Patent Description:
Traditional authentication measures typically rely on a user to provide one or more credentials to show that the user is an authorized user. For example, a mobile device attempting to authenticate a user may ask the user to supply a password before allowing the user to access the device. In an effort to reduce the burden on a user, some devices may now ask a user to supply a biometric credential. For example, a mobile device may include a fingerprint sensor configured to collect fingerprint biometric information, which may be compared with stored fingerprint information of a known user. As another example, a mobile device may use facial recognition to authenticate a known user. Biometric authentication may be advantageous as it allows a user to authenticate more quickly than, for example, entering a password or some other credential. Devices should be designed, however, to avoid replay and spoofing attacks, e.g., where a malicious entity attempts to trick biometric sensors into incorrectly indicating that the correct user is present. <CIT> relates to facial recognition authentication systems.

Techniques are disclosed relating to preventing or reducing security threats relating to biometric sensors, e.g., for facial recognition. In some embodiments, a device is configured to generate a pseudo-random sequence of image capture modes using at least two different modes. The sequence includes two-dimensional (with flood illumination) and three-dimensional (with depth illumination) capture modes. In some embodiments, a secure circuit is configured to verify the sequence in image data from the camera unit and may determine whether to allow facial recognition to proceed based on whether the sequence was used.

In some embodiments, a device is configured to use a secret illumination pattern (which may be referred to as a probing pattern) for at least one image associated with a facial recognition session. This probing pattern may be pseudo-randomly determined from among a plurality of illumination patterns (e.g., with statically configured arrays for different patterns and/or dynamically adjustable patterns). For example, the pattern may include only a subset of infrared dots in an array of dot projectors used for a depth capture mode. In some embodiments, a secure circuit is configured to verify that the illumination pattern is present in image data from the camera unit and may determine whether to allow facial recognition to proceed based on whether the pattern was used.

In some embodiments, the device is configured to use the secret illumination pattern only after verifying a pseudo-random sequence of capture modes, or vice versa, which may further reduce the likelihood of a successful attack.

This disclosure includes references to "one embodiment" or "an embodiment. " The appearances of the phrases "in one embodiment" or "in an embodiment" do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

Within this disclosure, different entities (which may variously be referred to as "units," "circuits," other components, etc.) may be described or claimed as "configured" to perform one or more tasks or operations. This formulation-[entity] configured to [perform one or more tasks]-is used herein to refer to structure (i.e., something physical, such as an electronic circuit). More specifically, this formulation is used to indicate that this structure is arranged to perform the one or more tasks during operation. A structure can be said to be "configured to" perform some task even if the structure is not currently being operated. A "secure circuit configured to perform an authentication" is intended to cover, for example, an integrated circuit that has circuitry that performs this function during operation, even if the integrated circuit in question is not currently being used (e.g., a power supply is not connected to it). Thus, an entity described or recited as "configured to" perform some task refers to something physical, such as a device, circuit, memory storing program instructions executable to implement the task, etc. This phrase is not used herein to refer to something intangible. Thus, the "configured to" construct is not used herein to refer to a software entity such as an application programming interface (API).

The term "configured to" is not intended to mean "configurable to. " An unprogrammed FPGA, for example, would not be considered to be "configured to" perform some specific function, although it may be "configurable to" perform that function and may be "configured to" perform the function after programming.

Reciting in the appended claims that a structure is "configured to" perform one or more tasks is expressly intended not to invoke <NUM> U. § <NUM>(f) for that claim element. Accordingly, none of the claims in this application as filed are intended to be interpreted as having means-plus-function elements. Should Applicant wish to invoke Section <NUM>(f) during prosecution, it will recite claim elements using the "means for" [performing a function] construct.

As used herein, the terms "first," "second," etc. are used as labels for nouns that they precede, and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.) unless specifically stated. For example, a mobile device may have a first user and a second user. The term "first" is not limited to the initial user of the device. The term "first" may also be used when only one user of the mobile device exists.

As used herein, the term "based on" is used to describe one or more factors that affect a determination. This term does not foreclose the possibility that additional factors may affect a determination. That is, a determination may be solely based on specified factors or based on the specified factors as well as other, unspecified factors. Consider the phrase "determine A based on B. " This phrase specifies that B is a factor is used to determine A or that affects the determination of A. This phrase does not foreclose that the determination of A may also be based on some other factor, such as C. This phrase is also intended to cover an embodiment in which A is determined based solely on B. As used herein, the phrase "based on" is thus synonymous with the phrase "based at least in part on.

The present disclosure is generally directed to techniques for preventing spoofing or replays of biometric data, e.g., images used for facial recognition. "Replay" attacks involve using previously-captured biometric information that is typically valid (e.g., image data of an authorized person's face that previously passed biometric authentication) in an attempt to authenticate an individual. Malicious entities may attempt to present previously-captured images of a user to a camera of a device, for example, to pass an authentication process as an enrolled user of the device. "Spoofing" attacks typically utilize invalid data, e.g., data from another device or module purporting to be from a device's camera or images of masks, busts, 3D projections, etc. that are not actually current images of a known user. For example, malicious entities may send signals pretending to be from a device's camera unit, to trick the device into thinking that its camera captured an image of the user, when the image was actually previously-captured by another camera. This is one example of an attack that involves spoofing a camera. As another spoofing example, a malicious entity may present a mask or bust of an enrolled user to a camera of the device in an attempt to pass an authentication process as the enrolled user. In various embodiments, the disclosed techniques may reduce or eliminate the effectiveness of such schemes, such that authorized users who intend to authenticate biometrically are successfully authenticated while others are denied.

Turning now to <FIG>, a block diagram of a computing device <NUM> is depicted. In the illustrated embodiment, computing device <NUM> includes a system on a chip (SOC) <NUM> having a central processing unit (CPU) <NUM>, memory <NUM> including an application <NUM>, secure enclave processor (SEP) <NUM>, camera unit <NUM>, and image processor <NUM>. In some embodiments, computing device <NUM> may be implemented differently than shown. For example, in some embodiments, elements may not be included in an SOC or different combinations of elements may be included in an SOC, additional elements may be included, etc..

CPU <NUM> may include one or more processor cores. Generally, a processor core may include circuitry configured to execute instructions defined in an instruction set architecture implemented by the processor. Processors may be implemented on an integrated circuit with other components as a system on a chip (SOC) or other levels of integration. Processors may further include discrete microprocessors, processor cores and/or microprocessors integrated into multichip module implementations, processors implemented as multiple integrated circuits, etc..

Memory <NUM>, in the illustrated embodiment, is configured to store program instructions of application <NUM>. Memory <NUM> may generally include circuitry for storing data. For example, memory <NUM> may be static random access memory (SRAM), dynamic RAM (DRAM) such as synchronous DRAM (SDRAM) including double data rate (DDR, DDR2, DDR3, DDR4, etc.) DRAM. Low power/mobile versions of the DDR DRAM may be supported (e.g. LPDDR, mDDR, etc.). Device <NUM> may include a memory controller (not shown) that may include queues for memory operations, for ordering (and potentially reordering) the operations and presenting the operations to the memory <NUM>. The memory controller may further include data buffers to store write data awaiting write to memory and read data awaiting return to the source of the memory operation. In some embodiments, the memory controller may include a memory cache to store recently accessed memory data. In some embodiments memory <NUM> may include program instructions, such as instructions of application <NUM> that are executable by one or more processors to cause device <NUM> to perform various functionality described herein.

Application <NUM>, in some embodiments, is an application executable by CPU <NUM> to facilitate performance of object recognition, e.g., for user authentication. Execution of application <NUM> may cause CPU <NUM> to communicate with camera unit <NUM> (e.g., via image processor <NUM>) to perform facial recognition. In some embodiments, SEP <NUM> is involved in the facial recognition process, in place of or in addition to CPU <NUM>. For example, SEP <NUM> may execute internal program code or include dedicated circuitry to facilitate facial recognition. Examples of applications for which authentication may be performed include, without limitation: payment application, third party applications, an application for downloading other application, an application that performs cryptographic operations, an application that provides access to sensitive data stored in the device etc..

SEP <NUM>, in the illustrated embodiment, is a secure circuit configured to authenticate an active user (i.e., the user that is currently interacting with device <NUM>), to perform an action such as a cryptographic operation (examples of cryptographic operations may include unlocking a device, accessing keychain data, auto-filling data in a browser, accessing payment data (e.g., in a separate secure element), authorizing a payment procedure, accessing or downloading an application, consenting to operations on the device <NUM> or a remote device, etc.). As used herein, the term "secure circuit" refers to a circuit that protects an isolated, internal resource from being directly accessed by an external circuit. This internal resource may be memory that stores sensitive data such as personal information (e.g., biometric information, credit card information, etc.), encryptions keys, random number generator seeds, control of peripheral devices or other circuitry, etc. This internal resource may also be circuitry that performs services/operations associated with sensitive data. As will be described below with reference to <FIG>, this circuitry may include an image sensor pipeline that is configured to verify biometric data captured by camera <NUM> for a user by comparing it with previous collected biometric data of an authorized user. In some embodiments, discussed in further detail below with reference to <FIG>, SEP <NUM> is configured to perform one or more procedures to verify biometric data that is indicated as being captured by camera unit <NUM> (e.g., by virtue of being sent on a bus connected to camera unit <NUM>, stored in a memory location used for image data from camera unit <NUM>, etc.).

