WO2016005496A1

WO2016005496A1 - Authentication method by means of a capacitive information carrier

Info

Publication number: WO2016005496A1
Application number: PCT/EP2015/065703
Authority: WO
Inventors: Jan Thiele; Sascha Voigt; Matthias Förster; Karin Weigelt; Andrew Ferber
Original assignee: T-Touch International S.À R.L.
Priority date: 2014-07-09
Filing date: 2015-07-09
Publication date: 2016-01-14

Abstract

The invention relates to a method for identifying a combination of a capacitive information carrier and a device comprising a capacitive surface sensor. In particular the invention relates to the use of the method to authenticate one or more users by means of the capacitive information carrier and the device comprising a capacitive surface sensor.

Description

Authentication method by means of a capacitive information carrier

The invention relates to a method for identifying a combination of a capacitive information carrier and a device comprising a capacitive surface sensor. In particular the invention relates to the use of the method to authenticate one or more user by means of the capacitive information carrier and the device comprising a capacitive surface sensor.

Background

Capacitive surface sensors detect the capacitance of an object based on capacitive coupling. Touch-sensitive screens or touch screens are a particular embodiment of capacitive surface sensors, which are optimized to detect the human body capacitance and sense touch inputs generated for instance by the finger touch of a user. Electronic devices comprising touch screens are nowadays abundantly available and used by millions of users throughout their daily life. Such devices include for instance smart phones, tablet computers, touch pads, PDA's, mp3 players and the like. On these devices the user typically uses his finger or a suitable conductive object, for instance a touch pen, to perform tasks such as typing, reading, surfing the internet, playing games or controlling software. Due to their user friendliness these devices have revolutionized the way people communicate, work, entertain themselves or access information. Furthermore capacitive sensors in the form of touch screens or integrated in touch displays are used in the industry e.g. to control machines, robots or to design products.

Apart from that capacitive surface sensors being part of the above mentioned mobile devices often serve as input devices for authentication methods, which have a wide range of applications in the private as well as the business sector. For instance online banking is nowadays routinely performed from smart phones or touch pads. Conventional authentication steps in these procedures involve the usage of PIN codes or TANs (transactions numbers). These codes, which represent the information that grants authorization, can however be easily copied or misused. Taking advantage of the capability of capacitive surface sensors to detect the shape of conductive patterns, WO 2010/043422 A1 proposes the usage of a capacitive information carrier as a unique code that can serve to authenticate players in card games. The information carrier can take the form of a flat card and comprises an electrically conductive layer situated on a non-conductive substrate. In WO

201 1/154524 A1 a system is described comprising a capacitive information carrier and a capacitive surface sensor, where the capacitive surface sensor is preferably a touch screen or touch pad incorporated in smart devices such as smart phones, tablet notebooks, mp3 players and the like. The capacitive information carrier in WO 201 1/154524 A1 comprises as well an electrically conductive layer situated on a non-conductive substrate. Here, the electrically conductive layer takes preferably the form of a touch structure (also referred to as a touch pattern), that when brought into contact with the touch screen of a smart device, is sensed as a multi-touch input. The capacitive information carrier can be used as an admission ticket, a playing card or an authenticity certificate that can be read by a device comprising a touch screen.

In US 2013/0194202 A1 a method for authenticating a transaction is described that uses a smart stamp tool and a smart device capable of processing data and comprising a touch screen. The smart stamp tool is composed of a mass of conductive material with a bottom surface, where a certain number of contact pads, typically five, are proud above the flat surface. When the smart stamp tool is brought into contact with the touch screen, the device interprets each contact pad as a separate touch input and stores the corresponding file containing parametric data for the coordinate positions for which the authentication grants a certain authorization such as a money transfer. For this comparison the distances and angles between the coordinate positions corresponding to the contact pads of the smart stamp tool are calculated.

The prior art describes the detection of electrically conductive objects, e.g. the conductive layer of a capacitive information carrier, by the means of capacitive surface sensors. To authenticate a conductive pattern on a capacitive surface sensor it is known from the prior art that said pattern have to be known by a software, which runs on the device comprising the capacitive surface sensor, e.g. a smartphone or a tablet. As soon as the software, e.g. an app running on the mobile device, detects a match between the conductive pattern currently placed on the surface sensor and one of the patterns, which are stored in the app and/ or a connected database, the conductive pattern is detected. In known applications prior art conductive patterns serve as identification codes that are decoded by a geometrical encoding. Due to the limited precision of a touchscreen and the freedom of the user on how to bring the conductive pattern into contact with the touchscreen the number of different identification codes is limited. Furthermore special cases such as movements or rotations of the pattern, handling errors and the like need to be balanced by the software. Additionally the software needs to balance differences related to the devices (e.g. size of displays) and Operating Systems (iOS, Android, Windows). To still provide a software which enables a reliable detection, these requirements lead to a limited amount of conductive patterns which may serve as identification codes.

The number of conductive patterns is further constrained by the accuracy of the capacitive surface sensor which detects them. In particular aberrations of the touch screen or capacitive surface sensor lead to slight mistakes in the detection of that conductive pattern. In the prior art the conductive patterns have to be therefore significantly different from each other to be detected as different patterns. This reduces further the amount of conductive patterns which may serve as identification codes. The number of identification codes is limited at the moment to creating the software to a certain limit. In the prior art, the conductive patterns have to be designed to represent a set of identification codes which are intended for a certain application.

Besides limiting the amount of codes, the known authentication methods pose an additional security risk. At least the person being responsible for creating the conductive pattern has to know the identification code to provide parametric data in a reference file. Moreover current authentication methods using capacitive surface sensors lack in speed and practicality.

The primary object of the invention was therefore to provide an authentication method using a capacitive surface sensor and a capacitive information carrier to overcome disadvantages of the prior art. In particular, the invention forms the basis to provide an authentication method that uses the identification of the combination of a capacitive surface sensor and capacitive information carrier that is unique, secure, fast and grants a much more accurate identification than methods in the prior art.

The objective is achieved by methods according to the independent claims. The invention therefore relates to a method for the identification of a combination of a capacitive information carrier and a device comprising a capacitive surface sensor comprising the following steps: a. providing the capacitive information carrier comprising at least one electrically conductive layer, wherein the pattern of the electrically conductive layer represents information readable by the capacitive surface sensor b. providing the device comprising the capacitive surface sensor and a data processing program ('app') comprising at least one teaching mode and at least one recognition mode

c. bringing the capacitive information carrier into contact with the capacitive surface sensor in the teaching mode, whereby at least one touch event is generated on the device and processed and stored by the app

d. bringing the capacitive information carrier into contact with the capacitive surface sensor in the recognition mode, whereby at least one touch event is generated on the device and processed by the app

e. comparing in the recognition mode at least one of the processed touch events of step c. with at least one generated and processed touch event of step d.

Preferred embodiments of the method are covered by the dependent claims. The method enables a unique, fast, secure and highly accurate identification of a combination of a capacitive information carrier and a device comprising a capacitive surface sensor. Due to the distinct identification of the combination of the information carrier and the device the method can particularly well serve as an authentication method.

The invention therefore also preferably relates to a method for identifying the combination of an information carrier and a device to authenticate one or more user by means of: a) a device comprising a capacitive sensor surface on which a data processing program (app) is installed comprising a teaching mode and a recognition mode b) a capacitive information carrier comprising an electrically non-conductive substrate that is at least partially coated with an electrically conductive layer, the pattern of which represents information which is readable by the device comprising the capacitive surface sensor, comprising the following steps: i) running the app in the teaching mode and bringing the capacitive information carrier into contact with the capacitive surface sensor of the device and processing and recording at least one touch event that is provided by the operating system of the device in the process ii) running the app in the recognition mode and bringing the capacitive information carrier into contact with the capacitive surface sensor of the device and recording and processing at least one touch event that is provided by the operating system of the device in the process and comparing at least one of these touch events with at least one of these touch events, which have been processed and recorded in the teaching mode in step (i).

In sense of the invention authentication method is preferably to be understood in its broadest form. That is any method that is used to grant an action or access based upon the provision of an authentication code. Preferably the authentication method therefore may authenticate one or more users and subsequently authorizes an action and/or an access for these users on the device. Preferably the authentication code is represented by the arrangement of the conductive pattern on the capacitive information carrier. The granting of an action or access refers to steps that are elicited within the app running on the device after the recognition mode is successfully completed, that is in particular after touch events generated and processed, preferably to touch frames, in the recognition mode are successfully assigned to touch events recorded and processed, preferably to touch frames, in the teaching mode.

