Patent Publication Number: US-2021185037-A1

Title: Biometric signature authentication and centralized storage system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of co-pending U.S. patent application Ser. No. 16/053,910, filed Aug. 3, 2018, and titled “Biometric Signature Authentication and Centralized Storage System,” which is a continuation of U.S. patent application Ser. No. 15/153,031, filed May 12, 2016, now U.S. Pat. No. 10,069,824, which claims priority to U.S. Provisional Application Ser. No. 62/160,298, filed May 12, 2015 and titled “System for Biometric Signature Information Storage and Authentication,” the entirety of each of which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to biometric authentication, and more particularly, though not necessarily exclusively, to biometric authentication using a biometric signature key stored in a centralized database. 
     BACKGROUND 
     A human heart includes unique wave patterns in the electrical activity. In electrocardiography, the human heart may be monitored to record electrical activity over a period of time. The electrical activity may be recorded using one or more electrodes having contact with the individual&#39;s skin. The electrodes may detect electrical changes on the skin due the depolarization from the heart muscle during each heartbeat. An electrocardiogram (“EKG”) may be used to trace the heart&#39;s electrical activity into line tracings. The EKG may be based on the electrical changes of the heart and may visually represent the biometric signature of the individual. The biometric signature may be dependent on various characteristics of the individual and the heart muscle of the individual being monitored (e.g., heart size, heart chamber structure, prior heart damage, etc.). The combination of characteristics resulting in the electrical changes may yield a biometric signature that is unique for each individual. 
     SUMMARY 
     In some aspects, a biometric authentication system may include a centralized database communicatively that is couplable to one or more external systems and includes stored biometric signature information for authenticating a user of the one or more external systems. The biometric authentication system may also include a processor communicatively coupled to the centralized database. The biometric authentication system may also include a memory communicatively coupled to the processor and including instructions executable by the processor for causing the processor to extract a first set of data attributes from a biometric signature of the user. The biometric signature may correspond to electrical activity of the user&#39;s heart obtained by a biometric sensor in physical contact with the user. The instructions may also be executable by the processor for causing the processor to compare one or more data attributes in the first set of data attributes to the stored biometric signature information in the centralized database. The stored biometric signature information may include a plurality of signature keys, each signature key of the plurality of signature keys corresponding to a stored set of data attributes extracted from corresponding biometric signatures of a plurality of users. The instructions may also be executable by the processor for causing the processor to identify user identifier information associated with a stored signature key of the plurality of signature keys matching the first set of data attributes. The instructions may also be executable by the processor for causing the processor to authenticate, based on a match between the one or more data attributes and the stored signature key, the user to access secure information associated with the user identifier information. 
     In additional aspects, a method may include receiving a biometric signature from a biometric sensor. The biometric signature corresponding to electrical activity of a user&#39;s heart measured by the biometric sensor. The method may also include extracting a first set of data attributes from the biometric signature. The method may also include comparing one or more data attributes in the first set of data attributes to stored biometric signature information in a centralized database accessible to one or more systems. The stored biometric signature information may include a plurality of signature keys, each signature key of the plurality of signature keys corresponding to a stored set of data attributes extracted from corresponding biometric signatures of a plurality of users. The method may also include identifying user identifier information associated with a stored signature key of the plurality of signature keys matching the first set of data attributes. The method may also include authenticating, based on a match between the first set of data attributes and the stored signature key, the user to access secure information associated with the user identifier information. 
     In further aspects, a non-transitory computer-readable medium comprising program code executable by a processor to cause the processor to receive a biometric signature from a biometric sensor. The biometric signature may correspond to electrical activity of a user&#39;s heart measured by the biometric sensor. The program code may also be executable by the processor to cause the processor to extract a first set of data attributes from the biometric signature. The program code may also be executable by the processor to cause the processor to compare one or more data attributes in the first set of data attributes to stored biometric signature information in a centralized database accessible to one or more systems. The stored biometric signature information may include a plurality of signature keys, each signature key of the plurality of signature keys corresponding to a stored set of data attributes extracted from corresponding biometric signatures of a plurality of users. The program code may also be executable by the processor to cause the processor to identify user identifier information associated with a stored signature key of the plurality of signature keys matching the first set of data attributes. The program code may also be executable by the processor to cause the processor to authenticate, based on a match between the one or more data attributes and the stored signature key, the user to access secure information associated with the user identifier information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional schematic diagram of an environment in which a biometric signature may be obtained according to some aspects of the present disclosure. 
