authentication phase said device is not proven to be authentic, alerting said user by any means so as to be able to prevent the execution of said operation phase,

[0018] It is ensured that the device is first authenticated and then the user is authenticated, and that the operations performed and the services provided are secure.

[0019] According to one embodiment, the preliminary device authentication phase is performed by the user.

[0020] According to one embodiment, the method comprising several time-spaced operating phases enables a preliminary device authentication phase to be performed before each operating phase.

[0021] According to one embodiment, the preliminary stage for authenticating the device performed by the user is based on a question / answer authentication process with the help of a device authentication secret, wherein the device authentication secret involves a preliminary question sent from the user to the device and a preliminary answer to the preliminary question sent from the device to the user, the preliminary question and the preliminary answer being secret such that they are only known or accessible to a single authentic user, such that the authenticity of the device is proven only if and only if the user verifies that there is an equivalence relationship between the answer given by the device to the preliminary question and the preliminary answer.

[0022] According to an alternative embodiment, if the device is not proven to be authentic at the end of the preliminary device authentication phase, the user may be prevented from performing the operation phase via the device itself.

[0023] According to one embodiment, the method further comprises a preliminary configuration phase in which the device is configured with an authentication secret (SDAS) of the device.

[0024] According to one embodiment, the preliminary device authentication phase is performed by the user.

[0025] According to one embodiment, the apparatus is configured with the preliminary question and the preliminary answer based on a question sent by the user using a question-to-answer generation process.

[0026] According to one embodiment, the preliminary device authentication phase is performed after the preliminary configuration phase has been performed and on the condition that no other preliminary authentication phase or operation phase of the device has been performed simultaneously.

[0027] According to the embodiment, the preliminary device authentication phase is performed after the preliminary configuration phase has been performed and on the condition that no other preliminary authentication phase or operation phase of the device has been performed simultaneously.

[0028] According to the described embodiment, the preliminary configuration phase is necessarily and sufficiently combined with a single preliminary device authentication phase or a predetermined plurality of consecutive preliminary authentication phases, or an infinite number of consecutive preliminary device authentication phases.

[0029] According to one embodiment, the preliminary step of authenticating the user by the device is based on a user authentication secret which is an operation answer from the user to the device, the operation answer being secret so as to be known and accessible only by a unique authentic user, so that the authenticity of the user is proven only if and only if the device verifies that there is an equivalence relationship between the answer provided by the user and the operation answer.

[0030] According to one embodiment, the preliminary question is different from the operational answer.

[0031] According to one embodiment, the method comprises a step of deleting sensitive or confidential data from the device, this operation being automatically performed at the end of a preset number of executions of consecutive preliminary device authentication phases in which the device has not been proven to be authentic. In particular, the step of deleting sensitive and confidential data from the device also erases the preliminary question and the preliminary answer when, at the end of a preset number of executions of consecutive preliminary phases for authenticating the device or the system, the user fails to provide the preliminary question corresponding to the preliminary answer, so that the device or the system will assume that the user is not an authentic user.

[0032] According to a second aspect, the subject of the invention is a method for providing a specific service to a user through the operation of a functional electronic device controllable by said user, said device containing sensitive or confidential data, wherein during an operation phase initiated by said user and comprising a step of authenticating said user through said device, said device performs a specific operation suitable for providing said service, said operation method also comprising a preliminary device authentication phase for verifying the authenticity of said device, prior to any operation phase, such that:

[0033] - if at the end of the preliminary device authentication phase the device is proven to be authentic, the user may perform the operation phase,

[0034] - if at the end of said preliminary device authentication phase said device is not proven to be authentic, alerting said user by any means so as to be able to prevent the execution of said operation phase,

[0035] It is ensured that the device is first authenticated and then the user is authenticated, and that the operations performed and the services provided are secure.

[0036] According to a third aspect, the subject of the invention is a functional electronic device controllable by a user regarding a determined service, the functional electronic device containing sensitive or confidential data, the functional electronic device being particularly designed for implementing the mutual authentication method and for implementing the operating method described above, in particular performing a preliminary device authentication phase.

[0037] According to one embodiment, at the end of the preliminary configuration phase, the device is configured with an authentication secret for the device, which is a preliminary question from the user to the device and a preliminary answer to the preliminary question from the device to the user.

[0038] In this way, the device knows and combines the authentication secret of the device with the authentication secret of the user.

