Enrollment device and method for facilitating biometric template enrollment

Abstract

According to a first aspect of the present disclosure, a registration device is provided, comprising: a token interface unit, configured to couple the registration device to an external user authentication token; a user interface unit, configured to provide visual information to a user through a plurality of optical output elements, wherein the visual information indicates the progress of the biometric template registration in the authentication token; and a user interface control unit, configured to receive input data indicating the progress from the authentication token through the token interface unit, and to control the user interface unit using the input data.

Description

Technical Field

[0001] The present disclosure relates to a registration device. In addition, the present disclosure relates to a method for facilitating registration of a biometric template, and to a corresponding computer program. Background Art

[0002] Fingerprint sensing devices such as capacitive fingerprint sensors can be integrated into user authentication tokens, such as smart cards. In order to personalize such user authentication tokens, fingerprint reference data should be registered in the user authentication token. More specifically, the fingerprint template should be stored in the security element of the token so that in operation, the captured fingerprint can be compared with the template to authenticate the user. The security element can be, for example, an embedded chip, more specifically, a tamper-proof integrated circuit with an installed or pre-installed smart card-level application (such as a payment application) with specified functions and specified security levels. In addition, the security element can implement security functions such as encryption functions and authentication functions. The registration of fingerprint reference data is usually performed under supervision in a secure environment, such as a banking location. This process is usually inconvenient and time-consuming for the user. Therefore, it is necessary to facilitate the registration of fingerprint reference data into the user authentication token of the described type. Summary of the invention

[0003] According to a first aspect of the present disclosure, a registration device is provided, comprising: a token interface unit, configured to couple the registration device to an external user authentication token; a user interface unit, configured to provide visual information to a user through a plurality of optical output elements, wherein the visual information indicates the progress of the biometric template registration in the authentication token; and a user interface control unit, configured to receive input data indicating the progress from the authentication token through the token interface unit, and to control the user interface unit using the input data.

[0004] In one embodiment, the optical output elements are organized in a linear array, or the optical output elements are organized in a circular array.

[0005] In one embodiment, the optical output element is a light emitting diode.

[0006] In one embodiment, the optical output element has different colors associated with different types of user feedback.

[0007] In one embodiment, different subsets of optical output elements are associated with different types of user feedback.

[0008] In one embodiment, at least one of said optical output elements is configured to flash.

[0009] In one embodiment, at least one of the optical output elements indicates successful registration of the biometric template in the authentication token.

[0010] In one embodiment, at least two optical output elements are associated with the iconic representation of the serial number.

[0011] In one embodiment, the registration device further comprises a power source, such as a battery or a supercapacitor.

[0012] In one embodiment, the biometric template is a fingerprint template.

[0013] In one embodiment, a template registration system comprises a registration device of the kind set forth and a user authentication token.

[0014] In one embodiment, the user authentication token is configured to detect finger touch and finger lift-off.

[0015] In one embodiment, the user authentication token is a smart card, a wearable device, a mobile phone, or a laptop.

[0016] According to a second aspect of the present disclosure, a method for facilitating biometric template registration is conceived, the method comprising: coupling a registration device to an external user authentication token via a token interface unit; providing visual information to a user via a plurality of optical output elements included in a user interface unit of the registration device, the visual information indicating the progress of biometric template registration in the authentication token; receiving, by a user interface control unit of the registration device, input data indicating the progress from the authentication token via the token interface unit, and controlling the user interface unit using the input data.

[0017] According to a third aspect of the present disclosure, there is provided a computer program comprising executable instructions which, when executed, carry out or control a method of the kind set forth. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments will be described in more detail with reference to the accompanying drawings, in which:

[0019] Figure 1 An illustrative embodiment of a registration device is shown;

[0020] Figure 2 An illustrative embodiment of a method for facilitating biometric template enrollment is shown;

[0021] Figure 3 An example of a template registration system is shown;

[0022] Figure 4 An example of capturing fingerprint features with a small area sensor is shown;

[0023] Figure 5Examples of validation and reference templates are shown;

[0024] Figure 6 An example of a fingerprint template registration and verification system is shown;

[0025] Figure 7 An illustrative embodiment of a registration device is shown;

[0026] Figure 8 An illustrative embodiment of a template registration system is shown;

[0027] Fig. 9 An illustrative embodiment of a template registration process is shown;

[0028] Fig. 10A An illustrative embodiment of a registration device housing is shown;

[0029] Fig. 10B Another exemplary embodiment of a registration device housing is shown;

[0030] Fig.11A An illustrative embodiment of an iconic representation of a sequence number is shown;

[0031] Fig. 11B shows an illustrative embodiment of a linear array of optical output elements;

[0032] Fig.12 shows the manner in which a registration device is coupled to an authentication token;

[0033] Fig.13 An illustrative embodiment of a fingerprint image capture sequence is shown;

[0034] Fig.14 An illustrative embodiment of a progress indicator transition state is shown;

[0035] Fig.15 An illustrative embodiment of a display control system is shown;

[0036] Fig.16A shows a signal timing diagram of a display control system;

[0037] Fig. 16B Another illustrative embodiment of a display control system is shown. DETAILED DESCRIPTION

[0038] Fingerprint sensing devices, such as capacitive fingerprint sensors, may be integrated into user authentication tokens, such as into smart cards. In order to personalize such user authentication tokens, fingerprint reference data should be registered into the user authentication token. More specifically, a fingerprint template should be stored in a secure element of the token so that in operation, a captured fingerprint can be compared with the template to authenticate the user. The registration of fingerprint reference data is usually performed in a secure environment, such as at a banking location, under supervision. This process is usually inconvenient and time-consuming for the user. Therefore, there is a need to facilitate the registration of fingerprint reference data into user authentication tokens of the kind described.