The method can therefore for instance be used to authenticate a user for access to secure information or perform subsequent actions such as authorizing money transactions or controlling devices. Advantageously, unlike for instance

authentication methods involving the recognition of finger prints, the method is however not limited to authenticate one user. Instead, it can serve as an

authentication method for multiple users, since it relies preferably only on the unique identification of the device and the information carrier and not on a user. Preferably, the capacitive information carrier according to the present invention can be applied to objects, i.e. it may for example be printed directly on a package or any 3D object. For other applications, it may be preferred to attach a label comprising a capacitive information carrier to a package and/or any conceivable object. Thus, the authentication method described can preferably be used to manage and identify products, packages or goods in factories or logistics.

In the context of the present invention it is preferred that the device comprising the capacitive surface sensor refers to smart devices that are capable of processing data and comprise a capacitive multi touch screen. In the context of the present invention, the terms device, capacitive surface sensor device, surface sensor device or touch screen device are also used to refer to the device comprising the capacitive surface sensor. Such devices include, but are not limited to touch pads, smart phones, PDAs, mp3 players track pads, television devices, touch displays, tablet notebook, tablet computers and the like. The touch screens of these devices are preferably capable of sensing the change of capacitance for instance if a fingertip or a conductive object is brought in contact with the touch screen. Moreover particularly preferable touch screens are capable of sensing the touch input of multiple fingertips at the same time. The projected capacitance touch technology (PCT) is an exemplary technology that allows such a multi-touch user input.

Advantageously, such touch screens are also particularly well suited to detect patterns of electrically conductive material.

In the sense of the present invention, the capacitive information carrier preferably comprises an electrically conductive layer situated on an electrically non-conductive substrate. Preferred substrates are paper, cardboard, wood-based material, composite material, glass, ceramics, textiles, leather, plastics, synthetic material or a combination thereof. Particularly suitable synthetic materials for the substrate are preferably selected from a group comprising PVC, PETG, PV, PETX, PE and synthetic paper. Preferably the substrate is light in weight; it may be transparent or intransparent as well as flexible or rigid. In the sense of the present invention the electrically conductive layer is preferably made of an electrically conductive material selected from the group comprising metal, materials comprising metal particles, materials comprising conductive particles, an ink containing metal, conductive polymers or a combination thereof. Preferred conductive particles comprise graphite or carbon black. Other materials including salts and electrolytes are however also possible, as well as inks, fluids and a combination thereof. Preferably the electrically conductive layer is substantially flat, that is that large parts of the connected areas of the conductive layer lie with one plane and have no elevations. Particularly preferred the conductive layer has a thickness of less than 100 μηη, more preferred less than 20 μηη and most preferred less than 1 μηη. Moreover it is preferred that the electrically conductive layer has an electrical surface resistivity or a specific surface resistivity of less than 1000 ohms/square, preferably less than 300 ohms/square particularly preferably less than 50 ohms/square. Preferably the layer of conductive material can be applied to the substrate by an additive, subtractive or semi-additive method in particular by a printing method or a film transfer method. A person skilled in the art knows how to perform examples of these methods such as flexo-printing of a graphite or carbon layer, screen-printing a graphite or carbon layer or a silver conductive paste, etching of a copper layer or the transferring aluminum by a cold foil transfer method onto the substrate. In particular a person skilled in the art knows how to use these or other methods to create a layer of an electrically conductive material with the above mentioned preferred properties on a substrate and structure this layer to form a predefined pattern. Such a patterned electrically conductive layer is preferably also referred to as a conductive pattern.

It is particularly preferred that the electrically conductive layer forms a pattern of one or more electrically conductive areas. A first preferred type of electrically conductive area is referred to as a touch point. In the context of the invention a touch point preferably resembles in size, shape, resistivity, conductivity and/or capacitance the tip of a human finger. It is particularly preferred that a touch point causes the same effect on a touch screen as a fingertip, that means it causes a local change in capacitance when the touch screen and the information carrier are brought into contact. Particularly preferable are shapes for a touch point resembling circular disks with diameters of preferable 1 mm to 20 mm, more preferable 4 mm to 15 mm and most preferable 6 mm to 10 mm. Further preferred embodiments for the shape of touch points are an ellipsoidal, a rectangular or a triangular shape. Particular preferably the touch point has a shape and size, so that it would fit into a circular disk with a diameter of preferable 1 mm to 20 mm, more preferable 4 mm to 15 mm and most preferable 6 mm to 10 mm and cover an area of preferably at least 20%, more preferably at least 60% and most preferably at least 80 % of the area of said circular disk. A second preferred type of an electrically conductive area is referred to as a conductive path. In the context of the invention preferably a conductive path resembles a line with a width of preferably less than 3 mm, more preferable less than 2 mm and most preferably less than 1 mm and connects one or more touch points. Additionally, the electrically conductive layer may comprise a third preferred type of an electrically conductive area which is referred to as a coupling area. In the context of the invention a coupling area is preferably larger than the size of a typical fingertip, thus preferably larger than a touch point and serves preferably to couple the potential of a user to the conductive layer. It is preferred that the coupling area is touched by a user, while the capacitive information carrier is brought into contact with the surface sensor of the device. Through touching the coupling area the potential of the touch pattern, in particular the potential of the touch points, is advantageously set onto the potential of said user. While in contact with the touch screen the touch points thereby advantageously cause a local change in

capacitance similar to the change in capacitance that the touching of a human fingertip would cause. Advantageously, the preferred coupling of a person to the conductive layer by means of a coupling area leads to a particular accurate detection of the touch pattern, in particular of the position of the touch points, by the touch screen of the device. It is further preferred that the coupling area is situated on the borders of the electrically conductive layer. Thereby it is preferably possible to touch the coupling area while bringing the conductive layer into contact with the surface sensor, without bringing the coupling area into contact with the touch screen.

The preferred embodiments of the electrically conductive layer of the capacitive information carrier are particularly well suited to represent a touch pattern. In the context of the present invention, a touch pattern is preferably understood as a pattern of the electrically conductive layer, which has the following properties.

When the information carrier is brought into contact with the device comprising a touch screen, the device will interpret the touch pattern as the touches of one or more fingertips. It is particularly preferred that the device interprets the position of one or more touch points of the touch pattern on the touch screen as the position of one or more touching fingers.

In the sense of the present invention, the bringing into contact of the information carrier with the device comprising the capacitive surface sensor provides one or more touch events.

In the context of the presented invention bringing the information carrier into contact with the device preferably means that the capacitive information is brought close to the surface sensor of the device, preferably in a distance that the capacitive surface sensor detects changes in capacitance due to the presence of the conductive layer of the information carrier. Particular preferred the bringing the information carrier into contact with the device means that the capacitive information carrier touches at least partially, more preferably over a substantial area of the conductive layer, the capacitive surface sensor of the device. In the preferred embodiment, wherein the conductive layer represents a touch pattern the bringing into contact of the information carrier with the device preferably means that all touch points of the information carrier are brought in a distance close enough, that the surface sensor senses a change in capacitance due to the presence of the touch points. Particularly preferred bringing into contact of the information carrier with the device means all touch points of the touch pattern touch the capacitive surface sensor.

In the context of the present invention, a touch event is preferably a software event provided by the operating system of the device comprising the capacitive surface sensor, whenever a parameter in the touch screen electronics is changing.

Preferably, the touch events can also be referred to as generated by the operating system of the device comprising the capacitive surface sensor. The operating system of the device refers preferably to the software that

communicates with the hardware of the device, in particular the touch screen, and allows other programs, such as the app, to run on the device. Examples for operating systems for devices comprising a capacitive surface sensor are Apple's iOS for the iPhone, iPad and iPod Touch or Android for operating a number of different smart phones, tablet computer or media players. Operating systems control and monitor the hardware of the device, in particular the capacitive surface sensor or a touch screen. Preferably operating systems for the devices used in the method according to the invention provide touch events, when the change in the electronic parameters of the touch screen indicates that a fingertip is brought into contact with the touch screen, a fingertip is moving over the touch screen or a fingertip is removed from the touch screen.