[0039] According to a fourth aspect, the present invention relates to a method for mutually authenticating a functional electronic system that can be controlled by a user regarding a determined service, the functional electronic system containing sensitive or confidential data, the functional electronic system comprising a plurality of electronic devices functionally associated with each other, the plurality of electronic devices being arranged to perform a specific operation or a series of operations suitable for providing the service during an operation phase initiated by the user and comprising a step in which the system authenticates the user, the method further comprising a preliminary system authentication phase before performing any operation phase, in which the authenticity of all or some of the plurality of devices included in the system is verified by implementing the authentication method described above for each verified device.

[0040] According to one embodiment, wherein a plurality of electronic devices form one or more functional chains with one or more upstream devices and one or more downstream devices, the method causes:

[0041] - if at the end of a preliminary authentication phase of an upstream device in a device chain this device is proven to be authentic, then also authenticating said downstream device in the same device chain,

[0042] - If at the end of the preliminary authentication phase of a device upstream in a chain of devices this device has not been proven to be authentic, the devices downstream of said device in the same chain of devices will not be authenticated while the system is found not to be authentic.

[0043] According to a fifth aspect, the subject of the present invention is a method for operating a functional electronic system controllable by a user so that the functional electronic system provides a certain service for the user, the system containing sensitive or confidential data and comprising a plurality of electronic devices functionally associated with each other, wherein in an operation phase initiated by the user and comprising a preliminary step of the system authenticating the user, the plurality of electronic devices perform an operation or a series of specific operations suitable for providing the service, the operation method also comprising a preliminary system authentication phase before performing any operation phase, in which the authenticity of all or some of the plurality of devices included in the system is verified by implementing the authentication method described above for each authenticated device, so that:

[0044] - if at the end of the preliminary system authentication phase the system is proven to be authentic, the user may then perform the operational phase,

[0045] - if at the end of said preliminary system authentication phase said system has not been proven to be authentic, warning said user by any means so as to be able to prevent the execution of said operation phase,

[0046] Ensure that the system is first authenticated and then the user is authenticated, and that the operations performed and the services provided are secure.

[0047] According to a sixth aspect, the present invention relates to a functional electronic system controllable by a user regarding a determined service, the functional electronic system containing sensitive or confidential data, the functional electronic system comprising a plurality of electronic devices as previously described which are functionally associated with each other, the plurality of electronic devices being particularly arranged for implementing the mutual authentication method as previously described, and for implementing the operating method as previously described, in particular for performing a preliminary authentication phase for all or some of the plurality of devices included in the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] We will now briefly describe the only Figure 1 For purely indicative and didactic purposes, this diagram is a general theoretical diagram of the steps of a possible method by which a user operates a functional electronic device controllable by said user, so that said functional electronic device provides a determined service to the user, said device containing sensitive or confidential data, said method:

[0049] - firstly a preliminary configuration phase based on a device authentication secret performed by the user is shown;

[0050] - a preliminary device authentication phase is then shown, in which the authenticity of the device is verified based on the device's authentication secret,

[0051] - Then, at the end of the preliminary device authentication phase, the device has been proven to be authentic and the method shows an operation phase initiated by the user and comprising preliminary steps of the device secretly authenticating the user by means of user authentication, an operation phase in which the device performs specific operations suitable for providing the service. DETAILED DESCRIPTION

[0052] Below is a detailed description of embodiments and different embodiments of the invention, with examples and reference to the drawings. As mentioned above, this presentation is to be understood in the context of the invention and with explanation of terms, and therefore does not require repetition.

[0053] The invention relates to and implements a functional and controllable electronic device (also a computer and communication electronic device) ED, which contains sensitive or confidential data DA, and more generally, the invention relates to a functional electronic system (also a computer and communication electronic system) ES, which includes a plurality of devices ED forming one or more functional chains with one or more upstream devices and one or more downstream devices. Like the devices ED, the system ES contains sensitive or confidential data DA. For the devices ED, the invention is presented in more detail. The presentation is exchanged for the system ES (that is, all or some of the devices ED it contains), in particular for systems containing sensitive or confidential data DA or for systems whose authenticity must be proved.

[0054] The invention concerns a user USER who controls an installation ED or a system ES by means of commands CO so that a determined service DS is provided to the user and the various phases or steps necessary for the operation of the installation ED or the system ES are performed.

