Method for securing the input of the digits of a personal identification code and corresponding device

Abstract

The invention relates to a method (100) for securing the input of the elements of a personal identification code, referred to as PIN, on a mobile terminal (TM) configured to communicate with a server (S), the method comprising the steps, implemented by the mobile terminal (TM), of: - receiving (101) a random sequence of elementary instructions from the server (S), the random sequence of elementary instructions being configured to present a drawing displayed on a touchscreen (ET) of the mobile terminal (TM) after the random sequence of elementary instructions has been executed by a processing module (MT) of the mobile terminal (TM), the displayed drawing corresponding to at least one from among input regions of a virtual keyboard (CV) and PIN elements (ECP) associated with the input regions (ZS); - executing (102) the random sequence of elementary instructions.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for securing the entry of figures in a personal identification code, and corresponding device.

[0003] The present invention relates to the field of payment applications, and in particular to software applications configured to transform a commercial mobile terminal intended for the general public into a payment terminal.

[0004] It is known to use a software application to transform a commercial mobile terminal intended for non-professional customers, for example a smartphone, into a payment terminal. Said software application implements a method configured to guarantee the confidentiality of the personal identification code (PIN code) entered on the mobile terminal to authenticate the holder of the payment card.

[0005] To this end, it is more particularly known to mix the relative positions, on the terminal screen, of the areas used for entering the different digits of the PIN code, so that these relative positions are different for a new transaction from what they were for the previous transaction. Said positions are determined randomly by a server separate from the mobile terminal; thus, these arrangements make it possible to defend against an attack by an auxiliary channel such as listening to terminal sensors, for example listening to an accelerometer or a gyroscope to guess the digits entered for the PIN code.

[0006] This known solution nevertheless has the disadvantage of being insufficient to counter the threat of an attacker who would listen to and analyze during its execution on the mobile terminal the payment application and / or the data flows exchanged between the payment application and the server, to identify the respective positions of the zones and digits of the PIN code, and thus determine a presentation of the virtual keyboard for entering the digits of the PIN code.

[0007] The invention therefore aims to propose a solution to all or part of these problems. To this end, the present invention relates to a method for securing the entry of elements of a personal identification code, called a PIN code, on a mobile terminal configured to communicate with a server, the method comprising the following steps implemented by the mobile terminal:

[0008] - receiving a random sequence of elementary instructions from the server, the random sequence of elementary instructions being configured to present a design displayed on a touch screen of the mobile terminal, after execution by a processing module of the mobile terminal of the random sequence of elementary instructions, said displayed design corresponding to at least one of input zones of a virtual keyboard and PIN code elements associated with the input zones,

[0009] - execution of the random sequence of elementary instructions.

[0010] According to one embodiment, the invention comprises one or more of the following characteristics, alone or in a technically acceptable combination.

[0011] According to one mode of implementation, the random sequence of elementary instructions results from a step, implemented by the server, of random ordering of an initial sequence of elementary instructions generated by the server, the initial sequence also being configured to present said displayed design, on the touch screen of the mobile terminal, after execution by the processing module of the mobile terminal of the initial sequence of elementary instructions.

[0012] According to these provisions, fraudulent eavesdropping by a third party on the sequence of elementary instructions will not allow him to determine an initial sequence of elementary instructions from which the random sequence originates; the random ordering in fact makes it possible to distribute the information in the sequence so that the fraudulent capture of a segment of the sequence of elementary instructions contains less information than a segment of the initial sequence of elementary instructions. According to these provisions also, the random sequence, like the initial sequence, of elementary instructions does not include a direct reference to the input zones and the PIN code elements associated with the input zones.According to one embodiment, the random sequence of elementary instructions comprises at least one instruction encoded by the server, the method comprising a decoding step prior to the execution of the random sequence of elementary instructions, to generate at least one decoded instruction from the random sequence of elementary instructions.

[0013] According to these provisions, fraudulent eavesdropping by a third party on data transmission between the server and the mobile terminal will be even more difficult to exploit.