         FIG. 2  is a block diagram of an authentication system for generating and storing a biometric signature key and authenticating a user using the biometric signature key according to some aspects of the present disclosure. 
         FIG. 3  is a block diagram depicting memory locations in a centralized database of the system of  FIG. 2  according to some aspects of the present disclosure. 
         FIG. 4  is a flow chart of a process for generating a biometric signature key according to some aspects of the present disclosure. 
         FIG. 5  is a flow chart of a process for authenticating a user using a biometric signature key according to some aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Certain aspects and examples of the present disclosure relate to generating a biometric signature key based on a unique heartbeat of a user and storing the biometric signature key in a centralized database that is accessible via a network to authenticate a user. In one example, a sensor of a user device may obtain a biometric signature from a user. The biometric signature may include a trace of electrical activity corresponding to the user&#39;s heartbeat. A system may receive the biometric signature from the user device via a network and extracts unique data attributes of the biometric signature. The system may save the unique data attributes as a signature key for the biometric signature of the user&#39;s heartbeat in a centralized database that is accessible by one or more systems having secure information, such as information corresponding to a personal account held by the user. The signature key may be stored in the centralized database in a manner that associates the signature key with the user. 
     In response to future requests by the user to view secure information on the user device, the sensor may obtain a second biometric signature from the user and transmits the second biometric signature to the system. The system may extract unique data attributes from the second biometric signature and compare them to an array of signature keys stored in the centralized database, each signature key in the array corresponding to a different user. If the system determines a match between the unique data attributes extracted from the second biometric signature and a stored signature key in the array, the system may identify user information corresponding to the user and associated with the stored signature key in the centralized database. The system may authenticate the user to view secure information associated with the user information. In some aspects, the system may transmit the secure information to the user device via the network for display. If the system may not determine a match between the unique data attributes and a stored signature key, the system does not allow secure information to be displayed on the user device. 
     Authenticating a user using biometric signature information may improve the quality of authentication beyond the capabilities of systems that may use conventional methods of authentication such as usernames, passwords, and security questions. Since the biometric signature information is unique to each user, authentication using biometric signature information may provide heightened confidence that the user is authorized to access secure information. 
     Using a centralized database to store biometric information may allow multi-system platforms having multiple systems in communication with the centralized database, each system having different types of secure information, to authenticate the user from each system using the biometric information. For example, the centralized database may reduce or eliminate a need for separate copies of the biometric signature or the signature key for each user of each system to be stored in separate system databases. A centralized database having a single copy of the signature key may conserve data storage space in the multi-system platform, collectively, as well as reduce labor costs and time in coordinating authentication systems for each of the systems. 
     Using a centralized database according to some aspects may also allow authentication in environments beyond a user device. For example, a multi-system platform may be hosted by a financial institution and include multiple financial systems. The centralized database may be accessible to an automated teller machine (“ATM”) having a sensor bar or other means for receiving a user&#39;s biometric signature. In this manner, the biometric signature information may replace a personal identification number and authenticate to access secure information to initiate secure transactions at the ATM (e.g., withdraw money, view account balances, etc.). The biometric authentication system according to some aspects may similarly be used to replace an identification card for initiating financial transactions in person at a branch of the financial institution. 
     Also, a biometric authentication system including biometric signature keys stored in a centralized database according to some aspects may allow for a modular multi-system platform. For example, new systems having secure user information may be added to the platform without requiring new authentication systems to be established for each system. The centralized database may dynamically expand to accommodate new users of each system as the biometric authentication system may be configured to generate a signature key in response to receiving a biometric signature from the new systems&#39; sensors. 