Camera module <NUM>, in the illustrated embodiment, is configured to collect biometric data from a user (e.g., a user's face) in order to authenticate the user. As used herein, "biometric data" refers to data that uniquely identifies the user among other humans (at least to a high degree of accuracy) based on the user's physical or behavioral characteristics. Camera <NUM> may use any suitable technique to collect biometric data. Accordingly, in some embodiments, camera <NUM> may include an infrared (IR) emitter and an IR camera that are configured to capture one or more two-dimensional and three-dimensional (e.g., flood and depth) image frames. When capturing a flood frame, the IR emitter may emit light from a single source, and the IR camera may collect two-dimensional image data from an object (e.g., a user's face or some other object purporting to be a user's face). When capturing a depth image frame, the IR emitter may project multiple light sources (e.g., using laser illumination) onto a user's face, and the IR camera may capture the reflections of those light sources to determine multiple depth points indicating distances from the IR camera to respective portions of the user's face. In some embodiments, the combination of flood and depth image data may allow for SEP <NUM> to compare faces in a three-dimensional space. In some embodiments, camera unit <NUM> is also configured to capture image data in the visible-light spectrum. In various embodiments, camera unit <NUM> communicates biometric data to SEP <NUM> via a secure channel. As used herein, the term "secure channel" refers to either a dedicated path for communicating data (i.e., a path shared by only the intended participants) or communicating encrypted data or signed data using cryptographic keys known only to the intended participants. In some embodiments, camera unit <NUM> and/or image processor <NUM> may perform various processing operations on biometric data before supplying it to SEP <NUM> in order to facilitate the comparison performed by SEP <NUM>. In some embodiments, application <NUM> may perform a registration process (which may also be referred to as an enrollment process) in which camera unit <NUM> captures biometric data from an authorized user in order to permit SEP <NUM> to subsequently authenticate the user.

<FIG> is a block diagram illustrating a portion of device <NUM> that includes SEP <NUM>, camera unit <NUM>, and image processor <NUM>, according to some embodiments. In some embodiments, image processor <NUM> may be omitted and its functionality may be performed by SEP <NUM>, for example.

In the illustrated embodiment, image processor <NUM> pseudo-randomly generates a sequence of image capture modes for a facial recognition session by camera unit <NUM>, where the camera unit is expected to use the generated sequence for the facial recognition session. In other embodiments, another element (such as SEP <NUM> or camera unit <NUM>) may be configured to generate the sequence. In the illustrated embodiment, image processor <NUM> provides the sequence information to the SEP <NUM> so that SEP <NUM> can confirm that the input data was captured in the expected sequence and also sends sequence control information <NUM> to camera unit <NUM> based on the determined sequence.

In some embodiments, camera unit <NUM> is configured to capture multiple pairs of images for a facial recognition session. Note that the pairs of images may be captured by different sensors in the same camera unit, the same sensor in the same camera unit, or by multiple different camera units, in some embodiments. Each pair includes an image captured using a two-dimensional capture mode (using flood illumination) and an image captured using a three-dimensional capture mode (using multiple points illumination, which may project on different regions). In some embodiments, image processor <NUM> and/or SEP <NUM> are configured to combine the images in each pair to generate a composite image that is used for facial recognition (e.g., to accurately map the geometry of a face). In some embodiments, image processor <NUM> and/or SEP <NUM> are configured to process the composite image to determine characteristics of the image (e.g., facial feature vectors), which SEP <NUM> is configured to compare with stored template characteristics one or more known users of device <NUM> (e.g., using one or more neural networks).

In other embodiments, any of various different image capture modes may be utilized in a pseudo-random sequence, including using different camera sensors, different illumination modes (e.g., flood, depth, different wavelengths of light, different intensities, etc.), different resolutions, different exposure times, etc. Although pairs of image captures are discussed herein, the pseudo-random sequence of capture modes is in no way limited to pairs of image captures. For example, a pseudo-random sequence could include N image captures of a first type followed by M image captures of a second type, various interleaving between the types, and so on. Speaking generally, the sequence may be pseudo-randomly determined for a particular group or set of image captures. In the specific context of image and depth capture, each set could include two flood and one depth capture, three depth and one flood capture, etc. In some embodiments, one or more of the image capture modes may not actually be used to capture image data used for facial recognition, but may simply be inserted into the sequence for security purposes. For example, a solo depth capture may be inserted into the sequence of image capture modes in a pseudo-random fashion, without being combined with a flood capture, in order to further add unpredictability to the sequence.

The pseudo-random sequence may be generated using any of various appropriate implementations, including one or more random number generators, which may be included in image processor <NUM> or SEP <NUM>. The term "pseudo-random" refers to values that satisfy one or more statistical tests for randomness but are typically produced using a definite mathematical process, e.g., based on one or more seed values, which may be stored or generated by SEP <NUM> and used by SEP <NUM> or sent to another processing element. In some embodiments, any of various sequences described herein as pseudo-random may actually be random, but true randomness is typically difficult to generate using computer hardware. In some embodiments, the number of image captures and/or the number of pairs of image captures may be pseudo-randomly determined.

In some embodiments, image processor <NUM> generates the pseudo-random sequence and informs camera module <NUM> of the sequence. Camera module <NUM> then produces image data <NUM> and stores it in a memory location accessible to image processor <NUM>. Image processor <NUM> then processes the image and stores the processed image data (with metadata indicating the sequence used) in a memory location accessible to SEP <NUM>. The image data may be cryptographically signed and/or encrypted using a session key. SEP <NUM> may verify image data authenticity and integrity before accessing the image data and then may that it exhibits the sequence indicated by the metadata. The metadata may be cryptographically signed and/or encrypted using a session key, in some embodiments. Similarly, the sequence may be encrypted when sent to camera module <NUM>, in embodiments in which camera module <NUM> supports encryption.

In some embodiments, image processor <NUM> selects an illumination pattern for one or more image captures by the camera unit <NUM> for a facial recognition session. In some embodiments, the illumination pattern is selected pseudo-randomly from among multiple patterns supported by camera unit <NUM>. The pattern may be referred to herein as a "probing" pattern, which may be different than other patterns used for depth capture for facial recognition matching. In other embodiments, another element (e.g., SEP <NUM>) is configured to select the pattern. In some embodiments, different devices are configured with different illumination patterns during manufacturing, and the pattern(s) may be kept secret, e.g., by secure keys that are only accessible to SEP <NUM>. In some embodiments, illumination pattern(s) are dynamically generated for a given facial recognition session.

In the illustrated embodiment, image processor <NUM> provides the pattern information to SEP <NUM> so that SEP <NUM> can confirm the pattern and also sends pattern control information <NUM> to camera unit <NUM> based on the determined pattern. In some embodiments, a single pattern or a small number of patterns may be implemented for a given device (e.g., by permanently configuring one or more special emitter arrays) and the pattern may be kept secret. In some embodiments, SEP <NUM> is configured to allow facial recognition authentication only if the selected pattern is detected in image data generated by camera unit <NUM>.

In some embodiments, the pattern uses only a subset of a plurality of illumination points available for depth capture. The illumination points may be individually controllable or may be controlled in groups. For example, for an exemplary 4x4 array of illumination points, each of the sixteen points may be individually controlled or the array may be split into groups (e.g., 2x2 quadrants) that device <NUM> is configured to enable or disable at the group granularity. The number, location, type, and/or intensity of points that are activated may be selected pseudo-randomly.

The illumination points may be laser generated, for example, and only a subset of the laser elements may be activated. The captured image using the selected illumination pattern may or may not be used for actual facial recognition processing. For example, illumination patterns may be selected that are not particularly useful in facial recognition, but may be useful for providing randomness to prove that image data was captured using known camera unit <NUM>.

In some embodiments, the disclosed illumination pattern techniques may be combined with other security mitigation techniques such as verification of a pseudo-randomly generated sequence. For example, device <NUM> may be configured to use a particular illumination pattern only after verification of a pseudo-random sequence of image capture modes, verification that image data is signed, verification of a nonce for each image, etc. In other embodiments, device <NUM> may be configured to generate a pseudo-random sequence of capture modes only after verifying a particular illumination pattern. In some embodiments, the illumination pattern may be used within the sequence of capture modes in a pseudo-random location in the expected sequence of image capture modes. Speaking generally, various verification techniques discussed herein may be used in combination in various orderings to improve authentication security.

In some embodiments, multiple illumination patterns may be selected (for use in sequence and/or in parallel) and may be used in the pseudo-random sequence of depth capture modes, and may further be pseudo-randomly interspersed among other image capture modes. Further, multiple illumination patterns may be used together, in parallel or in a particular sequence. In these embodiments, SEP <NUM> may be configured to allow facial recognition authentication only in response to verifying both the illumination patterns and the sequence of patterns and/or capture modes.

