A METHOD AND A DEVICE FOR VERIFYING LIVENESS OF A FINGER

Abstract

A method (700) for verifying liveness of a finger (102) of a user by capturing a first fingerprint sample (402) from the finger (102) placed on a display (104) by using a first sensor (106) placed under the display (104). The method (700) may comprise transmitting (702) light, by using a first light transmitting display area of the display (104), towards a first area of the finger (102), wherein the first light transmitting display area (108) is smaller than a first sensor area; capturing (704) reflected light from the finger (102) by the first sensor (104), wherein the reflected light (114) is transmitted through the display (104); and identifying (706) a first feature of the first fingerprint sample (402) by using the reflected light (114), wherein the first feature comprises scattered light from the finger (102), wherein the light transmitted from the display (104) comprises a first light component with a first wavelength from a first area of the display (104).

Claims

1.-12. (canceled)

13. A method for verifying liveness of a finger of a user, the method comprising: capturing a fingerprint sample from the finger placed on a display by using a first sensor placed within or under the display; extracting scattered light features from the fingerprint sample; comparing the scattered light features with a light scattering template; and if a match is found, generating a liveness acceptance signal, else generating a liveness rejection signal; wherein capturing the fingerprint sample involves transmitting light of a first light component with a first wavelength from the display towards the finger, and capturing light reflected from the finger by the first sensor, wherein the reflected light is transmitted through the display.

14. The method according to claim 13, wherein capturing the fingerprint sample comprises: transmitting light, from a first light transmitting display area of the display, towards the finger, wherein the first light transmitting display area is divided into subareas, wherein the light transmitted from the different subareas comprises different light components with different wavelengths; and capturing light reflected from the finger by the first sensor, wherein the reflected light is transmitted through the display.

15. The method according to claim 13, wherein capturing the fingerprint sample comprises: capturing a first fingerprint sample by transmitting light of a first light component with a first wavelength from the display towards the finger, and capturing light reflected from the finger by the first sensor, wherein the reflected light is transmitted through the display; capturing a second fingerprint sample by transmitting light of a second light component with a second wavelength from the display towards the finger, and capturing light reflected from the finger by the first sensor wherein the reflected light is transmitted through the display; and generating the fingerprint sample from the first and the second fingerprint samples as a composite fingerprint sample of the first and the second fingerprint samples.

16. The method according to claim 13, further comprising: determining a surrounding temperature and/or a surrounding brightness; and determining the wavelength(s) to be used in the step of transmitting light towards the finger based on the surrounding temperature and/or the surrounding brightness.

17. The method according to claim 13, wherein the light scattering template comprises information about how light with different wavelength behave in the finger.

18. The method according to claim 17, wherein the light scattering template further comprises information about how light with different wavelength behave in different spoof-materials.

19. The method according to claim 13, wherein capturing the fingerprint sample comprises illuminating only a part of the finger.

20. A mobile device configured to verify liveness of a finger of a user, the mobile device comprising: a display configured to transmit light towards the finger placed on the display, wherein the light includes a first light component with a first wavelength; a first sensor placed under or within the display, wherein the first sensor is configured to capture a fingerprint sample from the finger placed on the display; and a processor configured to extract scattered light features from the first fingerprint sample, compare the scattered light features with a light scattering template, and if a match is found, generate a liveness acceptance signal, else generate a liveness rejection signal.

21. The mobile device according to claim 20, further comprising a second sensor configured to determine a surrounding temperature and/or a surrounding brightness; wherein the first wavelength is determined based on the surrounding temperature and/or the surrounding brightness.

22. The mobile device according to claim 20, wherein the light scattering template comprises information about how light with different wavelength behave in the finger.

23. The mobile device according to claim 22, wherein the light scattering template further comprises information about how light with different wavelength behave in different spoof-materials.

24. The mobile device according to claim 20, wherein the display is configured to transmit light towards only a part of the finger placed on the display.

25. A system configured to verify liveness of a finger of a user, the system comprising a mobile device and a server; the mobile device including a display configured to transmit light towards the finger placed on the display, wherein the light comprises a first light component with a first wavelength, and a first sensor placed under or within the display, wherein the first sensor is configured to capture a fingerprint sample from the finger placed on the display, wherein the mobile device is configured to send the first fingerprint sample to the server; the server including a control unit, a transceiver, and a memory, wherein the server is configured to execute an extraction function to extract scattered light features from the fingerprint sample, and execute a comparison function to compare the scattered light features with a light scattering template, and if a match is found, generate a liveness acceptance signal to the mobile device, else generate a liveness rejection signal to the mobile device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Embodiments will now be described, by way of example, with reference to the accompanying schematic drawings, in which

[0043] FIG. 1 generally illustrates a system for capturing a fingerprint sample from a finger of a user.