[0039] More specifically, tokens such as smart wearable devices or smart cards with fingerprint-based user authentication functions require the user to register his biometric credentials (i.e., fingerprint templates) as reference data for subsequent verification of the token. In order to have sufficient storage space, sensitive biometric credentials must be securely stored in such fingerprint-authenticated tokens. Currently, this payment token registration process requires an external computer, smartphone or Internet connection, or requires registration at a bank branch. From a convenience point of view, it is best to perform fingerprint registration on the token in a private environment, i.e., at the location of the token holder, without compromising the security level of the token. To this end, the fingerprint template should be securely stored in a secure element embedded in such a token. However, before enabling this registration of the fingerprint template, the user's identity should be verified in some way so that the correct fingerprint template is registered, rather than the template of a malicious person (e.g., when the token has been stolen). As mentioned, this identity authentication is usually performed at the location of the token issuer (e.g., a bank), which is inconvenient and time-consuming for the user.

[0040] Figure 1An illustrative embodiment of a registration device 100 is shown. The registration device 100 comprises a token interface unit 102 and a user interface control unit 104 operatively coupled to each other. In addition, the registration device 100 comprises a user interface unit 106 operatively coupled to the user interface control unit 104. The token interface 102 is configured to couple the registration device 100 to a user authentication token (not shown) external to the registration device 100. The user interface unit 106 is configured to provide visual information to the user through a plurality of optical output elements (not shown), wherein the visual information indicates the progress of the registration of the biometric template in the authentication token. In addition, the user interface control unit 104 is configured to receive input data indicating the progress from the authentication token through the token interface unit 102, and to control the user interface unit 106 using the input data. Thus, it is achieved that the user can perform the registration process by himself, i.e. without the need for supervision at the token issuer's location. In addition, by visual feedback on the registration progress, it is achieved that the user is correctly guided to complete the registration process. This is particularly advantageous in the case where a relatively small sensor (e.g., a fingerprint sensor having a size of 8 mm×8 mm or less) must be used to register the biometric template.

[0041] Figure 2 An illustrative embodiment of a corresponding method 200 for facilitating biometric template enrollment is shown. The method 200 comprises the following steps: at 202, coupling an enrollment device to a user authentication token via a token interface unit, at 204, providing visual information to a user via a plurality of optical output elements included in a user interface unit of the enrollment device, the visual information indicating the progress of biometric template enrollment in the authentication token, and at 206, receiving input data indicating the progress from the authentication token via the token interface unit by a user interface control unit of the enrollment device and controlling the user interface unit using the input data.

[0042] Figure 3An example of a template registration system 300 is shown. The system 300 includes a registration device 302 and a fingerprint authentication token 304. The registration device 302 facilitates the registration of a fingerprint template in the fingerprint authentication token 304. The fingerprint authentication token 304 contains a fingerprint sensor 306 configured to capture a fingerprint image. Typically, features are extracted from the fingerprint image. Feature extraction is the process of extracting a biometric feature from a fingerprint image. The feature extraction process produces a fingerprint template, which is a data structure that encodes the biometric feature. The fingerprint template is then input into a matcher, which will match the fingerprint template as a reference template. After a positive match, the user will be successfully authenticated. However, before this authentication process can be applied, the fingerprint authentication token 304 should contain a reference template. The creation and storage of this reference template is called template registration. Therefore, the purpose of the registration device 302 is to facilitate the creation of a reference representation of at least one of the token holder's fingerprints and to store this representation securely within the fingerprint authentication token 304.

[0043] Figure 4 An example of capturing fingerprint features with a small area sensor 400 is shown. Fingerprint sensors cover a large area and are therefore expensive. In order to provide an economically viable authentication solution, the sensor size needs to be reduced so that the sensing area is significantly smaller than the fingerprint itself. In the case of such a small area fingerprint sensor, the area of ​​the fingerprint sensor may not be sufficient to capture all features of the fingerprint with only one fingerprint sample. Therefore, multiple samples are collected while slightly changing the position of the finger relative to the fingerprint sensor. As a result, the features of the fingerprint are distributed over multiple fingerprint samples.

[0044] Figure 5Examples of verification and reference templates 500, 502 are shown. When a fingerprint authentication request is made, the identity claim of the token holder can be verified by comparing the token holder's real-time fingerprint sample and its features with a securely stored reference template that includes a complete feature set of the token holder's fingerprint. A feature set is a collection of features. Such features can be, for example, fingerprint feature points, ridge directions, and ridge distances, where features can be described by their type, location, and characteristics. In order to facilitate the process of verifying identity claims, fingerprint samples and their extracted features are organized in a template that includes a feature set. Depending on the type of template, the number of feature sets contained may vary. In the case of a fingerprint, a feature set may include a list of fingerprint feature points characterized by fingerprint feature point type, location, and angle / direction in a reference plane. A reference template may include multiple feature sets, while a verification template may include only a single feature set representing the biometric features of a single finger. The smaller the sensor area relative to the size of the fingerprint, the more feature sets are required, and therefore features are required to form a reference template. In the case of an 8mm x 8mm sensor area, for example, approximately 12 to 16 feature sets, including 6 to 10 features, may be required per finger to produce a reference template that promotes good biometric performance. For a sensor with an 8mm x 8mm sensing area, this can total 128 acquired features, which may be derived from up to 35 fingerprint feature points. Fingerprint feature points can produce multiple feature detections due to shifts and rotations.