In some embodiments, SEP <NUM> is configured to generate a cryptographic nonce for each image captured by camera unit <NUM> for facial recognition. The term "nonce" is intended to be construed according to its well-understood meaning, which includes a random or pseudo-random number that is produced to be used once. In some embodiments, camera unit <NUM> or image processor <NUM> is configured to embed a received nonce with each image (or with composite image data or data that specifies image characteristics). In some embodiments, camera unit <NUM> or image processor <NUM> is configured to sign image data for each image (or composite image data or data that specifies image characteristics) using a session key established between SEP <NUM> and camera unit <NUM> or image processor. In some embodiments, SEP <NUM> is configured to confirm that incoming data includes the correct nonce and was signed and was signed using the session key before using the data for a facial recognition session (and may indicate a failure if the correct nonce is not found). In some embodiments, the nonce and/or signature using a session key may prevent replay using previously-captured images, which would not have the correct nonce and/or signature.

In some embodiments, SEP <NUM> is configured to communicate with one or both of image processor <NUM> and camera unit <NUM> using a secure channel. This may involve encrypted and/or cryptographically signed communications based on a secure exchange of cryptographic keys. One example of a technique for exchanging keys over a potentially public channel is to establish an elliptic curve Diffie Hellman (ECDH) session. In some embodiments, ECDH keys may be used to sign messages between processing elements in order to reduce the likelihood that received image data is being spoofed (e.g., by another processing element). Other public/private key techniques may similarly be used to sign data, in various embodiments. Various disclosed communications may be encrypted and/or signed.

Using these techniques, if a malicious device sends image data purporting to be from camera unit <NUM>, SEP may be able to detect that the image data is not actually from camera unit <NUM> if it is not correctly signed. In some embodiments, to improve security, SEP <NUM> is configured to use a different ECDH session and key for each facial recognition session. For example, once a user is authenticated or authentication fails for a given facial recognition session, SEP <NUM> may perform a new ECDH key exchange for the next facial recognition session.

In some embodiments, SEP <NUM> and/or image processor <NUM> are configured to communicate with camera unit <NUM> via a dedicated bus that is not available for communications by other modules. In some embodiments SEP <NUM> is configured to require re-authentication using a particular type of credential in response to a disconnect of the dedicated camera bus. For example, in some embodiments device <NUM> is configured to present a lock screen and require manual user entry of a PIN or password in response to disconnect of the dedicated camera bus. As another example, in some embodiments device <NUM> is configured to require multiple types of authentication credentials (e.g., both biometric and manual entry) in response to a disconnect of the dedicated camera bus. Additional examples of lockout types for a device are discussed in detail below.

Turning now to <FIG>, a block diagram of SEP <NUM> is depicted, according to some embodiments. In the illustrated embodiment, SEP <NUM> includes a filter <NUM>, secure mailbox <NUM>, processor <NUM>, secure ROM <NUM>, cryptographic engine <NUM>, a key storage <NUM>, an enclave image sensor pipeline <NUM>, and biometric storage <NUM> coupled together via an interconnect <NUM>. In some embodiments, SEP <NUM> may include more (or less) components than shown in <FIG>. As noted above, SEP <NUM> is a secure circuit that protects an internal resource such as components user authentication keys <NUM> and/or enclave image sensor pipeline <NUM>. As discussed below, SEP <NUM> implements a secure circuit through the use of filter <NUM> and secure mailbox <NUM>.

Filter <NUM>, in the illustrated embodiment, is circuitry configured to tightly control access to SEP <NUM> to increase the isolation of the SEP <NUM> from the rest of the computing device <NUM>, and thus the overall security of the device <NUM>. More particularly, in some embodiments, filter <NUM> is configured to permit read/write operations from a CPU <NUM> (or other peripherals on a fabric coupling CPU <NUM> and SEP <NUM>) to enter SEP <NUM> only if the operations address the secure mailbox <NUM>. Therefore, other operations may not progress from the interconnect <NUM> into SEP <NUM>, in these embodiments. In some embodiments, these techniques using filter <NUM> are applied to accesses to data for enclave image sensor pipeline <NUM>. Even more particularly, filter <NUM> may permit write operations to the address assigned to the inbox portion of secure mailbox <NUM>, and read operations to the address assigned to the outbox portion of the secure mailbox <NUM>. All other read/write operations may be prevented/filtered by the filter <NUM>. Therefore, secure mailbox <NUM> includes predetermined memory locations that are accessible to other elements in device <NUM> and the remainder of the circuitry in SEP <NUM> is not accessible to other elements of device <NUM>. In some embodiments, filter <NUM> may respond to other read/write operations with an error. In one embodiment, filter <NUM> may sink write data associated with a filtered write operation without passing the write data on to local interconnect <NUM>. In one embodiment, filter <NUM> may supply non-secure data as read data for a filtered read operation. This data (e.g., "garbage data") may generally be data that is not associated with the addressed resource within the SEP <NUM>. Filter <NUM> may supply any data as garbage data (e.g. all zeros, all ones, random data from a random number generator, data programmed into filter <NUM> to respond as read data, the address of the read transaction, etc.).

In some embodiments, filter <NUM> may only filter externally issued read/write operations. Thus, the components of the SEP <NUM> may have full access to the other components of computing device <NUM> including CPU <NUM>, memory <NUM>, image processor <NUM>, and/or camera unit <NUM>. Accordingly, filter <NUM> may not filter responses from interconnect <NUM> that are provided in response to read/write operations issued by SEP <NUM>.

Secure mailbox <NUM> is circuitry that, in some embodiments, includes an inbox and an outbox. Both the inbox and the outbox may be first-in, first-out buffers (FIFOs) for data, for example. The buffers may have any size (e.g. any number of entries, where each entry is capable of storing data from a read/write operation). Particularly, the inbox may be configured to store write data from write operations sourced from CPU <NUM>. The outbox may store write data from write operations sourced by processor <NUM>. (As used herein, a "mailbox mechanism" refers to a memory circuit that temporarily stores <NUM>) an input for a secure circuit until it can be retrieved by the circuit and/or <NUM>) an output of a secure circuit until it can be retrieved by an external circuit.

In some embodiments, software executing on CPU <NUM> (e.g., application <NUM>) may request services of SEP <NUM> via an application programming interface (API) supported by an operating system of computing device <NUM>-i.e., a requester may make API calls that request services of SEP <NUM>. These calls may cause corresponding requests to be written to mailbox mechanism <NUM>, which are then retrieved from mailbox <NUM> and analyzed by processor <NUM> to determine whether it should service the requests. Accordingly, this API may be used to deliver biometric data to mailbox <NUM>, request authentication of a user by verifying this information, and delivering an authentication result <NUM> via mailbox. By isolating SEP <NUM> in this manner, integrity of enclave image sensor pipeline <NUM> may be enhanced.

SEP processor <NUM>, in the illustrated embodiment, is configured to process commands received from various sources in computing device <NUM> (e.g. from CPU <NUM>) and may use various secure peripherals to accomplish the commands. Processor <NUM> may then execute instructions stored in secure ROM <NUM> and/or in a trusted zone of SoC memory <NUM>, such as authentication application <NUM> to perform an authentication of a user. In other embodiments, authentication application <NUM> may be stored elsewhere, e.g., as firmware that is loaded to a part of SoC memory. In these embodiments, secure ROM <NUM> may verify such firmware before executing it. For example, SEP processor <NUM> may execute application <NUM> to provide appropriate commands to enclave image sensor pipeline <NUM> in order to verify biometric data. In some embodiments, application <NUM> may include encrypted program instructions loaded from a trusted zone in memory <NUM>.

Secure ROM <NUM>, in the illustrated embodiment, is a memory configured to store program instruction for booting SEP <NUM>. In some embodiments, ROM <NUM> may respond to only a specific address range assigned to secure ROM <NUM> on local interconnect <NUM>. The address range may be hardwired, and processor <NUM> may be hardwired to fetch from the address range at boot in order to boot from secure ROM <NUM>. Filter <NUM> may filter addresses within the address range assigned to secure ROM <NUM> (as mentioned above), preventing access to secure ROM <NUM> from components external to the SEP <NUM>. In some embodiments, secure ROM <NUM> may include other software executed by SEP processor <NUM> during use. This software may include the program instructions to process inbox messages and generate outbox messages, etc..

Cryptographic engine <NUM>, in the illustrated embodiment, is circuitry configured to perform cryptographic operations for SEP <NUM>, including key generation as well as encryption and decryption using keys in key storage <NUM>. Cryptographic engine <NUM> may implement any suitable encryption algorithm such as DES, AES, RSA, etc. In some embodiments, engine <NUM> may further implement elliptic curve cryptography (ECC). In various embodiments, engine <NUM> is responsible for decrypting traffic received from camera unit <NUM> described above and encrypting traffic sent to other processing elements.