[0014] According to one embodiment, the at least one decoded instruction of the random sequence of elementary instructions is a function of at least one other previously decoded instruction in the random sequence of elementary instructions.

[0015] According to one embodiment, during the step of executing the sequence of decoded elementary instructions, at least one decoded instruction of the instruction sequence is erased after having been executed, and before the execution of the next instruction in the sequence.

[0016] According to these provisions, a copy of an internal memory of the mobile terminal will not allow the attacker to go back to the complete sequence of elementary instructions.

[0017] According to one aspect, the invention also relates to a method for securing the entry of elements of a personal identification code, called a PIN code, on a mobile terminal configured to communicate with a server, the method comprising the following steps implemented by the server:

[0018] - generation of a random sequence of elementary instructions, the random sequence of elementary instructions being configured to present a pattern displayed on a touch screen of the mobile terminal, after execution by a processing module of the mobile terminal of the random sequence of elementary instructions, the pattern displayed corresponding to at least one of input zones of a virtual keyboard and PIN code elements associated with the input zones, - transmission to the mobile terminal of the random sequence of elementary instructions.

[0019] According to one embodiment, said method comprises one or more of the following characteristics, alone or in combination.

[0020] According to one embodiment, the method further comprises a step of generating an initial sequence of elementary instructions, the initial sequence of elementary instructions being configured to present said drawing displayed on a touch screen of the mobile terminal, after execution by the processing module of the mobile terminal of the initial sequence of elementary instructions, an initial ordering of the initial sequence of elementary instructions corresponding to an arrangement on the screen of the mobile terminal of the input zones and the PIN code elements associated with the input zones; the step of generating the random sequence of elementary instructions comprising a random ordering of the initial sequence of elementary instructions, to randomly modify the initial ordering of the initial sequence of elementary instructions, the random ordering generating the random sequence of elementary instructions;

[0021] According to these provisions, fraudulent eavesdropping by a third party on the sequence of elementary instructions will not allow them to determine the initial sequence; the random ordering in fact makes it possible to distribute the information in the sequence so that the fraudulent capture of a segment of elementary instructions contains less information than a segment of the initial sequence. According to these provisions also, the initial sequence of elementary instructions does not include a direct reference to the input zones and the PIN code elements associated with the input zones.

[0022] According to these provisions, partial fraudulent listening by a third party of the sequence of elementary instructions will not allow them to determine the PIN code elements entered.

[0023] According to one embodiment, the method further comprises a step of encoding the random sequence of elementary instructions, prior to the transmission step, the encoding step generating at least one encoded instruction associated with at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of the at least one instruction and of at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions.

[0024] Under these provisions, determining the initial sequence of elementary instructions by fraudulent eavesdropping by a third party will be made even more difficult.

[0025] According to one aspect, the invention also relates to a mobile terminal configured to secure the entry of elements of a personal identification code, called a PIN code, the mobile terminal comprising a reception module configured to receive a random sequence of elementary instructions from a server, a touch screen and a processing module configured to execute the random sequence of elementary instructions, the random sequence of elementary instructions resulting from a random modification by the server, of an initial ordering of an initial sequence of elementary instructions previously generated by the server, the execution of the random sequence of elementary instructions having the effect of drawing on the touch screen at least one of, a virtual keyboard, input zones of the virtual keyboard, and PIN code elements associated with the input zones.

[0026] According to one embodiment, the processing module comprises a decoding module, the decoding module being configured to generate at least one decoded instruction from the random sequence of elementary instructions, the at least one decoded instruction from the random sequence of elementary instructions being a function of at least one previously decoded instruction in the random sequence of elementary instructions.