[0045] Figure 6 An example of a fingerprint template registration and verification system 600 (also referred to as a biometric subsystem) is shown. The biometric subsystem 600 of a fingerprint authentication token may be configured to permanently store reference templates and temporarily store verification templates. The biometric system may be operated in at least one of a registration and verification mode. In the registration mode, a reference template may be generated from many fingerprint samples and securely stored, while in the verification mode, a verification template may typically be generated from at least a single fingerprint sample. To generate a template for a single finger, the following steps may be performed:

[0046] Collecting fingerprint image samples through fingerprint sensor 602;

[0047] Preprocessing 604 the acquired image samples to optimize the samples for feature extraction 606;

[0048] Extracting 606 one or more feature sets of the one or more optimized images;

[0049] • Compile 608 the extracted feature set into a single template.

[0050] In the case of enrollment, the created reference template including many feature sets may be securely stored in a reference template database 610 within the biometric token. In the case of verification, the created verification template including only a single feature set may be forwarded to a matcher 612 embedded in the biometric token. The matcher 612 may retrieve a reference template from the reference template database 610 and may compare the reference template to the verification template. The matcher 612 may generate a similarity score that may indicate the probability that the verification template and the reference template have been created from a fingerprint sample of the same finger of the same token holder. Finally, the similarity score provided by the matcher 612 may be compared 614 to a minimum acceptance score (score threshold 616) that may be required to support the identity claim of the token holder. If the similarity score is, for example, equal to or above the score threshold 616, the authentication may be considered successful, otherwise the authentication may be considered failed.

[0051] Registration can be performed as an assisted registration at a registration agency, or as a self-service registration at a location determined by the token holder (e.g., at home). In order to facilitate registration, the token holder should go to the registration agency, which may be inconvenient. Therefore, many token holders prefer self-service registration rather than assisted registration. For self-service registration, the token holder must implement it through the following operations of the registration device:

[0052] Configure the fingerprint authentication token to enrollment mode;

[0053] · Performing the steps required to generate a reference template from multiple fingerprint samples of one or more fingers;

[0054] Securely store the reference template in a fingerprint authentication token;

[0055] After registration, verifying the authentication token can verify the identity claims of the real token holder.

[0056] In order to achieve good biometric performance with a small area sensor, enough enrollment samples must be collected to produce a good reference template. Cost constraints require that the sensing area be as small as possible, which means that as the sensor area shrinks, more and more enrollment samples must be collected. Without providing meaningful feedback to the token holder, the token holder may become overwhelmed or even annoyed if the feedback is not as expected, and may not complete the enrollment process. For thin, small, lightweight and low-cost enrollment devices, meaningful feedback known from mobile devices with text or graphic displays may not be feasible.

[0057] Additionally, in the case of smaller fingerprint sensors, very limited user feedback may be insufficient when, for example, more than six samples are required to provide good biometric performance, for example, due to the need to instruct the user to move their finger to provide various samples. For security reasons, tokens capable of self-registration may only be configured for one-time registration. In this case, a failure during registration due to an inadequate user interface may render the token unusable, requiring expensive replacement by the token issuer. In the case of authentication tokens with embedded feedback indicators, the number of samples collected per finger may be limited to six or fewer. If good biometric performance must be achieved with such a low number of samples, a fingerprint sensor with a resolution of at least 80 mm would be required. 2 The invention relates to a fingerprint sensor with a sensing area of ​​​​a small size, which may not be feasible or cost-effective for some tokens (e.g., smart cards and wearable devices). Therefore, according to the present disclosure, a user feedback element is integrated into the registration device, thereby facilitating the generation of low-cost biometric tokens while also facilitating a template registration process that is convenient for users.

[0058] Figure 7 An illustrative embodiment of a registration device 700 is shown. The registration device 700 includes a microcontroller 702, a power supply unit 704, at least one feedback indicator 706, and a progress bar 708. According to the present disclosure, the progress bar 708 may include a plurality of optical output elements (not shown) through which visual information indicating the progress of the biometric template registration is transmitted to the user. The feedback indicator 706 may also include an optical output element, which may be configured, for example, to provide visual information about error conditions. In a practical and effective embodiment, the power supply unit 704 is an integrated power source, such as a battery or a supercapacitor.

[0059] Figure 8 An exemplary embodiment of a template registration system 800 is shown. Figure 7 In addition to the registration device 700 shown in , the system 800 also includes a fingerprint authentication token 802. According to the present disclosure, the registration device 700 includes a token interface unit (not shown), which is configured to couple the registration device 700 to the fingerprint authentication token 802 (i.e., a fingerprint-based user authentication token). In this example, the token interface unit is a contact-based interface that complies with the technical standard ISO / IEC 7816, through which data can be exchanged with the authentication token 802 and power can be provided to the authentication token 802. The fingerprint authentication token 802 includes a security element 804, a biometric microcontroller 806, and a fingerprint sensor 808.