Key storage <NUM>, in the illustrated embodiment, is a local memory (i.e., internal memory) configured to store cryptographic keys. In some embodiments, these keys may include keys used to establish the secure channels between SEP <NUM> and other processing elements. As shown, in some embodiments, these keys include authentication keys <NUM>. The keys may allow for various cryptographic operations and also may be used for other elements of the system to indicate whether the user is authenticated (e.g., to indicate that the user is authenticated for specific operations, such as to a secure element for payment operations).

Enclave image sensor pipeline <NUM>, in some embodiments, is circuitry configured to compare biometric data captured from a user being authenticated with biometric data <NUM> of an authorized user. Various functionality described herein as being performed by image processor <NUM> may be performed by image sensor pipeline <NUM> in other embodiments or vice versa. In some embodiments, pipeline <NUM> may perform the comparison using a collection of neural networks included in pipeline <NUM>, each network being configured to compare biometric data captured in a single frame or composite frame with biometric data <NUM> captured in multiple frames for an authorized user. As shown, pipeline <NUM> may be configured to read, from memory <NUM>, biometric data <NUM>, which may be protected by encryption in some embodiments or being stored in an associated part of memory <NUM> that is only accessible to SEP <NUM>. (In another embodiment, SEP <NUM> may store data <NUM> internally. ) In various embodiments, image sensor pipeline <NUM> is configured to perform or facilitate disclosed anti-spoofing techniques.

Note that although biometric storage <NUM> is included in SEP <NUM> in the illustrated embodiment, in other embodiments SEP <NUM> is configured to encrypt authorized user biometric data <NUM> (e.g., using an encryption key in key storage <NUM>) and store the encrypted data outside of SEP <NUM>. In some embodiments, the encryption key used for such encryption never leaves SEP <NUM> and is unique to device <NUM>, which may improve security of such encrypted data when stored outside of SEP <NUM>. Biometric data <NUM> may include template data for storage and/or live data used for authentication.

<FIG> is a block diagram illustrating an exemplary camera unit <NUM>, according to some embodiments. In the illustrated embodiment, module <NUM> includes sensor <NUM>, flood illuminator <NUM>, and point illuminator array <NUM>. In some embodiments, the illustrated elements are all configured to operate using infrared signals. In other embodiments, camera unit <NUM> may be configured to operate using other wavelengths, e.g., may include both RBG and infrared emitters and/or sensors, etc..

Sensor <NUM>, in the illustrated embodiment, is configured to capture image data based on incoming radiation. In some embodiment, sensor <NUM> includes an array, e.g., of charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) elements. In some embodiments, imaging data from sensor <NUM> is usable to determine depth information, e.g., based on a known configuration and pattern generated by point illuminator array <NUM>. In some embodiments, device <NUM> is configured to combine an image captured using flood illuminator <NUM> with an image captured using point array illuminator <NUM> to generate a composite depth image, e.g., of a user's face.

Flood illuminator <NUM>, in the illustrated embodiment, is configured to generate a broad-beam of illumination in a desired spectrum. Thus, images captured using flood illuminator <NUM> may be used for two-dimensional analysis.

Point illuminator <NUM>, in the illustrated embodiment, is configured to generate a known pattern of points of illumination. For example, point illuminator may be implemented using one or more vertical-cavity surface-emitting laser (VCSEL) circuits. In some embodiments, a different light source element (e.g., laser) is used for each point of illumination. In other embodiments, a given light source may be used to generate multiple points of illumination, e.g., using diffractive lensing. Therefore, in various embodiments, point illuminator <NUM> is configured to generate multiple discrete points of illumination for image capture. These points of illumination may be used to generate three-dimensional image data (in combination with two-dimensional image data from flood capture mode, in some embodiments).

<FIG> is a diagram illustrating multiple exemplary arrays of point illuminators that may be included in element <NUM>, according to some embodiments. In the illustrated embodiment, a device includes multiple point illuminator arrays 510A-510N and one or more diffractive optics <NUM>. These arrays may be used for depth capture modes and/or generating a probing pattern, in some embodiments.

Point illuminator arrays <NUM>, in the illustrated embodiments, each include multiple emitters (e.g., VCSEL emitters) that are shown as circles and configured to generate points of illumination. The different arrays may each include the same number of emitters or different numbers of emitters. In some embodiments, a first set of one or more arrays is used for normal depth captures and a second set of one or more special arrays are used for one or more probing patterns, which may be used to authenticate camera unit <NUM>. In some embodiments, the special arrays are not used for normal depth capture modes (other than for detecting a probing pattern). In other embodiments, one or more arrays may be used for both.

Diffractive optic(s) <NUM>, in the illustrated embodiment, are configured to generate multiple points of illumination for a given emitter. For example, infrared emissions from a single emitter may be used to generate tens or hundreds of projected illumination points. The overall illumination pattern for depth capture mode may include tens of thousands of dots, for example. This may allow a relatively small number of emitters to generate points for a wide field of view. Diffractive optic(s) <NUM> may generate a known pattern and changes in the pattern in captured images (relative to capturing a flat object, for example) may be used to determine depth, when projected onto other objects.

As shown, emitters may be disabled permanently and/or dynamically in one or more arrays. For example, emitters may be permanently disabled during manufacturing of the device. In the illustrated example, arrays 510A and 510B have emitters at different positions disabled (e.g., as indicated using the dashed circuits), which may result in different probing patterns depending on which of these arrays are used. In dynamic embodiments, similar techniques of disabling different emitter positions may be used to generate different probing patterns at different times, using a given array. In some embodiments, metadata used to select a particular secret pattern does not indicate characteristics of the pattern (e.g., it may simply be an index of the pattern from an array of patterns) and characteristics of the pattern for verifying the pattern are controlled by SEP <NUM> (e.g., stored in SEP <NUM> or encrypted by SEP <NUM> and stored elsewhere). In some embodiments, one or more validations (e.g., verification of the pseudo-random sequence) must pass prior to firing a probing pattern, which may reduce the ability to replay a probing pattern. Further, multiple probing patterns may be used to increase replay difficulty, e.g., because a replayed image may be unlikely to have the same probing pattern as the currently-used probing pattern.

In some embodiments, the device is configured to use different special illuminator arrays or patterns for different facial recognition sessions, e.g., in a sequential or pseudo-random fashion. This may prevent malicious entities from capturing an illumination pattern and re-using the illumination pattern and/or may allow multiple probing pattern attempts before locking a user out of the device. In some embodiments, software running on device <NUM> is configured to select which special arrays are used for which facial recognition sessions (although the software may have no knowledge of the actual patterns implemented by the different sub-arrays). In some embodiments the software is executed by SEP <NUM>. In some embodiments, software executed elsewhere may use an API to request such functionality from SEP <NUM>.

In some embodiments, a manufacturer may implement arrays <NUM> with a sufficient number of emitters to implement a relatively large number of different patterns (e.g., hundreds or thousands of patterns or more). Therefore, in embodiments with permanent array configuration, the likelihood of a probing pattern used for one device also being used for another device may be quite low. In other embodiments, a manufacturer may use unique probing patterns for each device, such that a probing pattern used by one device will not be used by any other devices. Further, different orderings of probing patterns may be used on different devices in embodiments where at least some of the same probing patterns are used for different devices.

During manufacturing, a camera unit <NUM> may be paired with other circuitry in a device (e.g., SEP <NUM>) using the camera unit's configured probing pattern(s). For example, the manufacturer may capture one or more probing patterns using camera unit <NUM> and store captured data (which may be at least partially processed, e.g., to detect the pattern used) securely (e.g., within SEP <NUM> or encrypted by SEP <NUM> using a secret key specific to that SEP <NUM> and stored in another location). When device <NUM> is used for facial recognition, SEP <NUM> may verify that one or more frames of image data captured by camera unit <NUM> exhibit the expected probing pattern.

In some embodiments, probing patterns may be checked to within a threshold degree of matching but not require an exact match. This may be implemented for static and/or dynamic embodiments. This may allow verification of different patterns in the presence of noise or equipment failures (e.g., if a particular emitter that was expected to be turned on for a pattern is actually disabled due to equipment failure, the pattern still may be detected). Therefore, verification of the probing pattern may be performed to within a threshold certainty using one or more of various algorithms.

As discussed above, in some embodiments, device <NUM> is configured to dynamically enable or disable different emitters in an array <NUM> for a particular firing. For example, SEP <NUM> or image processor <NUM> may pseudo-randomly generate a requested pattern and SEP <NUM> may verify that camera unit <NUM> used the requested pattern. In some embodiments, template information specifying each pattern supported by camera module <NUM> (or each pattern that potentially may be used as a probing pattern) may be stored to determine matches with an expected pattern. In other embodiments, device <NUM> may be configured to verify an expected pattern without storing template image data for patterns, e.g., based on knowledge of the illuminator array and diffractive optics used.

In some embodiments, SEP <NUM> is configured to encrypt data used to specify what pattern is determined for use in a facial recognition session. For example, SEP <NUM> and camera module <NUM> may establish an ECDH session to encrypt information specifying which special arrays to fire for the probing pattern or information dynamically indicating which emitters in an array should be used to fire the probing pattern.