     A biometric authentication system according to some aspects may be particularly useful when the user device is a wearable device. Wearable user devices are becoming more compact in light of new technologies. Concurrent with the decreasing size of wearable user devices, many entities managing secure information are increasing the complexity of the login information acceptable for access to the secure information. Inputting complex (and often lengthy) login information on a small user device (e.g., a smart watch or a smart phone) may prove difficult to the user. Using biometric signature information may allow the biometric authentication system to authenticate a user more efficiently and more effectively. 
     Similarly, authentication using biometric signature information may also convenience the user by limiting the unintended display of secure information on the wearable user device. Many wearable user devices are wearable by the user in a manner that secure information displayed by the wearable user device is visible to individuals in close proximity to the user. Authentication using biometric signature information may prevent secure information from being displayed until the user implements an authentication process. For example, a user may receive a message alerting corresponding to updated secure information (e.g., a posted payment, an updated financial account balance) to provide the user. The user may select an option on the wearable user device (e.g., a displayed selection option, a button on the wearable user device, etc.) to authenticate the user based on the biometric signature information prior to the updated secure information being displayed. 
     Additional implementations of the system, including those unrelated to authentication of the user for access to secure information (e.g., analyzing stored biometric signature information for targeted marketing and incentives based on health indicators), may become apparent to those skilled in the art without departing from the scope of this invention. The illustrative examples are provided to introduce the reader to the general subject matter discussed herein and the disclosure is not limited to these examples. The following sections describe various additional non-limiting examples. 
     Various aspects of the present disclosure may be implemented using various user devices.  FIG. 1  is a cross-sectional schematic diagram of an environment in which a biometric signature may be obtained according to some aspects of the present disclosure. The environment includes a user device  100 . The user device  100  is a wearable computing device, such as a smart watch, patch, wristband, necklace, bracelet, or other device wearable on the skin  102  and having processing means. The user device  100  includes a sensor  104  that may be placed in physical contact with the skin  102  when the user is wearing the user device  100 . The sensor  104  may be a biometric sensor device that detects or measures a biometric signature  106  of the user. A user&#39;s biometric signature  106  may include wave patterns corresponding to the electrical activity of the user&#39;s heart. For example, physical contractions of the heart (e.g., heartbeats) may be caused by myocytes, cells found in muscle tissue that may initiate their own contractions without assistance from external nerves. Sinoatrial and atrioventricular nodes located in the upper-right and lower-right atriums of the heart, respectively, may coordinate a rhythmic sequence of the physical contractions. When a wave reaches the atrioventricular node, the wave may be delayed before being conducted through the cells lining the ventricles of the heart, causing the ventricles to contract and creating a unique wave pattern of the contraction. The biometric signature  106  may be unique for each individual, similar to a “fingerprint.” 
     In some aspects, the biometric signature  106  may be detected from the pulse or blood flow in an artery  108  below the surface of the skin  102 . The sensor  104  may measure the biometric signature  106  of the user and transmit it to the user device  100 . Although  FIG. 1  shows the user device  100  as a device wearable on the skin  102 , in other aspects, the user device  100  may include any computing device communicatively coupled to or including a sensor for obtaining a biometric signature without departing from the scope of the present disclosure. Non-limiting examples of the user device  100  include a personal computer, smartphone, personal digital assistant (“PDA”), or a tablet. 
     The user device  100  may transmit the biometric signature  106  to an authentication system configured to store information associated with the biometric signature  106  in a centralized database or to authenticate the user of to view secure information associated with the user in the centralized database. In some aspects, the user device  100  may communicate with the system through an intermediary device. For example, the user device  100  may be a watch configured to transmit the biometric signature  106  obtained from the user to a smartphone communicatively coupled to the watch (e.g., via Bluetooth, near-field communication, etc.) 