It is preferred that above mentioned operating systems precisely define the change of electronic parameters of the touch screen that will provide a touch event. Such parameters can include changes in electric currents or voltages measured at electrodes of a grid that can serve in the capacitive sensing of the touch screen. The scope of the method of the invention is however not limited to certain

implementations of how the device comprising the capacitive surface sensor defines and provides touch events. The operating system is preferably designed to provide touch events reflecting the interaction of a human finger or a conductive object with the touch screen. Advantageously touch points preferably resemble the properties of a fingertip in terms of size, shape, resistivity, conductivity and/or capacitance. In the preferred embodiment of the capacitive information carrier, where the electrically conductive pattern represents a touch pattern, touch events are advantageously generated to in particular reflect the contact, movement or re- movement of one or more touch points. Surprisingly, the method according to the invention however does not require a certain shape of an electrically conductive layer.

Advantageously, the shape of the electrically conductive layer, preferably the touch pattern, must not be known in the context of the authentification method according to the present invention, but the shape of the electrically conductive layer may preferably be recognizable by a touch screen. In the context of the present invention, a touch pattern may represent a particularly preferred embodiment of the electrically conductive layer.

Based on the prior art descriptions of authentication methods, a conductive pattern needs to be known for a correct identification of a capacitive information carrier on a device. This causes the disadvantages as mentioned above. It was totally surprising that it is not necessary that the pattern of the conductive layer, preferably the touch pattern, is known for the authentication method described herein. This is related to the teaching mode in which the device reads the pattern of the conductive layer, preferably the touch pattern. In the teaching mode, the information carrier is brought into contact with the device and through this process touch events are generated, recorded and processed by the app.

In the recognition mode the same information carrier is again brought into contact with the same device comprising the capacitive surface sensor and the touch events generated in this process are processed and recorded. This has the surprising effect that a comparison of the touch events generated, processed and stored in the teaching mode with processed touch events generated in the recognition mode is sufficient to robustly identify the combination of the capacitive information carrier and the device comprising the capacitive surface sensor. It is particularly preferred that touch events generated in the teaching mode or generated in the recognition mode are processed to touch frames. Advantageously a comparison of touch frames created in the teaching mode with touch frames created in the recognition mode is particularly robust to identify the combination of the capacitive information carrier and the device comprising the capacitive surface sensor. In other words the app builds its own database in the teaching mode.

Within the sense of the invention, there is surprisingly no need to include a certain set of parameters describing the pattern of the conductive layer at the moment of creating the software. This would limit the amount of usable identification codes from that point. Instead, advantageously unknown conductive patterns, serving as identification codes, can be added to the software by using the teaching mode and recording the touch events generated by these identification codes.

The correlation between the device comprising the capacitive surface sensor, the app that includes the created database and the capacitive information carrier comprising a conductive pattern leads to another surprising effect. State of the art authentication methods for conductive patterns need to balance differences in devices (size, hardware, operating systems etc). The authentication method described herein does not need to consider these variations because each conductive pattern is taught on a particular device. Moreover, using the device as a "learning" device makes the whole authentication process much more accurate since the smallest differences between devices will be considered, e.g. different calibrations, slightly damaged touch screens and the like.

It was particularly surprising to see that using the method, aberrations in the detection accuracy of the touch screen, for instance for a slightly damaged touch screen, a not optimal calibrated touch screen or caused by production tolerances, do not add up. In particular, as the method according to the present invention uses the capacitive detection of the touch screen first to 'learn' the information of the information carrier in the teaching mode and a second time to record the information of the information carrier again in the recognition mode. Surprisingly, instead of adding up aberrations in the detection method cancel and the identification of information carrier with a device is surprisingly robust, even with a slightly misaligned or damaged touch screen. Advantageously, the method thus does not require very well calibrated touch screen devices that can detect the physical pattern of an electrically conductive layer with a high accuracy as methods in the prior art. Instead, the method adapts to possible flaws in the detection procedure and nevertheless allows for a unique identification of the combination of the information carrier and the device. Advantageously, differences of various touch screens (various touch screen manufacturers, various touch screen models, various touch controller) do not have an impact on the recognition accuracy. It came as a surprise that a greater number of touch screen device types is compatible with this authentication method compared to state-of-the-art authentication methods.

In a preferred embodiment the method is characterized in that one or more touch events generated in the teaching mode and/or recognition mode are processed to generate a touch frame. As described above, preferably touch events are generated by the operating system of the device in case a change in the electronic parameters of the touch screen is detected. Preferably the operating system generates the touch events that reflect the touch, the movement or the re-movement of a fingertip or a conductive object on the touch screen. Touch events therefore preferably describe the change of a data structure referred to in the sense of the present invention as the touch data point. The touch data point is a data structure that preferably represent at least a pair of coordinates. This pair of coordinates preferably represents the coordinate position that a fingertip or a conductive object has on the touch screen. In particular it preferably refers to the position that a subset of the electrically conductive layer has on the touch screen, when the information carrier is brought into contact with the device. For the preferred embodiment, wherein the electrically conductive layer forms a touch pattern, the pair of coordinates of the touch data point preferably represents the position of one or more of the touch points on the touch screen. The touch data point can comprises however additional parameters such as a diameter, a width, a height, an elliptical minor- and major radius, a focal point or an eccentricity. Preferably the parameters assigned to the touch data point further characterize the properties of a fingertip or a conductive object in contact with the touch screen. In particular it is preferred that these additional parameters of the touch data point reflect properties of the subset of the electrically conductive layer, more preferred one or more of the touch points, of the capacitive information carrier. Preferably, touch events can be one of the following types: a touchstart, a touchmove, a touchend or a touchcancel. It is preferred that a touchstart can create a touch data point, a touchmove can change parameters of a touch data point and a touchend or a touchcancel can terminate a touch data point. In particular, a touch event can also affect one or more touch data points for instance one touchmove can describe the change of parameters in one or more touch data points. Preferably, a touch frame is a data structure that represents one or more touch data points at the same moment in time or in a time interval around the same moment of time. In this preferred embodiment the app therefore processes the recorded touch events up to a given point of time to create a touch frame for that time point. While touch events do not necessarily represent all touch data points at a given time, it is preferred that touch frames advantageously do represent all touch data points at a given time. Preferably, the touch events generated and recorded in the teaching mode are therefore processed to touch frames that comprise one or more touch data points and a time stamp representing said time point. Similarly, the touch events generated and recorded in the recognition mode are preferably processed to touch frames. It was surprising to see how much computing power and memory can be saved on the device by processing touch events to touch frames. Moreover the preferred embodiment advantageously facilitates the comparison of the processed touch events generated in the teaching mode and recognition mode. It was surprising that touch frames with said parameters represent a data structure that can be compared with little computing power, while maintaining enough information to confidently identify the combination of the capacitive surface sensor and the capacitive information carrier. It was particular surprising that by partly discarding information on single touch events and processing them to touch frames, which are then preferably compared, the combination of the information carrier and the device can be identified with even higher precision.

Another advantage of the preferred method, which exceeds the prior art is that there is no more a need to take into account information regarding the electrical features of a touchscreen, in order to differentiate between different touchscreens or devices. A touch frame, which was obtained in the teaching mode on a device comprising a touch screen, is a normative reference for the identification code on said

touchscreen on said device. Within this procedure the precision of detection is very high compared to geometrical encoding methods described in the prior art since it includes any features by the touchscreen, material and/or device.

Furthermore, it is not necessary to consider differences in operating systems since the aim of the invention is the authentication of a conductive pattern, preferably a touch pattern, on one selected device. This leads to an authentication method for which the conductive pattern does not need to be known since the database to compare the conductive pattern, preferably the touch pattern, is created on the device. Furthermore this allows the use of a much higher number of different conductive patterns since variations related to devices, operating systems and the disadvantages known from prior art do not need to be considered.

The same applies to the capacitive information carrier itself. Slight deviations caused by typical variations within the production process, e.g. process parameters, material variations and the like, result in slightly different information carriers although they are intended to be the same. It was totally surprising that these deviations, which are not preferred by state-of-the-art detection software, can further increase the amount of different conductive patterns, in particular touch patterns, and even improve the detection quality.

Moreover, it was surprising, that the method could uniquely identify the combination of a first information carrier with the device versus the combination of a second information carrier with the device, even though the electrically conductive pattern of the first and the second information carrier differed by an absolute minimal distance of less than 4 mm.

The method according to the invention thus allows for the usage of a lot more authentication codes represented by the shape of the conductive layer, preferably the touch pattern, of the information carrier than it has been possible in the prior art.

The higher the number of authentication codes that can be uniquely identified, the more difficult it becomes for a potential third party to guess the correct authentication code and/or copy the authentication code in an attempt to gain authorized access to information or the granting of actions. The preferred method is therefore particularly well suited for authentication methods requiring high security such as money transactions, online shopping, controlling of production machines in factories or providing access to confidential information. Moreover the invention enables the provision of authentication methods for numerous users related to activities such as online shopping, online betting or lotteries.

