FR3010813A1 - METHOD FOR AUTHENTICATING A USER OF A TERMINAL - Google Patents

Abstract

The present invention relates to a method for authenticating a user of a terminal (1) comprising a data processing module (11) and at least a first touch sensitive element (13), the method being characterized in that it comprises the implementation of steps of: (a) detecting by the at least one first touch sensitive element (13) of a stimulus sequence; (b) determining by the data processing module (11) a rhythm pattern defined by said stimulus sequence; (c) authentication or not of said user by the data processing module (11) according to the result of a comparison of said detected rhythm pattern with a reference rhythm pattern.

Description

GENERAL TECHNICAL FIELD The present invention relates to a method for authenticating a user of a terminal, in particular for unlocking the terminal.

STATE OF THE ART Touch terminals (smartphones, tablets, etc.) generally have a locking / unlocking mechanism which makes it possible to prevent the terminal from being activated inadvertently, for example in a pocket. The best known is the "slide to unlock" (see for example the patent application EP2299381), wherein the user must perform a lateral gesture on the surface of the screen to unlock the terminal.

Such a mechanism, however, allows any person, possibly ill-intentioned, to unlock a terminal and access the data it contains. To prevent this, the user of the terminal has the option to add security, which takes for example the entry of a 4-digit PIN. Alternatively it has been proposed methods of "pattern lock" in which the user unlocks his terminal by performing on the touch screen a confidential complex drawing. Most often, nine points are displayed on the screen, and the unlocking pattern is a sequence passing through at least four of them (see for example the international application W02011 / 143476). These security solutions provide satisfaction, but we now see that they present a flaw. Indeed, the entry of the code / drawing requires that the touch screen is visible by the user, and therefore potentially by the close observers. In addition, cleverly placed cameras (by malicious people or not) can be precise enough to capture these codes / drawings when a user leaves his terminal.

It would therefore be desirable to have a user authentication mechanism of a terminal that does not have these known security flaws, while being fast, ergonomic and intuitive for the user. PRESENTATION OF THE INVENTION The present invention thus relates in a first aspect to a method of authenticating a user of a terminal comprising a data processing module and at least a first touch sensitive element, the method being characterized in that it comprises the implementation of steps of: (a) detecting by the at least one first touch sensitive element of a stimulus sequence; (b) determining by the data processing module a rhythm pattern defined by said stimulus sequence; (c) authentication or not of said user by the data processing module according to the result of a comparison of said detected rhythm pattern with a reference rhythm pattern. Playing a rhythm is indeed a clever way to enter an authentication code on a terminal. It does not require to see the screen of the terminal, which makes it easy to deceive observers who would try to perceive the code. And even with a lot of attention, it is very difficult to capture a rhythm on the fly, resulting in significantly increased confidentiality. According to other advantageous and non-limiting characteristics: the method is for unlocking the terminal, step (a) being implemented when the terminal is in a locked state, step (c) comprising unlocking the terminal if the user is authenticated.

Unlocking is a particularly preferred application of the method, it is thus possible simultaneously to verify that a human is trying to use the terminal, and that the latter is an authorized user; the method comprises, prior to step (a), the detection of a stimulus of a second touch-sensitive element. This second element makes it possible to initiate a stimulus detection sequence, which makes it possible to indicate to the terminal when the rhythm will start, hence a better perception; step (a) is carried out for a predetermined duration from said detection of a stimulus of the second touch sensitive element. This predetermined duration makes it possible to standardize the complexity of the rhythm, and to facilitate its computer representation; step (a) comprises the transmission by the terminal of a periodic luminous and / or sound and / or vibratory signal during said predetermined duration.