       FIG. 2  is a block diagram of an authentication system  200  for generating and storing a biometric signature key and authenticating a user using the biometric signature key according to some aspects of the present disclosure. The authentication system includes a processor  202  and a memory  204  connected by a bus. The processor  202  may execute one or more operations for generating and storing a signature key corresponding to the biometric signature  106  obtained by the sensor  104  as described in  FIG. 1 . The signature key may be used to authenticate the user. The processor  202  may execute instructions stored in the memory  204  to perform the operations. The processor  202  may include one processing device or multiple processing devices. Non-limiting examples of the processor  202  include a field-programmable gate array, an application-specific integrated circuit (“ASIC”), and a microprocessor. The memory  204  may include a storage device that retains information when powered off. Non-limiting examples of the memory  204  include electrically erasable and programmable read-only memory, a flash memory, or any other type of non-volatile memory. 
     In some examples, at least a portion of the memory  204  may include a computer-readable medium from which the processor  202  can read instructions of the memory  204 . A computer-readable medium may include electrical, optical, magnetic, or other storage devices capable of providing the processor  202  with computer-readable instructions or other program code. Non-limiting examples of a computer-readable medium include magnetic disks, memory chips, read-only memory, random-access memory, an ASIC, a configured processor, optical storage, or any other medium from which the processor  202  may read instructions. The instructions may include processor-specific instructions generated by a compiler or an interpreter from code written in any suitable computer-programming language, including, for example, C, C++, C#, COBOL, Java, etc. The instructions include an application, such as key engine  206 , including one or more algorithms for generating a signature key corresponding to the biometric signature  106  of  FIG. 1  by extracting unique data attributes from the biometric signature  106 . In some aspects, the instructions may also cause the processor  202  to generate one or more user interfaces for displaying secure user information stored in a database accessible to the authentication system  200 . 
     In some aspects, the key engine  206  may include instructions for filtering out noise in the biometric filter to generate true biometric signature data. For example, the key engine  206  may cause the processor  202  to apply a filter, such as a band-pass filter to the biometric signature to attenuate noise from the measurement within certain frequency ranges. The true biometric signature data may be used to extract one or more data attributes unique to the user&#39;s biometric signature as the signature key. 
     In additional aspects, the key engine  206  may include instructions for determining unique data attributes in a biometric signature. For example, the instructions may be configured to interpret the biometric signature to distinguish the unique attributes from attributes that are common to some or all biometric signatures. The instructions may also be configured to distinguish the unique attributes from attributes that are variable depending on measurement factors of the sensor  104 . For example, the instructions may be configured to filter attributes of the biometric signature that are dependent variable factors. The variable factors may include the placement of the sensor on the skin, the rate of the user&#39;s heartbeat, or other known attributes that may change with respect to a user&#39;s biometric signature depending on the time that the biometric signature was obtained by the sensor  104 . 
     In additional aspects, the key engine  206  may include instructions for measuring intervals or distances between certain waves of the biometric signature. For example, a biometric signature for a heartbeat may include an electrocardiogram (“EKG”) having a P-wave representing the atrial depolarization of the heart, a QRS-complex corresponding to a combination of a Q-wave, R-wave, and S-wave and collectively representing ventricular depolarization, and a T wave representing ventricular repolarization. The waves may form a unique pattern and one or more intervals between certain waves may be identified and extracted as data attributes defining a signature key (e.g., the interval between a peak of the P wave and an R peak, the interval between the end of the P-wave and the R peak, the width of the P-wave, the interval between the S peak and the peak of the T-wave, etc.). In other aspects, the key engine  206  may include additional instructions for extracting unique data attributes from the biometric signature using one or more known methods. 
     The authentication system  200  also includes a centralized database  208 . The centralized database  208  may include a secure database in which the biometric signature  106 , or a signature key generated by the key engine  206  corresponding to the biometric signature  106 , may be stored. The centralized database may be accessible to multiple systems of a host platform to authenticate the user of each of the multiple systems using the biometric signature information. 