In some embodiments, multiple probing patterns are used during a facial recognition session. The patterns may be fired sequentially and/or in parallel. SEP <NUM> may verify that the specified timing and content of patterns is used. For example, if multiple probing patterns are fired at once, SEP <NUM> may verify the expected combination of patterns. In some embodiments, the timing of when one or more probing patterns is fired is randomized within a facial recognition session. This may include pseudo-randomly determining whether to fire the probing pattern before or after other events in the facial recognition and/or pseudo-randomly determining a point within a particular pre-determined interval within the session to fire the probing pattern (e.g., N ms may be allocated for firing the pattern and the actual firing time may occur pseudo-randomly within that time interval).

In some embodiments, SEP <NUM> is configured to validate a probing pattern by determining differences between the probing pattern and a normal depth capture pattern (i.e., a depth capture pattern used for depth determination for facial matching, which may differ from probing pattern(s) used for verification of camera unit <NUM>). This may be particularly useful in embodiments where the probing pattern illumination points are a subset of the normal illumination points. SEP <NUM> may instruct camera unit <NUM> to capture two frames of image data, one using the probing pattern and the other using the normal pattern and process the images to generate a differential between the two patterns. This may help account for varying conditions such as temperature, ambient lighting, etc., for example, by ensuring that the conditions are substantially the same for the probing pattern and normal pattern being distinguished. In some embodiments, this technique may reduce the probability of false detections and false rejections of the probing pattern.

In some embodiments, the same set of one or more probing patterns may be used for multiple users registered on a device. In other embodiments, different sets of probing patterns may be used for different users. Template image data for facial recognition may be stored for each of multiple users of the device.

<FIG> is a flow diagram illustrating an exemplary method for a secure facial recognition session using a probing pattern, according to some embodiments. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, device <NUM> determines an illumination pattern (examples of which are referred to herein as probing patterns) for a camera mode that uses multiple points of illumination. The illumination pattern may be fixed for a given device <NUM>, e.g., that such that the device always uses the same illumination pattern for the techniques of <FIG>. In other embodiments, SEP130 or image processor <NUM> is configured to select the illumination pattern from a plurality of illumination patterns, e.g., in a pseudo-random fashion. The patterns may be permanently configured during manufacturing or dynamically controlled, for example. In multi-user embodiments, the pattern may be selected for a particular user. In some embodiments, SEP <NUM> determines whether to use the flood illuminator <NUM> with the probing pattern and/or when to fire the flood illuminator relative to the pattern with multiple illumination points.

At <NUM>, in the illustrated embodiment, SEP <NUM> receives image information indicated as being captured by camera unit <NUM> (e.g., after it fires the determined illumination pattern and captures one or more images). The image information may be "indicated" as being captured by camera unit <NUM> based on metadata in the image information, a bus on which the information is received, timing of receiving the image data, etc. Note, however, that the information may not actually be captured by a camera unit of the apparatus, but may be captured by another unit masquerading as camera unit <NUM>. The illumination pattern may facilitate detection of such attacks, in some embodiments, by enabling detection of the masquerading camera unit based on absence of the expected probing pattern.

At <NUM>, in the illustrated embodiment, SEP <NUM> determines whether to authenticate a user in a facial recognition session based on whether the image information was captured using the determined illumination pattern. SEP <NUM> may indicate a facial recognition failure in response to determining that the image information was not captured using the determined illumination pattern. Confirmation of the pattern may indicate that the image data was not previously captured and replayed and/or was not captured by some other hardware masquerading as camera unit <NUM>, in various embodiments.

Note that although facial recognition is discussed herein for purposes of explanation, the disclosed techniques may be used in various other contexts to verify that images are not replayed and/or that images are captured by a known camera unit.

In some embodiments, various device data is stored that may be used for the disclosed techniques. This data may be stored during manufacturing (e.g., based on hardware characteristics of a particular device) or during enrollment of a user for facial recognition authentication. In some embodiments, device data is backed up to one or more servers, e.g., via the internet. In some embodiments, at least a portion of the device data is signed and/or encrypted by SEP <NUM>. The device data may allow restoration of a device to factory settings or a particular restore point, for example. The signing by SEP <NUM> may allow the SEP <NUM> to verify that the restore data is actually for the correct device while the encryption may prevent others from determining sensitive data.

In some embodiments, calibration data is stored during manufacturing for camera unit <NUM>. For example, temperature may affect infrared capture modes, so images captured at multiple different temperatures may be captured and stored. In some embodiments, the images may be encrypted, processed, compressed, etc. before storage. In some embodiments, SEP <NUM> is configured to sign and/or encrypt this data so that it cannot be tampered with without detection and/or cannot be interpreted by malicious entities. Another example of calibration data is camera alignment data. In some embodiments, sparse calibration data may be stored and a full set of calibration data may be generated by device <NUM> by capturing additional sensor data and processing it in combination with the sparse calibration data.

In some embodiments, calibration data may include high-resolution captures (e.g., depth and flood captures) of a known reference image.

Probing pattern data (e.g., frames captured using the probing pattern or outputs of processing such frames) may be stored with calibration data, e.g., after encryption by SEP <NUM>. In various embodiments, SEP <NUM> may include random data with the probing pattern data (or any other encrypted data discussed here) before encryption to increase security.

Template data for users may be similarly captured and stored when users are enrolled for facial recognition. For example, SEP <NUM> may capture multiple images of a user, process the images to generate a mathematical representation of a captured face (e.g., using feature vectors), and continue capturing images until the vectors meet one or more criteria. SEP <NUM> may encrypt the template data or store the template data internally. In some embodiments, multiple different facial poses may be captured during enrollment. SEP <NUM> may require another authentication type (e.g., a password or PIN) before allowing biometric enrollment. The captured images for enrollment may include various numbers of depth and flood image pairs, for example. In some embodiments, SEP <NUM> is configured to store data captured during the enrollment process, such as actual images captured during enrollment and/or mathematical representations of the face captured during enrollment. Saving the enrollment images themselves may allow mathematical representations to be re-generated, e.g., if the neural network is updated in the future, without requiring re-capturing of enrollment images. SEP <NUM> may sign and/or encrypt the enrollment data, in some embodiments, and verify the enrollment data before using it for facial recognition.

In some embodiments biometric data captured during enrollment is not stored anywhere other than device <NUM> (e.g., is not backed up using cloud techniques). In some embodiments, a diagnostic mode may allow sharing of biometric information, e.g., to help with support or troubleshooting relating to facial recognition.

In various embodiments, SEP <NUM> is configured to check authenticity of calibration and/or enrollment data, e.g., by confirming that the data was signed by SEP <NUM> and/or based on SEP <NUM> being able to decrypt the data, using its secret key, to generate data in an expected format.

<FIG> is a flow diagram illustrating an exemplary method for generating and storing calibration data, according to some embodiments. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, calibration data is determined for a camera unit. This may include capturing images in different conditions (e.g., different temperatures, orientations, etc.) using one or more camera modes (e.g., depth capture mode). This may include capturing one or more images of a known reference image. Determining the calibration data may include processing the captured image data, e.g., to determine characteristics of the data, compress the data, etc..

At <NUM>, in the illustrated embodiment, a processing element (e.g., SEP <NUM>) encrypts and/or cryptographically signs the calibration data. SEP <NUM> may perform this encryption and/or signature using an internal secret key that is unique to the SEP <NUM> of a given device.

At <NUM>, in the illustrated embodiment, the calibration data is stored. In some embodiments, calibration data is stored in SEP <NUM>. In other embodiments, the calibration data is stored outside of SEP <NUM>, and may be loaded into memory accessible to SEP <NUM> on boot, for example. In some embodiments, the calibration is stored remotely, e.g., to a cloud backup system.

<FIG> is a flow diagram illustrating an exemplary method for using calibration data, according to some embodiments. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, stored calibration data is accessed. This may be performed on boot of the device or in response to initiation of a facial recognition session, for example.

At <NUM>, in the illustrated embodiment, a processing element (e.g., SEP <NUM>) verifies the accessed calibration data. This may include decrypting the calibration data and/or verifying a cryptographic signature of the calibration data, for example. If the calibration data is not verified, an error condition may be indicated and biometric authentication may not be allowed. In some embodiments, the calibration data is decompressed. The verification may avoid tampering or replacement of calibration data If calibration data is compromised, it may be retrieved from backup storage (e.g., cloud backup) and restored.

At <NUM>, in the illustrated embodiment, a processing element (e.g., SEP <NUM>) uses the verified calibration data for processing in a facial recognition session. For example, the calibration data may be used for depth capture to determine facial feature vectors for face matching. The calibration data may also be used to process image data from one or more probing pattern captures to verify one or more probing patterns.

In some embodiments, device <NUM> is configured to impose a lockout in response to various event triggers. A lockout may prevent all access to a device for a predetermined time interval (or indefinitely) or may require additional authentication to bypass the lockout (e.g., using a password or PIN in addition to biometric authentication or a secret key known only to a manufacturer). For example, a "bio-lockout" may require one or more non-biometric authentication types before allowing access to device <NUM>. In various embodiments, multiple different types of lockout may be implemented in a given device, with different intervals, unlock conditions, etc. The following discussion provides non-limiting examples of events that cause a lockout, in some embodiments.