[0044] FIG. 2 illustrates a cloud computer environment.

[0045] FIG. 3a-d illustrates different ratios between a first sensor and a light transmitting display area of a display.

[0046] FIG. 4a-b generally illustrates a first and a second fingerprint sample.

[0047] FIG. 5 generally illustrates a first and a second feature area of a fingerprint sample.

[0048] FIG. 6a-b generally illustrates capturing a fingerprint sample, wherein the finger is pressed against the display with different pressure.

[0049] FIG. 7 illustrates a flow chart for verifying liveness of a finger of a user.

DETAILED DESCRIPTION

[0050] With reference to FIG. 1, an overview of a system 100 for capturing a fingerprint sample from a finger 102 of a user is illustrated by way of example. The system 100 may comprise a mobile device and a finger 102 of a user. The mobile device may be equipped with a display 104 and a first sensor 106. According to one example, the first sensor 106 may be placed under the display 104. According to another example, the first sensor 106 may be placed within the display 104.

[0051] The display 104 may be configured to transmit light 112 towards the finger 102. Upon the user may place its finger 102 on the display, a display area covered by the finger 102 may provide the transmitted light 112 towards the finger 102. The display area that may provide the transmitted light 112 is herein referred to as a light transmitting display area 108. The whole display area, or a subset of the display area, may be configured to act as the light transmitting display area 108. The area of the finger 102 that may be illuminated by the light is herein referred to as a finger area. The light transmitting display area 108 may be smaller than the finger area. Alternatively, or in combination, the light transmitting display area 108 may be larger than the finger area. Alternatively, or in combination, the light transmitting display area 108 may be equal to the finger area. In other words, the display 104 may be configured to transmit light 112 towards the total finger area, or towards a subset of the finger area, based on the size of the light transmitting display area 108.

[0052] The first sensor 106 may be configured to capture reflected light 114 from the finger 102. The reflected light 114 may be transmitted through the display 104. A total amount of the reflected light 114, or a subset of the reflected light 114, may be transmitted through the light transmitting display area 108. By way of example, the first sensor 106 may be a fingerprint sensor.

[0053] Further, the mobile device may comprise a protective glass 110. The protective glass 110 may be placed on top of the display 104. Further, the protective glass 110 may in turn be provided with a protective film, even though not illustrated, to further reduce a risk of scratches. Both the protective glass 110 and the protective film may affect the reflected light 114. Worth mentioning is also that the protective glass 110 is in first hand optimized with respect to the display 106 such that information displayed to the user is presented in an appealing way.

[0054] FIG. 2 generally illustrates a cloud computer environment 200. The cloud computer environment 200 may comprise a mobile device 202, a server 204, a database 206 and a network 208.

[0055] In addition to what have been discussed above, the mobile device 202 may further comprise a processor 210 and a memory 212. The mobile device 202 may be configured to capture a fingerprint sample from a finger 102 of a user by using the first sensor 106. According to an example, the mobile device 202 may be a mobile phone. According to another example, the mobile device 202 may be a smart card. The mobile device 202 may not be limited to these examples but can be any kind of mobile device 202 configured to capture the fingerprint sample. Further, the mobile device may comprise at least a second sensor 214. By way of example, the second sensor 214 may be configured to adjust the screen brightness. By way of example, the second sensor 214 may be configured to measure the outdoor temperature.

[0056] The server 204 may be configured to store the fingerprint sample. The server 204 may be configured to receive and send information from/to the mobile device 202 and/or the database 206. Alternatively, or in combination, the database 206 may be configured to store the fingerprint sample. The database 206 may be configured to receive and send information from/to the mobile device 202 and/or the server 204. The network 208 may be configured to enabling the communication between the mobile device 202 and the server 204. Alternatively, or in combination, the network 208 may be configured to enabling the communication between the mobile device 202 and the database 206. Alternatively, or in combination, the network 208 may be configured to enabling the communication between the server 204 and the database 206.

[0057] With reference to FIG. 3a-3d, a mobile device 202 equipped with a display 104 and a first sensor 106 is illustrated by way of examples. The display 104 may be configured to transmit light towards a finger 102 of a user. The display 104 may comprise a light transmitting display area 108 which is the part of the display 104 that may provide transmitted light towards the finger 102. The transmitted light from the display 104 may comprise a light component with a wavelength. The light transmitting display area 108 may be divided into subareas of the light transmitting display area 108. Different subareas may transmit the same light component towards the finger 102. Alternatively, or in combination, different subareas may transmit different light components towards the finger 102. By the term different light components, it is meant light components with different wavelengths, and hence, different energy. Upon that may be the case, different parts of the finger 102 may be illuminated by different wavelengths. Thus, the different wavelengths may penetrate differently depth into the finger 102 and based on that, different information of the finger 102 may be captured.