     The authentication system  200  also includes a network interface  210 . The network interface  210  may be coupled to the processor  202  and the memory  204  via the bus. The network interface  210  may include a network card or other device communicatively coupled to a network  212  to allow user devices, such as the user device  100 , to access the centralized database  208  for authenticating the user to view secure information on the user device. In some aspects, the network interface  210  may transmit user interfaces generated by the key engine  206  via the network  212  including the secure information. 
     The user device  100  includes a processor  214  and a memory  216  connected to a bus. The processor  214  may include one or more processors, including without limitation one or more general-purpose processors or one or more special-purpose processors ((such as digital signal processing chips, graphic acceleration processors, etc.). The processor  214  may execute one or more operations for receiving biometric signature information from the sensor  104  and transmitting, via a communication device, the biometric signature information to the authentication system  200  via the network. The processor  214  may execute instructions stored in the memory  216  to perform the operations. Non-limiting examples of the processor  214  may include a field-programmable gate array (“FPGA”), an application-specific integrated circuit (“ASIC”), a microprocessor, etc. 
     The memory  216  may include any type of storage device that retains stored information when powered off. Non-limiting examples of the memory  216  may include electrically erasable and programmable read-only memory (“EEPROM”), a flash memory, or any other type of non-volatile memory. In some examples, at least a portion of the memory  216  may include a non-transitory computer-readable medium from which the processor  214  can read the instructions. A computer-readable medium may include electronic, optical, magnetic, or other storage devices capable of providing the processor  214  with computer-readable instructions or other program code. Non-limiting examples of computer-readable medium include, but are not limited to, magnetic disks, memory chips, ROM, random-access memory (“RAM”), an ASIC, a configured processor, optical storage, or any other medium from which a computer processor can read the instructions. The instructions may include processor-specific instructions generated by a compiler or an interpreter from code written in any suitable computer-programming language, including, for example, C, C++, C#, Java, etc. In some aspects, the memory  216  may also include storage space (e.g., datastore  218 ) in which content and data may be stored. For example, in some aspects, the datastore  218  may store a local copy of the biometric signature  106  or the signature key generated by the authentication system  200 . 
     The user device  100  also includes a keyboard  220 , a selection tool  222 , and a display unit  224 . The keyboard  220 , the selection tool  222 , and the display unit  224  may be coupled to the processor  214  and the memory  216  via the bus. The keyboard  220  may be physical keyboard or may be a virtual keyboard displayed on the display unit  224  and selectable by the account holder via the selection tool  222  to input alphanumeric and other characters (e.g., a touchscreen keyboard). The selection tool  222  may include a mouse, a touchpad, a touch screen, or other suitable means to allow an account holder to select items or other available selections presented to the account holder on the display unit  224 . The display unit  224  may display user interfaces generated by the authentication system  200 . In some aspects, the display unit  224  may include any CRT, LCD, OLED, or other device for displaying the user interfaces. 
     Although the authentication system  200  is shown as communicatively coupled to the user device  100  by the network  212 , one or more intermediary computing devices may be positioned in the communication path between the user device  100  and the authentication system  200 . For example, the user device  100  may be communicatively coupled to an intermediary user device, such as a laptop, mobile phone, desktop computer, personal digital assistant, tablet, etc. The intermediary user device may be communicatively coupled to the authentication system  200  via the network  212 . The authentication system  200  may receive requests and commands from the user device  100  through the intermediary user device and configure the user interfaces to be provided to the user device  100  through the intermediary user device in response to the requests and commands. 