[0060] exist Figure 8In the illustrated registration setting, the fingerprint authentication token 802 may be configured to receive control commands from the registration device 700. In addition, the fingerprint authentication token 802 may be configured to provide response information to the registration device 700. The registration device 700 may be configured to process the received response information; supplement the response information with information generated by the registration device 700 itself; and provide corresponding user feedback through the progress bar 708 and the supplementary feedback indicator 706. The progress bar 708 may be composed of various feedback elements (i.e., optical output elements), thereby forming a display.

[0061] Control commands can be configured to stimulate the authentication token to do the following:

[0062] Check the normal status of the fingerprint authentication token;

[0063] Configure the authentication token to wait for a finger touch and capture a fingerprint sample when a touch is detected;

[0064] Preprocess the collected fingerprint samples and extract biometric features;

[0065] Compile reference templates based on extracted biometric features;

[0066] Compile verification templates based on extracted biometrics;

[0067] Configure the authentication token to compare the verification template to the reference template and determine whether the token holder is authentic or an imposter;

[0068] Permanent storage of reference templates.

[0069] The response information may indicate:

[0070] ·Approve the orders received;

[0071] One or more errors during command transmission;

[0072] The normal state of the fingerprint authentication token;

[0073] The fingerprint authentication token has detected a finger touch;

[0074] The fingerprint authentication token has detected that the finger has been lifted off;

[0075] The fingerprint authentication token has collected fingerprint samples;

[0076] Count of successfully collected fingerprint samples;

[0077] The serial number of the finger being registered;

[0078] Verify the matching results of the template with the reference template and further failure conditions:

[0079] οRegistration successful;

[0080] οCritical power conditions of the registration device;

[0081] ο Tokens that have been registered and locked for further registration;

[0082] ο Token-less communication;

[0083] οToken failure;

[0084] ο Collection errors;

[0085] ο Validation errors;

[0086] οRegistration errors;

[0087] οTimeout error.

[0088] Fig. 9 An illustrative embodiment of a template registration process 900 is shown. After power-up and self-test, an external "Finger-Loop" may be started. For each finger to be registered, an internal "Sample-Loop" may be executed. The "Sample-Loop" may collect the required number of "Max_Samples", may check whether the sample quality is capable of extraction, if so, may extract the relevant feature set, and may add the relevant feature set to the temporary template. If the sample quality is not acceptable, the sample capture may be repeated. When all feature sets of the "Max-Sample" samples have been added to the temporary template, additional samples may be collected and used to generate a verification template. Next, the verification template may be verified against a temporary reference template. In the case of positive verification, the temporary reference template may be judged as acceptable and permanently stored; otherwise, the "Sample_Loop" may be repeated a predefined number of times. When the "Finger-Loop" has successfully executed the number of times indicated by "Max_Finger", the registration may be completed. In order to avoid infinite looping in error situations, error situations such as a maximum number of low-quality samples per "Sample_Loop" and a maximum number of unsuccessful "Sample_Loops" may provide loop exit conditions.

[0089] If the fingerprint authentication token is configured to perform those steps that are not performed by the registration device, the registration device may not have to control all execution steps. The registration device will control the steps of power-up, registration device self-test, and stimulation of the external "Finger_Loop". In addition, the registration device will perform the reception, decoding and display of response information. Because the specific requirements given by the payment network provider for the registration procedure can be fully handled by the token, it is beneficial to let the authentication token control as many of these steps as possible, as this will help, for example, in standardization of registration devices. Standardization may require standardized commands to start self-service registration and a standardized set of response messages that may cover all feedback information that will be provided to the token holder.

[0090] In one embodiment, the optical output elements are organized in a linear array, or the optical output elements are organized in a circular array. Both linear arrays and circular arrays can produce practical and effective embodiments that do not take up too much space and are relatively easy to manufacture. For example, such arrays can be easily integrated into the housing of the registration device. In addition, in a practical and effective embodiment, the optical output elements are light emitting diodes. Light emitting diodes are small and energy-efficient.

[0091] Fig. 10A An illustrative embodiment of a registration device housing 100 is shown. In this embodiment, the optical output elements are organized in a linear array. It should be noted that the dimensions shown are examples only; the skilled person will appreciate that other dimensions are possible.

[0092] Fig. 10B Another illustrative embodiment of a registration device housing 1002 is shown. In this embodiment, the optical output elements are organized in a circular array. It should be noted that the dimensions shown are examples only; the skilled person will appreciate that other dimensions are possible.

[0093] Thus, all components forming the registration device may be comprised in a housing in which the progress indicator is embedded. The volume of the housing may be less than 20 cm 3. The weight of the registration device can be small enough to ensure that a fingerprint authentication token coupled to the registration device can operate in a very similar manner as providing a token (e.g., a smart card) to an authentication terminal for authentication. Therefore, a fingerprint sample collected by this device can have a very similar mass to a sample collected when the token is provided to the authentication terminal, which may result in a low rejection rate (FRR). The registration device can be equipped with an energy storage unit, such as a primary battery, a secondary battery, or a supercapacitor. A good example of such an energy storage device is a CR2016 lithium button battery. In order to keep the housing thin, the user interface can be constructed of thinner optical feedback indicators, such as very thin light emitting diodes (LEDs). Other displays such as LCD displays will require thicker housings and more complex controls, but these are not excluded. Therefore, other optical output elements can also be used instead of LEDs. The registration progress can be symbolized in an analog style, i.e., any unstable properties such as flickering are not applied, thereby producing a stable display. The analog progress indicator is also easier to understand for technically unskilled token holders.

