Patent Publication Number: US-11032271-B2

Title: Authentication based on shared secret seed updates for one-time passcode generation

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application is related to U.S. patent application Ser. No. 16/264,897, entitled “Authentication Based on Shared Secret Updates,”; and U.S. patent application Ser. No. 16/264,877, entitled “Client-Driven Shared Secret Updates for Client Authentication,”, each filed contemporaneously herewith and incorporated by reference herein. 
     FIELD 
     The field relates generally to information processing systems, and more particularly to authentication techniques in such systems. 
     BACKGROUND 
     Many modern authentication solutions are based upon a client proving knowledge to a server of a shared secret value, such as a password, a personal identification number, or a symmetric key. Similarly, one-time passcode solutions leverage shared knowledge of a shared secret seed to perform time-based or counter-based computations by the client and the server to prove knowledge of the shared secret seed. While efficient, such shared secret cryptography techniques suffer from an inability to ensure that only one client shares a given shared secret with the server. The continued assumption that only the one client and the server have the shared secret cannot be verified. 
     A need therefore exists for improved techniques for protecting shared secrets, such as shared secret seeds. 
     SUMMARY 
     In one embodiment, a method comprises, in response to a first authentication of a client using a given one-time passcode derived from a given shared secret seed, updating, by a server, the given shared secret seed using one or more of the given one-time passcode and a timestamp from the first authentication as part of a secret update protocol to generate an updated given shared secret seed; and evaluating a second authentication using a new one-time passcode derived from the updated given shared secret seed. 
     In some embodiments, an anomaly is detected when the client attempts the second authentication using a one-time passcode and the server determines that the one-time passcode was generated by a previously used shared secret seed. The server may store a set of previously accepted one-time passcodes and evaluate one or more of the previously accepted one-time passcodes to validate the new one-time passcode. In at least one embodiment, the client initiates an undo operation to undo the update of the given shared secret seed, and wherein the given shared secret seed is restored upon a successful authentication of the client. 
     Other illustrative embodiments include, without limitation, apparatus, systems, methods and computer program products comprising processor-readable storage media. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an information processing system configured for performing authentication in one embodiment of the disclosure; 
         FIG. 2  shows another information processing system configured for performing authentication in at least one embodiment of the disclosure; 
         FIG. 3  is a system diagram of an exemplary mobile device on which at least one embodiment of the disclosure can be implemented; 
         FIG. 4  is a system diagram of exemplary mobile device components, in accordance with one embodiment of the disclosure; 
         FIG. 5  is a flow diagram of an authentication and shared secret seed update process, according to one illustrative embodiment of the disclosure; 
         FIGS. 6 and 7  illustrate chains of shared secret seeds, according to one or more embodiments of the disclosure; 
         FIG. 8  illustrates an exemplary processing platform that may be used to implement at least a portion of one or more embodiments of the disclosure comprising a cloud infrastructure; and 
         FIG. 9  illustrates another exemplary processing platform that may be used to implement at least a portion of one or more embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the present disclosure will be described herein with reference to exemplary communication, storage and processing devices. It is to be appreciated, however, that the disclosure is not restricted to use with the particular illustrative configurations shown. One or more embodiments of the disclosure provide methods, apparatus and computer program products for authenticating a user using shared secret seed updates for one-time passcode (OTP) generation. 
     In one or more embodiments, techniques are provided for shared secret seed evolution that leverage previous communications between two parties to evolve the shared secret seed in a known way. In some embodiments, if an OTP derived from the shared secret seed is used by a third party without the knowledge of the client, upon future communication with the client, the server can detect an inconsistency indicating the use of the OTP derived from the shared secret seed by the third party. Remediation actions can then be implemented to establish a new shared secret seed known only by the client and server. 
     One challenge in shared secret authentication is ensuring that the shared secret, such as a shared secret seed, remains unknown to other parties. Existing attempts to protect shared secrets involve, for example, dedicated secure hardware, layered encryption, password vaults, and other techniques. However, the core assumption of these authentication systems is that the shared secret is only known to the client and server. These secrets are often valid for a long period of time and breaking the assumption of secrecy can lead to significant adverse consequences. 
     Moreover, if an attacker can intercept the channel between the client and the server, an opportunity exists for a Man-in-the-Middle (MITM) attack, whereby the attacker accesses the transmission from the client to the server to obtain the OTP derived from the shared secret seed and then the attacker uses the OTP to authenticate as the client (or a user of the client). In addition, OTPs can be generated at will if the shared secret seed is stolen. While this can be overcome under some circumstances, the disclosed solution also provides a detection capability for such attacks. 
     In one or more embodiments, the disclosed shared secret seed evolution techniques update the shared secret seed of a user (or corresponding client) to create a chain of shared secret seeds. This shared secret seed evolution is driven by use of the current shared secret seed. When a given shared secret seed is used for OTP authentication, the given shared secret seed is updated based on some aspect of the authentication to create a new shared secret seed, as discussed hereinafter. As both the client and server observe the successful authentication, in some embodiments, they can both update their copy of the shared secret seed, creating a chain of shared secret seed values. In this manner, should the shared secret seed be compromised, the server can observe an inconsistency in authentication attempts that would indicate that the shared secret seed information is being leveraged by multiple clients, as discussed further below. Generally, the server can detect and respond to cloning and other attacks or anomalies, such as MITM attacks. In some situations, the authentication server may not know which authentication attempt was invalid. It may be unknown, for example, whether the current user is a legitimate user or an “attacker.” Moreover, there could be situations where an alert would be raised that is not actually an attack, but represents an anomaly. In the OTP case, for example, the user may forget to update his or her shared secret seed (which is not necessarily an attack, but may be considered an anomaly). 
