Patent Publication Number: US-2020280550-A1

Title: System and method for endorsing a new authenticator

Description:
BACKGROUND 
     Field of the Invention 
     This invention relates generally to the field of data processing systems. More particularly, the invention relates to a system and method for endorsing a new authenticator. 
     Description of Related Art 
       FIG. 1  illustrates an exemplary client  120  with a biometric device  100 . When operated normally, a biometric sensor  102  reads raw biometric data from the user (e.g., capture the user&#39;s fingerprint, record the user&#39;s voice, snap a photo of the user, etc) and a feature extraction module  103  extracts specified characteristics of the raw biometric data (e.g., focusing on certain regions of the fingerprint, certain facial features, etc). A matcher module  104  compares the extracted features  133  with biometric reference data  110  stored in a secure storage on the client  120  and generates a score based on the similarity between the extracted features and the biometric reference data  110 . The biometric reference data  110  is typically the result of an enrollment process in which the user enrolls a fingerprint, voice sample, image or other biometric data with the device  100 . An application  105  may then use the score to determine whether the authentication was successful (e.g., if the score is above a certain specified threshold). 
     While the system shown in  FIG. 1  is oriented towards biometric authentication, various other or additional authentication techniques may be employed on the exemplary client  120 . For example, the client-side authenticators may be based on a PIN or other secret code (e.g., a password) entered by the user and/or may be triggered based on user presence (e.g., a button that user pushes to verify presence). 
     Systems have been designed for providing secure user authentication over a network using biometric sensors. In such systems, the score generated by the application, and/or other authentication data, may be sent over a network to authenticate the user with a remote server. For example, Patent Application No. 2011/0082801 (“&#39;801 Application”) describes a framework for user registration and authentication on a network which provides strong authentication (e.g., protection against identity theft and phishing), secure transactions (e.g., protection against “malware in the browser” and “man in the middle” attacks for transactions), and enrollment/management of client authentication tokens (e.g., fingerprint readers, facial recognition devices, smartcards, trusted platform modules, etc). 
     The assignee of the present application has developed a variety of improvements to the authentication framework described in the &#39;801 application. Some of these improvements are described in the following set of U.S. Patent Applications (“Co-pending Applications”), all filed Dec. 29, 1012, which are assigned to the present assignee and incorporated herein by reference: Ser. No. 13/730,761, Query System and Method to Determine Authentication Capabilities; Ser. No. 13/730,776, System and Method for Efficiently Enrolling, Registering, and Authenticating With Multiple Authentication Devices; Ser. No. 13/730,780, System and Method for Processing Random Challenges Within an Authentication Framework; Ser. No. 13/730,791, System and Method for Implementing Privacy Classes Within an Authentication Framework; Ser. No. 13/730,795, System and Method for Implementing Transaction Signaling Within an Authentication Framework. 
     Briefly, the Co-Pending Applications describe authentication techniques in which a user enrolls with authentication devices (or Authenticators) such as biometric devices (e.g., fingerprint sensors) on a client device. When a user enrolls with a biometric device, biometric reference data is captured (e.g., by swiping a finger, snapping a picture, recording a voice, etc). The user may subsequently register the authentication devices with one or more servers over a network (e.g., Websites or other relying parties equipped with secure transaction services as described in the Co-Pending Applications); and subsequently authenticate with those servers using data exchanged during the registration process (e.g., cryptographic keys provisioned into the authentication devices). Once authenticated, the user is permitted to perform one or more online transactions with a Website or other relying party. In the framework described in the Co-Pending Applications, sensitive information such as fingerprint data and other data which can be used to uniquely identify the user, may be retained locally on the user&#39;s authentication device to protect a user&#39;s privacy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which: 
         FIG. 1  illustrates an exemplary client equipped with a biometric device; 
         FIG. 2  illustrates one embodiment of a system for authorizing a new authenticator with a relying party; 
         FIG. 3  illustrates additional details of one embodiment of a system for authorizing a new authenticator with a relying party; 
         FIG. 4  illustrates one embodiment of a method for authorizing a new authenticator with a relying party; 
         FIG. 5  illustrates a one embodiment in which an old authenticator authorizes a new authenticator with a plurality of relying parties; 
         FIG. 6  illustrates one particular embodiment in which a control system controls authorization of new authenticators within an organization; and 
         FIGS. 7A-B  illustrate exemplary system architectures on which the embodiments of the invention may be implemented; 
         FIGS. 8-9  illustrate exemplary embodiments of a system for executing embodiments of the invention. 