[0094] Fig. 10A and 10B Two embodiments of such user interfaces are shown. Fig. 10A A progress indicator including linearly organized feedback elements is shown, and Fig. 10B A progress indicator comprising feedback elements organized in a circle is shown. A circular configuration may better represent a reproducing finger sampling cycle, but may be more complex to integrate into a registration device.

[0095] Fig.11A An illustrative embodiment of an iconic representation 1100 of a serial number is shown. Fig. 10A In the illustrated embodiment, the feedback elements constituting the progress indicator are marked with an iconized representation of their serial number, for example, progress bar element 1 may be marked with one icon element, progress bar element 2 may be marked with two icon elements, and so on. Thus, in one embodiment, at least two optical output elements are associated with an iconized representation of the serial number. Fig.11A As shown, this allows for a simple link to the written feedback message provided by the supplementary user manual. Experimental results with test subjects show that such iconized markings make it easier for token holders to identify the corresponding text message in the user manual, especially when the messages can be sorted according to the ordinal number of the relevant icon element. This approach can also simplify the production and maintenance of such user manuals.

[0096] In one embodiment, the optical output element has different colors, which are associated with different types of user feedback. This helps to provide sufficient feedback to the user. For example, a red indicator can be used to indicate an error situation, while a green indicator can be used to indicate a successful verification. Therefore, it may be beneficial to assign meaningful colors to the feedback indicator element, such as the colors mentioned in Table 1. Considering that specific colors such as indicating failure, success, and neutrality may vary from country to country, this color assignment may be adjusted according to local requirements. However, token holders who cannot distinguish the applied colors (e.g., color blind token holders) can still receive meaningful feedback through the position of the feedback indicator element and the associated icon.

[0097]

[0098] Table 1

[0099] Fig. 11B A schematic embodiment of a linear array 1102 of optical output elements is shown. In this embodiment, feedback indicator element 1 (i.e., optical output element 1104) may represent negative feedback, display indicator elements 2 to 7 (i.e., optical output element 1106) may form a progress indicator, and feedback indicator element 8 (i.e., optical output element 1108) may represent positive feedback. In addition, optical output element 1104 may have a red color, optical output element 1106 may have a yellow color, and optical output element 1108 may have a green color. The optical output elements do not necessarily need to be arranged in a linear manner as shown in Figure 11B; technicians may envision other arrangements of optical output elements while maintaining the logical meaning of each optical output element. For example, the optical output elements may be arranged in a circular array. In addition, in one embodiment, different subsets of optical output elements are associated with different types of user feedback. In this example, optical output element 1104 may provide generic negative feedback (e.g., regarding generic error conditions), optical output element 1106 may show the progress of template registration (e.g., for each step of the registration process, including specific success and error conditions), and optical output element 1108 may provide generic positive feedback (e.g., successful completion of registration). Thus, in one embodiment, at least one of the optical output elements indicates successful registration of the biometric template in the authentication token. This will further facilitate providing adequate feedback to the user.

[0100] Fig.1212 shows how a registration device is coupled to an authentication token. In a first state 1202, the authentication token has not yet been coupled to the registration device. In a second state 1204, the authentication token has been coupled to the registration device via a contact-based interface. In this example, the authentication token is a smart card. However, the authentication token can also be another device, such as a wearable device, a mobile phone, or a laptop. In general, the authentication token can be any device having a biometric sensor (e.g., a fingerprint sensor), in particular, a biometric sensor with a small area.

[0101] Fig.13 An illustrative embodiment of the timing 1300 of fingerprint image capture is shown. According to this embodiment, the token holder can control the fingerprint acquisition timing. This method avoids the situation where the token holder is overwhelmed by the tight acquisition time. Instead, the token holder may spend time to understand and explore the acquisition principle, and after understanding, the acquisition speed can be increased. Ensuring that the token holder can enroll without time pressure may have a positive impact on FRR. To facilitate this method, the authentication token can be configured to detect finger touch and finger lift-off. The capture process can wait for the token holder to present his finger to the token's sensor. Only when the finger touch has been detected can the acquisition process continue. The process continues after activating the positive feedback indicator, which signals the token holder that his fingerprint has been collected and the token holder can lift the finger. Within the token holder's reaction time, the process further performs feature extraction and storage. After completing the feature extraction, the authentication token can wait for the token holder to lift the finger. Once the finger lift-off has been detected, the positive feedback indicator can be deactivated, and the process can finally check whether the acquisition was successful and whether it may be necessary to advance the progress indicator. If necessary, advance the progress indicator.

[0102] basically, Fig.13 The capture process shown includes the following handshake mechanism:

[0103] - Finger touch

[0104] o Activate positive feedback (e.g., turn on Fig. 11B The optical output element 1108 in

[0105] -Lift your fingers away

[0106] ο Disable positive feedback (e.g., turn off Fig. 11B The optical output element 1108 in

[0107] o Advance the progress indicator if necessary (e.g., turn on Fig. 11B The next one in the optical output element 1106)

[0108] This handshake mechanism provides the token holder with full control over the timing of the registration sequence, thus preventing the token holder from being overwhelmed by a tight schedule. To signal readiness to the token holder, the first progress indicator element (e.g., Fig. 11B The first of the optical output elements 1106 shown).