     In some embodiments, the shared secret seed is modified after a successful authentication attempt by using information from the authentication as part of a shared secret seed update protocol to generate an updated shared secret seed. The information from the authentication comprises, for example, the given one-time passcode and/or a timestamp of the authentication. By incorporating this information from the authentication into the updated shared secret seed, and thus, the next authentication attempt, an authentication chain is created (in a similar manner as blocks in a blockchain containing pointers to previous blocks). 
       FIG. 1  shows a computer network  100  configured in accordance with an illustrative embodiment of the disclosure. The computer network  100  comprises a plurality of user devices  102 - 1 ,  102 - 2 , . . .  102 -M, collectively referred to herein as user devices  102 . The user devices  102  are coupled to a network  104 , where the network  104  in this embodiment is assumed to represent a sub-network or other related portion of the larger computer network  100 . Accordingly, elements  100  and  104  are both referred to herein as examples of “networks” but the latter is assumed to be a component of the former in the context of the  FIG. 1  embodiment. Also coupled to the network  104  is a processing platform  105 . 
     The user devices  102  may comprise, for example, mobile telephones, laptop computers, tablet computers, desktop computers or other types of computing devices. Such devices are examples of what are more generally referred to herein as “processing devices.” Some of these processing devices are also generally referred to herein as “computers.” 
     The user devices  102  in some embodiments comprise respective computers associated with a particular company, organization or other enterprise. In addition, at least portions of the computer network  100  may also be referred to herein as collectively comprising an “enterprise network.” Numerous other operating scenarios involving a wide variety of different types and arrangements of processing devices and networks are possible, as will be appreciated by those skilled in the art. 
     Also, it is to be appreciated that the term “user” in this context and elsewhere herein is intended to be broadly construed so as to encompass, for example, human, hardware, software or firmware entities, as well as various combinations of such entities. 
     The network  104  is assumed to comprise a portion of a global computer network such as the Internet, although other types of networks can be part of the computer network  100 , including a wide area network (WAN), a local area network (LAN), a satellite network, a telephone or cable network, a cellular network, a wireless network such as a Wi-Fi or WiMAX network, or various portions or combinations of these and other types of networks. The computer network  100  in some embodiments therefore comprises combinations of multiple different types of networks, each comprising processing devices configured to communicate using internet protocol (IP) or other related communication protocols. 
     The processing platform  105  has an associated database  106  configured to store shared secret seed information  107  that optionally includes each shared secret seed used for OTP authentication by a user and a corresponding timestamp and derived OTP value when a given shared secret seed was used, as discussed further below. 
     As discussed further below in conjunction with  FIGS. 5 through 7 , in order to detect inconsistencies in an authentication chain of shared secret seeds, the server can optionally store some additional data as part of the shared secret seed information  107 , beyond a current shared secret seed value. In various embodiments, the stored additional data varies, depending on what the client sends to the server as part of an authentication attempt. For example, the server can store the submitted OTP value and timestamp of the authentication when a particular shared secret seed was used. Assuming that the client and the server can agree on the time of an authentication (for example, within some predefined tolerance), the client and the server can both use that information to update their secret seeds appropriately. 
     In some embodiments, the timestamp is not needed. In such embodiments, reused OTP values derived from secret seeds are detected by checking if the supplied authentication information is correct for any previous secret seed. This approach may be impractical due to performance reasons (e.g., having to search a large number of previously submitted secret seeds and derived OTP values for prior authentication attempts of a given user). Thus, storing the timestamp and submitted OTP values along with the previously used secret seeds allows the server to efficiently detect reused secret seeds, with the assumption that the client provides the timestamp of the last known successful authentication (from the view of the client) when submitting a current authentication. 
     The database  106  in the present embodiment is implemented using one or more storage systems associated with the processing platform  105 . Such storage systems can comprise any of a variety of different types of storage including, for example, network-attached storage (NAS), storage area networks (SANs), direct-attached storage (DAS) and distributed DAS, as well as combinations of these and other storage types, including software-defined storage. 
     Also associated with processing platform  105  are input-output devices  108 , which illustratively comprise keyboards, displays or other types of input-output devices in any combination. Such input-output devices are used to support one or more user interfaces to the processing platform  105 , as well as to support communication between the processing platform  105  and other related systems and devices not explicitly shown. 
     In one or more embodiments of the disclosure (such as the example embodiment depicted in  FIG. 1 ), the processing platform  105  comprises an authentication server  112 . Authentication events, such as an evaluation of an OTP derived from a shared secret seed submitted by a user, initiated at respective ones of the user devices  102 , are directed to the authentication server  112  over the network  104  for processing. The authentication server  112  can determine if a given access attempt is authentic, based on an evaluation of the responsive OTP derived from a shared secret seed from the user submitted in response to a challenge. Upon verification of the presented authentication factors, the authentication server  112  grants the requesting user device  102  access to one or more protected resources of the computer network  100  (such as further depicted in  FIG. 2 , for example). Although shown as an element of the processing platform  105  in this embodiment, the authentication server  112  in other embodiments (such as depicted in  FIG. 2 , for example) can be implemented at least in part externally to the processing platform  105 , for example, as a stand-alone server, set of servers or other type of authentication system coupled to the network  104 . 
     The processing platform  105  in the  FIG. 1  embodiment is assumed to be implemented using at least one processing device. Each such processing device generally comprises at least one processor and an associated memory, and implements one or more functional modules for controlling certain features of the processing platform  105 . 