In some embodiments, reboot of device <NUM> or a remote indication from a user may cause lockout. In some embodiments, a determination that a time interval has occurred since a last successful authentication of a user may cause a lockout. For example, if a user has not authenticated for multiple days, entry of a PIN or password may be required in addition to biometric authentication. In some embodiments, removal of a SIM card while device <NUM> is locked may cause a lockout. In some embodiments, dismissing an emergency screen in one or more ways may cause a lockout. In some embodiments, circumventing lockout may require permission from another trusted device or the user may be required to call a service to gain access.

Lockout triggers relating to biometric authentication may include: a particular number of unsuccessful match biometric attempts (attempts may only be counted if a face or fingerprint is detected, but does not match a known user, for example), a particular number of failures to match a sequence of image capture modes, a particular number of unsuccessful probing pattern checks, receipt of an image capture frame (e.g., by SEP <NUM>) after expiration of a session key, receipt of an image capture frame with a missing or incorrect nonce, receipt of an image capture frame with a missing or incorrect signature, detected discrepancies relating to a received frame counter, a user not meeting an attention awareness threshold (e.g., because the user's eyes are not open or the user is not looking at or paying attention to the device), etc..

Note that, in some embodiments, multiple ones of these events may be counted together. As one example, both unsuccessful facial recognition matches and failures to match a sequence of image capture modes may be counted together and the count compared to a single threshold. Further, different triggers may cause different lockout intervals, and additional triggers may increase a current lockout interval.

<FIG> is a flow diagram illustrating an exemplary method for using a pseudo-random sequence in a secure facial recognition session, according to some embodiments. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, device <NUM> determines a pseudo-random sequence of image capture modes for a plurality of groups of image captures. In the illustrated embodiment, each group includes a first illumination mode and a second illumination mode (a flood and a point illumination mode. In some embodiments, these illumination modes correspond to a two-dimensional capture mode and a three-dimensional capture mode. In the illustrated embodiment, the ordering of the illumination modes for each group is pseudo-randomly determined. In other embodiments, the method of <FIG> may be performed by determining a pseudo-random sequence of image capture modes for a single group of image captures. In some embodiments, the number of captures in the sequence is pseudo-randomly determined. One example of a group of image captures is a pair of flood and depth captures that are combined to create a composite frame for facial recognition matching. In this context, a first pair may pseudo-randomly selected to be depth capture followed by flood capture and a second pair may pseudo-randomly selected to be flood capture followed by depth capture, and so on. In other embodiments, other types of sequences of capture modes may be implemented (e.g., with randomness among larger sets of captures than pairs, additional capture modes, etc.).

At <NUM>, in the illustrated embodiment, SEP <NUM> receives information indicated as being captured by a camera unit (e.g., camera unit <NUM> may receive information indicated the determined sequence, capture image data using the sequence, and send the image data to SEP <NUM>). Note that the information may not actually be captured by a camera unit of the apparatus, but may be captured by another unit masquerading as camera unit <NUM>. The pseud-random sequence may facilitate detection of such spoofing, in some embodiments.

At <NUM>, in the illustrated embodiment, SEP <NUM> determines whether to authorize in response to analyzing the image information and determining whether the image information was captured using the pseudo-random sequence of image capture modes. In some embodiments, SEP <NUM> may initiate firing of a probing pattern only after validating the sequence for a particular facial recognition session. If the sequence is not recognized, a facial recognition failure may occur, or SEP <NUM> may specify that another sequence should be captured. At this point, SEP <NUM> may also store and/or transmit information indicating that the incorrect sequence was detected and device <NUM> may implement one or more additional authentication requirements (e.g., requiring a manual entry of one or more authentication credentials in addition to facial recognition, a check for a maximum number of attempts before locking device <NUM> at least temporarily, etc.). If the sequence is verified, authentication may proceed (e.g., face matching, probing pattern, etc.). Verification of the sequence may substantially reduce the likelihood that the sequence was replayed from an earlier image of the user or generated by hardware masquerading as camera unit <NUM>, in various embodiments.

<FIG> is a flow diagram illustrating an exemplary method for using multiple types of validation in a secure facial recognition session, according to some embodiments. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, device <NUM> initiates a facial recognition session. The session may be initiated in response to user input, e.g., using a physical button or selecting an option via a touchscreen. In some embodiments, a facial recognition session may be initiated in response to indication of a user interacting with device <NUM> such as movement of device <NUM> (e.g., indicating that a user has picked up device <NUM>) or based on detection of a face or gaze of a user. In various embodiment, the session may be initiated automatically, e.g., when a user raises device <NUM> or taps the screen. In some embodiments, device <NUM> may automatically initiate the session before displaying a notification on a screed of device <NUM>. In some embodiments, device <NUM> may prompt the user to being a facial recognition session (e.g., when requested by a third-party application) by indicating that biometric authentication should be performed (e.g., the user should look at the device) or the user should input a passcode. Method element <NUM> may include powering on hardware, accessing camera calibration data, communicating to establish one or more session keys between components, etc. As shown, a failure at <NUM> may cause flow to proceed to <NUM> and additional authentication (e.g., non-biometric authentication) may be required.

At <NUM>, in the illustrated embodiment, device <NUM> determines whether a face is detected. This initial facial detection may be performed on data from camera unit <NUM> but the images used to determine whether a face is present may or may not be used for facial recognition comparison. If a face is not detected, flow remains at element <NUM> until a face is detected. If a face is detected, flow proceeds to <NUM>. As shown, after a timeout interval and failure to detect a face, device <NUM> may sleep as shown in method element <NUM> (which may prevent excessive battery use, for example).

In some embodiments, device <NUM> may generate a bounding box around the detected face and may use the bounding box for subsequent operations (e.g., face matching, probing pattern validation, etc.). For example, image processor <NUM> may generate feature vectors only for objects within the bounding box. The bounding box may be determined using facial landmarks (e.g., nose, mouth, eyes, etc.) and may be used to generate a canonical face size that is used for facial recognition matching.

In some embodiments, device <NUM> may also check whether the user is paying attention at <NUM>, e.g., by tracking their eye movement. If the user is not looking at the device, face detection element <NUM> may fail. This may avoid a user's face being used for biometric authentication when they are sleeping or not paying attention, for example.

At <NUM>, in the illustrated embodiment, device <NUM> performs face match and sequence validation operations. In some embodiments, application software communicates with SEP <NUM> via an API to initiate element <NUM>. SEP <NUM> may compare feature vectors from image frames processed by image processor <NUM> with template feature vectors for one or more users. SEP <NUM> may implement one or more neural networks to perform this comparison. Further, SEP <NUM> may determine whether a sequence of image capture modes was correctly used, e.g., using the techniques discussed above with reference to <FIG>. In some embodiments, the sequence of capture modes is randomized for each facial recognition session. If face match or sequence validation fails, flow may proceed back to <NUM>. If face match or sequence validation fails and a count of retry attempts has reached a threshold, flow may proceed to <NUM>. Note that failure at this point may prevent a probing pattern from being fired (which may occur at <NUM> as discussed below), which may increase security of the probing pattern. In some embodiments, failure at <NUM> may impose a delay and/or may require detection of user intention to continue a facial recognition session (e.g., based on gaze, gesture, physical input such as a button, manual input such as using a touchscreen, etc.) before proceeding to face detection <NUM>.

At <NUM>, in the illustrated embodiment, SEP <NUM> validates a probing pattern. For example, SEP <NUM> may utilize the techniques described above with reference to <FIG>. As discussed above, the pattern may be permanently implemented in a special emitter array or dynamically generated and may be selected pseudo-randomly in either case. Multiple probing patterns may be validated. The probing pattern may be fired at various different location in the sequence and the location may be randomized, in some embodiments. In some embodiments, if a probing pattern fails, one or more retries may be allowed, in which case flow may proceed back to element <NUM>. SEP <NUM> or some other element may select the probing pattern.

At <NUM>, in the illustrated embodiment, SEP <NUM> performs face matching for the image data captured using the probing pattern. In some embodiments, this ensures that the probing pattern was used to capture the same face that was matched at <NUM>. The matching of <NUM> may include comparison of feature vectors for the probing pattern frame(s) with previously captured frames during the facial recognition session (e.g., the sequence of captures validated at <NUM>). In other embodiments, the matching may also be performed with user template data, in addition to or in place of matching with the captures from the sequence. If this matching fails, flow may proceed to <NUM>.

At <NUM>, in the illustrated embodiment, SEP <NUM> determines an authentication decision. If the decision is positive, a user may be allowed to unlock device <NUM> or perform cryptographic operations such as to provide an authentication decision to other elements, enable or disable peripheral devices, access key chain data, perform operation with a key accessible by SEP <NUM>, access auto-fill data for a browser or other form, access data protected by SEP keys, allow payment functionality, download or access an application, etc..

At <NUM>, additional authentication is required. In some embodiments method element <NUM> may correspond to multiple different lockout modes, which may impose timeout intervals, non-biometric authentication requirements, etc..