[0055] With respect to the device ED or system ES or user USER, the object of the present invention is to ensure mutual authentication, i.e., the user USER can first verify that the device ED or system ES is the correct device or system, and the device ED or system ES can then verify that the user USER is the correct user. In this way, it is guaranteed that the specific operation SO performed by the device ED or system ES and the determined service DS finally provided to the user USER are safe, including being safe for the user USER. Therefore, it should be understood that the user USER can only control the device ED or system ES when the device ED or system ES is real and not a virtual or illegal device or system, and when the USER user is real and not a fake or illegal user. If the device ED or system ES does not seem to be real, the user will not be able to perform the specific SO operation because the user will be blocked from performing this operation. Similarly, if the user does not seem to be real, the user will not be able to perform the specific operation SO because the user will be blocked from performing this operation.

[0056] It is then assumed that the device ED or the system ES is real and the user USER is real.The description of the invention explains what happens when the device ED or the system ES is not real and the user USER is not real.

[0057] In one embodiment, user USER is a real person.

[0058] In another embodiment, user USER is an avatar of a real person. This avatar is legal for the operations involved, and legally possesses codes, secrets, etc. possessed by the real person, so that he can legally act on behalf of the real person.

[0059] The term "operation phase" OP denotes the phase initiated by the user USER through commands CO, in which the device ED or the system ES performs appropriate specific operations SO specifically designed to provide the service DS to the user USER.

[0060] The term "operation phase" UAP denotes a preliminary step comprised in the operation phase OP, in which the device authenticates the user USER by means of a user authentication secret UAS.

[0061] The term “preliminary device or system authentication phase” SDAP denotes a phase in which the user USER verifies the authenticity of the device ED or system ES, for example with the aid of a device or system authentication secret SDAS.

[0062] The term "preliminary device or system configuration phase" SDCP denotes the phase in which the device ED or the system ES is configured with a device or system authentication secret SDAS. In one embodiment, the configuration is done by a user USER.

[0063] The method of operation of the device ED or system ES is such that it includes, before executing any operation phase OP, a preliminary device or system authentication phase SDAP as a supplement to the operation phase OP, which is executed before the operation phase OP and regulates the ability to execute the operation phase OP. If at the end of the preliminary device or system authentication phase SDAP the device ED or system ES is found to be authentic, the user USER can execute the operation phase OP, whereas if at the end of the preliminary device or system authentication phase SDAP the device ED or system ES is not proven to be authentic, the user USER can prevent the execution of the operation phase OP.

[0064] In this way, the method of operating the device ED or the system ES incorporates a method for mutual authentication of the device ED or the system ES and its user USER. In this way, first the device ED or the ED system is authenticated, and then the user USER. And this is how the specific operations SO performed by the device ED or the ED system and the services DS provided to the user USER are ensured. The invention can be seen equally well from the perspective of the method of operating the device ED or the system ES incorporating this mutual authentication process or from the perspective of the mutual authentication process itself, which is intended to be integrated and integrated into this mutual authentication process.

[0065] According to one embodiment in which several operation phases are planned over time, a preliminary device or system authentication phase SDAP is performed before each operation phase OP.

[0066] In one possible embodiment, the preliminary device or system authentication phase SDAP performed by the user USER, with the help of the authentication secret of the device or system SDAS, is based on a question / answer authentication process, including a preliminary question PQ from the user USER to the device ED or system ES and a preliminary answer PA to the preliminary question PQ from the device ED or from the system ES to the user USER. The preliminary question PQ and the preliminary answer PA are different and secret so as to be known or accessible only by the only real user USER. In this way, the authenticity of the device ED or system ES is proved only if and only if the user USER verifies that there is an equivalence relationship between the answer ADS to the preliminary question PQ provided by the device ED or system ES and the preliminary answer PA.

[0067] It should be understood that authenticating a device or system SDAP through the aforementioned question / answer authentication process is not exclusive or restrictive. Other processes that provide advanced authentication may also be considered. The present invention therefore also includes embodiments based on authentication processes equivalent to the question / answer process. It should also be understood that the preliminary device or system authentication phase SDAP may include a combination of several authentication processes, questions / answers, or equivalents to provide a higher level of authentication. This is how the expression "preliminary device or system authentication phase SDAP is based on a question / answer authentication process" should be understood.