[0027] According to one embodiment, the processing module is configured to erase at least one decoded instruction from the instruction sequence after it has been executed by the processing module, and before the execution of the next instruction in the sequence. According to another aspect, the invention also relates to a server configured to secure an entry on a mobile terminal of the elements of a personal identification code, called PIN code, the server being configured to communicate with the mobile terminal, the server comprising a generation module configured to generate an initial sequence of elementary instructions, the initial sequence of elementary instructions being configured to draw, on a touch screen of the mobile terminal, at least one of a virtual keyboard, input areas of the virtual keyboard, and PIN code elements associated with the input areas,when the initial sequence of elementary instructions is executed by a processing module of the mobile terminal, an initial ordering of the initial sequence of elementary instructions corresponding to an arrangement on the screen of the mobile terminal of the input zones and the PIN code elements associated with the input zones of the virtual keyboard, the generation module being further configured to randomly modify the initial ordering of the initial sequence of elementary instructions and generate a random sequence of elementary instructions, the server further comprising a transmission module configured to transmit to the mobile terminal the random sequence of elementary instructions.,

[0028] According to one embodiment, the generation module further comprises an encoding module, the encoding module being configured to generate at least one encoded instruction associated with at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of the at least one instruction and at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions.

[0029] According to another aspect, the invention also relates to a system configured for securing the entry of elements of a personal identification code, called a PIN code, on a mobile terminal according to one of the embodiments described above, the system comprising a server according to one of the embodiments described above, and the mobile terminal. For a better understanding, an embodiment and / or implementation of the invention is described with reference to the attached drawings representing, by way of non-limiting example, an embodiment or implementation respectively of a device and / or a method according to the invention. The same references in the drawings designate similar elements or elements whose functions are similar.

[0030] [Fig. 1] is a schematic representation of the elements of a system configured to implement the method according to the invention, to secure entry of the elements of a PIN code on a virtual keyboard drawn on the touch screen of a mobile terminal communicating with a server.

[0031] [Fig. 2] illustrates an example of a virtual keyboard drawn with differently shaped input areas.

[0032] [Fig. 3] is a schematic presentation of the sequencing of steps implemented by the mobile terminal and by the server.

[0033] To make it much more difficult for the attacker to determine the layout of the virtual keyboard for entering the PIN code elements, and then to deduce the digit entered by touch input on an input area of ​​the virtual keyboard, it is necessary to delete the high-level instructions configured in the payment application of the mobile terminal for drawing the input areas of the virtual input keyboard on the screen of the mobile terminal, such as {“draw key”, “draw digit”}, and to replace these high-level instructions with a sequence of low-level instructions for the drawing operations of the virtual input keyboard, for example “draw polygon”.Said sequence of low-level instructions configured for the drawing operations of the virtual input keyboard is calculated and made randomly variable by the server, before being transmitted to the application of the mobile terminal in a sequential and encrypted manner which does not reveal the nature, the object, and the parameters of the drawing operations, so that only the payment application on the mobile terminal has the rules for interpreting the sequence of low-level instructions transmitted to it. In a complementary manner and as an additional precaution, the instructions are executed and deleted immediately after, one after the other, on the fly as they are received from the server.

[0034] According to these provisions, an analysis of the flow of instructions transmitted by the server to the application on the mobile terminal, which would involve breaking the encryption used to protect the transmitted data, will not reveal the presentation of the virtual input keyboard on the screen of the mobile terminal.

[0035] Indeed, according to these provisions, the virtual input keyboard is not defined in terms of high-level operations relating to the display of input zones positioned on the screen and numbers associated with these input zones, but in terms of a sequence of elementary graphic drawing operations which does not directly reveal information on the positioning of the input zones, and the numbers associated with these input zones, unless the sequence of elementary graphic drawing operations is decoded or the graphics memory is directly “dumped” to obtain the image rendered by the execution of the entire sequence of elementary operations.

[0036] This approach also allows for drawing input areas, or keys on the touch-sensitive virtual keyboard, of different sizes, as shown as an example in Figure 2.

[0037] Figure 1 is a schematic representation of the elements of a system comprising a mobile terminal TM and a server S, configured to communicate and implement the method according to the invention, so as to secure entry of the elements of a PIN code on a virtual keyboard CV drawn on a touch screen ET of the mobile terminal TM.