[0109] In one embodiment, at least one of the optical output elements is configured to flash. This will further facilitate providing adequate feedback to the user. In particular, if the token holder should be notified to change fingers, a signal completely different from all other signals may be emitted. This distinction may be achieved by assigning a flashing attribute to the progress indicator. In order to make the flashing attribute unique and identifiable, the flashing attribute may be assigned only to such finger change signals. Table 2 shows possible combinations of feedback signal indicators that may be used for the progress bar.

[0110]

[0111] Table 2

[0112] In order to design a user-friendly progress indicator sequence, it may be useful to keep in mind that the token holder may not be familiar with the registration process. For example, where the token is configured for a one-time registration, the token holder may not understand the registration process. Therefore, the sequence advancement may be configured to start off smoothly, for example by requiring fewer acquisitions at the beginning of the sequence. Towards the end of the sequence, the token holder may lose patience; therefore, advancement may be made to require fewer acquisition samples again. For the middle part of the registration process, it may be acceptable to require one more sample to advance. An approach to designing a good progress sequence may take the following form.

[0113] Fig.14 1400. Assume that the number of fingerprint samples to be collected for one finger is s, and the number of progress indicator elements is p (eg, Fig. 11B ), the number of transitions t between the progress indicator state transitions can be calculated as:

[0114] t=p-1 (Equation 1)

[0115] For (s of t), the number of samples Δs to be collected before the progress indicator can be advanced can be calculated as:

[0116]

[0117] Since the progress bar may only increment by integers, the increment is rounded up to the next integer. It is important to ensure that the increment Δs is at least 1. Due to the rounding method, the last progress indicator may not be activated as required, because m samples are lost to reach the last progress indicator element. This number m can be calculated as:

[0118]

[0119] In some embodiments, the m missing increments are assigned to the increments Δs of the t state transitions st i , so that the transition from the central state to st c Start, increment Δs i Increase by 1 until m increments have been allocated. For example, the state transition has Fig.14 The simplified state diagram of FIG. 1 shows S=10 and p=6 (ignoring the acquisition samples). Each state can be mapped to a display code as shown in Table 2.

[0120] Update increment Δs i The sequence consists of increasing / decreasing the index i by -1, +1, -2, +2, and so on. Using this method, transitions with increasing increments are placed around the central state transition st c The groups are roughly symmetrical, where the index c can be calculated as:

[0121]

[0122] In one example, setting s=12 and p=6 yields the following values:

[0123]

[0124] m=12-(6-1)*2=2 (Equation 6)

[0125]

[0126] st1=2, st2=2+1, st3=2+1, st4=2, st5=2 (Equation 8)

[0127] It should be noted that the progress may require fewer samples in the initial state transition, which may help token holders quickly familiarize themselves with the registration procedure. In some embodiments, the samples that should be collected to transition from the initial state to the subsequent state can be set to an arbitrary number, for example, a smaller number. This may be needed to accommodate the needs of inexperienced token holders. Assuming that the first transition is set to an arbitrary number a, p new ,t new and new Substituting p, t, and s to apply the formula (Equation 1)...(Equation 4):

[0128] p new =p-1 (Equation 9)

[0129] t new =p-2 (Equation 10)

[0130] s new =sa (Equation 11)

[0131] For the embodiment where (s<t), the index j of the transition state can be calculated based on the common number i of the sample as:

[0132]

[0133] In one example, setting s=4 and p=6 yields the index:

[0134]

[0135]

[0136]

[0137]

[0138] In some embodiments, when (s<t), the number of transitions t is reduced to the number of transitions t r ,in:

[0139] t r =s (Equation 17)

[0140] This is enough to:

[0141] p=S+1 (Equation 18)

[0142] In the latter case, the number of progress indicator elements can be reduced to provide meaningful user feedback and to avoid the progress indicator advancing beyond one process indicator position. When all required samples have been collected for a finger, a reference template can be generated for the finger and securely stored in the authentication token, but the template for normal authentication does not need to be enabled. Next, a verification sample can be collected and processed into a verification template, which can be matched with the previously stored reference template. In the case of a positive match, the reference template can be enabled for normal authentication and therefore stored permanently, and the positive feedback indicator can be activated to issue a positive verification signal. In the case of a negative verification result, the generated reference template can be deleted again and an error message as shown below can be issued. If all required reference templates have been positively verified, the positive feedback indicator can be permanently activated to indicate the successful registration of the token holder. The token holder can complete the registration by removing the token from the registration device.

[0143] In addition, in some embodiments, the feedback indicator element can be used in an alternative mode to provide differentiated feedback to the error situation. For this reason, a feedback indicator representing negative feedback can be activated, and one of the progress indicator elements can be optionally activated in parallel at the same time (see Table 3). The icon representation of the feedback indicator element can then be applied so that it can be found in a table printed in the user guide manual to provide text error feedback to the token holder. Therefore, the design of the registration device can be made language-independent. Language conversion is preferably achieved through a user manual, which can be easily updated and translated. Another benefit of this method is that the manufacturing cost of the registration device is low due to the large amount of "once and for all" method implementation. In addition, it may be beneficial to only assign common verification errors or continuously collected errors to negative feedback indicators. In some embodiments, multiple error messages can be assigned to the same combination of feedback indicator elements to reduce the number of error messages that must be identified by the token holder, thereby avoiding the token holder from being overwhelmed.