In some embodiments, the techniques of <FIG> may be performed within a relatively small time interval, e.g., in less than a second, to quickly and intuitively allow biometric authentication. In some embodiments, image data captured during a facial recognition session is discarded after determining an authentication result for the session.

Examples of different failures that may occur in <FIG> include, without limitation: no face and sequence not detected, which may cause the facial recognition session to start over (this may allow up to a threshold number of retries), face detected but sequence not detected in <NUM> (this may allow no retries or one retry), frame counter failure, camera or projection failures (e.g., due to lack of power), nonce failure, failure in frame signatures, etc. Ones of these failures may or may not cause device lockout, in some embodiments.

In some embodiments, before allowing biometric authentication, device <NUM> is configured to require a user to set up device <NUM> with a passcode for unlocking the device. Biometric authentication (e.g., facial recognition) may then be used to unlock device <NUM> without using the passcode. This may allow device <NUM> to require a longer and/or more complex passcode than traditional passcodes, e.g., because the user may use the passcode less frequently. A stronger passcode may increase the overall security of device <NUM>. In some embodiments, device <NUM> will always accept a passcode for a known user instead of facial recognition. In some embodiments, the passcode is required in the following exemplary situations: the device has just been turned on or restarted, the device has not been unlocked within a threshold time interval, the passcode has not been used to unlock the device within a threshold time interval, the device has received a remote lock command, facial recognition has been unsuccessful more than a threshold number of attempts, or power off or emergency mode has been initiated and then canceled.

In some embodiments, when biometric authentication is disabled, keys for highly protected data (e.g., data controlled by SEP <NUM>) are discarded. Examples of such data may include keychain information such as form-filing information based on past activity of one or more authorized users on websites. In these embodiments, protected data is then inaccessible until device <NUM> is unlocked using the passcode. In some embodiments, when biometric authentication is enabled, such keys are not discarded when the device locks, but are wrapped with a key provided by SEP <NUM>. If a facial recognition session is successful, SEP <NUM> may provide the key for unwrapping the data protection keys and unlock device <NUM>. This cooperation between data protection and biometric authentication systems may increase security. In various embodiments, one or more keys relating to facial recognition are discarded when passcode entry is required, e.g., as discussed above.

<FIG> is a block diagram illustrating an exemplary non-limiting organization of modules among CPU <NUM>, SEP <NUM>, image processor <NUM>, and camera unit <NUM>. The illustrated organization is shown for purposes of explanation, but is not intended to limit the scope of the present disclosure. As used herein, the term "module" refers to program instructions executable to perform a function and/or circuitry configured to perform the function. Thus, various functionality described with reference to <FIG> may be performed by executing program instructions or by dedicated circuitry, for example.

In various embodiments, application <NUM> or home screen <NUM> may initiate a facial recognition session. For example, a user may perform an action indication facial recognition is desired (e.g., moving a device in a certain way such as turning it over or picking it up, pushing a physical button on a device, selecting a graphical option on a device, making a particular facial expression when looking at the device, saying a particular word or phrase, etc.). Application <NUM> may be a third party application, an operating system, a mobile payment application, etc..

For a payment application, for example, a payment may be authorized based on biometric authentication in combination with an indication of an intent to make a payment. Re-authentication may be required to change payment method, for example. In some embodiments, successful facial recognition must be confirmed within a time interval after the indication of intent to make a payment.

In some embodiments, third-party applications cannot access sensitive data relating to biometric authentication, but simply request biometric authentication and are notified whether the authentication was successful. Secure data such as keychain items may be protected by SEP <NUM>, which may require a successful facial recognition session or entry of a passcode before releasing this data. Applications may be able to use facial recognition as a subsequent factor in multi-factor authentication. Further, third-party applications may be able to generate and use keys (e.g., ECC keys) that are protected by SEP <NUM>.

Biometric API <NUM>, in the illustrated embodiment, is used by application <NUM> and home screen application <NUM> to access device functionality. In some embodiments, API <NUM> may include both a user level and kernel level API. As shown in the illustrated example, API <NUM> may be used to send commands via camera interface <NUM> and SEP driver <NUM> (each of which may in turn implement an API for communicating with their respective components). Thus, an application <NUM> may request a facial recognition and/or specify parameters for the session (e.g., what security techniques are implemented) without having any exposure to sensitive data controlled by SEP <NUM> (such as identification of a probing pattern, template data for user facial characteristics, or the sequence of image capture modes for example).

In some embodiments, API <NUM> may allow an application to specify that only a portion of available validation techniques should be implemented. For example, the API <NUM> may allow specification of which elements of the method of <FIG> should be implemented for a particular facial recognition session.

Camera interface <NUM>, in the illustrated embodiment, is configured to allow communications with image processor <NUM> via API <NUM>. Similarly, driver <NUM>, in the illustrated embodiment, is configured to allow communications with SEP <NUM> via API <NUM>. In some embodiments, an illuminator interface module (not explicitly shown) is configured to allow communications between CPU <NUM> and one or more illumination modules via API <NUM>.

Image processor <NUM>, in the illustrated embodiment, includes generate sequence module <NUM> which may be configured to pseudo-randomly generate the sequence of image capture modes and communicate it to camera unit <NUM> and SEP <NUM> (e.g., via image metadata <NUM>). In the illustrated embodiment, image processor <NUM> also includes face detect module <NUM> which may be configured to detect a face in frames captured by <NUM> to start a facial recognition session (e.g., image processor <NUM> may wait for module <NUM> to detect a face before generating the sequence with module <NUM>). In the illustrated embodiment, image processor <NUM> also include process image module <NUM>, which may be configured to process image data from camera unit <NUM> to generate image metadata <NUM>.

Image metadata <NUM> may be stored in memory accessible to both image processor <NUM> and SEP <NUM> and may include feature vector data, sequence data, signature data, etc. In some embodiments, process image module <NUM> is configured to generate frame numbers for each frame or composite frame of image data and store the frame numbers in image metadata <NUM>.

Camera unit <NUM>, in the illustrated embodiment, includes sign image data module <NUM> which is configured to sign data using a secret key of camera unit <NUM>. This may allow verification that image data is actually generated by camera unit <NUM> rather than another camera unit.

SEP <NUM>, in the illustrated embodiment, further includes control module <NUM> which may be configured to perform various operations described. For example, control module <NUM> may run one or more neural networks to generate feature vectors for enrollment and/or matching image metadata <NUM> with template data <NUM>. For initialization, control module <NUM> may establish secure session(s) with one or more other components. Control module <NUM> may also decrypt calibration data <NUM> and/or check that calibration data <NUM> is properly signed. SEP <NUM> may then send at least a portion of calibration data <NUM> to image processor <NUM> to facilitate processing by module <NUM>. For facial matching, control module <NUM> may be configured to check if authentication is allowed, wait for user attention, and instruct image processor <NUM> to proceed with capturing the sequence. SEP <NUM> may then verify the sequence and perform matching based on image metadata <NUM>. SEP <NUM> may also verify signatures of image metadata <NUM>, verify that the frame looks as expected, and verify the nonce for each frame.

Calibration data <NUM>, in the illustrated embodiment, is stored outside of SEP <NUM> and encrypted, but in other embodiments it may be stored within SEP <NUM> (e.g., in element <NUM>). Generally, any of various functionality described herein as performed by SEP <NUM> may be performed without use of a secure circuit. Using a secure circuit to perform various functionality, however, may greatly increase security of facial recognition sessions.

In the illustrated embodiment, SEP <NUM> includes face match module <NUM> configured to perform facial recognition matching and secret pattern detect module <NUM> to detect one or more probing patterns in image metadata <NUM>. Control module <NUM> may indicate when to fire a probing pattern and which pattern to fire.

The organization and elements of <FIG> are shown for purposes of explanation but are not intended to limit the scope of the present disclosure. In various embodiments, elements may be omitted or added and functionality described as performed by one element may be performed by one or more other elements.

<FIG> is a flow diagram illustrating an exemplary method for using multiple types of validation in a secure facial recognition session, according to some embodiments. The method of <FIG> may be performed during manufacturing of device <NUM>, for example. The method shown in <FIG> may be used in conjunction with any of the computer circuitry, systems, devices, elements, or components disclosed herein, among others. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired.

At <NUM>, in the illustrated embodiment, at least one illuminator array is configured to generate a pattern of illumination points. This may include permanently disabling one or more emitters in the array, for example. In some embodiments, this may be performed in such a manner that the disabled emitters are not detectable visually. In some embodiments, multiple arrays may be configured, e.g., with different patterns.

At <NUM>, in the illustrated embodiment, one or more images are captured using the configured pattern of illumination points. For example, the camera module <NUM> may capture one or more frames while the illumination pattern is being emitted.

At <NUM>, in the illustrated embodiment, the one or more captured images are processed to generate illumination pattern information. This may include generating differential information between the pattern and another pattern (e.g., a complete pattern from an array of the same size). In various embodiments, various processing techniques may be used to generate characteristics of the pattern (which may then be used as a template to verify the probing pattern in the future).