     More particularly, the processing platform  105  in this embodiment comprises a processor  120  coupled to a memory  122  and a network interface  124 . 
     The processor  120  illustratively comprises a microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other type of processing circuitry, as well as portions or combinations of such circuitry elements. 
     The memory  122  illustratively comprises random access memory (RAM), read-only memory (ROM) or other types of memory, in any combination. The memory  122  and other memories disclosed herein may be viewed as examples of what are more generally referred to as “processor-readable storage media” storing executable computer program code or other types of software programs. 
     One or more embodiments of the disclosure include articles of manufacture, such as computer-readable storage media. Examples of an article of manufacture include, without limitation, a storage device such as a storage disk, a storage array or an integrated circuit containing memory, as well as a wide variety of other types of computer program products. The term “article of manufacture” as used herein should be understood to exclude transitory, propagating signals. 
     The network interface  124  allows the processing platform  105  to communicate over the network  104  with the user devices  102 , and illustratively comprises one or more conventional transceivers. 
     The processor  120  further comprises an enrollment module  130  and an authentication and shared secret seed update module  132 . 
     It is to be appreciated that this particular arrangement of modules  130  and  132  illustrated in the processor  120  of the  FIG. 1  embodiment is presented by way of example only, and alternative arrangements can be used in other embodiments. For example, the functionality associated with the modules  130  and  132  in other embodiments can be distributed across multiple processing nodes, or separated across a larger number of modules within processor  120 . As another example, multiple distinct processors can be used to implement different ones of the modules  130  and  132  or portions thereof. 
     At least portions of the enrollment module  130  and/or authentication and shared secret seed update module  132  may be implemented at least in part in the form of software that is stored in memory  122  and executed by processor  120 . Similarly, at least portions of the authentication server  112  of the processing platform  105  can be implemented at least in part in the form of software that is stored in memory  122  and executed by processor  120 . 
     It is to be understood that the particular set of elements shown in  FIG. 1  for authentication of a user in authentication processes involving user devices  102  of computer network  100  is presented by way of illustrative example only, and in other embodiments additional or alternative elements may be used. Thus, another embodiment may include additional or alternative systems, devices and other network entities, as well as different arrangements of modules and other components. 
     By way of example, in other embodiments, the processing platform  105  can be eliminated and associated elements such as authentication server  112 , enrollment module  130  and/or authentication and shared secret seed update module  132  can be implemented elsewhere in the computer network  100 . 
     An exemplary process utilizing authentication and shared secret seed update module  132  of the processing platform  105  in computer network  100  will be described in more detail with reference to the flow diagram of  FIG. 5 . 
       FIG. 2  is a system diagram of an illustrative embodiment of the disclosure. By way of illustration,  FIG. 2  depicts an alternative embodiment to  FIG. 1 , wherein the authentication server(s)  112  is/are not resident on the processing platform  105  or user device(s)  102 , but rather are separate devices. Accordingly, as depicted in  FIG. 2 , user device  102  communicates with a protected resource  270   a  over network  104 . As detailed further below, at least one embodiment of the disclosure can also include a user device  102  that includes a protected resource  270   b  residing thereon. In an example implementation, a user authenticates online with one or more authentication servers  112 - 1  through  112 -N (hereinafter, collectively referred to as authentication servers  112 ) before obtaining access to protected resource  270   a  and/or  270   b  (hereinafter, collectively referred to as protected resource  270  unless otherwise specified). 
     According to one aspect of the disclosure, as noted above, the user of the user device  102  is authenticated by authentication servers  112  using an OTP derived from a shared secret seed of the user, and/or other forms of cryptographic information. The exemplary communications among the system elements  102 ,  104  and  270  of  FIG. 2  employed to achieve authentication by the authentication servers  112  are discussed further below. 
     It is to be appreciated that a given embodiment of the disclosed system may include multiple instances of user device  102  and protected resource  270 , and possibly other system components, although only single instances of such components are shown in the simplified system diagram of  FIG. 2  for clarity of illustration. 
     As noted herein, user device  102  may represent a portable device, such as a mobile telephone, personal digital assistant (PDA), wireless email device, game console, etc. The user device  102  may alternatively represent a desktop or laptop personal computer (PC), a microcomputer, a workstation, a mainframe computer, a wired telephone, a television set top box, or any other information processing device which can benefit from the use of authentication techniques in accordance with the disclosure. 
     The user device  102  may also be referred to herein as simply a “user.” The term “user,” as used in this context, should be understood to encompass, by way of example and without limitation, a user device, a person utilizing or otherwise associated with the device, or a combination of both. An operation described herein as being performed by a user may therefore, for example, be performed by a user device, a person utilizing or otherwise associated with the device, or by a combination of both the person and the device. Similarly, a password, biometric sample, one-time password, or other cryptographic information described as being associated with a user may, for example, be associated with a user device  102 , a person utilizing or otherwise associated with the device, or a combination of both the person and the device. 
     As also depicted in  FIG. 2 , the authentication servers  112  can be associated with a third party entity, such as an authentication authority, that processes authentication requests on behalf of web servers and other resources, as well as verifies the cryptographic information that is presented by a user device  102 . 
     Further, the protected resource  270  may be, for example, an access-controlled application, data store, web site or hardware device. In other words, a protected resource  270  is a resource that grants user access responsive to an authentication process, as will be described in greater detail below. For example, protected resource  270   a  may include an access-controlled file, an e-mail, a protected application, a remote application server such as a web site or other software program or hardware device that is accessed by the user device  102  over a network  104 . 