In a preferred embodiment the method is characterized in that in the teaching mode more than 100, preferably more than 1 ,000 and more preferably more than 10,000 touch events are generated, processed and stored within the app. Advantageously these preferred numbers of touch events acquired during the teaching mode lead to a surprisingly robust identification of the combination of the device and the information carrier. In particular more than 100, preferably more than 1000 und more preferably more than 10 000 touch events characterize the interaction of the information carrier with the surface sensor of the device during the teaching mode surprisingly well. Moreover preferably the device visually indicates the number of touch events that are generated during the teaching mode and the teaching mode terminates, when the preferred number of touch events is reached. To this end, the app in the teaching mode may display for instance a percentage bar, a counter, a clock or other visual indicators of the number of touch events generated during the teaching mode in respect to the number of preferred touch events. Advantageously such a visual indicator motivates a user to move the capacitive information carrier over the touch screen of the device during the teaching mode until the preferred number of touch events is reached. It was surprising that such a visual indicator further leads to a more homogeneous und continuous movement of the information carrier over the touch screen by the user. This surprisingly continuous and homogeneous movement leads advantageously to the recording of touch events during the teaching mode that particularly well reflect conductive pattern, preferably the touch pattern, of the capacitive information carrier.

In a further preferred embodiment, the method is characterized in that the assignment of touch events to a touch frame is performed at time intervals of less than 1000 ms, preferably less than 200 ms and more preferably less than 50 ms. As described above a touch frame preferably represents the touch data points at the same time point or a time interval around said time point. Said touch data points are preferably created by processing touch events. The assignment of touch events to a touch frame at time intervals of less than 1000 ms, preferably less than 200 ms and more preferably less than 50 ms therefore leads to consecutive touch frames that preferably represent the state of touch data points at time points separated by said preferred time intervals. It was surprising that consecutive touch frames with said preferred time intervals reflect the conductive pattern, preferably the touch pattern, of the capacitive information carrier particularly well. For an average user moving the capacitive information carrier over the touchscreen of the device the preferred time intervals secure a particularly well spread distribution of the touch frames. It was particular surprising that the assignment of touch frames with the preferred time intervals leads to a well distinguishable separation of touch data points stored in consecutive touch frames, while avoiding aliasing effects.

In a further preferred embodiment, the method is characterized in that in the teaching mode more than 100, preferably more than 1 ,000 and more preferably more than 10,000 touch frames are generated and stored. The preferred number of touch frames lead advantageously to a particularly accurate identification of the combination of the capacitive information carrier and the device. Moreover by storing more than 100, preferably more than 1000 and more preferably more than 10 000 touch frames the comparison in the recognition mode is particularly efficient. That means that the likelihood that at least one touch frame generated in the recognition mode matches one of said stored touch frames is particularly high. In a particularly preferred embodiment the visual display of the touch screen indicates the number of touch frames generated and stored in the teaching mode, wherein more preferred the number of stored touch frames is visualized in respect to said number of preferred touch frames. Preferably visual indicators suitable for this task comprise, but are not limited to, percentage bars, clocks or counters. In one embodiment the teaching mode is terminated once the number of preferred touch frames is generated and stored.

In a further preferred embodiment, the method is characterized in that the teaching mode is terminated, when for any coordinate position for a touchstart on the capacitive surface sensor, a touch frame is generated and stored, which comprises a touch data point, for which the distance of the coordinate position of said touch data point and said coordinate position of a touchstart is smaller than a

predetermined radius preferably of 10 mm or more preferably of 5 mm. The distance criteria is preferably given in mm the conversion to the corresponding pixel number for a given size of a touch screen is however straightforward. The set of possible coordinate positions for a touchstart for a capacitive sensor preferably spans the coordinate grid of the capacitive surface sensor for which touch events, in particular those creating a touch data point, can be detected. Advantageously, the teaching mode is therefore terminated once the coordinate position of at least one touch data point of a stored touch frame is sufficiently close to any of the possible coordinate position of the coordinate grid of the capacitive surface sensor.

In a further preferred embodiment a visual display indicates the distribution of the touch data points stored in the touch frames generated in the teaching mode.

Particularly preferred the touch screen may display a first color. During the teaching mode, touch events are generated by moving of the capacitive information carrier over said touch screen. It is preferred that for all touch data points stored in the hence generated touch frames, the color of the display is changed to a second color in a predetermined radius around the coordinate position of said touch points of preferably 5 mm or more preferably 2.5 mm. Preferably, by moving the capacitive information carrier over the touch screen and thereby generating new touch events,, the color of the display of the touch screen advantageously changes successively from the first color to the second color. In the sense of the preferred embodiment, by moving the information carrier of the touch screen the display is therefore "swiped free". In a particular preferred embodiment the teaching mode is determined when at least 70 % more preferably at least 90% of the touch screen display the second color. It is preferred that the teaching mode is terminated, when at least 70% more preferably at least 90% of the area of the display of the touch screen is "swiped free". Such a preferred embodiment advantageously leads to a particularly well spread distribution of touch events generated during the teaching mode.

Surprisingly, the distribution of touch events generated and processed to touch frames in the teaching mode therefore leads to a particular fast and accurate matching to a touch frame in the recognition mode. It was particularly surprising that the visualization of the number of stored touch frames leads to an optimal movement of an average user moving the capacitive information carrier over the touch screen, whereby the touch events reflect particularly well the possible positions of the touch patterns on the touch screen of the device.

In a preferred embodiment, the method is further characterized in that touch frames are stored in a touch continuum in the teaching mode according to the time points they represent. As described above, a touch frame is preferably a data structure comprising one or more touch data points and a time stamp representing the time point that the one or more touch data points belong to. A touch continuum is preferably a data structure that represents one or more touch frames in

chronological order according to said time stamp of the touch frames. The touch continuum is advantageously similar to an array data structure. Moreover the touch continuum can be processed and handled surprisingly fast. This applies in particular to operations that compare created touch frames in the recognition mode with numerous touch frames stored in the teaching mode and are chronologically stored in the touch continuum.

In a further preferred embodiment the method is characterized in that from said touch continuum one or more touch frames are selected to be stored in a touch dictionary. A touch dictionary is preferably a data structure that represents a set of one or more touch frames. Preferably the touch dictionary is created by processing a touch continuum comprising created touch frames in the teaching mode. For instance, by preferably using filter criteria on the properties of the touch frames, only touch frames that match those criteria will be assigned to a touch dictionary.

Preferably a touch dictionary represents thus a subset of touch frames of a touch continuum, which are not necessarily in chronological order. Instead in a preferred embodiment, the touch frames comprise one or more touch data points for the same time point. Advantageously, the touch dictionary comprises therefore those touch frames that best characterized the interaction between the capacitive information carrier and the device comprising the capacitive surface sensor in the teaching mode. In particular the touch dictionary represents preferable an array structure and can serve for a fast comparison of touch frames in the teaching mode and in the recognition mode. In a further preferred embodiment it may be preferred that the teaching mode is not just carried out ones the capacitive information carrier is placed for the first time on the device but also in the background during the recognition process. That means that the touch frames generated during the recognition mode are preferably not just used to authenticate the capacitive information carrier, but also to further improve the detection quality. Since the teaching mode takes place again more touch frames which may not have been captured during the initial teaching mode can be added. It is preferred that said touch frames are only added to the touch dictionary in case the authentication during the recognition mode is successful, wherein a successful authentication preferably means that a pre-defined number of touch frames generated in the recognition mode are matched to corresponding touch frames stored in the touch dictionary. This leads to a more precise authentication since more touch frames are integrated. In a further preferred embodiment it be possible to adapt the touch dictionary after at least two teaching modes to contain the best 10.000 touch frames.

In a further preferred embodiment a touch frame from the touch continuum is selected to be stored in the touch dictionary, if it possesses an expected number of touch data points, wherein the expected number of touch data points is at least 3, preferably 4 and particularly preferably 5. Preferably, in the app, a parameter for the expected number of touch data points that a touch frame entails is defined.