At <NUM>, in the illustrated embodiment, the illumination pattern information is stored in circuitry included in or controlled by a secure circuit. For example SEP <NUM> may store the information internally or may encrypt the information using a secret key and store the information in another location of device <NUM>. This may allow SEP <NUM> to verify the probing pattern in the future without other entities being able to determine the probing pattern. In some embodiments, the stored information includes actual image data captured using the probing pattern. In other embodiments, image data captured using the probing pattern is not stored at all, but only attributes of the image data such as a code that indicates which illumination points are turned on and off (e.g., generated in element <NUM>).

The present disclosure has described various exemplary circuits in detail above. It is intended that the present disclosure cover not only embodiments that include such circuitry, but also a computer-readable storage medium that includes design information that specifies such circuitry. Accordingly, the present disclosure is intended to support claims that cover not only an apparatus that includes the disclosed circuitry, but also a storage medium that specifies the circuitry in a format that is recognized by a fabrication system configured to produce hardware (e.g., an integrated circuit) that includes the disclosed circuitry. Claims to such a storage medium are intended to cover, for example, an entity that produces a circuit design, but does not itself fabricate the design.

<FIG> is a block diagram illustrating an exemplary non-transitory computer-readable storage medium that stores circuit design information, according to some embodiments. In the illustrated embodiment semiconductor fabrication system <NUM> is configured to process the design information <NUM> stored on non-transitory computer-readable medium <NUM> and fabricate integrated circuit <NUM> based on the design information <NUM>.

Non-transitory computer-readable medium <NUM>, may comprise any of various appropriate types of memory devices or storage devices. Medium <NUM> may be an installation medium, e.g., a CD-ROM, floppy disks, or tape device; a computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a nonvolatile memory such as a Flash, magnetic media, e.g., a hard drive, or optical storage; registers, or other similar types of memory elements, etc. Medium <NUM> may include other types of non-transitory memory as well or combinations thereof. Medium <NUM> may include two or more memory mediums which may reside in different locations, e.g., in different computer systems that are connected over a network.

Design information <NUM> may be specified using any of various appropriate computer languages, including hardware description languages such as, without limitation: VHDL, Verilog, SystemC, SystemVerilog, RHDL, M, MyHDL, etc. Design information <NUM> may be usable by semiconductor fabrication system <NUM> to fabrication at least a portion of integrated circuit <NUM>. The format of design information <NUM> may be recognized by at least one semiconductor fabrication system <NUM>. In some embodiments, design information <NUM> may also include one or more cell libraries which specify the synthesis and/or layout of integrated circuit <NUM>. In some embodiments, the design information is specified in whole or in part in the form of a netlist that specifies cell library elements and their connectivity.

Semiconductor fabrication system <NUM> may include any of various appropriate elements configured to fabricate integrated circuits. This may include, for example, elements for depositing semiconductor materials (e.g., on a wafer, which may include masking), removing materials, altering the shape of deposited materials, modifying materials (e.g., by doping materials or modifying dielectric constants using ultraviolet processing), etc. Semiconductor fabrication system <NUM> may also be configured to perform various testing of fabricated circuits for correct operation.

In various embodiments, integrated circuit <NUM> is configured to operate according to a circuit design specified by design information <NUM>, which may include performing any of the functionality described herein. For example, integrated circuit <NUM> may include any of various elements shown in <FIG>, or <FIG>. Further, integrated circuit <NUM> may be configured to perform various functions described herein in conjunction with other components. Further, the functionality described herein may be performed by multiple connected integrated circuits.

As used herein, a phrase of the form "design information that specifies a design of a circuit configured to. " does not imply that the circuit in question must be fabricated in order for the element to be met. Rather, this phrase indicates that the design information describes a circuit that, upon being fabricated, will be configured to perform the indicated actions or will include the specified components.

In some embodiments, a non-transitory computer-readable medium has instructions stored thereon that are executable by a computing device to perform operations comprising: determining a pseudo-random sequence of image capture modes for a plurality of pairs of image captures, wherein each pair includes captures using a first illumination mode and a second illumination mode, wherein the ordering of the first and second illumination modes for each pair is pseudo-randomly determined; receiving image information indicated as being captured by a camera unit; and determining whether to authorize facial recognition in response to analyzing the image information and determining whether the image information was captured using the pseudo-random sequence of image capture modes.

In some embodiments, a non-transitory computer-readable medium has instructions stored thereon that are executable by a computing device to perform operations comprising: determining an illumination pattern for a camera mode that uses multiple points of illumination; receiving image information captured by a camera unit; and determining whether to indicate a facial recognition failure based on determining whether the image information not captured using the determined illumination pattern.

In some embodiments, an apparatus comprises: a camera unit; one or more processing elements configured to, for a facial recognition session: determine a pseudo-random sequence of image capture modes for a plurality of image captures; receive first image information for a set of image captures, wherein the first image information is indicated as being captured by the camera unit based on the sequence; determine an illumination pattern for a camera mode that uses multiple points of illumination; request that the camera unit capture one or more images using the determined illumination pattern, wherein the apparatus is configured to emit the determined illumination pattern for the facial recognition session only after verification of the sequence of image capture modes; receive second image information indicated as being captured by the camera unit using the illumination pattern; and determine whether to indicate a facial recognition failure based on determining whether the second image information was captured using the determined illumination pattern.

In some embodiments, an apparatus comprises: one or more processing elements configured to, for a facial recognition session: detect whether a face is visible in images captured by a camera unit; in response to detecting a face, determine a pseudo-random sequence of image capture modes for a plurality of image captures; receive first image information indicated as being captured by the camera unit; in response to determining that the first image information was captured using the pseudo-random sequence of image capture modes, process the first image information for comparison with template facial information for one or more users; in response to detecting a match for a user of the one or more users, determine an illumination pattern for a three-dimensional capture mode that uses multiple points of illumination; receive second image information indicated as being captured by the camera unit based on the determined illumination pattern; in response to determining that the second image information exhibits the determined illumination pattern, determine whether a face shown in the second image information matches a face of the user; and authenticate the user in response to determining that the face shown in the second information matches a face of the user.

In some embodiments, the pseudo-random sequence of image capture modes includes a plurality of pairs of image captures, wherein each pair includes a two-dimensional capture mode and a three-dimensional capture mode, wherein the ordering of the two-dimensional and three-dimensional capture modes for each pair is pseudo-randomly determined, and wherein the image capture modes are supported by a camera unit.

In some embodiments, a method of manufacturing a mobile device, comprises: configuring at least one illuminator array to generate a pattern of illumination points; capturing, by a camera unit of the mobile device, one or more images using the configured pattern of illumination points; processing the one or more captured images to generate illumination pattern information; using a secure circuit of the mobile device to store the illumination pattern information in a mobile device configured to use the illuminator array for depth capture imaging.

In some embodiments, the method further comprises encrypting the illumination pattern, using the secure circuit, and storing the encrypted illumination pattern externally to the mobile device. In some embodiments, the method further comprises causing the encrypted illumination pattern to be transmitted to the mobile device for a restore procedure for the mobile device. In some embodiments, the illumination pattern information includes a frame of image data captured using the pattern. In some embodiments, the illumination pattern information includes an index of the pattern in a set of known patterns. In some embodiments, the illumination pattern information specifies one or more characteristics of the pattern.

In some embodiments, a non-transitory computer-readable medium has instructions stored thereon that are executable by a computing device to perform operations comprising: configuring at least one illuminator array to generate a pattern of illumination points; capturing one or more images using the configured pattern of illumination points; processing the one or more captured images to generate illumination pattern information; using a secure circuit to store the illumination pattern information in a mobile device configured to use the illuminator array for depth capture imaging.

Although specific embodiments have been described above and have been depicted in the accompanying appendix below, these embodiments are not intended to limit the scope of the present disclosure, even where only a single embodiment is described with respect to a particular feature. Examples of features provided in the disclosure are intended to be illustrative rather than restrictive unless stated otherwise. For example, references to the term "phone" may encompass any suitable mobile device. Accordingly, the above and below descriptions are intended to cover such alternatives, modifications, and equivalents as would be apparent to a person skilled in the art having the benefit of this disclosure.

The present disclosure further contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. For example, in the case of unlocking and/or authorizing devices using facial recognition, personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection should occur only after receiving the informed consent of the users. Additionally, such entities would take any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures.

Claim 1:
An apparatus, comprising:
a camera unit (<NUM>);
one or more processing elements configured to:
determine a pseudo-random sequence of image capture modes for a plurality of groups of image captures, wherein each group includes at least a capture using a first illumination mode and a capture using a second illumination mode, wherein the first and second illumination modes use different illuminators of the camera unit, wherein
the ordering of the first and second illumination modes for each group is pseudo-randomly determined and wherein the first illumination mode uses flood illumination and the second illumination mode uses multiple discrete points of illumination and each group is a pair of captures using the first illumination mode and the second illumination mode;
receive image information for a set of image captures, wherein the image information is indicated as being captured by the camera unit;
determine whether to authorize facial recognition in response to analyzing the image information and determining whether the image information was captured using the pseudo-random sequence of image capture modes.