[0038] Usually, the elements of a PIN are numbers, as shown in Figure 1, but the elements of the PIN can include any other graphical symbol accepted by the entry application.

[0039] The elements of the PIN code are each associated with an input zone ZS of the touch screen ET of the mobile terminal TM, so that the user, by touching an input zone ZS, selects an element of the PIN code, for example a number, associated with said input zone ZS. Usually the input zones ZS are represented on the touch screen ET by simple and identical shapes, for example a square or a rectangle, as illustrated in the figure. But the input zones ZS can also take various shapes, or different from each other, as illustrated in figure 2.

[0040] The mobile terminal TM is a piece of equipment intended for the general public comprising a touch screen ET and a processing module MT configured to execute sequences of instructions, in particular software applications, and to communicate with a remote server S. The mobile terminal is preferably a smartphone; it can also be a tablet, or a laptop for example.

[0041] The mobile terminal TM comprises in particular a reception module MRx configured to receive a random sequence of elementary instructions from the server S; said random sequence of instructions is for example generated by the server from an initial sequence of elementary instructions, said initial sequence of elementary instructions itself being generated by the server S. Said initial sequence of elementary instructions is configured to be executable on the processing module MT of the mobile terminal TM, and to draw, on the touch screen ET of the mobile terminal TM, the virtual keyboard CV, the input zones ZS of the virtual keyboard CV, and / or the PIN code elements ECP associated with the input zones ZS, when the initial sequence of elementary instructions is executed by the processing module MT of the mobile terminal TM.The server S comprises a generation module MG configured to generate 202 the random sequence of elementary instructions, for example from the initial sequence of elementary instructions by randomly modifying an initial ordering of the initial sequence of elementary instructions, the random sequence of elementary instructions remaining configured to draw, on the touch screen ET of the mobile terminal TM, the virtual keyboard CV, the input zones ZS of the virtual keyboard CV, and / or the PIN code elements ECP associated with the input zones ZS, when the random sequence of elementary instructions is executed by the processing module MT of the mobile terminal TM. The random ordering makes it possible to distribute the information in the sequence so that the fraudulent capture of a segment of elementary instructions includes diffuse information which is difficult to exploit until all of the information is available.Thus, fraudulent eavesdropping by a third party on the sequence of elementary instructions will not allow him to determine the initial sequence. Furthermore, the initial sequence of elementary instructions does not include a direct reference to the input zones and the PIN code elements associated with the input zones. Thus, fraudulent eavesdropping by a third party on the sequence of elementary instructions will not allow him to determine the input zones and the PIN code elements that are the subject of the sequence of instructions.

[0042] Optionally, the processing module MT comprises a decoding module MD, the decoding module being configured to decode all or part of the random sequence of elementary instructions which has been encoded by an encoding module ME of the server S, before being transmitted by the server S to the mobile terminal TM. Optionally, only part of the random sequence of elementary instructions is encoded by the encoding module ME; in this case only this part of the random sequence of elementary instructions is decoded by the decoding module MD of the processing module MT of the mobile terminal TM.

[0043] For example, an encoding of an elementary instruction of the random sequence of elementary instructions is a function of at least one other elementary instruction preceding said elementary instruction in the random sequence of elementary instructions. In this case, the generation of said decoded elementary instruction will be a function of the at least one other decoded elementary instruction preceding said elementary instruction in the random sequence of elementary instructions.

[0044] In order to enhance the security of the encoding / decoding operation, the MT processing module of the mobile terminal may be configured to erase at least one decoded instruction from the instruction sequence after it has been executed by the MT processing module, and before the execution of the next instruction in the sequence. According to these provisions, a recopy of an internal memory of the mobile terminal (MT) will not allow the attacker to go back to the complete sequence of elementary instructions; thus, determining the initial sequence of elementary instructions by fraudulent listening by a third party will be made even more difficult.