Moreover preferably a touch frame of the touch continuum that possesses exactly this number of expected touch data points is selected to be stored in the touch dictionary. Preferably, said expected number of touch data points represents the number of touch events that the information carrier creates on average when brought into contact with the touch screen of the device. In the preferred

embodiment, wherein the electrical conductive layer of the capacitive information carrier represents a touch pattern, said number of expected touch data points is preferably equal to the number of touch points of the conductive layer. Preferably the app does not have to contain however information on the exact shape of the touch pattern. Advantageously, by selecting touch frames that contain a certain number of touch data points for storage in the touch dictionary, the touch frames are selected that best represent the physical appearance of the touch pattern. It was surprising that this selection process represents a very fast operation that robustly diminishes errors. For instance, if for a certain time point the information carrier was not fully placed on the touch screen, the touch frame representing that time point likely contains a fewer number of touch data points than expected. Moreover, if for instance a user accidently places in addition to the information carrier a fingertip on the touch screen during the teaching mode, one or more touch frames may be created that possess more touch data points than expected. Furthermore, due to a fast movement or a bending of the capacitive information carrier touch frames may be created with a number of touch data points diverting from the expected number. Advantageously, the selection of touch frames based upon the number of expected touch data points avoids erroneous touch frames. Moreover, the expected number of touch frames may also be determined by averaging the number of touch data points for all touch frames stored in the touch continuum. Advantageously, in this case not even the expected number of touch data points for a given information carrier has to be known prior to starting the app. Instead, in the teaching mode, the app robustly determines the expected number based upon said averaging procedure. In a further preferred embodiment, a touch frame from the touch continuum is selected to be stored in the touch dictionary, if the minimal absolute distance to a previous touch frame that possesses the same number of touch data points is less than 10 mm, preferably less than 5 mm and more preferably less than 2 mm. Herein preferably the difference in time between a touch frame and the following touch frame is less than 200 ms, preferably less than 100 ms and most preferably less than 50 ms.

The minimal absolute distance between the first touch frame and the second touch frame is preferably calculated as follows. For a first touch data point of the first touch frame the distance to all touch data points in the second touch frame is calculated and the minimal value of those distance values is stored. Next, for a second touch data point of the first touch frame, the distance to all touch data points of the second touch frame is calculated, except for the touch data point for which the distance to the first touch data point of the first touch frame was determined to be the minimal value.

Again the minimal value of those distance values is stored. The procedure is continued for a third, a forth and so on until for the last touch data point of the first touch frame. The minimal absolute distance between the first touch frame and the second touch frame corresponds to the sum of all hence calculated minimal distance values. Herein preferably the distance between two touch data points is calculated as the distance between the coordinate position (X1 ,Y1 ) of the first touch data point and the coordinate position of the second touch data point (X2,Y2) by using any metric preferably by i) using the Pythagorean theorem:

ii) summing the difference in the X and Y coordinates:

(Χ1 - Χ2) + (Υ1 - Υ2)_{! θΓ} iii) by summing the difference square in the X and Y coordinates:

(XI - X2)² + (Yl - Y2)²

In a further preferred embodiment the method is characterized in that at least one touch frame created in the recognition mode is compared with one or more touch frames stored in the touch dictionary. The comparison of a touch frame created in the recognition mode with the touch frames stored in the touch dictionary preferably determines how similar these touch frames are. If the similarity degree is sufficiently high, both touch frames are considered to match. Preferably, this process is continued until a pre-defined number of matching touch frames is found. In this case, the authentication of the combination of the information carrier and the device is preferably considered successful. For a particular accurate authentication it may be preferred that a high number of touch frames is compared. Advantageously, tests have shown that for this comparison the touch dictionary is a particularly well suited data structure. In particular, the selection process of touch frames from a touch continuum, preceding the generation of a touch dictionary, makes the comparison process surprisingly fast. Moreover, it was particular surprising to see that even though the touch dictionary comprises less touch frames than a touch continuum, the comparison of those touch frames with touch frames created by the recognition mode is not only possible with a higher speed, but also with a higher accuracy.

In a further preferred embodiment, the method is characterized in that a hash function assigns hash values to one or more touch frames and that the hash value of at least one touch frame stored in the touch dictionary is compared to the hash value of at least one touch frame created in the recognition mode. Preferably the touch frame is transformed to a string-type data, which can serve as an input for the hash function. More preferably the coordinate position of the touch data points stored in the touch frame are converted to a string-type data. However other parameters characterizing the touch data points in the touch frame such as a diameter, a width, a height, an elliptical minor- and major radius, a focal point or an eccentricity may also be added to the string-type data that characterizes the touch frame. In principle any binary data characterizing the touch frame can be used for the hash function. For instance a touch frame may contain three touch data points with the following coordinate positions (100,100), (200,200) and (300,300). In an example, and without being limited to, the data stored in such a touch frame is transformed to the following string "(100,100)(200,200)(300,300)" representing the coordinates of the three touch data points. Preferably the string-type data is given to the hash function, which transforms the string to a hash, which can serve as an identifier for the touch frame. In principle a number of hash algorithms or hash function can be used to perform this task. Preferably however the hash function may be selected from the group compromising MD5, SHA-1 , SHA-2, SHA-3, Grostl, BLAKE or WHIRPOOL. Herein a particular preferred hash function is the SHA-1 hash function. Applying the SHA-1 hash function on the exemplary string

"(100,100)(200,200)(300,300)" the hash

68164c8c52fac55faf7f38d8b7127f984c6e63f3 results. Other hash functions as the ones listed above, but without being limited to, may create different hashes.

However independent of the exact hash function that is used on the string-type data representing the data stored in the touch frame preferably the hash function creates a hash, that can serves as an identifier for the touch frame. Preferably, said hash representing the touch frame serves as an identifier in a binary tree. Particularly preferred all touch frames stored in the touch dictionary are transformed by a hash function to hashes, which then serve as an identifier in a binary tree. Moreover, during the recognition mode the created touch frames are preferably also transformed to hashes using said hash function. The touch frames created in the recognition mode are then preferably compared to touch frames stored in the touch dictionary by comparing the corresponding hashes. That preferably means that, if the hash for the touch frame created in the recognition mode is found in the binary tree containing the hashes of the touch frames stored in the touch dictionary, the touch frame created in the recognition mode is considered to "match" a touch frame from the touch dictionary. Preferably if a pre-defined number of such matches is reached the recognition mode is terminated and it can be concluded with high confidence that the same information carrier was used during the recognition mode as well as during the teaching mode. Reaching the pre-defined number of matching touch frames therefore advantageously authenticates the combination of the information carrier and the device with a high accuracy. It was surprising, that creating characteristic hashes for each touch frame in the above described preferred manner, enables to compare touch frames with low computation power, while maintaining a high accuracy. For instance for touch frames containing 5 touch data points more than 10 000 different hashes can be created based upon the coordinates of the touch data pointes that uniquely identify each touch frame.

Moreover it was particularly surprising that using hashes the comparison of a touch frame created in the recognition mode with more than 10 000 touch frames stored in the touch dictionary takes less than 100 ms. Herein the organization of hashes in a binary tree saved in particular computation time.

In a further preferred embodiment the touch frame stored in the touch dictionary is compared with a touch frame created in the recognition mode by calculating the minimal absolute distance between both touch frames. Preferably both touch frames are considered to "match" if the minimal absolute distance between the touch frames is less than 5 mm and more preferably less than 2 mm. A minimal absolute distance of 0 mm indicates that the coordinate positions of the touch data points of both touch frames are identical. Preferably touch frames however that are not identical, but for which the minimal absolute distance is less than 5 mm and more preferably less than 2 mm, are also considered a match. It was surprising that even such matches of not identical, but similar touch frames is sufficient to accurately authenticate the combination of the information carrier and the device. Preferably, the number of matches, which are necessary for a successful authentication, is chosen upfront. If the pre-defined number of matches is reached during the recognition mode the authentication of the combination of the information carrier and the device is preferably considered successful. Advantageously, a matching criteria between touch frames that uses a minimal absolute distance, in particular that defines the threshold of the minimal absolute distance at 5 mm, preferably at 2 mm, represents an accurate comparison strategy that is sufficiently fast. Preferably the number of matches, that define a successful identification, can therefore be set to preferably at least one, more preferably more than 3 and most preferably more than 10. Thereby the accuracy of the authentication method is particularly high, while the time that the recognition mode takes is not too large to render the method impractical.