         FIG. 10  illustrates one embodiment in which metadata is used by a relying party to authenticate a client; 
         FIG. 11  illustrates one embodiment of an architecture for bootstrapping user binding to an authenticator using data such as a code securely provided to the user; 
         FIG. 12  illustrates one embodiment of an architecture for bootstrapping user binding to an authenticator using biometric data; 
         FIG. 13  illustrates one embodiment of an architecture for bootstrapping user binding to an authenticator using a physical device such as a SIM card; 
         FIG. 14  illustrates one embodiment of the invention utilizing portions of the FIDO protocol; 
         FIG. 15  illustrates one embodiment of the invention for securely sharing cryptographic data; 
         FIG. 16  illustrates one embodiment which utilizes a data migration card (DMC); 
         FIG. 17  illustrates a system in accordance with one embodiment of the invention; 
         FIG. 18  illustrates a system on a chip (SoC) in accordance with one embodiment; and 
         FIGS. 19-21  illustrate different embodiments for sharing authentication data between different authenticators. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Described below are embodiments of an apparatus, method, and machine-readable medium for authorizing a new authenticator. Throughout the description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are not shown or are shown in a block diagram form to avoid obscuring the underlying principles of the present invention. 
     The embodiments of the invention discussed below involve authentication devices with user verification capabilities such as biometric modalities or PIN entry. These devices are sometimes referred to herein as “tokens,” “authentication devices,” or “authenticators.” While certain embodiments focus on facial recognition hardware/software (e.g., a camera and associated software for recognizing a user&#39;s face and tracking a user&#39;s eye movement), some embodiments may utilize additional biometric devices including, for example, fingerprint sensors, voice recognition hardware/software (e.g., a microphone and associated software for recognizing a user&#39;s voice), and optical recognition capabilities (e.g., an optical scanner and associated software for scanning the retina of a user). The user verification capabilities may also include non-biometric modalities, like PIN entry. The authenticators might use devices like trusted platform modules (TPMs), smartcards and secure elements for cryptographic operations and key storage. 
     In a mobile biometric implementation, the biometric device may be remote from the relying party. As used herein, the term “remote” means that the biometric sensor is not part of the security boundary of the computer it is communicatively coupled to (e.g., it is not embedded into the same physical enclosure as the relying party computer). By way of example, the biometric device may be coupled to the relying party via a network (e.g., the Internet, a wireless network link, etc) or via a peripheral input such as a USB port. Under these conditions, there may be no way for the relying party to know if the device is one which is authorized by the relying party (e.g., one which provides an acceptable level of authentication strength and integrity protection) and/or whether a hacker has compromised or even replaced the biometric device. Confidence in the biometric device depends on the particular implementation of the device. 
     The term “relying party” is sometimes used herein to refer, not merely to the entity with which a user transaction is attempted (e.g., a Website or online service performing user transactions), but also to the secure transaction servers implemented on behalf of that entity which may performed the underlying authentication techniques described herein. The secure transaction servers may be owned and/or under the control of the relying party or may be under the control of a third party offering secure transaction services to the relying party as part of a business arrangement. 
     The term “server” is used herein to refer to software executed on a hardware platform (or across multiple hardware platforms) that receives requests over a network from a client, responsively performs one or more operations, and transmits a response to the client, typically including the results of the operations. The server responds to client requests to provide, or help to provide, a network “service” to the clients. Significantly, a server is not limited to a single computer (e.g., a single hardware device for executing the server software) and may, in fact, be spread across multiple hardware platforms, potentially at multiple geographical locations. 
     System and Method for Authorizing a New Authenticator 
     In some instances, it may be useful to allow a new authenticator to be enabled using registered authenticators on existing client devices. For example, if the user purchases a new device with a new set of authenticators, it would be beneficial to provide the user with a way to automatically register all of the new authenticators using the existing authenticators. 
     The embodiments of the invention described below allow a user to authorize the authenticator(s) on a new client device using an existing/old, trusted client device that is registered with one or more relying parties. In particular, these embodiments may be used to enable new authenticators on new or existing client devices and keep the registrations in sync between multiple client devices.   