     One or more additional systems may be coupled to the authentication system  200  to access the centralized database  208  and authenticate the user. For example,  FIG. 2  shows a remote system  226  coupled to the authentication system  200  and the user device  100  via the network  212 . In one example, the user device  100  may access the remote system  226  to view secure information  230  stored in a database or other storage device of the remote system  226 . In another example, the user device  100  may access the remote system  226  to access secure information for conducting a transaction. The remote system  226  may access the authentication system  200  via the network  212  to authenticate the user. The remote system  226  also be communicatively coupled to the authentication system via an enterprise service bus  228  in addition to, or alternatively to, the network  212 . The enterprise service bus  228  may include architecture to allow different systems to privately communicate outside of a public network, such as the Internet. In some aspects, the remote system  226  may access the centralized database  208  via the enterprise service bus  228  to authenticate the user. In additional and alternative aspects, the remote system  226  and the authentication system may be communicatively coupled via a wireless or wired network separate from the network  212 . 
     In some aspects, the remote system  226  may include a sensor  232  in addition to, or alternatively to, the secure information. For example, the remote system  226  may include a physical bank having a sensor  232  to authenticate a user to deposit or withdraw money into a user&#39;s account. The sensor  232  may be similar to the sensor  104  of the user device  100 . For example, the sensor  232  may be placed in contact with a user&#39;s skin to obtain a biometric signature of the user that may be transmitted from the remote system  226  to the authentication system  200  via the network  212 , the enterprise service bus  228 , or another network for authenticating the user. 
       FIG. 3  is a block diagram depicting memory locations in a centralized database  208  according to some aspects of the present disclosure. The centralized database  208  may associate information within each location to authenticate a user. In some aspects, the information within each location may be associated in one or more indices in the centralized database  208 . For example, an index may include one or more columns, each including information that is associated with other information in the same column of the index. In additional and alternative aspects, the information may be associated using pointers, objects, or other means for associating information in the centralized database  208 . In some aspects, the information stored in the centralized database  208  may be separated or partitioned by information type to allow the processor  202  of the authentication system  200  of  FIG. 2  to query information based on a first type and use the associations to determine information of a second type associated with the first type of information. 
     User identifiers  300  are stored in the centralized database  208  and include information corresponding to an identity of an account holder, member, or other user of the authentication system  200  (or a remote system  226  in communication with the authentication system  200 ). In some aspects, the user identifiers  300  may include a unique set of alphanumeric characters, such as an online banking (“OLB”) number assigned to accountholders to distinguish holders of each account managed by a financial institution. In other aspects, the unique user identifiers  300  may include a unique set of alphanumeric characters provided by or issued to each user, including, but not limited to, a social security number. The user identifiers  300  may be associated with authentication information  302 , electrocardiograms (“EKGs”)  304 , signature keys  306 , and, in some aspects, secure information  308  stored in the centralized database  208 . 
     The authentication information  302  may include information that may be used to authenticate the account holder to view the secure information  308  stored in the centralized database  208  or in databases of remote systems. In some aspects, the authentication information  302  may include information provided by the user, including, but not limited to, a username, password, social security number, passcode, or other authenticating information. In other aspects, the authentication information  302  may include information provided to the user, such as, but not limited to, a personal identification number (“PIN”). The authentication information  302  may be stored in the centralized database  208  and compared with input from the user via the user device  100  of  FIGS. 1 and 2  for a match to conclude that the user is authorized to view the secure information  308 . In additional and alternative aspects, the authentication information  302  may be used to associate a biometric signature received from the user device  100  with an appropriate user. For example, the authentication system  200  may receive the biometric signature and determine a user identifier  300  to associate the biometric signature with by first requiring the user to enter authentication information  302  already associated with the user identifier  300  in the centralized database  208 . 
     The centralized database  208  also includes EKGs  304 . The EKGs  304  may include copies of the biometric signature  106  received from the user device  100 . In some aspects, the centralized database  208  may store the EKGs  304  in the centralized database  208  temporarily to generate the signature keys  306 . In other aspects, the centralized database  208  may store the EKGs  304  longer-term. For example, the EKGs  304  may be used as a backup for the signature key  306  (e.g., to recreate a signature key  306  in case a file corresponding to the signature key  306  is corrupted). In another example, the EKGs  304  may be used for non-authenticating purposes, such as targeted marketing for products and services based on health analyses performed using the EKGs  304 . The signature keys  306  may be associated with the user identifiers  300  and the EKGs  304 . The signature keys  306  may include, for each EKG  304 , a unique set of data attributes extracted from the biometric signature corresponding to the EKGs  304 . In some aspects, the signature keys  306  may include a subset of the EKGs  304 . In other aspects, the signature keys  306  may include data attributes or data points from the EKGs  304 . 