     Additionally, in at least one embodiment of the disclosure, protected resource  270   b  can include one or more applications or data residing on the user device  102  itself. For example, such a protected resource  270   b  can include access to a mobile data management container for launching applications on the user device  102  (such as a mobile device), which can be protected requiring authentication in order to run the application(s) protected by the container. Further, protected resource  270   b  could also include an access-controlled file, e-mail, protected application, remote application server such as a web site or other software program or hardware device that is accessed by the user device  102  over network  104 . Similarly, it is possible that in order to unlock the mobile platform to perform operations, a successful authentication might be required. 
       FIG. 3  is a system diagram of an exemplary mobile device  300  on which at least one embodiment of the disclosure can be implemented. By way of illustration, as shown in  FIG. 3 , the exemplary mobile device  300  comprises a user interface  303  configured to receive user input and provide user output, such as a data file and/or data file location selection(s), such as described herein. One or more embodiments of the disclosure can include components such as a display screen, a capacitive touch display, and a push-button keyboard implemented for use in connection with the user interface  303 . 
     Additionally, the mobile device  300  includes a network interface  305  configured to connect the mobile device  300  to a communications medium such as, for example, Wi-Fi and/or cellular telephony. Accordingly, the network interface  305  enables the mobile device  300  to communicate with the other components of an electronic environment. 
     The mobile device  300  further comprises a memory  309  configured to store one or more software constructs including, for example, an operating system  311 , an authentication application  313 , data for protected resources  315  (e.g., documents and restricted applications), a cryptographic information file  317 , as well as other suitable or relevant material. 
     In one or more embodiments, processing circuitry  307  of the mobile device  300  is configured to operate in accordance with the software constructs stored in the memory  309 . By way of example, when the processing circuitry  307  runs the operating system  311 , the processing circuitry  307  provides a secure electronic platform on which a user is able to carry out work. Such an electronic platform is capable of operating, for example, as a container to protect data requiring user authentication before permitting access. Further, when the processing circuitry  307  runs the authentication application  313 , the processing circuitry  307  communicates with a local authentication client  325  in a secure manner, for example, to obtain cryptographic information  317 ( a ),  317 ( b ) from a storage buffer  327 , as additionally described herein. 
     Additionally, for completeness, cellular phone circuitry  319  within mobile device  300  allows the user to establish cellular phone calls with other callers having remote devices, as would be appreciated by one skilled in the art. 
     It should be appreciated that the processing circuitry  307  can include one or more processors running specialized software components, such as detailed in connection with the techniques detailed herein and further depicted in  FIG. 4 . 
     In at least one embodiment of the disclosure, once the mobile device  300  is able to obtain valid cryptographic information, the user of the mobile device  300  is able to perform local user authentication to access protected resources. Accordingly, as noted, the mobile device  300  is provisioned with the authentication application  313  and cryptographic information file  317  holding cryptographic information to be used in connection with an authentication process. For example, and as further detailed herein, such cryptographic information within cryptographic information file  317  can include one or more shared secret seeds of the user in some embodiments. 
     Consequently, the processing circuitry  307  of the mobile device  300  can perform a local authentication operation using cryptographic information file  317  stored in the memory  309 . In at least one embodiment of the disclosure the processing circuitry  307  runs the authentication application  313 , which directs the user of the mobile device  300 , via the user interface  303 , to enter cryptographic information (such as, for example, OTPs derived from shared secret seeds of the user) which is captured as one or more input elements  317 ( a ),  317 ( b ), etc. While the captured cryptographic information  317 ( a ),  317 ( b ), etc. is temporarily stored in the storage buffer  327  of the local authentication client  325 , the authentication application  313  evaluates the captured user-provided cryptographic information  317 ( a ),  317 ( b ), etc. with a shared secret seed of the user (e.g., provided during enrollment in file  317 ) to determine a likelihood of a match and/or plausibility of the user-provided cryptographic information. 
     If a match or otherwise positive resolution is determined via this evaluation, the authentication application  313  permits the user to access a protected resource (such as, for example, data in association with element  315  that are stored in the memory  309 ). 
       FIG. 4  is a system diagram of exemplary mobile device components, in accordance with at least one embodiment of the disclosure. As depicted in  FIG. 4 , a user can enter cryptographic information via user interface  303 . This entered cryptographic information is captured as one or more input elements  317 ( a ),  317 ( b ). Such input elements can include, as noted above, the user-provided OTPs derived from a shared secret seed of the user. 
     Accordingly, the captured one or more input elements  317 ( a ),  317 ( b ), etc. can be stored in cryptographic information file  317  to be subsequently used in conjunction with fuzzy logic to carry out an authentication process. 
     Consequently, a corresponding cryptographic flow (carried out, for example, by authentication application  313  as run by operating system  311 ) can take the following exemplary form. The user is prompted (via user interface  303 ) as part of a challenge to enter cryptographic information in connection with an authentication request to access a protected resource associated with the mobile device (for example, the user wishes to access and/or unlock his or her smart phone). The entered cryptographic information is captured by the processing circuitry  307  as one or more input elements  317 ( a ),  317 ( b ) that are temporarily stored in the storage buffer  327  of the local authentication client  325 . 
     Subsequently, the authentication application  313  evaluates the captured user-provided cryptographic information  317 ( a ),  317 ( b ), etc. with the original challenge in file  317  stored in memory  309  to determine a likelihood of a match and/or plausibility of the user-provided response(s). If the user-entered input elements  317 ( a ),  317 ( b ) are deemed to be matching and/or plausible, authentication is deemed successful and the user is granted access to the protected resource in question. 