[0068] According to one possible embodiment, the operation of configuring the device ED or system ES with the device or system authentication secret SDAS (preliminary question PQ and preliminary answer PA) is performed using questions from the user USER through a question-answer generation process (such as a function, procedure or algorithm).

[0069] Regarding the interaction between the preliminary device or system configuration phase SDCP and the operation phase OP prior to the authentication of the device or system SDAP, several embodiments can be envisaged. Thus, according to one embodiment, the preliminary device or system authentication phase SDAP is executed after the preliminary device or system configuration phase SDCP has been executed, while no other preliminary device or system authentication phase SDAP or operation phase OP is executed. Moreover, according to other embodiments, the preliminary device or system authentication phase SDAP is executed after the preliminary device or system configuration phase SDCP has been executed by means of executing one or more of several other preliminary device or system authentication phases SDAP or operation phases OP. In addition, according to an embodiment, the preliminary device or system configuration phase SDCP is necessarily and fully combined with a single preliminary device or system authentication phase SDAP or a preset plurality of consecutive preliminary authentication phases SDAP or an infinite number of consecutive preliminary device authentication phases SDAP.

[0070] The user authentication secret UAS implemented in the user authentication step UAP is an operation answer OA from the user USER to the device ED or the system ES, wherein the operation answer is secret so as to be known and accessible only by the real user, so that the authenticity of the user is proved only if and only if the device ED or the system ES verifies that there is an equivalence relationship between the answer AU provided by the user and the operation answer OA.

[0071] On a preliminary basis, the operation phase OP comprises a user authentication step UAP which regulates the ability to perform said operation phase OP. If at the end of the preliminary user authentication step UAP the user USER is proved to be authentic, said user USER can perform the operation phase OP, whereas if at the end of the preliminary user authentication step UAP the user is not proved to be authentic, said user can prevent the execution of the operation phase OP.

[0072] Several embodiments are conceivable. In one embodiment, an operation question OQ from the device ED or the system ES is provided to the user USER, to which the user must respond with an operation answer OA. Alternatively, the initiation of the operation phase OP itself forces the user USER to provide the device ED or the system ES with an operation answer OA. In any case, if the answer provided by the user AU differs from the operation answer OA, the device ED or the system ES will consider that the user is not a genuine user, which will have the effect that the operation SO will not be performed and the service DS will not be provided.

[0073] As with device or system authentication, user authentication by the aforementioned question / answer authentication process is not exclusive or limiting. Other processes that provide advanced authentication may also be considered. The present invention therefore also includes embodiments based on authentication processes equivalent to the question / answer process. It should also be understood that the preliminary user authentication step UAP may include a combination of several authentication processes, questions / answers, or equivalents to provide a higher level of authentication.

[0074] According to one embodiment, the preliminary question PQ is different from the operational answer OA.

[0075] According to one embodiment, the method comprises a step of deleting sensitive or confidential data DA from the device ED or system ES. The deleting step is automatically performed at the end of a preset number of consecutive executions of a preliminary device or system authentication phase SDAP in which the device ED or system ES has not been proven to be authentic.

[0076] According to a supplementary embodiment, the step of deleting sensitive or confidential data DA from the device ES or system ES also involves deleting the preliminary question PQ and the preliminary answer PA when the user USER fails to provide the preliminary question PQ corresponding to the preliminary answer PA at the end of a preset number of consecutive executions of the preliminary device or system authentication phase SDAP, so that the device ED or system ES will consider that the user is not a genuine user.

[0077] In case the method involves a system ES, a preliminary system authentication phase SDAP is performed before any operating phase OP, wherein the authenticity of all or some of the plurality of devices ED comprised by the system ES is verified by implementing the authentication method described above for each authenticated device ED.

[0078] In such a system ES, a plurality of electronic devices ED may form one or more functional chains with one or more upstream devices ED and one or more downstream devices ED. In this case, it may be the case that, on the one hand, if the device ED upstream of the device chain ED is proved to be authentic at the end of the preliminary stage SDAP for authentication of the device ED, the downstream device ED in the same device chain ED is also authenticated, and on the other hand, if the device ED upstream of the device chain ED is proved to be not authentic at the end of the preliminary stage SDAP for authentication of the device ED, the downstream device ED in the same device chain ED is not authenticated, and the system ES is proved to be not authentic.