[0144]

[0145] Table 3

[0146] Fig.15An illustrative embodiment of a display control system 1500 is shown. As mentioned, the optical output element can be a light emitting diode (LED). In the system 1500, these LEDs are controlled by a microcontroller 1502 using four control signals R1, R2, C1, C2. This produces an implementation scheme that supports a registration device with a low-cost (low pin count) microcontroller (MCU). In this system 1500, three states, high, low and high impedance (Hi-Z, input mode), can be used to control the anti-parallel LEDs. Table 4 shows a feasible truth table for implementing the control of eight LEDs. The LEDs can be time-division multiplexed. Time-division multiplexing can reduce the brightness of the LEDs because the duty cycle of one LED may be only 1 / 1. The duty cycle can be increased by appropriately assigning the LEDs to logic signals (specifically, progress indicator elements). It is feasible that more than one LED can be activated in parallel, which can reduce the number of LED combinations required to send a specific state signal, thereby increasing the duty cycle. If necessary, the technician can add more signals Ri, Ci to control more LEDs. The technician will understand that for Fig. 11B The embodiment of the display shown in FIG. 1 may require no more than three different states to display any desired display state, thereby increasing the duty cycle to 33% or more. In addition, a series resistor may not be required to protect the driver circuit that provides the logic signals R1, R2, C1, C2, thereby producing a low-cost user interface embodiment.

[0147] led C1 C2 R1 R2 1 H HkDJ L HkDJ 2 L HkDJ H HkDJ 3 HkDJ H L HkDJ 4 HkDJ L H HkDJ 5 H HkDJ HkDJ L 6 L HkDJ HkDJ H 7 HkDJ H HkDJ L 8 HkDJ L HkDJ H

[0148] Table 4

[0149] Fig.16A and 16B 1 shows a signal timing diagram 1600 of a display control system, and a corresponding exemplary embodiment of a display control system 1602. In this embodiment, Fig.15 The display control system shown in FIG. 1 supplements the contact interface for communicating with the authentication token, resulting in a low-cost implementation of a registration device using an 8-pin MCU. In this embodiment, the timing of the RST signal can be defined by the RC combination of Rt, Ct, saving one I / O pin. If desired, the RST signal can be generated by R1, R2, C1, C2 without significant impact on the functionality of the feedback indicator.

[0150] The systems and methods described herein may be implemented, at least in part, by one or more computer programs, which may exist in various forms, active and inactive, in a single computer system or across multiple computer systems. For example, they may exist as software programs consisting of program instructions in source code, object code, executable code, or other formats for performing certain steps. Any of the above may be embodied in a computer-readable medium, which may include storage devices and signals, in compressed or uncompressed form.

[0151] As used herein, the term "computer" refers to any electronic device that includes a processor, such as a general-purpose central processing unit (CPU), a special-purpose processor, or a microcontroller. A computer is capable of receiving data (input), performing a series of predetermined operations on the data, and generating results (output) in the form of information or signals. Depending on the context, the term "computer" will refer specifically to a processor or more generally to a processor associated with a collection of related elements contained in a single housing or enclosure.

[0152] The term "processor" or "processing unit" refers to a data processing circuit, which may be a microprocessor, a coprocessor, a microcontroller, a microcomputer, a central processing unit, a field programmable gate array (FPGA), a programmable logic circuit, and / or any circuit that manipulates signals (analog or digital) based on operating instructions stored in a memory. The term "memory" refers to one or more storage circuits, such as read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and / or any circuit that stores digital information.

[0153] As used herein, a "computer-readable medium" or "storage medium" may be any means that can contain, store, communicate, propagate, or transport a computer program for use by or in association with an instruction execution system, apparatus, or device. A computer-readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples of computer-readable media (a non-exhaustive list) may include the following: an electrical connection with one or more wires, a portable computer floppy disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CDROM), a digital versatile disk (DVD), a Blu-ray disc (BD), and a memory card.

[0154] It should be noted that the above embodiments have been described with reference to different subject matters. Specifically, some embodiments may have been described with reference to method claims, while other embodiments may have been described with reference to apparatus claims. However, a person skilled in the art will appreciate from the above that, unless otherwise indicated, any combination of features relating to different subject matters, in particular a combination of features of a method claim and features of an apparatus claim, in addition to any combination of features belonging to one type of subject matter, is also deemed to be disclosed by this document.

[0155] In addition, it should be noted that the drawings are schematic. In different drawings, similar or identical elements are represented by the same reference numerals. In addition, it should be noted that in order to provide a concise description of the illustrative embodiments, the implementation details that belong to the customary practice of technicians may not be described. It should be understood that in the development of any such implementation, as in any engineering or design project, a large number of implementation-specific decisions must be made to achieve the specific goals of the developer, such as complying with system-related and business-related constraints, which may be different between different implementations. In addition, it should be understood that such development work may be complex and time-consuming, but it will still be a routine work of design, manufacture and production for ordinary technicians.

