RELATED APPLICATIONS

This application claims the benefit of priority of United Kingdom Patent Applications Nos. 1713469.3 and 1713471.9 both filed Aug. 22, 2017, the contents of which are incorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a method of verifying that (or determining whether) a biometric feature of a live human is present. More particularly, the present invention relates to a method of verifying that (or determining whether) a biometric feature of a live human is present for use as part of a biometric recognition system and/or method. The invention extends to a corresponding apparatus and system.

Biometric authentication, identification, and verification systems are used in a variety of applications (including surveillance, access control, gaming and virtual reality, and driver monitoring systems) as a way of verifying the identity of a user.

Biometric systems typically involve enrolling an authorised user's biometric feature(s) (e.g. the user's face, fingerprints, teeth, or iris) in a database, and, at a later time, automatically matching the authorised user's face presented to the system against one or more entries in the database based on a calculated index of similarity.

Such systems may be vulnerable to ‘spoof’ or ‘presentation’ attacks, in which an attacker claims an authorised user's identity by presenting a falsified biometric feature of the authorised user to the system, for example by use of a mask, a photograph, a video, or a virtual reality representation of the authorised user's biometric feature. This may mean that otherwise accurate biometric systems suffer from security risks.

Existing techniques for mitigating the risks of presentation attacks often require the cooperation and/or knowledge of the user/attacker (as in the case of ‘challenge-response’ tests), which, once an attacker has knowledge of the required response, may be relatively easily overcome (i.e. any system incorporating the known techniques may be easy to ‘spoof’). Furthermore, many existing techniques require specialised hardware, which may reduce the utility of such techniques.

Aspects and embodiments of the present invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.

SUMMARY OF THE INVENTION

According to at least one aspect described herein, there is provided a method for determining whether a biometric feature of a live human is present, comprising: using a camera, capturing visual data of a presented biometric feature; transmitting a signal towards the biometric feature; using a sensor, capturing data related to a reflected signal from the presented biometric feature; and determining whether the visual data and the reflected signal data relate to a biometric feature having realistic dimensions thereby to determine that a live biometric feature is present.

By determining whether the data relates to a biometric feature having realistic dimensions, a live biometric feature can be determined to be present without the need for any active response from a user.

Optionally, determining whether the visual data and the reflected signal data relate to a biometric feature having realistic dimensions comprises determining whether the visual data and the reflected signal data in combination relate to a biometric feature having realistic dimensions. The visual data may relate to an angular size of the presented biometric feature and the reflected signal data may relate to a distance of the presented biometric feature from the sensor and/or the shape of a presented biometric feature.

Determining whether the visual data and the reflected signal data relate to a biometric feature having realistic dimensions may comprise comparing the visual data and the reflected signal data against a model related to realistic dimensions of a biometric feature. The model may relate to a ratio of angular size and distance from the sensor for a live biometric feature. The method may further comprise collecting data for use in the model, wherein the data for use in the model may comprise visual data and reflected signal data of a biometric feature of a live human and visual data and reflected signal data of a falsified biometric feature of a live human. The model may be a trained classifier, which may be trained based on presented biometric features of live humans and presented falsified biometric features of live humans. Optionally, the model comprises a convolutional neural network.

Optionally, data related to the presented biometric feature is transmitted for remote processing. Optionally, transmitting a signal comprises transmitting a signal in accordance with a predetermined pattern. The pattern may be formed from at least one pulse and at least one pause, and may be configured such that at least one pulse in the reflected signal is received during the at least one pause in the transmitted signal. The pattern may be selected (optionally, randomly) from a plurality of patterns.

Transmitting a signal may comprise using a single transmitter. Optionally, a single sensor is used to capture data related to a reflected signal.

Optionally, the biometric feature is one or more of: a face; a hand; a palm; a thumb; and one or more fingers. The method may further comprise, using a screen, presenting the captured visual data to the presented biometric feature. A live human may be instructed (using the screen) to locate the biometric feature at a particular position relative to the camera and/or the sensor and/or to perform a particular gesture with the biometric feature.

The sensor may be a microphone, and the signal may be a sound wave (preferably, an ultrasound wave). The frequency of the ultrasound wave may be randomly selected within a predetermined range.

The method may form part of a multi-modal method for determining whether a biometric feature of a live human is present.