[0045] According to one aspect, the invention relates to a server S configured to secure an entry on a mobile terminal TM of the elements of a personal identification code, called PIN code, the server being configured to communicate with the mobile terminal TM; the server comprises a generation module MG configured to generate 202 a random sequence of elementary instructions; said random sequence of instructions is for example generated by the server S from an initial sequence of elementary instructions, said initial sequence of elementary instructions itself being generated by the server S.Said initial sequence of elementary instructions is configured to be executable on the processing module MT of the mobile terminal TM, and to draw, on the touch screen ET of the mobile terminal TM, the virtual keyboard CV, the input zones ZS of the virtual keyboard CV, and / or the PIN code elements ECP associated with the input zones ZS, when the initial sequence of elementary instructions is executed by the processing module MT of the mobile terminal TM; an initial ordering of the initial sequence of elementary instructions corresponds to an arrangement on the screen of the mobile terminal of the virtual keyboard CV, the input zones ZS of the virtual keyboard CV, and the PIN code elements ECP associated with the input zones ZS of the virtual keyboard CV.According to this particular mode of implementation of step 202 of generating the random sequence of elementary instructions, the generation module MG is further configured to randomly modify the initial ordering of the initial sequence of elementary instructions and thus generate said random sequence of elementary instructions. Other modes of implementation of step 202 of generating the random sequence of elementary instructions are conceivable.

[0046] The server S finally includes a transmission module MTx configured to transmit to the mobile terminal TM the random sequence of elementary instructions.

[0047] The generation module MG of the server further comprises an encoding module ME, the encoding module being configured to encode at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of said at least one instruction and at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions.

[0048] According to another aspect, the invention relates to a system comprising a server S according to one of the embodiments described previously, and a mobile terminal TM according to one of the embodiments described previously.

[0049] According to one aspect, the invention relates to a method 100 implemented by a mobile terminal TM according to one of the embodiments described previously, the method 100 comprising the following steps, with reference to FIG. 3:

[0050] - reception 101 of a random sequence of elementary instructions from the server S; the random sequence of elementary instructions results for example from a step implemented by the server S, of random ordering of an initial sequence of elementary instructions itself generated 201 by the server S, the initial sequence and the random sequence of elementary instructions each being configured to draw, on a touch screen ET of the mobile terminal TM, the same graphic representation of a virtual keyboard, input zones of a virtual keyboard CV and / or PIN code elements ECP associated with the input zones ZS, when the initial or random sequence of elementary instructions is executed on the mobile terminal TM, by a processing module MT of the mobile terminal TM,

[0051] - execution 102 of the random sequence of elementary instructions.

[0052] Optionally, the method 100 further comprises a decoding step 101 bis prior to the execution of the random sequence of elementary instructions, to generate at least one decoded instruction from the random sequence of elementary instructions.

[0053] In particular, the at least one decoded instruction of the random sequence of elementary instructions may be a function of at least one other instruction previously decoded in the random sequence of elementary instructions. Even more particularly, during the execution step 102 of the sequence of decoded elementary instructions, at least one decoded instruction of the instruction sequence is erased, after having been executed and before the execution of the next instruction in the sequence. Thus, a copy of an internal memory of the mobile terminal TM will not allow the attacker to go back to the complete sequence of elementary instructions.

[0054] According to another aspect, the invention also relates to a method 200 for securing the entry of elements of a personal identification code, called PIN code, on a mobile terminal TM configured to communicate with a server S, the method 200 comprising the following steps implemented by the server S:

[0055] - generation 202 of a random sequence of elementary instructions, the random sequence of elementary instructions being configured to present a design displayed on a touch screen ET of the mobile terminal TM, after execution by a processing module MT of the mobile terminal TM of the random sequence of elementary instructions, the displayed design corresponding to a virtual keyboard, input zones of a virtual keyboard CV, and / or PIN code elements ECP associated with the input zones ZS,