       FIG. 5  is a flow diagram of an exemplary authentication and shared secret seed update process  500 , according to one illustrative embodiment. As shown in  FIG. 5 , a test is initially performed during step  510  to determine if a client is authenticated using a given OTP derived from a shared secret seed. Once it is determined during step  510  that a client has been authenticated using the given OTP derived from the shared secret seed, the server updates the given shared secret seed during step  520  using the given OTP and/or a timestamp of the authentication to generate the updated shared secret seed. 
     In one or more embodiments, the update performed during step  520  comprises an exclusive OR (XOR) operation or a hash operation applied to (i) at least a portion of the given shared secret seed, and/or (ii) the given one-time passcode from the authentication and/or an expanded version of the given one-time passcode from the authentication. It is noted that, in some embodiments, the client and the server both independently update the shared secret seed upon a successful authentication. The secret seed can be updated when necessary, for example, using one or more of the following techniques:
         the accepted OTP is applied to an XOR operation with the least or most significant bits of the shared secret seed (e.g., while this would lead to a small change in the seed, that would be sufficient to dramatically change the output of the OTP generation function; given the limited space of OTP values though, such XORing could lead to situations where seeds that were used previously are used again (e.g., creating loops with multiple exit paths in the seed chaining tree));   the seed and OTP are hashed together to generate a new shared secret seed;   the accepted OTP is repeated or otherwise padded out to the size of the shared secret seed before the XOR operation is applied (this changes more digits of the shared secret seed, but is still potentially vulnerable to the collisions mentioned above);   the accepted OTP is expanded to the size of the shared secret seed before the XOR operation is applied (in further variations, password based key derivation functions, scripts, or other password stretching/strengthening algorithms are used); and   when the OTP is a truncation of a longer output, the un-truncated output could be applied to the XOR operation (if the un-truncated output is used to generate multiple OTP values, however, care would need to be taken to align on restart procedures once the new shared secret seed has been established; this may, however, make searching on the server more efficient as one computation results in multiple OTP values; more variations on this option are possible if the transmission channel between the client and server is modified).       

     As used herein, the term “expanded version” of an OTP comprises an OTP obtained by padding, expanding and/or un-truncating an original version of the OTP, as would be apparent to a person of ordinary skill in the art. 
     The exemplary authentication and shared secret seed update process  500  then evaluates a new authentication (e.g., of the client or a malicious client) during step  530  using a new OTP derived from the updated shared secret seed. 
     An attack is optionally detected during step  540  when the client attempts a new authentication using an OTP and the server determines that the shared secret which generated the OTP was previously used for authentication. Finally, upon such a detected attack, a recovery workflow is initiated during step  550 . For example, a reset workflow can be initiated to limit how long an attacker can potentially access the account of the user. 
     As part of the authentications of steps  510  and  530 , the client can optionally communicate the timestamp of the prior authentication to the server. As noted above, the stored shared secret seed information  107  optionally includes each shared secret seed used for authentication by a user and a corresponding timestamp and OTP value when a given shared secret seed was used. In this manner, the server can use the communicated timestamp of the prior authentication to access and evaluate the shared secret seed and/or OTP used with the prior authentication when evaluating a current authentication. Furthermore, if the channel between the client and the server is a bi-directional channel, then the server can notify the client that the authentication succeeded and that the secret state seed needs to be updated. On the client side, a browser extension or a password vault could be employed to make a client-side shared secret seed update process seamless when interacting with web sites. 
       FIG. 6  illustrates a shared secret seed chain  600 , according to one illustrative embodiment of the disclosure. As shown in  FIG. 6 , the exemplary shared secret seed chain  600  comprises a seed  610  (Seed). During step  620 , a user authenticates with an OTP derived from the shared secret seed  610 . In connection with the authentication of the user at step  620 , the seed  610  is updated to an updated seed  630  (Seed′) (for example, using the exemplary authentication and shared secret seed update process  500  of  FIG. 5 ). In some embodiments, the updated seed  630  is generated by applying an exclusive OR operation to the seed  610  and the OTP submitted with the authentication of step  620 . 
     During step  640 , the user authenticates with an OTP derived from the updated seed  630 . In connection with the authentication of the user at step  640 , the seed  610  is further updated to a new seed  650  (Seed″) (for example, using the exemplary authentication and shared secret seed update process  500  of  FIG. 5 ). The new seed  650  is generated by applying an exclusive OR operation to the updated seed  630  and the OTP submitted with the authentication of step  640 . 
       FIG. 7  illustrates a shared secret seed chain  700 , according to one illustrative embodiment of the disclosure. As shown in  FIG. 7 , the exemplary shared secret seed chain  700  comprises a seed  710  (Seed). During step  720 , a user authenticates with an OTP derived from the shared secret seed  710 . In connection with the authentication of the user at step  720 , the seed  710  is updated to an updated seed  730  (Seed′) (for example, using the exemplary authentication and shared secret seed update process  500  of  FIG. 5 ). The updated seed  730  is generated by applying an exclusive OR operation to the seed  710  and the OTP submitted with the authentication of step  720 . 
     During step  740 , assume that an attacker intercepted the OTP derived from the updated seed  730  (e.g., using a MITM attack) and then authenticates at a time to with an OTP derived from the updated seed  730 . In connection with the authentication of the user at step  740 , the updated seed  730  is further updated to a new seed  750  (Seed″) (for example, using the exemplary authentication and shared secret seed update process  500  of  FIG. 5 ). The new seed  750  is generated by applying an exclusive OR operation to the updated seed  730  and the OTP submitted with the authentication of step  740 . 