According to at least one aspect described herein, there is provided a method for determining whether a biometric feature of a live human is present, comprising: using a camera, capturing visual data of a presented biometric feature, wherein the visual data relates to an angular size of the presented biometric feature; transmitting a signal towards the biometric feature; using a sensor, capturing data related to a reflected signal from the presented biometric feature, wherein the reflected signal data relates to a distance of the presented biometric feature from the sensor; and comparing the visual data and the reflected signal data against a model related to possible angular sizes and possible distances from the sensor for a live biometric feature thereby to determine that a live biometric feature is present.

According to at least one aspect described herein, there is provided a method of verifying the identity of a user, comprising performing a method as described herein; and verifying the identity of the user by comparing biometric information of the user (which optionally comprises information related to the user's biometric feature(s)) against a database of biometric information of verified users.

According to at least one aspect described herein, there is provided apparatus for determining whether a biometric feature of a live human is present, comprising: a camera for capturing visual data of a presented biometric feature; a module adapted to transmit a signal towards the biometric feature; a sensor for capturing data related to a reflected signal from the presented biometric feature; and a module whether the visual data and the reflected signal data relate to a biometric feature having realistic dimensions thereby to determine that a live biometric feature is present.

The module adapted to transmit a signal may be a loudspeaker; and the signal may be an ultrasound signal. The sensor for capturing data related to a reflected signal may be a microphone. The apparatus may be in the form of one or more of: a smartphone; a laptop computer; a desktop computer; or a tablet computer; an automated passport control gate; and an entry system.

According to at least one aspect described herein, there is provided a system for determining whether a biometric feature of a live human is present, comprising: a user device, comprising: a camera for capturing visual data of a presented biometric feature; a module adapted to transmit a signal towards the biometric feature; and a sensor for capturing data related to a reflected signal from the presented biometric feature; and a remote determination module adapted to determine whether the visual data and the reflected signal data relate to a biometric feature having realistic dimensions thereby to determine that a live biometric feature is present.

According to at least one aspect described herein, there is provided a method for determining whether a biometric feature of a live human is present, comprising: using a sensor, capturing data related to a presented biometric feature; applying a stimulus to the presented biometric feature, wherein the stimulus is capable of causing an involuntary response from a biometric feature of a live human; and determining whether the data indicates that the involuntary response has occurred thereby to determine whether a biometric feature of a live human is present.

By determining whether an involuntary response has occurred, a live biometric feature can be determined to be present without the need for any active (i.e. voluntary) response from a user.

Applying a stimulus may comprise transmitting a signal, wherein the signal may be adapted to cause an involuntary response from a biometric feature of a live human. Optionally, transmitting a signal comprises transmitting a signal in accordance with a predetermined pattern. Determining whether the data indicates that the involuntary response has occurred may comprise determining whether a pattern corresponding to the predetermined pattern is present in the captured data. The pattern may be formed from at least one pulse and at least one pause, and may be selected from a plurality of patterns. Optionally, the pattern is randomly selected.

The transmitted signal may be detected using a further sensor. Determining whether the data indicates that the involuntary response has occurred may comprise comparing data from the sensor and the further sensor and/or applying a time correction to data from the sensor and data from the further sensor. The further sensor may be a microphone, and the signal may comprise a sound wave (preferably, an ultrasound wave).

Optionally, the involuntary response is a movement of at least part of the biometric feature. The sensor may be a camera, and the captured data may be visual data. Determining whether the data indicates that the involuntary response has occurred may comprise determining whether the visual data includes rolling shutter artefacts indicative of the movement of at least part of the biometric feature. The movement may be generally elastic, and preferably has a maximum extent of less than 2 mm, more preferably less than 1 mm, still more preferably less than 0.5 mm, and most preferably less than 0.2 mm.

The biometric feature may be a head. The movement may be a movement of one or more of: hair; and facial skin. The method may further comprise identifying features on the presented biometric feature where movement is expected to occur and/or magnifying a pre-determined frequency band corresponding to a frequency of the movement of at least part of the biometric feature.

Optionally, determining whether the data indicates that the involuntary response has occurred comprises comparing data captured using the sensor while the stimulus is applied to data captured using the sensor while the stimulus is not applied.