[0056] The generation 202 of a random sequence of elementary instructions may for example comprise a step 201 of generating an initial sequence of elementary instructions, the initial sequence of elementary instructions being configured to present said drawing displayed on a touch screen ET of the mobile terminal TM, after execution by the processing module MT of the mobile terminal TM of the initial sequence of elementary instructions, an initial ordering of the initial sequence of elementary instructions corresponding to a layout on the screen of the mobile terminal TM of the virtual keyboard, of the input zones ZS of the virtual keyboard and / or of the PIN code elements ZS associated with the input zones ZS of the virtual keyboard;the step 202 of generating the random sequence of elementary instructions according to this exemplary implementation, comprising in particular a random ordering of the initial sequence of elementary instructions, to randomly modify the initial ordering of the initial sequence of elementary instructions, the random ordering generating the random sequence of elementary instructions; - transmission 203 to the mobile terminal TM of the random sequence of elementary instructions.;

[0057] According to these provisions, fraudulent eavesdropping by a third party on the sequence of elementary instructions will not allow them to determine the initial sequence; the random ordering in fact makes it possible to distribute the information in the sequence so that the fraudulent capture of a segment of elementary instructions contains less information than a segment of the initial sequence. According to these provisions also, the initial sequence of elementary instructions does not include a direct reference to the input zones and the PIN code elements associated with the input zones.

[0058] According to these provisions, partial fraudulent listening by a third party of the sequence of elementary instructions will not allow them to determine the PIN code elements entered.

[0059] To enhance the security of the method, the method further comprises a step 202bis of encoding the random sequence of elementary instructions, prior to the transmission step 203, the encoding step 202bis generating at least one encoded instruction associated with at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of the at least one instruction and at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions. Thus, determining the initial sequence of elementary instructions by fraudulent eavesdropping by a third party will be made even more difficult.

Claims

CLAIMS 1. Method (100) for securing the entry of elements of a personal identification code, called PIN code, on a mobile terminal (TM) configured to communicate with a server (S), the method comprising the following steps implemented by the mobile terminal (TM): - reception (101) of a random sequence of elementary instructions from the server (S), the random sequence of elementary instructions being configured to present a design displayed on a touch screen (ET) of the mobile terminal (TM), after execution by a processing module (MT) of the mobile terminal (TM) of the random sequence of elementary instructions, said displayed design corresponding to at least one of input zones of a virtual keyboard (CV) and PIN code elements (ECP) associated with the input zones (ZS), - execution (102) of the random sequence of elementary instructions.

2. Method (100) according to claim 1, the random sequence of elementary instructions results from a step, implemented by the server (S), of random ordering (202) of an initial sequence of elementary instructions generated by the server (S), the initial sequence also being configured to present said displayed drawing, on the touch screen (ET) of the mobile terminal (TM), after execution by the processing module (MT) of the mobile terminal (TM) of the initial sequence of elementary instructions.

3. Method (100) according to one of claims 1 or 2, in which the random sequence of elementary instructions comprises at least one instruction encoded by the server (S), the method (100) comprising a decoding step (101 bis) prior to the execution of the random sequence of elementary instructions, to generate at least one decoded instruction from the random sequence of elementary instructions.

4. Method (100) according to one of claims 1 to 3, in which the at least one decoded instruction of the random sequence of elementary instructions is a function of at least one other instruction decoded previously in the random sequence of elementary instructions.

5. Method (100) according to claim 4, wherein during the step of executing (102) the sequence of decoded elementary instructions, at least one decoded instruction of the sequence of instructions is erased after having been executed, and before the execution of the next instruction in the sequence.

6. Method (200) for securing the entry of elements of a personal identification code, called PIN code, on a mobile terminal (TM) configured to communicate with a server (S), the method comprising the following steps implemented by the server (S): - generation (202) of a random sequence of elementary instructions, the random sequence of elementary instructions being configured to present a design displayed on a touch screen (ET) of the mobile terminal (TM), after execution by a processing module (MT) of the mobile terminal (TM) of the random sequence of elementary instructions, the displayed design corresponding to at least one of input zones of a virtual keyboard (CV) and PIN code elements (ECP) associated with the input zones (ZS), - transmission (203) to the mobile terminal (TM) of the random sequence of elementary instructions.