       FIG. 2  provides a high level overview of authenticator authorization in accordance with one embodiment of the invention. A client device with an old/existing authenticator (Aold)  202  (i.e., a device which has an authenticator which is registered with one or more relying parties  250 ), establishes a connection with the user&#39;s new client device  200 . The particular manner in which the connection is established is not pertinent to the underlying principles of the invention. In one embodiment, the connection comprises a secure/encrypted connection (e.g., established via SSL, TLS, etc). Various techniques may be used such as near field communication (NFC), Bluetooth, Wifi Direct, using a quick response (QR) code and establishing an HTTPS connection, or over a standard network connection (e.g., via WiFi or Ethernet). 
     In one embodiment, once the connection is established between the client with Aold  202  and the client with Anew  200 , a secure protocol is implemented (described in detail below) to transfer and integrate the registration data from the old/existing client  202  to the new client  200 . For example, in one embodiment, the old client  202  sends registration data to the new client  200  which then generates a new set of key pairs (e.g., one for each relying party) and sends the public keys back to the old client  202  along with an indication of the types of authenticators on the new client  200 . The client with Aold then generates a signed authorization object (e.g., using the public keys, authenticator identification data, and user account data) which it sends to each respective relying party  250 . 
     As illustrated in  FIG. 3 , an authenticator authorization application  390 ,  391  may be executed on the new device  200  and old device  202 , respectively, to establish the secure connection, exchange the authorization data, and verify the registrations with a secure transaction service  304  on each relying party  250 . As used herein, an “old authenticator” (Aold) is an authenticator that a user has already registered with one or more relying parties. A “new authenticator” (Anew) is one which the user wishes to enable with all the relying party registrations currently being used with the old authenticator. Thus, the authentication engine  311  in the described embodiments has previously registered one or more old authentication devices  322 - 323  with a relying party. The goal of one embodiment is to transfer registrations from the old authentication engine  311  to the new authentication engine  310  to enable the new authenticators  320 - 321  with each relying party. 
     As illustrated the new client  200  and the old client  202  both include secure storage  325  and  326 , respectively, for storing the registration data for each relying party (e.g., public/private key pairs used during authentication). In addition, the relying party  250  includes a secure transaction database  325  for securely storing registration data for each of the client devices  200 - 202  (e.g., user account data, authenticator identification data, public keys provided by for each authenticator, etc). 
     In one embodiment, the user initiates the authenticator authorization application  390  on the new client device  200  and the authenticator authorization application  390  on the old client device  202  to establish the initial secure connection. The authenticator authorization applications  390 - 391  may be mobile device apps or applications specifically designed to perform the authorization operations described herein. In another embodiment, the authenticator authorization applications may be browser plugins executed in response to the user indicating that he/she wishes to perform authorization (e.g., via a web page with embedded Javascript or other applet or executable program code). Moreover, the authenticator authorization applications  390 - 391  may be software modules within a larger application such as an authentication application designed to manage authentications with relying parties. It should be noted, however, that the underlying principles of the invention are not limited to any particular implementation of the authenticator authorization applications  390 - 391 . 
     In one embodiment, to approve the authorization operations on the old device  202 , the user is verified by the authentication engine  311  on the old device (e.g., providing biometric input to a user authentication device  322 - 323 ). Similarly, in one embodiment, the user may be verified by the authentication engine  310  on the new client device  200 . These two verification steps may provide authorization for the authenticator authorization applications  390 - 391  to perform the authorization process. 
     As mentioned, at the start of the authorization process, the authenticator authorization applications  390 - 391  establish a secure connection (e.g., using Bluetooth, WiFi, etc). In one embodiment, the authenticator authorization application  390  on the new client device  200  receives a set of registration data for each relying party with which the old client device  202  is registered. The registration data may include usernames and a unique code associated with the user&#39;s account on each relying party. This unique code associating the user with each relying party is sometimes referred to herein as an “AppID.” In some embodiments, where a relying party offers multiple online services, a user may have multiple AppIDs with a single relying party (one for each service offered by the relying party). 
     In one embodiment, the authenticator authorization application  390  on the new client  200  then generates a new public/private key pair for each relying party (e.g., one for each Username+AppID pair). The authenticator authorization application  390  on the new client  200  sends the authenticator authorization application  391  on the old client  202  the key pair (or just the public key) along with an authenticator ID identifying each new authenticator type (e.g., an Authenticator Attestation ID or “AAID”). The user may then be prompted to confirm the authorization of the new authenticator(s). 