     The user then attempts to authenticate with an OTP derived from the updated seed  730  (e.g., the last shared secret seed value known to the user) during step  760  at a time t 1 . Thus, when the real user attempts to authenticate, the authentication fails because the secret seed of the user is no longer up-to-date with the server (e.g., the updated seed  730  was already changed in connection with the attacker authentication of step  740 ). Thus, an attack is detected at state  770 . 
     In some embodiments, attack detection can occur in real-time in connection with the authentication, or attack detection can be deferred until a later time (e.g., every night the server could perform batch processing to analyze failed authentications, for example, depending on the number of users of the system). 
     The disclosed shared secret seed update techniques thus allow detection after-the-fact. If, during authentication, the client provides a reference to what the client believes is the previous OTP (or other data that allows the server to look up the previously used OTP and/or shared secret seed), the server would be able to identify a fork in the authentication chain. A fork can be considered a deviation from an expected evolution of a secret seed. The server could recognize that a user submitted a valid authentication for a previously used secret seed, but that was invalid for the current authentication due to another client forking the chain of shared secret seeds  700  at a previous time. Upon attack detection, the server can invalidate the shared secret seed of the user and force a recovery workflow (e.g., a reset workflow) in order to limit how long an attacker can potentially access the account of a user. The server can also require additional authentication factors to login as part of the recovery workflow. Further, the server can optionally take additional actions as part of the recovery workflow, including notifying the user or triggering an internal protocol to investigate a possible breach. 
     In one or more embodiments, if the token client provides a timestamp of the last known successful authentication, the server can search for the corresponding shared secret seed (as timestamps are typically monotonically increasing) and determine if that seed would have produced the submitted OTP. If this lookup yields a seed that is not the most recently stored seed value, then something has gone wrong because the user is submitting a valid OTP from the wrong authentication chain. The token of the user can be locked until the potential cloning can be identified and/or resolved. 
     In some embodiments, the chaining of shared secret seeds in the manner shown in  FIGS. 6 and 7  enable the server to potentially detect whether a breach has occurred, in which secret seeds of multiple users have been stolen. By monitoring the number of forked authentication chains across a user population, for example, the server can observe anomalies and take action. For example, if the number of detected forked authentication chains spikes to above-normal levels (e.g., based on a predefined threshold or another criteria), an internal protocol could be triggered thereby requiring all users to perform step-up authentication until a possible breach can be investigated and/or resolved. 
     A challenge arises if OTPs continue to be communicated through a “human channel” which is commonly used today. In this case, a person must transcribe digits displayed on the token into the form being sent to the server. In this scenario, information can be sent to the server by making the displayed token value be the XOR of the current OTP and the previous OTP that was accepted by the server. While conforming to the existing OTP transmission channel, this solution would be made more efficient if the server also stored a history of accepted OTP values in the shared secret seed information  107  in addition to the previously used shared secret seeds and corresponding timestamps, as noted above. In this manner, the server could more efficiently lookup the shared secret seed at the time of the last known successful authentication by the client to detect cloning. 
     Client User Interface 
     A dynamic shared secret seed based upon the last successful OTP potentially creates usability challenges. With traditional TOTP (time-based OTP) user interfaces, the OTP value is displayed and changes every X seconds. Applying this user interface approach with a dynamic shared secret seed would introduce some challenging corner cases. Consider the following use cases:
         1. The user enters the current OTP using seed A into their virtual private network (VPN) just as the time-period is rolling over. Another OTP using seed A is then displayed.   2. The authentication is successful, and the user is prompted to immediately authenticate again.   3. The user enters the currently displayed OTP that was computed using seed A; the problem is that the server is now using seed B. Thus, the authentication fails.       

     Another new challenge also potentially exists: an attacker that possesses the token of a user could coerce the device to be out-of-sync with the server by indicating fake successful authentications. If the attacker can do this several times, the server may not be able to detect the fork. Assume that the client token submits the current OTP along with a reference to the previous OTP assumed to be valid. If an attacker could steal the current seed and then cause the client device to perform two seed updates, the attacker would now have a valid seed from the perspective of the server, and because the original seed was updated twice, the previous OTP referenced in an authentication event would not exist on the server. Essentially, the attacker would have stolen the legitimate OTP chain and prevented the user from alerting the server. 
     One or more embodiments recognize that an appropriate user interface for use with shared secret seed updates can address these challenges. In some embodiments, the exemplary user interface for use with shared secret seed updates supports local biometric authentication of a user before allowing the user to indicate a successful authentication with their token. After locally authenticating, a dialog box can be presented to the user showing the current OTP value with buttons present to indicate whether or not the authentication was successful. Displaying a dialog box with a static OTP prevents the roll-over corner case described above. If the user leaves this dialog box open too long prior to entering the OTP into their application (e.g., a VPN), then the authentication would fail and the user would have to start over. 
     In some embodiments, the client can initiate an undo operation to undo the update of the given shared secret seed performed, for example, during step  520  of  FIG. 5 . For example, the client may have accidentally initiated the update through an erroneous interaction with a token and may optionally have a limited predefined period of time to correct the error. In response to the undo operation, the given shared secret seed is restored upon a successful authentication of the client (e.g., a biometric authentication). 