Optionally, determining whether the data indicates that the involuntary response has occurred comprises comparing data captured using the sensor against a model, wherein the model represents an involuntary response of a live human to the stimulus. Data related to an involuntary response of a biometric feature of a live human to the stimulus and a response of a falsified biometric feature of a live human may be collected for use in the model. The model may be a trained classifier, which may be trained based on presented biometric features of live humans and presented falsified biometric features of live humans. The model may comprise a convolutional neural network. Data related to the presented biometric feature may be transmitted for remote processing.

Captured visual data may be presented to the presented biometric feature using a screen.

The method may form part of a multi-modal method for determining whether a biometric feature of a live human is present.

According to at least one aspect described herein, there is provided a method of verifying the identity of a user, comprising performing a method as described herein; and verifying the identity of the user by comparing biometric information of the user (which optionally comprises information related to the user's biometric feature(s)) against a database of biometric information of verified users.

According to at least one aspect described herein, there is provided apparatus for determining whether a biometric feature of a live human is present, comprising: a sensor for capturing data related to a presented biometric feature; a module adapted to apply a stimulus to the presented biometric feature, wherein the stimulus is capable of causing an involuntary response from a biometric feature of a live human; and a module adapted to determine whether the data indicates that the involuntary response has occurred thereby to determine whether a biometric feature of a live human is present.

The sensor may be a camera; and the captured data may be visual data. The module adapted to transmit a signal may be a loudspeaker; and the signal may be an ultrasound signal. The apparatus may further comprise a microphone for detecting the transmitted signal. The apparatus may be in the form of one or more of: a smartphone; a laptop computer; a desktop computer; or a tablet computer; an automated passport control gate; and an entry system.

According to at least one aspect described herein, there is provided a system for determining whether a biometric feature of a live human is present, comprising: a user device, comprising: a sensor for capturing data related to a presented biometric feature; and a module adapted to apply a stimulus to the presented biometric feature, wherein the stimulus is capable of causing an involuntary response from a biometric feature of a live human; and a remote determination module adapted to determine whether the data indicates that the involuntary response has occurred thereby to determine whether a biometric feature of a live human is present.

According to at least one aspect described herein, there is provided a method of perturbing an object using a user device, comprising, using a loudspeaker of the user device, transmitting an ultrasound signal towards the object. The method may further comprise, using a camera, detecting a perturbation of the object in response to the ultrasound signal.

The invention extends to methods, system and apparatus substantially as herein described and/or as illustrated with reference to the accompanying figures.

The invention also provides a computer program or a computer program product for carrying out any of the methods described herein, and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention also provides a signal embodying a computer program or a computer program product for carrying out any of the methods described herein, and/or for embodying any of the apparatus features described herein, a method of transmitting such a signal, and a computer product having an operating system which supports a computer program for carrying out the methods described herein and/or for embodying any of the apparatus features described herein.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure, such as a suitably programmed processor and associated memory.

Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

As used herein, the term ‘biometric feature’ preferably connotes a part or characteristic of a human body which can be used to identify a particular human.

As used herein, the term ‘live human’ preferably connotes a living human being (i.e. not a recording or any other kind of indirect representation of a living human).

As used herein, the term ‘head’ preferably connotes a human head, including the face and hair. As used herein, the term ‘face’ is to be preferably understood to be interchangeable with the term ‘head’.

As used herein, the term ‘loudspeaker’ preferably connotes any electroacoustic transducer for transmitting sound waves. As used herein, the term ‘microphone’ refers to connotes any electroacoustic transducer for receiving sound waves.

As used herein, the term ‘audio’ preferably connotes sound, including both audible frequencies and ultrasound frequencies.

As used herein, the term ‘ultrasound’ preferably connotes sound having a frequency above 18 kHZ (which is barely perceptible, or not perceptible, for the majority of humans), more preferably between 18 KHz to 22 Khz or alternatively between 20 kHz and 30 MHz.

As used herein, the term ‘realistic’ preferably connotes that an article (which may or may not be real) has characteristics corresponding to a real article.

As used herein, the term ‘dimension’ preferably connotes a measurable characteristic of an article (such as the size of an article) or a measurable characteristic of a relationship between an article and another article (such as the distance between two articles).

As used herein, the term ‘angular size’ preferably connotes one or more apparent dimensions of an object from a given point of view, preferably one or more apparent dimensions of an object within a field of view of a camera.

As used herein, the term ‘involuntary’ preferably connotes an action that is not consciously controlled.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