     The centralized database  208  also includes secure information  308 . In some aspects, the secure information  308  may include account information corresponding to a financial account held by the user (e.g., a personal checking account, a savings account, etc.). In some aspects, the secure information  308  may represent points or objects to secure information physically stored on another database. In other aspects, the secure information  308  may represent information physically stored in the centralized database  208 . 
     In one example, the secure information  308  may include balance information corresponding to a checking account held by the user. The secure information  308  may be associated with the user identifiers  300  to allow the secure information  308  to be retrieved subsequent to authenticating the user using the signature key  306  or the authentication information  302 . For example, a user may enter a biometric signature that is processed by the authentication system  200  to extract unique data attributes. The data attributes may be compared with each of the signature keys  306  to determine a match. If a match is determined, the authentication system  200  may determine the user identifier  300  associated with the matching signature key  306 . The authentication system  200  may retrieve secure information  308  associated with the user identifier  300  identified and transmit the secure information  308  for display on the user device  100 . 
       FIG. 4  is a flow chart of a process for generating a signature key according to some aspects of the present disclosure. The process is described with reference to  FIGS. 1-3 , unless otherwise indicated, though other implementations are possible without departing from the scope of the present disclosure. 
     In block  400 , the processor  202  receives textual authentication information. The textual authentication information may correspond to authentication information  302  stored in the centralized database  208 . In one example, the textual authentication information may include user login information received by the authentication system  200  in response to user input from a displayed user interface on the user device  100 . In some aspects, the user login information may include information such as a username, password, or personal identification number, inputted by the user via an interface generated and displayed by the key engine  206  or a software application stored on the user device  100 . 
     In some aspects, the processor  202  may receive the textual authentication information from the user device  100  via the network  212  and compare it with authentication information  302  stored in the database to determine a match. The processor  202  may identify a user identifier  300  associated with the authentication information  302  found to match the textual authentication information entered on the user device  100 . 
     In block  402 , a biometric signature  106  is received. In some aspects, the biometric signature  106  may be obtained by a sensor  104  of the user device  100  and transmitted by the user device  100  via the network  212  to the authentication system  200 . In other aspects, the biometric signature  106  may be obtained by a sensor  232  of the remote system  226  and transmitted to the authentication system  200  via the network  212  or the enterprise service bus  228 . In some aspects, the processor  202  may receive the biometric signature  106  and store it as an EKG  304  in the centralized database  208 . 
     In block  404 , a signature key is generated using the biometric signature  106 . In some aspects, the processor  202  may execute instructions from the key engine  206  and extract unique data attributes from the EKG  304  corresponding to the biometric signature  106  for the signature key. For example, the unique data attributes may include intervals between wave peaks in the biometric signature  106 . In some aspects, the processor  202  may process the biometric signature prior to extracting the unique data attributes. For example, the processor  202  may apply a filter to the biometric signature  106  to separate the biometric information from noise generated in obtaining or transmitting the biometric signature  106  to the authentication system  200 . 
     In block  406 , the signature key is associated with the user in the centralized database  208 . In some aspects, the signature key may be stored in a list of signature keys  306  in a manner that associates the signature key with a user identifier  300 . For example, as described in  FIG. 3 , the signature key may be associated with a user identifier  300  via an object, pointer, or by some other means. 