Such a signal gives the user the rate at which he must play his rhythm; said periodic signal comprises 14 cycles over said predetermined duration. A rhythm played on 14 beats is codable on 14 bits, that is exactly the size of the current PIN codes, hence the possibility of using with few modifications existing programs; - The periodic signal has a frequency of about 2 Hz. Two stimuli per second is optimal for the user: it allows to enter a complex code in just seven seconds, without the user is particularly likely to make mistakes; said periodic signal consists of a plurality of elementary pulses. In the form of elementary pulses, the signal is similar to a metronome and best guides the user; the first touch-sensitive element is a tactile surface and the second touch-sensitive element is a button.

The present method is particularly suitable for touch terminals with a side lock button, the touch surface can for example be typed directly into the pocket; the rhythmic pattern is represented by a sequence of elements associated with consecutive elementary intervals of time, each element being determined as a striking or as a silence. The code by keystrokes / silences allows a recognition and a very practical management of rhythmic patterns; each elementary interval of time corresponds to a period of said periodic signal. Thus the user only has to type or not at each period of the signal to play the rhythm; an element of the rhythmic pattern is determined as a strike if at least one stimulus is detected by said first touch-sensitive element on said elementary time interval, and a silence otherwise. This management of keystrokes offers a certain tolerance, facilitating the recognition of the rhythm even if the user does not play it with precision; - the rhythmic pattern is represented as a Morse type code.

Morse code is known and easily usable in the present process. According to a second aspect, the invention relates to a method of configuring a reference rhythm pattern comprising a data processing module and at least a first touch-sensitive element, the method being characterized in that it comprises the implementation of steps of: (a) Detecting by the at least one first touch sensitive element of a first stimulus sequence and then a second stimulus sequence; (b) determining by the data processing module a rhythm pattern defined by each of the first and second stimulus sequences; (c) If the result of a comparison of the two detected rhythm patterns is positive, definition by the data processing module of one of the rhythm patterns detected as a new reference rhythm pattern.

This method makes it possible, in addition to the authentication method, to easily change the reference rate of the user, without risk of error.

According to a third aspect, the invention relates to a terminal comprising at least a first touch sensitive element configured to detect a stimulus sequence; and a data processing module configured to implement: a module for determining a rhythmic pattern defined by said stimulus sequence; a module for authenticating a user of said terminal as a function of the result of a comparison of said detected rhythm pattern with a reference rhythm pattern.

Such a terminal unlocks as explained easily and discreetly. According to a fourth and fifth aspect, the invention respectively relates to a computer program product comprising code instructions for executing a method according to the first aspect of the invention of authenticating a user of a terminal and / or a method according to the second aspect of the invention for configuring a reference rhythm pattern; and computer-readable storage means on which a computer program product comprises code instructions for executing a method according to the first aspect of the invention of authenticating a user of a terminal and / or a method according to the second aspect of the invention for configuring a reference rhythm pattern.

PRESENTATION OF THE FIGURES Other features and advantages of the present invention will appear on reading the description which follows of a preferred embodiment. This description will be given with reference to the accompanying drawings in which: - Figure 1 is a diagram of an example of a terminal for which the method according to the invention is implemented; FIG. 2 represents an example of a rhythmic pattern encountered during the implementation of a preferred embodiment of the method according to the invention. DETAILED DESCRIPTION User Authentication and Terminal Unlocking The present method is a method of authenticating a user of a terminal 1 as shown in FIG.