     In one embodiment, the authenticator authorization application  391  generates a signed authorization object comprising a signature over the tuple of the AAID, the public key and the AppID for each relying party. In one embodiment, the signature is generated using the current authentication key associated with the relying party (e.g., a private key associated with the old authenticator for the relying party). The authenticator authorization application  391  then authenticates to each of the relying parties (e.g., via the old authentication engine  311  and one or more old authenticators  322 - 323 ) and includes the signed authorization object as an extension to one of the authentication messages. 
     Upon receiving the signed authentication message, the secure transaction service  304  may then verify the signature (e.g., using the public key corresponding to the private key used to generate the signature). Once verified, it may identify the user&#39;s account with the AppID and store the new AAID and the new public key for the new authenticator(s) within the secure transaction database  325 . The user may subsequently authenticate using the new authenticators  320 - 321  without re-registering with each relying party  250 . 
     Although illustrated in  FIGS. 2-3  as a new user device, the underlying principles of the invention may also be implemented in a scenario where a user installs a new authenticator on an existing client device. For example, the user may upgrade or add an authenticator to an existing desktop, notebook or other type of client. In such a case, the communication of between the authenticator authorization applications  390 - 391  shown in  FIG. 3  may occur internally (e.g., via internal function calls between software modules implemented on the client). 
     One embodiment of a method for authorizing a new authenticator is illustrated in  FIG. 4 . The method may be implemented within the context of a system such as shown in  FIG. 3 , but is not limited to any particular system architecture. 
     At  401 , the user triggers the authorization of one or more new authenticators (Anew) and establishes a secure communication channel with the old authenticator(s) (Aold). As mentioned, the secure communication channel may be established via a direct connection (e.g., via NFC, Bluetooth, etc) or over a network (e.g., via an Ethernet or WiFi connection). 
     At  402 , the new authenticator receives a username and user/relying party ID code for each relying party. 
     At  403 , the new authenticator generates a public/private key pair for each username/AppID pair (e.g., for each unique relying party account). 
     At  404 , the old authenticator receives the key pairs and an authenticator attestation ID code identifying the type of each new authenticator (e.g., an AAID). The user may then be asked to confirm the authorization operation. 
     At  405 , the old authenticator generates a signed authorization object comprising a signature over the tuple of the AAID, the public key and the AppID for each relying party. As mentioned, the signature may be generated using the current authentication key associated with the relying party (e.g., a private key associated with the old authenticator for the relying party). 
     At  406 , the old authenticator authenticates to each relying party and includes the signed authorization object as an extension to the authentication message. Once this operation is successfully completed, the user may then authenticate with each relying party using the new device and/or new authenticators. 
       FIG. 5  graphically illustrates a sequence of operations in which a new authenticator  501  is authorized for use with a plurality of relying parties R 1 -Rn using an old authenticator  502  on an old client  500 . As mentioned, after receiving account data related to each of the relying parties, the new authenticator  501  generates new key pairs for each of the relying parties R 1 -Rn and provides the new key pairs to the old authenticator  502 . The old authenticator  502  then generates a secure authorization object containing data related to the new authenticator  501  (e.g., the AAID) and a new key for each authenticator. It then performs authentication with each of the relying parties R 1 -Rn and includes the authentication object. Following verification (e.g., in which a signature on the authorization object is verified), the new authenticator  501  is automatically registered at each relying party R 1 -Rn. 
     In one embodiment, each relying party R 1 -Rn can choose whether or not to accept the new authenticator  501 . For example, if the AAID indicates an authenticator type which is not sufficiently reliable or accurate, then the relying party may choose to deny the new registration. Thus, each relying party may maintain an authenticator database (i.e., Metadata) containing data for all known authenticators (e.g., identified by AAID). It may then query the database in response to receiving the authorization object from the old authenticator, determine the characteristics of the new authenticator, and determine whether those characteristics are acceptable. 
     In one embodiment of the invention, an authenticator can specify a more generic “confirmation” method, where the authenticators may be indirectly controlled by the same entity, but still belong to different users. For example, in  FIG. 6 , the old authenticator  601  might be integrated into an Owner Control System  601  controlled by a single owner/operator (e.g., a corporation or government entity). The new authenticator  612  in this example may be authenticator belonging to a staff computer  611  and authorization of the new authenticator  612  may be trigger by the owner control system  601  using a known trusted authenticator  602 . In this example, the interactions between the new authenticator  612  and old authenticator  602  may be as described above (e.g., the new authenticator generating new key pairs and the old authenticator sending an authorization object to a device  621  comprising an owner or vendor trust anchor  622  (e.g., for storing authenticator registration data as does the secure transaction database  325  of the secure transaction service  304  in  FIG. 3 ). 
