METHOD AND DEVICE FOR AUTHENTICATING A USER

A method of deriving authentication data comprises selecting an illumination configuration from a plurality of predetermined illumination configurations; illuminating at least a part of the user in a manner corresponding to the selected illumination configuration; capturing an image of at least a portion of the illuminated user; and determining whether to authenticate the user based on the captured image.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Whilst various embodiments of the system described herein are described below, the system described herein is not limited to these embodiments and variations of these embodiments may well fall within the scope of the invention which is to be limited only by the appended claims.

The system described herein is generally directed to a method of operation of a mobile device to trigger a “biometric scan” using a series of short screen flashes, with differing screen lighting configurations. Images of the user illuminated with these lighting configurations or patterns (e.g. illumination configurations) are captured using a high-definition, front-facing camera. Using this method, the device is able to capture a three-dimensional image of the user's face, by abstracting differences between the different lighting conditions. This allows a relatively robust “biometric unlock” key to be provided. This biometric unlock key, feature, or mechanism, is difficult to circumvent without a three-dimensional rendition of the user's face as it is the three-dimensional nature of the user's face that gives rise to different captured images with different illumination configurations. The system described herein may use existing single-camera mobile devices, where the camera is aligned on the front face of the device, next to a standard backlit display.

According to an embodiment of the system described herein, a method of authenticating a user relies on two separate operating states: an initial “learning” state and a “triggered unlock” state.

As seen inFIG. 1, there is provided mobile device10comprising activator11, video camera12and display screen13. Mobile device10also comprises a processor and memory (not shown) for carrying out various processes and functions in mobile device10, and for storing data for later use. The memory stores instructions for running a biometric authentication and unlock mechanism of mobile device10, and the processor is arranged to read and execute these instructions. The device may comprise any suitable operating system for operating the software, such as Android, BSD, iOS, Windows, etc.

In order to teach the biometric unlock mechanism those physical features of the user's face to look for, there is a need for mobile device10to “learn” the face of the individual. This state is triggered when the user requests a new biometric protection layer to be added to mobile device10, through standard device menus and configuration options. For example, the user could download an application which, when installed on mobile device10, allows the user to launch the biometric unlock mechanism.

Once the user has selected the option to “learn” a biometric unlock pattern, mobile device10will activate front-facing camera12, and present the user with a preview of their own face. Overlaid on this image, mobile device10presents guide line14for the user to align their face correctly, to ensure the proper alignment of the user's face relative to display screen13. In a preferred embodiment, an image of the user's entire face is fit within the boundaries of guide line14.

Once mobile device10has detected that the user's face is properly aligned (through basic pattern matching and recognition), mobile device10prompts the user to remain steady, and replaces the display contents with three illumination configurations (FIGS. 2 to 4). In the first illumination configuration seen inFIG. 2, the left half of display screen13is lit whilst is right half is unlit. In the second illumination configuration seen inFIG. 3, the left half of display screen13is unlit whilst is right half is lit. In the third illumination configuration seen inFIG. 4, the top half of display screen13is lit whilst is bottom half is unlit.

These flashes of light are designed to illuminate the user's face with varying positions of light—one from each side on the horizontal plane, and one from the top. Whilst the user's face is illuminated, mobile device10captures the input from front-facing camera12for each illumination configuration.

Once the face has been illuminated in this pattern, mobile device10is able to derive data (e.g. authentication data) by synthesising a combined set of data based on the differences between the scans. Using a “clean” capture of the user's face, device10creates a network of nodes on key facial features (corners of the eye, corners of the mouth, tip of the nose, position of the ears, temples, nostrils and eyebrows). Alongside this, a delta of shadows cast by the user's features, when illuminated from the sides and from above, will be stored alongside the standard biometric data. These shadows will be abstracted to a series of simplified measures (such as nose length, eye depth, etc), for rapid acquisition and recognition. This data is then stored in the persistent memory on mobile device10.

FIG. 5illustrates the steps taken by mobile device10in order to derive authentication data, in accordance with the above embodiment. In step40, the user is illuminated with a plurality of different illumination configurations. In step42, for each illumination configuration, front-facing camera12captures an image of the user. In step44, the processor of mobile device10derives authentication data from the captured images.

When the user has configured mobile device10to use the biometric unlock mechanism, mobile device10operates as normal, and can be locked using the standard hardware or software trigger.

When mobile device10is activated and brought out of sleep mode (or booted for the first time), for example by using activator14, the biometric authentication mechanism engages. Front-facing camera12of mobile device10turns on, scanning every half second for a recognisable face. At this time, the user is presented with guide line14overlaid over the live video image, as perFIG. 1.

When a face is recognized (e.g. when mobile device10determines that a face is present within the boundaries of guide line14), mobile device10prompts the user to remain steady, and flashes a series of illumination patterns or configurations matching those which were fired during the “learning” phase (FIGS. 2 to 4). During this time, the input from front-facing camera12is recorded.

Using the same method as in the “learning” step, above, a series of biometric measures and statistics are gathered from the input. By adding a “variance weighting” to each measurement, the system may compensate for varying ambient lighting conditions and movement of the user's face.

By comparing the initially captured biometric vectors and measurements to the weighted scanned measurements, mobile device10may authenticate the user and in so doing may unlock mobile device10, assuming the characteristics or parameters of the new if they match (or are within a suitable range of one another). Alternatively, mobile device10remains locked if enough variance between the characteristics is present.

After a number of failed attempts, or after the user manually selects to skip this process, the device will fall back to a secondary unlock method, such as a traditional password or PIN mode. The number of retries or the possibility to fall back altogether is configurable in the device settings and configuration menus.

FIG. 6illustrates the steps taken by mobile device10in order to authenticate (or not) the user. In step50, the user is illuminated with a first illumination configuration. In step52, front-facing camera12captures an image of the user illuminated with the first illumination configuration. In step54, the user is illuminated with a second illumination configuration (different to the first illumination configuration). In step56, front-facing camera12captures an image of the user illuminated with the second illumination configuration. This process can repeat (e.g. the user can be illuminated with a third illumination configuration, different to the first and second illumination configurations). In step58, the processor of mobile device10determines whether to authenticate the user based on the captured images.

Many combinations, modifications, or alterations to the features of the above embodiments will be readily apparent to the skilled person and are intended to form part of the system described herein. Furthermore, a person skilled in the art will recognize that any of the features described as specifically relating to one embodiment may be used in any other embodiment, by making the appropriate changes.

Various embodiments discussed herein may be combined with each other in appropriate combinations in connection with the system described herein. Additionally, in some instances, the order of steps in the flowcharts, flow diagrams and/or described flow processing may be modified, where appropriate. Further, various aspects of the system described herein may be implemented using software, hardware, a combination of software and hardware and/or other computer-implemented modules or devices having the described features and performing the described functions. The system may further include a display and/or other computer components for providing a suitable interface with other computers and/or with a user. Software implementations of the system described herein may include executable code that is stored in a computer-readable medium and executed by one or more processors. The computer-readable medium may include volatile memory and/or non-volatile memory, and may include, for example, a computer hard drive, ROM, RAM, flash memory, portable computer storage media such as a CD-ROM, a DVD-ROM, a flash drive or other drive with, for example, a universal serial bus (USB) interface, and/or any other appropriate tangible or non-transitory computer-readable medium or computer memory on which executable code may be stored and executed by a processor. The system described herein may be used in connection with any appropriate operating system.