[0156] Finally, it should be noted that the skilled person should be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in the claims. The words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. The measures recited in the claims may be implemented by hardware comprising several distinct elements and / or by a suitably programmed processor. In a device claim enumerating several components, several of these components may be implemented by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0157] List of Reference Numerals

[0158] 100 registered devices

[0159] 102 Token Interface Unit

[0160] 104 User interface control unit

[0161] 106 User interface unit

[0162] 200 Methods for facilitating biometric template enrollment

[0163] 202 Coupling the registration device to the user authentication token via the token interface unit

[0164] 204 providing visual information to the user via a plurality of optical output elements included in the user interface unit of the registration device, the visual information indicating the progress of the registration of the biometric template in the authentication token

[0165] 206 The user interface control unit of the registration device receives input data indicating the progress from the authentication token through the token interface unit, and uses the input data to control the user interface unit

[0166] 300 Template Registration System

[0167] 302 Registered Device

[0168] 304 Fingerprint Authentication Token

[0169] 306 Fingerprint Sensor

[0170] 400 Capturing fingerprint features with a small area sensor

[0171] 500 Verification template finger 1

[0172] 502 Reference template finger 1

[0173] 600 Fingerprint Template Registration and Verification System

[0174] 602 Fingerprint Sensor

[0175] 604 Image Preprocessing

[0176] 606 Feature Extraction

[0177] 608 Template Builder

[0178] 610 Reference Template Database

[0179] 612 Matcher

[0180] 614 Comparator

[0181] 616 Score Threshold

[0182] 700 Registered Device

[0183] 702 Microcontroller

[0184] 704 Power Supply

[0185] 706 Feedback Indicator

[0186] 708 Progress Bar

[0187] 800 Template Registration System

[0188] 802 Fingerprint Authentication Token

[0189] 804 Security Element

[0190] 806 Biometric Microcontroller

[0191] 808 Fingerprint Sensor

[0192] 900 Template Registration Process

[0193] 1000 Registration device housing

[0194] 1002 Registration device housing

[0195] 1100 Iconic representation of serial number

[0196] 1102 Linear array of optical output elements

[0197] 1104 Optical output element

[0198] 1106 Optical output element

[0199] 1108 Optical output element

[0200] 1202 Registering the first state of device coupling

[0201] 1204 Second state of registration device coupling

[0202] 1300 Fingerprint Image Capture Timing

[0203] 1400 Progress indicator transition status

[0204] 1500 Display Control System

[0205] 1502 Microcontroller

[0206] 1600 Display control system signal timing diagram

[0207] 1602 Display control system.

Claims

1. A registration device, characterized in that: include: a token interface unit configured to couple the registration device to an external user authentication token, wherein the authentication token comprises a fingerprint sensor; a user interface unit configured to provide visual information to a user through a plurality of optical output elements, the visual information indicating a progress of fingerprint feature template registration in the authentication token; and a user interface control unit configured to receive input data indicating the progress from the authentication token through the token interface unit and control the user interface unit using the input data, Wherein, the registration device is configured to send a control command to the authentication token through the token interface unit, process the response information received from the authentication token through the token interface unit, and provide corresponding user feedback through the user interface unit, wherein the authentication token is configured to detect a finger touching the fingerprint sensor and detect the finger being lifted from the fingerprint sensor, and in response to the finger touching, activate an optical output element among multiple optical elements to provide a positive feedback indication, and in response to acquiring a fingerprint from the finger, the optical output element is deactivated to indicate that the fingerprint has been acquired and the finger can be lifted from the fingerprint sensor, thereby allowing the user of the authentication token to control the timing of fingerprint acquisition.

2. The registration device according to claim 1, characterized in that: The optical output elements are organized in a linear array, or wherein the optical output elements are organized in a circular array.

3. The registration device according to claim 1 or 2, characterized in that: The optical output element is a light emitting diode.

4. The registration device according to claim 1, characterized in that: The optical output elements have different colors associated with different types of user feedback.

5. The registration device according to claim 1, characterized in that: Different subsets of the optical output elements are associated with different types of user feedback.

6. The registration device according to claim 1, characterized in that: At least one of the optical output elements indicates successful registration of a biometric template in the authentication token.

7. The registration device according to claim 1, characterized in that: At least two optical output elements are associated with the iconic representation of the serial number.

8. A template registration system, characterized in that: Comprising a registration device according to any preceding claim and a user authentication token.

9. A method for facilitating biometric template registration, characterized in that, The method comprises: coupling the enrollment device to an external user authentication token via a token interface unit, wherein the authentication token includes a fingerprint sensor; providing visual information to a user through a plurality of optical output elements included in a user interface unit of the registration device, the visual information indicating the progress of the registration of the fingerprint feature template in the authentication token; and receiving, by a user interface control unit of the registration device, input data indicating the progress from the authentication token via the token interface unit, and controlling the user interface unit using the input data, Wherein, the registration device is configured to send a control command to the authentication token through the token interface unit, process the response information received from the authentication token through the token interface unit, and provide corresponding user feedback through the user interface unit, wherein the authentication token is configured to detect a finger touching the fingerprint sensor and detect the finger being lifted from the fingerprint sensor, and in response to the finger touching, activate an optical output element among multiple optical elements to provide a positive feedback indication, and in response to acquiring a fingerprint from the finger, the optical output element is deactivated to indicate that the fingerprint has been acquired and the finger can be lifted from the fingerprint sensor, thereby allowing the user of the authentication token to control the timing of fingerprint acquisition.

10. A computer-readable storage medium, characterized in that: The method comprises executable instructions which, when executed, carry out or control the method according to claim 9.

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