7. Method (200) according to the preceding claim, further comprising a step of generating (201) an initial sequence of elementary instructions, the initial sequence of elementary instructions being configured to present said drawing displayed on a touch screen (ET) of the mobile terminal (TM), after execution by the processing module (MT) of the mobile terminal (TM) of the initial sequence of elementary instructions, an initial ordering of the initial sequence of elementary instructions corresponding to an arrangement on the screen of the mobile terminal (TM) of the input zones (ZS) and of the PIN code elements (ZS) associated with the input zones;the step of generating (202) the random sequence of elementary instructions comprising a random ordering of the initial sequence of elementary instructions, to randomly modify the initial ordering of the initial sequence of elementary instructions, the random ordering generating the random sequence of instructions; elementary; 8. Method (200) according to one of claims 6 or 7, further comprising a step of encoding (202bis) the random sequence of elementary instructions, prior to the transmission step (203), the encoding step (202bis) generating at least one encoded instruction associated with at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of the at least one instruction and of at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions.

9. Mobile terminal (TM) configured to secure the entry of elements of a personal identification code, called PIN code, the mobile terminal (TM) comprising a reception module (MRx) configured to receive a random sequence of elementary instructions from a server (S), a touch screen (ET) and a processing module (MT) configured to execute the random sequence of elementary instructions, the random sequence of elementary instructions resulting from a random modification by the server (S), from an initial ordering of an initial sequence of elementary instructions previously generated by the server (S), the execution of the random sequence of elementary instructions having the effect of drawing on the touch screen (ET) at least one of, a virtual keyboard (CV), input zones (ZS) of the virtual keyboard, and PIN code elements (ECP) associated with the input zones (ZS).

10. Mobile terminal (TM) according to claim 9, wherein the processing module (MT) comprises a decoding module (MD), the decoding module being configured to generate at least one decoded instruction from the random sequence of elementary instructions, the at least one decoded instruction from the random sequence of elementary instructions being a function of at least one previously decoded instruction in the random sequence of elementary instructions.

11. Server (S) configured to secure entry on a mobile terminal (TM) of the elements of a personal identification code, called PIN code, the server being configured to communicate with the mobile terminal (TM), the server comprising a generation module (MG) configured to generate an initial sequence of elementary instructions, the initial sequence of elementary instructions being configured to draw, on a touch screen (ET) of the mobile terminal (TM), at least one of a virtual keyboard, input zones (ZS) of the virtual keyboard (CV), and PIN code elements (ECP) associated with the input zones (ZS), when the initial sequence of elementary instructions is executed by a processing module (MT) of the mobile terminal (TM), an initial ordering of the initial sequence of elementary instructions corresponding to an arrangement on the screen of the mobile terminal of the input zones (ZS) and the PIN code elements (ECP) associated with the input zones (ZS) of the virtual keyboard (CV),the generation module (MG) being further configured to randomly modify the initial ordering of the initial sequence of elementary instructions and generate a random sequence of elementary instructions, the server further comprising a transmission module (MTx) configured to transmit to the mobile terminal (TM) the random sequence of elementary instructions., 12. Server (S) according to claim 11, wherein the generation module (MG) further comprises an encoding module (ME), the encoding module being configured to generate at least one encoded instruction associated with at least one instruction of the random sequence of elementary instructions, the at least one encoded instruction being a function of the at least one instruction and at least one other instruction of the random sequence of elementary instructions, the at least one other instruction preceding the at least one instruction in the random sequence of elementary instructions.

13. System configured to secure the entry of elements of a personal identification code, called PIN code, on a mobile terminal (TM) according to one of claims 9 or 10, the system comprising a server according to one of claims 11 or 12, and the mobile terminal (TM).

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