The latter can be any equipment, especially a mobile terminal, portable type, smartphone, tablet, digital music player, etc. having a data processing module 11 (typically a processor), a data storage module 12 (a memory, for example Flash). The terminal 1 may be a terminal connected to a network, in particular wireless (wireless telephone network, WiFi network), or not (for example an MP3 player). The terminal 1 comprises interface means with a user. This interface comprises at least one touch-sensitive element 13, 14. By touch-sensitive element is meant an area of the surface of the terminal 1 that the user can touch / knock / press / push / press in order to interact with the terminal 1. It can be a touch surface, a touch of a keyboard, a button, etc. One can even consider an impact sensitive area (for example equipped with an accelerometer or microphone) under the hull. The present method is not limited to any particular technology, it is sufficient that this or these elements 13, 14 are able to detect a tapping by the user. The detection of a stimulus by a sensitive element causes the sending to the data processing module 11 of a characteristic signal. In general terms, the term "stimulus" will be called a manual action of a user detectable by a touch-sensitive element 13, 14. For example, if the sensing element is a key or a button, the stimulus will be a press on this key or this button. If the sensing element is a tactile surface the stimulus will be a touch of the surface. If the sensing element is an impact sensitive area the stimulus will be an impact of the shell. In the following description, we will take the example of a touch terminal comprising a touch screen substantially covering one side of the terminal, and at least one side button. The touch surface will be designated as the first touch sensitive element 13, and the button will be designated as the second touch sensitive element 14. The terminal 1 may comprise a large number of touch sensitive elements, a touch surface may also be included as a plurality of zones defining distinct sensitive elements (for example an upper area of the touch screen and a lower area of the touch screen can be defined, constituting two first touch sensitive elements 13a and 13b).

The present method is directed to the authentication of a user, alternatively for example to entering a code. It can be implemented at any time when the identity of the person handling the terminal 1 may have to be verified (attempt to access personal data, modification of system parameters, management of bank data, etc.). It can also be implemented for the unlocking of the terminal 1. By "unlocking" is meant passage of the terminal 1 of a "locked" state to an "unlocked" state.

In the "locked" state, all or part of the touch-sensitive elements of the surface of the terminal 1 have a degraded operation, that is to say that they do not allow the functionalities that they allow in the state "Unlocked". For example, for a touch terminal, the main touch surface is rendered inoperative, or only makes it possible to reach an unlocking screen (a display in which the user is for example asked to make an unlocking drawing). It is not possible to call, activate an application, etc. Often, only one sensitive element is fully operational (in our example button 14). The locked / unlocked states are managed by the data processing module 11 which triggers or not actions following the detection of stimuli of the sensitive elements 13, 14 according to the current state of the terminal.

Switching from the unlocked state to the locked state is generally very simple (in particular it may suffice to press the button 14). On the other hand, to go from the locked state to the unlocked state requires a sequence of particular actions that can only be done voluntarily by a human, and very difficult by accident (for example in the pocket). The present method makes it possible to unlock the terminal 1. It will be understood that the terminal 1 can simultaneously have several alternative ways of being unlocked in addition to the one that will now be described.

Rhythms The method comprises the steps of: (a) detecting by the at least one first touch sensitive element 13 of a stimulus sequence; (b) determining by the data processing module 11 a rhythm pattern defined by said stimulus sequence; (c) authentication or not of said user by the data processing module 11 according to the result of a comparison of said detected rhythm pattern with a reference rhythm pattern.

Specifically, the user who wants to authenticate and if necessary unlock his terminal 1 must reproduce a rhythm. It is this rhythm that constitutes the code authenticating the user. The stimuli of the sensitive surface or surfaces 13 that constitute this rhythm can be done without having to see the screen of the terminal. Indeed, the movement of the finger of the user is not taken into account, as we will see only the cadence and temporality of the gesture import. Such a solution improves the confidentiality of authentication by requiring an observer extreme attention and visibility from different angles (if multiple sensitive elements on multiple sides are used, see below) and access to the sound environment . It is even possible for the user to authenticate while his terminal 1 is still in his pocket (by typing through), which makes it completely impossible to intercept the code. It should be noted that, by sequence, we naturally mean at least two stimuli, or even at least three, or even at least four, or even more stimuli. Indeed the notion of rhythm imposes a certain duration and a certain movement. An isolated stimulus can not be considered a rhythm. In addition it is desirable that the pace is not trivial for the level of security is sufficient.