[0058] An advantages by using different light components with different wavelengths is that the body absorbs the energy of the different wavelengths differently well and different energy can penetrating into the skin with differently depth. Based on the above, different and complementary information can be captured and a more efficient and precise way of capturing fingerprint samples is achieved.

[0059] The first sensor 106 may be configured to capture reflected light from the finger 102. The first sensor 106 may be placed under the display 104. The first sensor 106 may be placed within the display 104. The first sensor 106 and the light transmitting display area 108 may be fully or partly overlapping.

[0060] According to an example, as illustrated in FIGS. 3a and 3b, the first sensor 106 is larger than the light transmitting display area 108. The first sensor 106 and the light transmitting display area 108 are of a circular shape. Neither the first sensor 106 nor the light transmitting display area may be limited to be of the circular shape. By using this arrangement, part of the reflected light may travel through the light transmitting display area 108 to the first sensor 106 while part of the reflected light may travel beside the light transmitting display area 108, as illustrated in FIG. 3b. This arrangement may be used when a subset of the finger area may be illuminated. By using this arrangement, scattered light from the finger may be captured in the fingerprint sample. Upon comparing the scattered light with characteristics for scattered light for fingers, a liveness verification of the finger may be performed. Liveness verification may increase the security when performing fingerprint recognition. Liveness verification of the finger may be discussed more in detail in FIG. 4a-b and FIG. 7.

[0061] According to another example, as illustrated in FIGS. 3c and 3d, the first sensor 106 is smaller than the light transmitting display area 108. By using this arrangement, all of the reflected light may travel through the light transmitting display area 108 to the first sensor 106, as illustrated in FIG. 3d. This arrangement may be used when the whole finger area may be illuminated. By using this arrangement, the fingerprint from the whole finger 102 may be captured in the fingerprint sample.

[0062] Different ratio between the first sensor 106 and the light transmitting display area 108 may provide different and complementary information about the fingerprint sample. Alternatively, or in combination, this may provide different and complementary information about the ridges and/or valleys and/or swirls of the finger. Capturing different fingerprint samples by using different ratio between the first sensor 106 and the light transmitting display area 108 and/or different light components may provide a constitutive fingerprint sample comprising all information in one sample.

[0063] With reference to FIG. 4a-b, a first and a second fingerprint sample 402, 408 is illustrated by way of example.

[0064] According to the first fingerprint sample 402, only part of the finger 102 may have been illuminated by the light. The first fingerprint sample 402 may have a first fingerprint area. The first fingerprint sample 402 may comprise a first fingerprint 404 and scattered light 406 from the finger. The light may scatter differently depending of the material the light is transmitting to and reflected from. By way of example, upon there may be a piece of spoof-material placed on the display instead of a real finger, the scattered light may occur in a different manner in the fingerprint sample 402 compared to upon there may be a real finger placed on the display. By way of example, the spoof-material can be modeling clay, glue or paper. The spoof-material is not limited to these examples but can be any material used for creating fake fingerprints. By analyzing the scattered light 406 of the fingerprint sample, the authenticity of the liveness of the finger may be analyzed. By way of example, the scattered light may be compared to a light scattering template. The light scattering template may comprise information about how different light, with different wavelength, may behave in the finger 102. The light scattering template may comprise information about how different light, with different wavelength, may behave in the spoof-material. If the comparison may be a match, the first fingerprint sample 402 may be a valid finger. Therefore, unlike today when machine learning or deep learning is used, may this solution, for verifying liveness of the finger, contribute to a more secure verification.

[0065] According to the second fingerprint sample 408, the whole finger may have been illuminated by the light. The second fingerprint sample 408 may have a second fingerprint area. The first fingerprint area may be a subset of the second fingerprint area. The second fingerprint sample 408 may comprise a second fingerprint 410. The first and second fingerprint sample 402, 408 may be illuminated by the same light component. Alternatively, or in combination, the first and second fingerprint sample 402, 408 may be illuminated by different light components with different wavelengths.

[0066] FIG. 5 generally illustrates a fingerprint sample 500 from a finger 102 of a user. By way of example, the fingerprint sample 500 may be in line with the first or second fingerprint sample 402, 408 illustrated in FIG. 4a-b. The fingerprint sample 500 may comprise a first feature area 502 and a second feature area 504. The second feature area 504 may be a subset of the first feature area 502. The first feature area 502 may comprise a first feature of the fingerprint sample 500. The second feature area 504 may comprise a second feature of the fingerprint sample 500. The second feature may be a subset of the first feature.