In a further preferred embodiment the method is characterized in that the computational steps to compare the touch frame created during the recognition mode with the touch frames stored in the touch dictionary are performed by the graphics unit processor (GPU) of the device. Preferably the GPU of the device comprise more than 100 cores. In comparison the central processing unit (CPU) of a typical smart device comprising a touch screen possesses one, two or at the most four cores. For instance the HTC One S smart phone comprises two cores since it possesses a dual-core CPU. Using the CPU and performing iteratively the computational steps to compare the touch frames generated during the recognition mode with the touch frames stored in the touch dictionary only one core of the CPU is used. With such a way of linear programming for instance for the HTC One S smart phone the comparison of one touch frame with 10 000 touch frames stored in the touch dictionary by determining the minimal absolute distance takes about 500 ms to 1000 ms. Multi-threading these computational steps to take advantage of the two cores of the HTC One S can reduce the time to about 300 ms. That means it is only possible to compare a few touch frames per second created in the recognition mode to 10 000 touch frames stored in touch dictionary. The time it takes to compare touch frames created in the recognition mode to all touch frames stored in the touch dictionary also depends on the number of touch frames stored in the touch dictionary. If for instance in the teaching mode preferably 10 000 touch frames are stored and compared to the touch frames created in the recognition mode a single recognition process may take round about one hour.

Surprisingly however it is also possible to outsource the calculations on the GPU of the device. Preferably the computational steps to compare a touch frame created in the recognition mode with the touch frames stored in the dictionary is therefore performed by a parallel algorithm taking advantage of the multi-core GPU of the device. Preferably the data of the touch frames stored in the touch dictionary are stored in a linear memory as a primitive data type that is a data type that can be read particularly fast. Preferably said data of the touch frames comprises the coordinate positions and the diameter of the touch data points, but may also comprise additional data characterizing the touch data points such as a width, a height, an elliptical minor- and major radius, a focal point or an eccentricity.

Preferably moreover each of the touch frames of the touch dictionary is compared in parallel using different cores of the GPU to a touch frame created in the recognition mode. To this end for instance on a smart device with an Android operation system the algorithm is run as a RenderScript Kernel, for other operating system similar parallel algorithm scripts may be used. Preferably, the comparing algorithm computes a similarity parameter between each of the touch frames stored in the touch dictionary and the touch frame created in the recognition and saves that similarity parameter preferably in a linear memory list. Preferably said similarity parameter between two touch frames corresponds to the minimal absolute distance between both touch frames, wherein a small value of the minimal absolute distance corresponds to a high degree of similarity and a large value of the minimal absolute distance corresponds to a low degree of similarity. To find the similarity parameter that indicates the highest degree of similarity between any of the touch frames in the touch dictionary and the touch frame generated in the recognition mode, the similarity parameters stored in the linear memory list are compared to each other in parallel using a KernelScript or a different suited algorithm operating in parallel on the GPU. In an example, without being limited to, the similarity parameters may be a set {A,B,C,D,E,F,G,H} of minimal absolute distances, where for the sake of simplicity A<B<C<D<E<F<G<H. For such a set the algorithm preferably compares A to B, in parallel with C to D, E to F and G to H. For each of the comparisons the values representing the higher similarity are kept. In the exemplary case that corresponds to the respective values with a lower minimal absolute distance, thus A,C,E,G. In the next step A is compared to C in parallel with E being compared to G and A and E are kept as the values with the smaller minimal absolute distance. Finally A is compared to E yielding A as the lowest value for the minimal absolute distance for this example. In this example the touch frame in the touch dictionary associated with similarity parameter A, exhibits the highest similarity to the touch frame created in the recognition mode. If the minimal absolute distance of A is smaller than a determined threshold, for instance 5 mm or preferably 2 mm, the comparison of the touch frame created in the recognition mode with the touch frame associated with A would be considered a match. Preferably the touch frame of the touch dictionary associated with the similarity parameter that represents the highest similarity with the touch frame created in the recognition mode is considered a match, if said similarity parameter satisfies the predetermined similarity degree. For example in the preferred case that the similarity parameter is the minimal absolute distance, the similarity condition would be, that the absolute minimal distance is preferably between 0 mm and 5 mm more preferably between 0 mm and 2 mm. It was completely surprising how fast the preferred parallel implementation of the comparison of one touch frame with all touch frames of the touch dictionary can be performed even if a high number of touch frames are compared. For instance for a HTC S smart phone device, comparing a touch frame created during the recognition mode with 10 000 touch frames stored in the touch dictionary by the preferred parallel algorithm takes only 20 ms to 50 ms. This is particularly advantageous, because in said preferred embodiment touch events generated during the recognition mode can be assigned to touch frames with preferably 50 ms or more preferably 20 ms, while the hence generated touch frame can be simultaneously compared to all touch frames in the touch dictionary. Advantageously therefore preferably an extensive data accumulation for the generated touch frames during the recognition mode is avoided. The preferred embodiment performing the comparison of touch frames in the recognition by computing on the GPU in parallel therefore allows for a particular accurate and fast authentication of the combination of the information carrier and the device. In a further preferred embodiment the method is characterized in that the electrically conductive layer of the information carrier is situated in one plane and the information carrier is a substantially flat object. One embodiment can be preferably a card. It is particularly preferred that said capacitive information carrier has a preferable thickness of 0,05 to 1 ,5 mm.

The preferred flat geometry of the capacitive information carrier allows particularly well for a capacitive interaction between the capacitive surface sensor and the information carrier, when brought into contact. Said preferred geometry of the information carrier therefore leads to a fast reading of the conductive pattern of the capacitive information carrier by the device. Moreover, the preferred dimensions of the capacitive information carrier are particularly practical to transport the capacitive information carrier, e.g. a credit card, on a daily basis. For instance, it is preferred that the card can be put into the credit card holder of a wallet. The flat information carrier is therefore particularly well suited to be used according to the method of identification on a frequent basis for activities such as online shopping, gaming or money transfer. Furthermore a substantially flat capacitive information carrier, e.g. a card, can be produced particularly economically by using common printing methods and therefore be produced in large quantities at low cost.

In a preferred embodiment the method is characterized in that the conductive layer of the information carrier is situated in one or more faces of a three dimensional object. In another embodiment the method is characterized in that the conductive layer of the information carrier is situated in one or more planes adapting to the surface of a three dimensional object. It is preferred that the three dimensional object has one or more substantially planar surfaces. It is particularly preferred that the three dimensional object has one or more faces, which are preferably defined as planar surfaces forming the boundary of a three dimensional object. It is furthermore particularly preferred that the faces of the three dimensional object are panels.

It is particularly preferred that at least one face bears a pattern of the electrically conductive layer. In a further embodiment multiple face of the three dimensional object exhibit a pattern of the electrically conductive layer readable by the device comprising the surface sensor. Moreover, preferably a first conductive pattern on a first face of the three dimensional object is galvanically connected to a second conductive pattern on a second face of the three dimensional object. In another preferred embodiment different conductive patterns on different faces are not galvanically connected. In a particular preferred embodiment the conductive patterns on one of the faces of the three dimensional object presents a touch pattern. Particular preferred different touch patterns on different faces of the three dimensional object are galvanically connected by one or more conductive paths. In another preferred embodiment one face of the object contains the touch points and the connecting lines while the coupling area is situated on another face. It is also preferred that touch points and connecting lines are situated on more faces and being electrically connected to at least one coupling area situated on another face. Examples of preferred three-dimensional objects are cubes, cylinders, cones or pyramids. However, also more complex three-dimensional objects with at least one substantially flat surface are preferably suited as a capacitive information carrier. In the sense of the presented invention this may include, but without being limited to, bottles, game figures, telephones, books, mugs, packages, lamps etc. In this preferred embodiment the information carrier may therefore take the shape of any of these objects or other objects. The preferred embodiment of the information carrier serves therefore particularly well to identify products or packages for instance for logistic purposes. It is further preferred that the conductive patterns on the face of the three dimensional objects are not visible, for example because preferably a layer of intransparent material covers the conductive layer. It may be preferred that consumer buying said products or packages, to which a conductive layer is applied, do not see the conductive layer on the products or packages.

Moreover, preferably different touch patterns representing different identification codes may be present on different faces of the three dimensional object. Therefore one information carrier may also trigger one or more actions on the device.

Moreover, advantageously the same three dimensional object may be used to present multiple touch patterns to the device and generate more complex authentication code sequences. Preferably, the authentication code sequence involves the placing of at least two touch patterns in a defined temporal order. Such a complex authentication code sequence leads to a particularly secure

authentication method.