Recognition Phase To mark the beginning of the recognition phase of a rhythm, the user advantageously begins by informing the terminal 1 that he will start his rhythm. This information can be done via a first stimulus of the first sensitive element 13 which initiates the stimulus sequence, but preferably the method comprises prior to step (a) the detection of a stimulus of a second touch sensitive element 14, especially when the process aims to unlock the terminal 1 (step (a) is indeed in this case implemented when the terminal 1 is in a locked state, and therefore degraded. the second element 14 can make the stimulation of the at least one first element 13 allowed despite the locked mode, alternatively the stimulation of the first element 13 is always possible in locked mode). In particular, the second sensitive element 14 is a predetermined key, remote from the first element or elements 13. Preferably, as explained it is a side button (or higher) of the terminal, in particular that used to switch the terminal mode Locked. This detection of a stimulus of the second touch sensitive element 14 then advantageously triggers for a predetermined duration the phase of detection of the stimuli, in other words step (a). This predetermined duration corresponds to the time available to the user to "enter" the rhythm. It should be noted that there may be between the detection of a stimulus of the second sensitive element and the beginning of said predetermined duration a small interval of preparation of the user (the time he puts his finger in front of the first sensitive element). All this makes the recognition phase intuitive, and facilitates the correct detection of the stimulus sequence played by the user. It should be noted that more than one first sensitive element 13 can be involved (as explained, it is possible to cut a touch screen into two zones, the user playing the rhythm by tapping with two fingers). Under these conditions, it can be considered that step (a) sees the detection of an independent sequence of stimuli for each first touch sensitive element 13. Indeed, any rhythm played on n elements can be seen as the juxtaposition of n rhythms each played on a single element. On the other hand, at the level of an area considered as a single sensitive element 13, the impact position has no importance. It is also possible to consider several disjoint areas as forming this single sensitive element. For example, in the case of a terminal 1 keyboard (12 keys in general), we can consider that all the keys form a common sensory element. The user can play his rhythm by pressing any key on the keyboard, while making an observer believe that he is entering a particular code, when in fact only the rhythm matters. Rhythmic Pattern In the second step (b), the data processing module 11 (which has received from the first responsive element 13 a signal describing the received stimuli) determines a rhythm pattern defined by said stimulus sequence.

In other words, the data processing module 11 identifies in the stimulus sequence the rhythm thought by the user, and represents it in a numerically exploitable form. According to a first embodiment, it is possible to analyze the length of the stimuli, and for example to represent the rhythmic pattern 20 as a Morse type code taking into account the duration of the support (short / long stimulus). According to a second embodiment, which is preferred, it is possible to observe "strikes" and "silences" in the rhythm played by the user. Consecutive elementary intervals of time are defined (for example 0.5 seconds, as will be seen later), and in each elementary interval the data processing module 11 determines whether this interval is a typing or a silence. And an interval is determined as a strike if at least one stimulus is detected by said first touch sensitive element 13 on said elementary time interval, and otherwise silence. Each elementary interval can be seen as the time interval between two "beats" (in the musical sense) of a pulsation.

FIG. 2 represents a time sequence comprising 14 consecutive elementary intervals. The dots represent more or less long and more or less precise stimuli on the element 13 on the part of the user. The stars will be explained later.

The rhythmic pattern determined by the data processing module 11 is then hit-silence-keystroke-keystroke-silence-keystroke-strikestrap-silence-silence-f rappes-strikes-silences-keystrokes, which gives a code 10110111001101 in binary. The choice to represent the rhythm on 14 beats is interesting because a 4-digit PIN code is already coded on 14 bits, one can thus reuse the existing mechanisms of comparison of codes. Metronome According to a preferred embodiment, the terminal 1 can mark the beats in the manner of a metronome. For this, step (a) comprises the transmission by the terminal 1 of a periodic luminous signal and / or sound and / or vibratory (respectively by the screen, a flash, a buzzer, a speaker, a vibrator, etc.) during said predetermined time.