[0067] The second feature area 504 may comprise information that may need to be further analyzed. The second feature area 504 may comprise information that may be characteristic for a specific user. The system for capturing a fingerprint sample discussed above may “learn the user” over time. The term learn the user should be interpreted as the system know where the characteristics for the specific user may be found in the fingerprint sample. Upon that may be the case, the system may only capture spot-checks of the fingerprint sample to verify the user.

[0068] FIG. 6a-b generally illustrates a system 600 for capturing a fingerprint sample. The system 600 is in line with the system 100 discussed in FIG. 1.

[0069] In FIG. 6a, it is illustrated a finger 102 placed on the display 104 with a pressure X. In FIG. 6b, it is illustrated the finger 102 placed on the display 104 with a pressure Y. Herein, the pressure X is smaller than the pressure Y. As a consequence, the height of the finger 102 illustrated in FIG. 6a is larger than the height of the finger 102 illustrated in FIG. 6b. The height of the finger 102 illustrated in FIG. 6a is A and the height of the finger 102 illustrated in FIG. 6b is B, thus, A is larger than B.

[0070] Upon the user may press the finger 102 against the display with a higher pressure, the density may be higher as well. As a consequence, the energy, of the transmitted light, penetrating into the finger 102 may penetrate deeper upon the density is higher.

[0071] Thus, the transmitted light may penetrate into the finger 102 differently depth based on the pressure from the finger 102 the user may put against to display.

[0072] Upon the light penetrates differently deep into the finger 102, different information about the finger 102 may be captured.

[0073] FIG. 7 is a flow chart generally illustrating an example of a method 700 for verifying authenticity of a finger of a user by capturing a first fingerprint sample 402 from the finger 102. The first fingerprint sample 402 may be captured by using a first sensor 106 placed under a display 104, wherein the user may place the finger 102 on the display 104. The method 700 comprises the following steps.

[0074] First, transmitting 702 light, by using a light transmitting display area 108 of the display 104, towards a first area of the finger 102. The light transmitting display area 108 may be smaller than the area of the first sensor 106. The light transmitted from the display 104 may comprise a first light component with a first wavelength from a first area of the display 104.

[0075] Thereafter, capturing 704 reflected light from the finger 102 by the first sensor 106. The reflected light may be transmitted through the display 104.

[0076] Then, identifying 706 a first feature of the fingerprint sample 402 from the finger 102 by using the reflected light. The first feature of the first fingerprint sample 402 may comprise scattered light from the finger 102.

[0077] Optionally, the method 700 may comprise capturing a second fingerprint sample 408. The second fingerprint sample 408 may be captured by transmitting light, by using a second light transmitting display area of the display 104, towards a second area of the finger 102. Then, capturing reflected light from the finger 102 by the first sensor 106, wherein the reflected light is transmitted through the display 104. Thereafter, identifying a first feature of the second fingerprint sample 408 by using the reflected light. The light transmitted from the second light transmitting display area may comprise a second light component with a second wavelength from a second area of the display. The first and second light component may be the same light component with the same wavelength. Alternatively, or in combination, the first and second light component may be different light components with different wavelengths.

[0078] Further, the step of transmitting 702 light may comprise determining environmental data for the user. The environmental data may be determined by using at least one second sensor 214. Based on the environmental data, the transmitted light may be adapted.

[0079] The step of identifying 706 the first feature of the first and/or second fingerprint sample 402, 408 may comprise generating a first and/or second composite fingerprint sample by using the reflected light from the first and/or second light component. Alternatively, or in combination, the step of identifying 706 the first feature of the first and/or second fingerprint sample 402, 408 may comprise generating the first and/or second composite fingerprint sample by combining a plurality of generated fingerprint samples. Each of the generated fingerprint sample may comprise different areas of the finger.

[0080] Alternatively, or in combination, the method 700 may further comprise identifying a second feature of the first and/or second fingerprint sample 402, 408 from the finger 102 by using the reflected light. The second feature of the first and/or second fingerprint sample 402, 408 may be based on a second feature area. The second feature area may be a subset of a first feature area, wherein the first feature area may be used for identifying the first feature of the first and/or second fingerprint sample.

[0081] Alternatively, or in combination, the method 700 may further comprise extracting scattered light features from the first fingerprint sample 402. Retrieving a light scattering template. Thereafter, comparing the scattered light features with the light scattering template and if a match is found, generating a liveness acceptance signal, else generating a liveness rejection signal. The light scattering template may comprise information about how different light, with different wavelength, may behave in the finger 102. The light scattering template may comprise information about how different light, with different wavelength, may behave in different spoof-materials.

[0082] Alternatively, or in combination, the method 700 may further comprise extracting fingerprint features from the second fingerprint sample 408. Retrieving a fingerprint template. Thereafter, comparing the fingerprint features with the fingerprint template, and if a match is found, generating a fingerprint match acceptance signal, else generating a fingerprint match rejection signal.

[0083] From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.