     In one or more embodiments, the undo operation and associated functionality are part of an updated user interface. As noted above, for the described roll-over corner case, the user manually enters an OTP into the user interface that was displayed on a token. For example, as described above, the authentication server updates the shared secret seed of the user with each successful authentication of the user. In this scenario, the user must be aware that the authentication succeeded, in order to know whether or not to update the shared secret seed with the OTP token. For example, in at least one implementation, the user interacts with the token (for example, by pressing a button) to indicate to the token that the last OTP was accepted and that the shared secret seed requires an update. If the user or a third party accidentally, or otherwise improperly, initiates an update of the shared secret seed, the authenticated undo operation allows the given shared secret seed to be restored. In other words, the prior value of the shared secret seed is maintained. The particular processing operations and other network functionality described in conjunction with the flow diagrams of  FIGS. 5 through 7  are presented by way of illustrative example only, and should not be construed as limiting the scope of the disclosure in any way. Alternative embodiments can use other types of processing operations to update a shared secret seed responsive to an authentication of a user. For example, the ordering of the process steps may be varied in other embodiments, or certain steps may be performed concurrently with one another rather than serially. 
     In one or more embodiments, the disclosed techniques for authenticating a user using shared secret seed updates optionally include a detection mechanism for detecting if a shared secret seed is used by more than one client (e.g., cloning), or if an authentication is captured and used by an attacker (e.g., Man-in-the-Middle attack). In some instances, the disclosed secret seed evolution techniques can be used to prevent such attacks. 
     Among other benefits, the disclosed techniques for authenticating a user using shared secret seed updates that chain successful authentications together significantly reduce the valid lifetime of an OTP derived from a shared secret seed, for example, from an order of years down to an order of hours (or even less). Thus, the risk of a stolen secret seed is significantly reduced, since the window for authentication is much smaller (e.g., attackers can no longer indefinitely authenticate after stealing a shared secret seed or an OTP derived from the shared secret seed). 
     One or more embodiments of the disclosure provide improved methods, apparatus and computer program products for authentication using shared secret seed updates. The foregoing applications and associated embodiments should be considered as illustrative only, and numerous other embodiments can be configured using the techniques disclosed herein, in a wide variety of different applications. 
     It should also be understood that the disclosed authentication techniques, as described herein, can be implemented at least in part in the form of one or more software programs stored in memory and executed by a processor of a processing device such as a computer. As mentioned previously, a memory or other storage device having such program code embodied therein is an example of what is more generally referred to herein as a “computer program product.” 
     The disclosed techniques for authenticating a user using shared secret seed updates may be implemented using one or more processing platforms. One or more of the processing modules or other components may therefore each run on a computer, storage device or other processing platform element. A given such element may be viewed as an example of what is more generally referred to herein as a “processing device.” 
     As noted above, illustrative embodiments disclosed herein can provide a number of significant advantages relative to conventional arrangements. It is to be appreciated that the particular advantages described above and elsewhere herein are associated with particular illustrative embodiments and need not be present in other embodiments. Also, the particular types of information processing system features and functionality as illustrated and described herein are exemplary only, and numerous other arrangements may be used in other embodiments. 
     In these and other embodiments, compute services can be offered to cloud infrastructure tenants or other system users as a Platform-as-a-Service (PaaS) offering, although numerous alternative arrangements are possible. 
     Some illustrative embodiments of a processing platform that may be used to implement at least a portion of an information processing system comprise cloud infrastructure including virtual machines implemented using a hypervisor that runs on physical infrastructure. The cloud infrastructure further comprises sets of applications running on respective ones of the virtual machines under the control of the hypervisor. It is also possible to use multiple hypervisors each providing a set of virtual machines using at least one underlying physical machine. Different sets of virtual machines provided by one or more hypervisors may be utilized in configuring multiple instances of various components of the system. 
     These and other types of cloud infrastructure can be used to provide what is also referred to herein as a multi-tenant environment. One or more system components such as a cloud-based authentication engine, or portions thereof, are illustratively implemented for use by tenants of such a multi-tenant environment. 
     Cloud infrastructure as disclosed herein can include cloud-based systems such as Amazon Web Services (AWS), Google Cloud Platform (GCP) and Microsoft Azure. Virtual machines provided in such systems can be used to implement at least portions of a cloud-based authentication platform in illustrative embodiments. The cloud-based systems can include object stores such as Amazon S3, GCP Cloud Storage, and Microsoft Azure Blob Storage. 
     In some embodiments, the cloud infrastructure additionally or alternatively comprises a plurality of containers implemented using container host devices. For example, a given container of cloud infrastructure illustratively comprises a Docker container or other type of Linux Container (LXC). The containers may run on virtual machines in a multi-tenant environment, although other arrangements are possible. The containers may be utilized to implement a variety of different types of functionality within the storage devices. For example, containers can be used to implement respective processing devices providing compute services of a cloud-based system. Again, containers may be used in combination with other virtualization infrastructure such as virtual machines implemented using a hypervisor. 
     Illustrative embodiments of processing platforms will now be described in greater detail with reference to  FIGS. 8 and 9 . These platforms may also be used to implement at least portions of other information processing systems in other embodiments. 
       FIG. 8  shows an example processing platform comprising cloud infrastructure  800 . The cloud infrastructure  800  comprises a combination of physical and virtual processing resources that may be utilized to implement at least a portion of the disclosed authentication system. The cloud infrastructure  800  comprises multiple virtual machines (VMs) and/or container sets  802 - 1 ,  802 - 2 , . . .  802 -L implemented using virtualization infrastructure  804 . The virtualization infrastructure  804  runs on physical infrastructure  805 , and illustratively comprises one or more hypervisors and/or operating system level virtualization infrastructure. The operating system level virtualization infrastructure illustratively comprises kernel control groups of a Linux operating system or other type of operating system. 