In a further preferred embodiment the method is characterized in that it serves to authenticate one or more users. It is preferred that the successful identification of the combination of the information carrier and the device results in the

authentication of one or more users. Preferably the conductive pattern on the substrate of the capacitive information carrier serves as authentication code for identifying one or more users and the granting of an action or the access of information to said users. It is moreover preferred that the method according to the present invention serves as an authentication method for one or more users and comprises the following steps:

1 ) a user initializes the app in the teaching mode

3) the user brings the capacitive information carrier into contact with the capacitive surface sensor of the device, wherein the information carrier may be moved over the surface sensor

4) generating at least one touch event during the contact of the information carrier with the surface sensor,

5) processing one or more touch events to a coordinate position and a diameter, which corresponds to the position and expansion of at least one touch point of the electrically conductive pattern of the information carrier on the surface sensor at a time point, and storing the coordinate position and the diameter as a touch data point for that time point

6) storing one or more touch data points that correspond to the same time point in a touch frame

6b) storing touch frames in chronological order in a touch continuum

7) selecting one or more touch frames from the touch continuum for storage in a touch dictionary

8) terminating the teaching mode

9) starting the recognition mode

10) said user or a second user brings the capacitive information carrier into contact with the capacitive surface sensor of the device, wherein the information carrier may be moved over the surface sensor 1 1 ) generating at least one touch event during the contact of the information carrier with the surface sensor

12) processing one or more touch events to a coordinate position and a diameter, which corresponds to the position and expansion of at least one touch point of the electrically conductive pattern of the information carrier on the surface sensor at a time point, and storing the coordinate position and the diameter as a touch data point for that time point,

13) storing one or more touch data points that correspond to the same time point in a touch frame

14) comparing at least one touch frame from step 13 with at least one of the stored touch-frames from the touch dictionary and determining the degree of the similarity between both touch frames

15) If the degree of the similarity satisfies a similarity condition, the compared touch frames are considered as a match

16) If the pre-determined number of matched touch frames is reached, the authentication of the user is successful and an action and/or an access authorized

As described above a preferred parameter that quantifies the similarity between two touch frames is the absolute minimal distance and the associated preferred similarity condition is that the absolute minimal distance is smaller than a predefined threshold. This threshold has to be chosen upfront according to the security requirements of the application. The absolute minimal distance is preferably smaller than 5 mm, more preferably smaller than 2 mm and most preferably 0 mm. If the similarity condition is satisfied the comparison is preferably considered a match. The number of matches, which are necessary for a successful authentication are preferably chosen upfront according to the security requirements of the application. If the pre-defined number of matches have been achieved the authentication is successfully completed. In this case preferably an action and/or the access to information is granted to the hence authenticated user.

However the similarity between two touch frames may also be determined in other ways. For instance in another preferred embodiment described above a hash function determines the hash for each touch frame and the similarity between the two touch frames is determined by comparing the corresponding hashes. In this case the preferred similarity condition would be that both hashes are identical. Preferably if the hashes of the touch frames are identical the touch frames are considered to match. The number of matches, which are necessary for a successful authentication are preferably chosen upfront according to the security requirements of the application. If the pre-defined number of matches have been achieved the authentication is successfully completed. Advantageously the preferred

authentication method may allow for the authentication of more than one user for the authorization of the same action and/or access. Preferably the identification code is represented by the conductive pattern of the capacitive information carrier and can therefore be handed from one user to a different user. Preferably however the authentication method may comprise additional steps of authentication than the identification of the capacitive information carrier and the device. For instance the authentication method may comprise an additional step in which the user provides supplemental information as an additional security feature. Such information may preferably comprise, without being limited to a username, a password, biometric data such as a finger print or a retinal scan or a second capacitive information carrier. Advantageously, the additional features preferably augment the security of the authentication method by combining multiple authentication methods. Moreover preferably the supplemental information may distinguish multiple users that are authenticated by presenting the capacitive information carrier to the device. For instance, it may be preferred that multiple users are authorized to perform a money transfer from a given device. A capacitive information carrier according to the present invention may serve as an identification code for the authentication of these users on the device. All users with access to said information carrier are preferably authenticated to transfer money from said device. However, it may be preferable that each of the users is authorized to transfer e.g. a different amount of money or from a different account. Said supplemental information may preferably provide an additional authentication method by which for example different authorization levels may be granted for different users.

Brief description of the drawings

Fig. 1 Schematic drawing for a preferred embodiment of a device

comprising a capacitive surface sensor and a capacitive information carrier Fig. 2, 3 Schematic representation of preferred touch events

Fig. 4 Schematic representation of a preferred processing of touch events to touch frames and a touch continuum

Fig. 5 Schematic representation of a preferred embodiment of a touch data point

Fig. 6 Schematic representation of a preferred embodiment of a touch frame

Fig. 7 Schematic representation of a preferred embodiment of a touch

continuum

Fig. 8 Schematic representation of a preferred embodiment of a selection of touch frames for the storage in a touch dictionary

Fig. 9 Schematic representation of a preferred embodiment of a touch

dictionary

Fig. 10 Schematic representation of preferred determination of the minimal absolute distance between two touch frames

Schematic representation of a preferred embodiment of the information carrier with multiple touch patterns on the faces of a three dimensional object

Schematic representation of a preferred embodiment of the method to authenticate one or more users

Fig. 1 is a schematic representation of a device 10 that comprises a touch screen 12 and a capacitive information carrier 14. The depicted preferred embodiment of the device 10 is a smart phone capable of processing data and running software such as an app comprising a teaching and a recognition mode. A particularly preferred embodiment of a capacitive surface sensor is a touch screen. Most smart phones, such as the one depicted in Fig. 1 , comprise capacitive touch screens. The capacitive information carrier 14 comprises an electrically conductive touch pattern 18 situated on an electrically non-conductive substrate 16. A particularly preferred embodiment of the electrically conductive layer is a touch pattern. Fig. 1 depicts the touch pattern 18 as an example. As described above preferably a touch pattern is interpreted by the device as the simultaneously touch of one or more fingertips, when brought into contact with a touch screen. To this end preferably a touch pattern comprises one or more touch points, one or more conductive paths and/or one or more coupling areas. As detailed above a touch point preferably resembles a fingertip in terms of size, shape, resistivity, conductivity and/or capacity. In Fig. 1 a particularly preferred shape for touch points is depicted. In this example the touch points 20 have a circular shape with a diameter of 6 mm to 10 mm. The example of the touch pattern 18 in Fig. 1 comprises five touch points 20, which are connected via five conductive paths 22 with each other as well as with one coupling area 24. Preferably the information carrier 14 is positioned on the device 10, so that all five touch points 20 of the exemplary touch pattern 18 depicted in Fig. 1 are in contact with the touch screen 12. Preferably, during this process, a user touches the coupling area 24. Thereby the potential of the touch pattern 18 is advantageously set onto the potential of said user. In particular the potential of the touch points 20 are thereby set onto the potential of the user and cause a local change in capacitance on the touch screen similar as a finger touch. The device therefore preferably interprets the touch pattern 18 in Fig. 1 as five touches. In this case the positioning of the five touch points 20 can advantageously serve as a unique identification code that is applied on the capacitive information carrier 14 and can be read by the device. As described above the bringing into contact of a touch pattern with the device preferably results in the generation of touch events.

Fig. 2 is a schematic representation of examples of touch events 26 that are preferably triggered, when an information carrier is brought into contact with a device. For instance in Fig. 2 at time point t1 two touchstarts 28 are generated representing the positioning of a first and a second touch point on the touch screen at the coordinate position (X=10, Y=10) and (X=10, Y=20). At time point t2 a third touchstart 28 is generated representing the positioning of a third touch point on the touch screen at the coordinates (X=10, Y=10). At time point t3 a touchmove 30 is generated representing the moving of the first touch point to a new position on the touch screen to (X=20, Y=10). At time point t4 a touchend 32 is created representing the removing of the third touch point from the touch screen. The touch events 26 are preferably processed to touch frames. A touch frame at time point t6, highlighted by the dotted line, for example comprises two touch data points (id 1 and id2) and has the time stamp t6. The first touch data point has the coordinates (X=20, Y=10) and represents the position of the first touch point on the touch screen. The second touch data point contains the coordinates (X=20, Y=10) and represents the position of the second touch point on the touch screen. However it is also possible to process the touch events 26 at different time points. Although not shown in Fig. 2 e.g., a touch frame with the time stamp t3 would be generated containing three touch data points with the coordinates (X=20,Y=10), (X=10,Y=20) and (X=10,Y=10).