     In block  408 , the signature key may be optionally transmitted to the user device  100 . For example, in some aspects, the user device  100  may include a software application operating using a client-side engine corresponding to the key engine  206  of the authentication system  200 . In some aspects, the user device  100  may store a copy of the signature key in the datastore  218  of the user device  100  to allow the user device  100  to authenticate the user locally. In other aspects, the signature key may be stored locally as a backup in the event of a breach or corruption of the centralized database  208 , or for other purposes, such as authentication the user device  100  instead of, or in addition to, authenticating the user. 
       FIG. 5  is a flow chart of a process for authenticating a user using a biometric signature key according to some aspects of the present disclosure. The process is described with reference to  FIGS. 1-3 , unless otherwise indicated, though other implementations are possible without departing from the scope of the present disclosure. 
     In block  500 , a biometric signature is received. The biometric signature may be received by the processor  202  of the authentication system  200  from the user device  100 . In some aspects, the biometric signature may be obtained by the sensor  104  of the user device  100  and transmitted to the authentication system  200  via the network  212 . 
     In block  502 , unique data attributes may be extracted from the biometric signature. In some aspects, the processor  202  may execute instructions of the key engine  206  to extract the data attributes similar to the process for generating a signature key described in block  404  of  FIG. 4 . For example, the unique data attributes may correspond to intervals between wave peaks in the biometric signature. 
     In block  504 , the unique data attributes are compared to signature keys  306  stored in the centralized database  208 . In some aspects, the comparison may include a direct comparison of the attributes with the signature keys  306  to determine an exact match. In other aspects, the comparison may include a relational comparison to determine a match. For example, the unique data attributes may correspond to intervals or distances between different portions of different waves of the biometric signature, such as intervals between wave peaks in the biometric signature. The specific interval between each peak may change depending on factors such as heart rate or the health of the user during a sensor measurement, but the relationship or ratio between different intervals may remain constant. The comparison between the attributes and the stored signature keys  306  may then take into account the ratios between different attributes in determining a match. 
     In block  506 , if a match is determined between the unique data attributes and a stored signature key  306 , the processor  202  identifies the user associated with the stored signature key  306  matching the unique data attributes. Each signature key  306  may be associated with a user identifier  300  in the centralized database  208 . The processor  202  may use the user identifier  300  associated with the signature key  306  to determine the user. 
     In block  508 , the user may be authenticated. In some aspects, the secure information associated with the user may be transmitted to the user device  100  for display on the display unit  224 . In some aspects, the identified user identifier  300  associated with the matching signature key  306  may include secure information associated in a database. The processor  202  or network interface  210  may transmit the secure information  308  to the user device  100  via the network  212  for display. In additional and alternative aspects, the user may be authenticated to access the secure information for conducting a secure transaction. 
     In block  510 , if a match is not determined between the unique data attributes and a stored signature key  306 , the user is not authenticated. No secure information may be transmitted to the user device  100  or accessed by the user. In some aspects, the processor  202  may generate a user interface including a message indicating that the user is not authenticated to view secure information on the user device  100 . 
     In some aspects, the user may wish to view secure information  230  stored in a database of a remote system  226  or accessible to the remote system  226  from another database. The user may additionally wish to conduct a secure transaction from the remote system  226  using the secure information. In one example, the remote system  226  may include an ATM machine. The user may place his hands onto, or otherwise contact, the sensor  232  of the remote system  226 . The sensor  232  may obtain a biometric signature from the remote system  226  and transmit the biometric signature to the authentication system  200  via the network  212  or the enterprise service bus  228  for authenticating the user as described in blocks  500 - 506 . If the user is authenticated, the authentication system  200  may transmit an authentication signal to the remote system  226 . In some aspects, the authentication signal may indicate that the user is authenticated to view secure account information or conduct a secure transaction using the secure account information in the remote system  226 . In other aspects, the authentication signal may correspond to user identification information that may be compared to user identification information in a database of the remote system  226  to retrieve the appropriate secure information. If the user is not authenticated by the authentication system  200 , the user may be required to enter conventional authentication information (e.g., a PIN) or be denied access to the secure account information, as described in block  510 . 
     The foregoing description of the examples, including illustrated examples, of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of this invention. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.