[0079] The device ED or the system ES according to the invention is specifically designed to implement the mutual authentication method and the method of operation described above, in particular for performing a preliminary device or system authentication phase SDAP. This device ED or this system ES is configured with and therefore comprises and combines the authentication secrets of the device or SDAS system on the one hand and the authentication secrets of the UAS user on the other hand.

[0080] Now, only refer to the Figure 1 . It represents the user USER and the device ED or system ES in two columns on the left and right, respectively. It shows three consecutive blocks stacked from top to bottom on the time axis, namely the preliminary configuration phase SDCP, the preliminary device or system authentication phase SDAS and finally the operation phase OP, which is itself divided into two blocks, the first corresponding to the preliminary user authentication step UAP and the second corresponding to the appropriate operation phase. As previously explained, these two blocks can be nested to a greater or lesser extent.

[0081] The diagram shows that the device ED or system ES contains sensitive or confidential data DA, including and combining on the one hand a device or system authentication secret SDAS and on the other hand a user authentication secret UAS (symbolically represented by a locked padlock).

[0082] The diagram shows that the two secrets are opened consecutively, first the device or system authentication secret SDAS and secondly the user authentication secret UAS (symbolically represented by an open lock).

[0083] Once authenticated, a device ED or system ES is indicated with a horizontal stripe, and similarly, once authenticated, a user is indicated with a horizontal stripe.

[0084] The diagram shows that user commands CO relating to the device ED or system ES performing specific operations SO intended to provide the user with a determined service DS only occur once the device ED or system ES has been combined authenticated (by the user) and the user has been authenticated.

Claims

1. A method for performing a transaction with an electronic device, the electronic device being configured to initiate an operation phase of the transaction upon receiving a command from a user, and to perform tasks during the operation phase to provide the user with a determined service corresponding to a predetermined transaction, Before executing the operating phase, the method comprises: The configuration phase of the electronic device includes configuring the electronic device with a preliminary question and a preliminary answer, The initial authentication stage of the user on the electronic device includes: sending a preliminary question by the user to the electronic device, receiving, by the user from the electronic device, an answer to the preliminary question, verifying by the user whether the answer provided by the electronic device corresponds to an expected preliminary answer, wherein the configuration phase is performed before the preliminary authentication phase, and the preliminary question and the preliminary answer are secret and believed to be known to the user, wherein the electronic device is configured to enable the user to prevent the execution of the operation phase if the user wishes after receiving the answer from the electronic device, Then, the electronic device authenticates the user, including: providing the user with an operation question by the electronic device, receiving, by the electronic device, an answer from the user and comparing the user's answer with an expected operational answer, The method also includes deleting, by the electronic device, confidential data if the user fails to provide the preliminary question during a predetermined number of times the user performs the preliminary authentication phase of the electronic device.

2. The method according to claim 1 comprises a plurality of preliminary configuration phases and a number of operation phases of the electronic device performed over time, each preliminary configuration phase comprising configuring the electronic device with a preliminary question and a preliminary answer, wherein the preliminary configuration phase of the electronic device is performed before each operation phase. The method of claim 1 , wherein deleting the confidential data from the electronic device comprises deleting the preliminary question and the preliminary answer.

4. The method according to any one of claims 1 and 3, comprising: providing a plurality of electronic devices forming a functional chain to perform the transaction, the functional chain comprising at least one upstream electronic device and one downstream electronic device, - perform a preliminary authentication phase of said upstream electronic device, and - If the upstream electronic device is authenticated, the preliminary authentication phase of the downstream electronic device is performed, otherwise the preliminary authentication phase of the downstream electronic device is not performed.

5. An electronic device for performing a transaction, the electronic device being configured to initiate an operation phase of the transaction upon receiving a command from a user, and to perform tasks during the operation phase to provide the user with a determined service corresponding to a predetermined transaction, the electronic device comprising confidential data, the confidential data comprising a preliminary question and a preliminary answer, and being configured to: During the initial authentication phase of the user to the electronic device: Receive initial questions, providing said preliminary answer as an answer to said preliminary question, enabling the user to prevent the execution of the operating phase if the user wishes after receiving the answer from the electronic device, During the authentication phase of the user by the electronic device: providing said user with an operational question, receiving an answer from the user and comparing the user's answer to an expected operational answer, and If the preliminary question is not received during a predetermined number of times the user performs the preliminary authentication phase of the electronic device, the confidential data is deleted.

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