This periodic signal may consist of a plurality of elementary pulses (for example a vibration at the time of each time). This corresponds to the stars shown in FIG. 2. This signal makes it possible to limit the risks of error since it imposes a tempo on the user. The latter only has to type or not each of the 25 beats of the predetermined duration. According to the code size mentioned before, said periodic signal advantageously comprises 14 cycles on said predetermined duration, each elementary time interval then corresponds to a period of said periodic signal. If the elementary intervals are 0.5 seconds, the periodic signal has a frequency of about 2 Hz.

Authentication and Unlocking At the end of step (b), the data processing module has the rhythmic pattern played by the user.

In the last step (c), the data processing module 11 compares this detected rhythm pattern with a reference rhythm pattern, which is in particular stored on the data storage module 12. The reference rhythm pattern is a representation of the "Expected" rhythm, in other words the confidential rate of the user that allows the authentication of the user of the terminal 1. It should be noted that there may be several reference patterns. In the case where the rhythmic pattern is represented by a 14-bit code, a simple logical comparison is implemented. If the result of the comparison is positive, the data processing module authenticates the user and, where appropriate, implements the unlocking of the terminal 1 (transition from the locked state to the unlocked state). In the opposite case, the authentication is rejected, and the terminal 1 remains in the locked state. The user may have made a mistake, and the terminal 1 can then offer to try to play the rhythm again. It can be expected that after a certain number of errors the terminal 1 is blocked, and that for example only a manual entry of a code to unlock it again. Changing the reference rhythm pattern In the unlocked state, the terminal 1 may provide an application that allows the user to enable / disable the pace authentication mechanism, and to set a new confidential reference rate. This can be done in accordance with a method according to a second aspect of the invention of configuring a reference rhythm pattern (in particular for locking a terminal).

This method has an operation close to that of the authentication method. It begins with the detection by the at least one first touch-sensitive element 13 of a first stimulus sequence and then a second stimulus sequence. In other words, we ask the user to play twice (or more) in a row the rhythm he wants to define as a new reference rhythm. This repetition ensures that the user has not made a mistake, and that the rhythm he is recording is the one he wants.

For each of the first and second stimulus sequences, the data processing module 11 determines a rhythm pattern (as explained above). If the result of a comparison of the two detected rhythm patterns is positive (in other words that the two patterns determined are identical), the data processing module 11 defines one of the detected rhythm patterns (which are then the same) as new rhythmic pattern of reference, instead of the old. As explained before, it is possible to require a sufficient complexity of the rhythm (for example at least four stimuli), the change of the reference pattern refused if the patterns detected (even identical) are too simple. If the change is accepted, the next attempt to authenticate the user of the terminal 1, the new reference rhythm pattern will have to be played.

Terminal According to a second aspect, the invention relates to a terminal, in particular a mobile terminal, implementing the method according to the first aspect and advantageously the method according to the second aspect, such as that shown in Figure 1. Thus, this terminal 1 comprises as explained at least data processing means 11 and a first touch element 13. It can be any known equipment such as a laptop, a smartphone, a touch pad, an MP3 player, etc. The at least one first touch sensitive element 13 is thus configured to detect (possibly when the terminal 1 is in a locked state) a stimulus sequence (advantageously at least two stimulus sequences, for implementing the configuration method of the invention. 'a rhythmic pattern of reference). The data processing module 11 is itself configured to implement: a module for determining a rhythmic pattern defined by said stimulus sequence (advantageously a rhythmic pattern for each of the stimuli sequences); an authentication module of a user of said terminal 1 as a function of the result of a comparison of said detected rhythm pattern with a reference rhythm pattern; and optionally - an unlock module of the terminal 1 if the user is authenticated. For the implementation of the method of configuring a reference rhythm pattern, the data processing module 11 can be further configured to implement a definition module, if the result of a comparison of the two rhythm patterns detected. is positive, one of the rhythmic patterns detected as a new rhythmic pattern of reference.