Fig. 3 is another schematic representation of examples of touch events 26 that are preferably triggered, when an information carrier is brought into contact with a device. Similar to Fig. 2 in Fig. 3 a first and a second touch start 28 is generated at time point t1 corresponding to the position of a first and a second touch point on the touch screen. At time point t2 a second third touch start 28 is generated. Again similar to Fig. 2 in Fig.3 at time point t3 a touch move 30 is generated that represents the moving of the first touch point to a new coordinate position. However in Fig. 3 at time point t6 a touchcancel 34 is generated. The touchcancel 34 leads to the termination of all touch data points. While a touch frame with a time stamp t4 prior to the touchcancel 34, would contain three touch data points, a touch frame with a time stamp t7, indicated by the dotted line, contains no touch data points. Fig. 4 is a preferred schematic representation of how touch events are preferably processed to touch frames containing touch data points. The exemplary touch data points 36 contain data such as a coordinate position (X,Y) or a diameter. Preferably said data characterizes the position of a touch point on the touch screen that corresponds to said touch data point 36. Multiple touch data points 36 for the same time point are stored in a touch frame 38, having a time stamp of said time point.

Moreover touch frames 38 with different time stamps are preferably stored in chronological order according to said time stamps in a touch continuum 40.

In Fig. 5 a schematic example of a touch data point 36 is illustrated.

Fig. 6 shows the touch frame 38 as a schematic example of a touch frame containing five touch data points 36.

Fig. 7 depicts a touch continuum 40 as a schematic representation, which contains six different touch frames for successive time points. Each touch frame contains five touch data points 36 and in the schematic representation touch data points 36 that belong to the same touch frame are depicted by the same grey scale.

Fig. 8 shows a schematic representation of the generation of a touch dictionary 42 from of a touch continuum 40. In the example the touch continuum 40 contains eight touch frames 38, however based upon a selection rule only five touch frames 38 are selected to be stored in the touch dictionary 42. Preferred selection rules are described in detail above and may be based e.g. on the number of touch data points that a touch frame possesses.

In Fig. 9 the touch dictionary 42 is a schematic representation of a projection of a touch dictionary. Preferably touch dictionaries may contain more than 10 000 touch frames. In the schematic presentation of the touch dictionary 42, single touch frames and touch data points are not distinguishable.

Fig. 10 is a schematic representation of how the minimal absolute distance between two touch frames 38 is calculated. In the example each of the two touch frames 38 contains five touch data points 36, represented either by an unfilled circle or a dark filled circle. For each of the touch data points 36 in the first touch frame 38 the corresponding closest touch data point 36 in the second touch frame is determined. The absolute distance is calculated by the sum of distances between these pairs of touch data points 36. Herein di is the distance between the first touch data point 36 of the first touch frame 38 and the first touch data point 36 of the second touch frame 38 and so on.

Fig. 1 1 is a schematic representation of a preferred embodiment of the information carrier with multiple touch patterns on the faces of a three dimensional object. In the example the three-dimensional object is a cuboid and three out of the six faces of the cuboid are visible. Two of the visible faces show a touch pattern 18. Each of the two touch patterns 18 comprises five touch points 20, five conductive paths 22 and one coupling area 24. In the example the touch patterns 18 that are situated on the neighboring faces are not galvanically connected. In other preferred embodiments however touch patterns may also be connected. Such an exemplary cuboid may for instance represent a package or a cardboard box. Other preferred embodiments are described in more detail above. Fig. 12 a-h depicts schematically preferred steps of a method that serves to authenticate a user by identifying the combination of a touch screen device and a capacitive information carrier. Fig. 12a shows a smart phone as a preferred example of a device 10 comprising a capacitive surface sensor 12. The app comprising a teaching mode and a recognition mode is installed on the device 10. Fig. 12b shows the user holding a capacitive information carrier 14 in form of a card. In Fig. 12c the user starts the app in the teaching mode. Next, as shown in Fig. 12d, the user brings the capacitive information carrier 14 in contact with the touch screen 12 of the device 10. The user may move the information carrier 14 over the touch screen 12, while the device 10 detects and processes the thereby generated touch events. A progress bar displays the progress of the teaching mode. As detailed above in a preferred embodiment, the progress bar reflects the number of so far generated touch events or created touch frames compared to the number aspired. In Fig. 12e, the recognition mode is started. As shown in Fig. 12g, in the recognition mode, the app may ask the user for supplemental information such as a user name, a password or a birth date. Subsequently, as depicted in Fig. 12g, the app prompts the user to bring the information carrier 14 into contact with the device 10.

Preferably the user moves the information carrier 14 over the touch screen 12 of the device 10. During this process touch events are generated and preferably processed to touch frames. Moreover, as detailed above, in the recognition mode the app compares the created touch frames with touch frames stored in the touch dictionary. If the app can successfully match a touch frame created in the recognition mode with at least one touch frame in the touch dictionary the authentication is completed. The number of matches needed for a successful authentication and if needed a determined similarity degree is preferably chosen upfront according to the security requirements of the application. If the pre-defined number of matches have been achieved, the authentication is successfully completed. As depicted in Fig. 12h a successful authentication may grant an action for the user such as the transaction of money.

List of reference numbers

10 device comprising a touch screen

12 touch screen

14 capacitive information carrier

16 substrate of the information carrier

18 touch pattern

20 touch point

22 conductive path

24 coupling area

26 touch event

28 touchstart

30 touchmove

32 touchend

34 touchcancel

36 touch data point

38 touch frame

40 touch continuum

42 touch dictionary

Claims

1. A method for the identification of a combination of a capacitive information carrier and a device comprising a capacitive surface sensor, comprising: a. providing the capacitive information carrier comprising at least one electrically conductive layer, wherein the pattern of the electrically conductive layer represents information readable by the capacitive surface sensor b. providing the device comprising the capacitive surface sensor and a data processing program ('app') comprising at least one teaching mode and at least one recognition mode c. bringing the capacitive information carrier into contact with the capacitive surface sensor in the teaching mode, whereby at least one touch event is generated on the device and processed and stored by the app d. bringing the capacitive information carrier into contact with the capacitive surface sensor in the recognition mode, whereby at least one touch event is generated on the device and processed by the app e. comparing at least one of the processed touch events generated in the teaching mode with at least one processed touch event generated in the recognition mode.

2. The method according to claim 1 , characterized in that one or more touch events are processed to create a touch frame.

3. The method according to any of the preceding claims, wherein in the

teaching mode more than 100, preferably more than 1 ,000 and more preferably more than 10,000 touch events are generated, processed and stored.

4. The method according to any of the preceding claims, wherein the assignment of touch events to a touch frame is performed at time intervals of less than 1000 ms, preferably less than 200 ms and more preferably less than 50 ms.

5. The method according to any of the preceding claims, wherein in the

teaching mode more than 100, preferably more than 1 ,000 and more preferably more than 10,000 touch frames are created and stored.

6. The method according to any of the preceding claims, wherein the touch frames created in the teaching mode are assigned to a touch continuum as a chronological set.

7. The method according to any of the preceding claims, wherein one or more touch frames from said touch continuum are selected to be stored in a touch dictionary.

8. The method according to any of the preceding claims, wherein a touch frame from the touch continuum is selected to be stored in the touch dictionary, if it possesses an expected number of touch data points, whereby the expected number of touch data points is at least 3, preferably 4 and particularly preferably 5.

9. The method according to any of the preceding claims, wherein a touch frame from the touch continuum is selected to be stored in the touch dictionary, if the minimal absolute distance to the previous touch frame that contains the same number of touch data points is less than 10 mm, preferably less than 5 mm and more preferably less than 2 mm.

10. The method according to any of the preceding claims, wherein at least one touch frame created in the recognition mode is compared with at least one touch frame stored in the touch dictionary.

11. The method according to any of the preceding claims, wherein a hash function assigns hash values to one or more touch frames and that the hash value of at least one touch frame stored in the touch dictionary is compared to the hash value of at least one touch frame created in the recognition mode.

12. The method according to any of the preceding claims, wherein a touch frame stored in the touch dictionary is compared with a touch frame created in the recognition mode by calculating the minimal absolute distance between both touch frames.

13. The method according to any of the preceding claims, wherein the

computational steps to compare the touch frame created during the recognition mode with the touch frames stored in the touch dictionary are performed in parallel by the graphics unit processor (GPU) of the device.

14. The method according to any of the preceding claims, wherein the

electrically conductive layer of the information carrier is situated on a substantially flat object.

15. The method according to any of the preceding claims, wherein the

electrically conductive layer of the information carrier is situated in one or more planes adapting to the surface of a three dimensional object.

16. The method according to any of the preceding claims, wherein the method serves to authenticate one or more users.