     The cloud infrastructure  800  further comprises sets of applications  810 - 1 ,  810 - 2 , . . .  810 -L running on respective ones of the VMs/container sets  802 - 1 ,  802 - 2 , . . .  802 -L under the control of the virtualization infrastructure  804 . The VMs/container sets  802  may comprise respective VMs, respective sets of one or more containers, or respective sets of one or more containers running in VMs. 
     In some implementations of the  FIG. 8  embodiment, the VMs/container sets  802  comprise respective VMs implemented using virtualization infrastructure  804  that comprises at least one hypervisor. Such implementations can provide authentication functionality of the type described above for one or more processes running on a given one of the VMs. For example, each of the VMs can implement authentication control logic and associated shared secret seed update techniques for providing authentication functionality for one or more processes running on that particular VM. 
     An example of a hypervisor platform that may be used to implement a hypervisor within the virtualization infrastructure  804  is the VMware® vSphere® which may have an associated virtual infrastructure management system such as the VMware® vCenter™. The underlying physical machines may comprise one or more distributed processing platforms that include one or more storage systems. 
     In other implementations of the  FIG. 8  embodiment, the VMs/container sets  802  comprise respective containers implemented using virtualization infrastructure  804  that provides operating system level virtualization functionality, such as support for Docker containers running on bare metal hosts, or Docker containers running on VMs. The containers are illustratively implemented using respective kernel control groups of the operating system. Such implementations can provide authentication functionality of the type described above for one or more processes running on different ones of the containers. For example, a container host device supporting multiple containers of one or more container sets can implement one or more instances of authentication control logic and associated shared secret seed update features for use in protecting shared secret seeds. 
     As is apparent from the above, one or more of the processing modules or other components of the authentication server  112  may each run on a computer, server, storage device or other processing platform element. A given such element may be viewed as an example of what is more generally referred to herein as a “processing device.” The cloud infrastructure  800  shown in  FIG. 8  may represent at least a portion of one processing platform. Another example of such a processing platform is processing platform  900  shown in  FIG. 9 . 
     The processing platform  900  in this embodiment comprises at least a portion of the given system and includes a plurality of processing devices, denoted  902 - 1 ,  902 - 2 ,  902 - 3 , . . .  902 -K, which communicate with one another over a network  904 . The network  904  may comprise any type of network, such as a WAN, a LAN, a satellite network, a telephone or cable network, a cellular network, a wireless network such as WiFi or WiMAX, or various portions or combinations of these and other types of networks. 
     The processing device  902 - 1  in the processing platform  900  comprises a processor  910  coupled to a memory  912 . The processor  910  may comprise a microprocessor, a microcontroller, an ASIC, an FPGA or other type of processing circuitry, as well as portions or combinations of such circuitry elements, and the memory  912 , which may be viewed as an example of a “processor-readable storage media” storing executable program code of one or more software programs. 
     Articles of manufacture comprising such processor-readable storage media are considered illustrative embodiments. A given such article of manufacture may comprise, for example, a storage array, a storage disk or an integrated circuit containing RAM, ROM or other electronic memory, or any of a wide variety of other types of computer program products. The term “article of manufacture” as used herein should be understood to exclude transitory, propagating signals. Numerous other types of computer program products comprising processor-readable storage media can be used. 
     Also included in the processing device  902 - 1  is network interface circuitry  914 , which is used to interface the processing device with the network  904  and other system components, and may comprise conventional transceivers. 
     The other processing devices  902  of the processing platform  900  are assumed to be configured in a manner similar to that shown for processing device  902 - 1  in the figure. 
     Again, the particular processing platform  900  shown in the figure is presented by way of example only, and the given system may include additional or alternative processing platforms, as well as numerous distinct processing platforms in any combination, with each such platform comprising one or more computers, storage devices or other processing devices. 
     Multiple elements of an information processing system may be collectively implemented on a common processing platform of the type shown in  FIG. 8 or 9 , or each such element may be implemented on a separate processing platform. 
     For example, other processing platforms used to implement illustrative embodiments can comprise different types of virtualization infrastructure, in place of or in addition to virtualization infrastructure comprising virtual machines. Such virtualization infrastructure illustratively includes container-based virtualization infrastructure configured to provide Docker containers or other types of LXCs. 
     As another example, portions of a given processing platform in some embodiments can comprise converged infrastructure such as VxRail™, VxRack™, VxBlock™, or Vblock® converged infrastructure commercially available from VCE, the Virtual Computing Environment Company, now the Converged Platform and Solutions Division of Dell EMC. 
     It should therefore be understood that in other embodiments different arrangements of additional or alternative elements may be used. At least a subset of these elements may be collectively implemented on a common processing platform, or each such element may be implemented on a separate processing platform. 
     Also, numerous other arrangements of computers, servers, storage devices or other components are possible in the information processing system. Such components can communicate with other elements of the information processing system over any type of network or other communication media. 
     As indicated previously, components of an information processing system as disclosed herein can be implemented at least in part in the form of one or more software programs stored in memory and executed by a processor of a processing device. For example, at least portions of the functionality shown in one or more of the figures are illustratively implemented in the form of software running on one or more processing devices. 
     It should again be emphasized that the above-described embodiments are presented for purposes of illustration only. Many variations and other alternative embodiments may be used. For example, the disclosed techniques are applicable to a wide variety of other types of information processing systems. Also, the particular configurations of system and device elements and associated processing operations illustratively shown in the drawings can be varied in other embodiments. Moreover, the various assumptions made above in the course of describing the illustrative embodiments should also be viewed as exemplary rather than as requirements or limitations of the disclosure. Numerous other alternative embodiments within the scope of the appended claims will be readily apparent to those skilled in the art.