Computer Program Product According to a fourth and fifth aspect, the invention relates to a computer program product comprising code instructions for executing (on the data processing module 11 of the terminal 1) a method according to the first authentication aspect of a user of a terminal 1 and / or a method according to the second configuration aspect of a reference rhythm pattern, and storage means readable by a computer equipment (for example the data storage module 12 of the terminal 1) on which there is this computer program product.

Claims (17)

REVENDICATIONS1. A method of authenticating a user of a terminal (1) comprising a data processing module (11) and at least a first touch-sensitive element (13), the method being characterized by comprising steps of: (a) detecting by the at least one first touch sensitive element (13) of a stimulus sequence; (b) determining by the data processing module (11) a rhythm pattern defined by said stimulus sequence; (c) authentication or not of said user by the data processing module (11) according to the result of a comparison of said detected rhythm pattern with a reference rhythm pattern. 2. Method according to claim 1, for unlocking the terminal (1), step (a) being implemented when the terminal (1) is in a locked state, step (c) comprising unlocking the terminal (1) if the user is authenticated. 3. Method according to one of claims 1 and 2, comprises prior to step (a) the detection of a stimulus of a second sensing element (14). The method of claim 3, wherein step (a) is performed for a predetermined time from said sensing of a stimulus of the second touch sensitive element (14). 5. The method according to claim 4, wherein step (a) comprises transmitting by the terminal (1) a luminous periodic signal and / or sound and / or vibratory during said predetermined time. 6. Method according to one of claims 5, wherein said periodic signal comprises 14 cycles on said predetermined time. 7. Method according to one of claims 5 and 6, wherein said periodic signal has a frequency of about 2 Hz. 8. Method according to one of claims 5 to 7, wherein said periodic signal consists of a plurality of elementary pulses. 9. Method according to one of claims 3 to 8, wherein the first touch sensitive element (13) is a touch surface and the second touch sensitive element (14) is a button. 10. Method according to one of claims 1 to 9, wherein the rhythmic pattern is represented by a sequence of elements associated with consecutive elementary intervals of time, each element being determined as a strike or as a silence. The method of claim 10 in combination with one of claims 4 to 8, wherein each elementary time interval corresponds to a period of said periodic signal. The method according to one of claims 10 and 11, wherein an element of the rhythmic pattern is determined as a strike if at least one stimulus is detected by said first touch sensitive element (13) on said elementary time interval, and a silence otherwise. 13. Method according to one of claims 1 to 9, wherein the rhythmic pattern is represented as a Morse type code. 14. A method of configuring a reference rhythm pattern comprising a data processing module (11) and at least a first touch-sensitive element (13), the method being characterized in that it comprises the implementation of steps of: (a) detecting by the at least one first touch sensitive element (13) a first stimulus sequence and then a second stimulus sequence; (b) determining by the data processing module (11) a rhythm pattern defined by each of the first and second stimulus sequences; (c) if the result of a comparison of the two detected rhythm patterns is positive, setting by the data processing module (11) of one of the rhythm patterns detected as a new reference rhythm pattern. A terminal (1) comprising at least a first touch sensitive element (13) configured to detect a stimulus sequence; and a data processing module (11) configured to implement: a module for determining a rhythmic pattern defined by said stimulus sequence; - An authentication module of a user of said terminal (1) according to the result of a comparison of said detected rhythm pattern with a reference rhythm pattern. 16. Computer program product comprising code instructions for the execution of a method according to one of the claims 1 to 13 for authenticating a user of a terminal (1) and / or a method according to claim 14 for configuring a reference rhythm pattern. 17. A storage medium readable by a computer equipment on which a computer program product comprises code instructions for the execution of a method according to one of claims 1 to 13 for authenticating a user of a device. terminal (1) and / or a method according to claim 14 for configuring a reference rhythm pattern.