     Exemplary Authentication System Architectures 
     It should be noted that the term “relying party” is used herein to refer, not merely to the entity with which a user transaction is attempted (e.g., a Website or online service performing user transactions), but also to the secure transaction servers implemented on behalf of that entity which may perform the underlying authentication techniques described herein. The secure transaction servers may be owned and/or under the control of the relying party or may be under the control of a third party offering secure transaction services to the relying party as part of a business arrangement. These distinctions are indicated in  FIGS. 7A-B  discussed below which show that the “relying party” may include Websites  731  and other network services  751  as well as the secure transaction servers  732 - 733  for performing the authentication techniques on behalf of the websites and network services. 
     In particular,  FIGS. 7A-B  illustrate two embodiments of a system architecture comprising client-side and server-side components for authenticating a user. The embodiment shown in  FIG. 7A  uses a browser plugin-based architecture for communicating with a website while the embodiment shown in  FIG. 7B  does not require a browser. The various user confirmation and authorization techniques described herein may be employed on either of these system architectures. For example, the authentication engines  310 ,  311  and authenticator authorization applications  390 ,  391  may be implemented as part of the secure transaction service  701  including interface  702 . It should be noted, however, that the embodiments described above may be implemented using logical arrangements of hardware and software other than those shown in  FIGS. 7A-B . 
     Turning to  FIG. 7A , the illustrated embodiment includes a client  700  equipped with one or more authentication devices  710 - 712  for enrolling and authenticating an end user. As mentioned above, the authentication devices  710 - 712  may include biometric devices such as fingerprint sensors, voice recognition hardware/software (e.g., a microphone and associated software for recognizing a user&#39;s voice), facial recognition hardware/software (e.g., a camera and associated software for recognizing a user&#39;s face), and optical recognition capabilities (e.g., an optical scanner and associated software for scanning the retina of a user) and non-biometric devices such as a trusted platform modules (TPMs) and smartcards. A user may enroll to the biometric devices by providing biometric data (e.g., swiping a finger on the fingerprint device) which the secure transaction service  701  may store as biometric template data in secure storage  720  (via interface  702 ). 
     While the secure storage  720  is illustrated outside of the secure perimeter of the authentication device(s)  710 - 712 , in one embodiment, each authentication device  710 - 712  may have its own integrated secure storage. Additionally, each authentication device  710 - 712  may cryptographically protect the biometric reference data records (e.g., wrapping them using a symmetric key to make the storage  720  secure). 
     The authentication devices  710 - 712  are communicatively coupled to the client through an interface  702  (e.g., an application programming interface or API) exposed by a secure transaction service  701 . The secure transaction service  701  is a secure application for communicating with one or more secure transaction servers  732  over a network and for interfacing with a secure transaction plugin  705  executed within the context of a web browser  704 . As illustrated, the Interface  702  may also provide secure access to a secure storage device  720  on the client  700  which stores information related to each of the authentication devices  710 - 712  such as a device identification code, user identification code, user enrollment data (e.g., scanned fingerprint or other biometric data), and keys used to perform the secure authentication techniques described herein. For example, as discussed in detail below, a unique key may be stored into each of the authentication devices during registration and used when communicating to servers  730  over a network such as the Internet. 
     Once the user has enrolled with an authentication device on the client  700 , the secure transaction service  701  may register the authentication device with the secure transaction servers  732 - 733  over the network (e.g., using the registration techniques described herein) and subsequently authenticate with those servers using data exchanged during the registration process (e.g., encryption keys provisioned into the biometric devices). The authentication process may include any of the authentication techniques described herein (e.g., generating an assurance level on the client  700  based on explicit or non-intrusive authentication techniques and transmitting the results to the secure transaction servers  732 - 733 ). 
     As discussed below, certain types of network transactions are supported by the secure transaction plugin  705  such as HTTP or HTTPS transactions with websites  731  or other servers. In one embodiment, the secure transaction plugin is initiated in response to specific HTML tags inserted into the HTML code of a web page by the web server  731  within the secure enterprise or Web destination  730  (sometimes simply referred to below as “server  730 ”). In response to detecting such a tag, the secure transaction plugin  705  may forward transactions to the secure transaction service  701  for processing. In addition, for certain types of transactions (e.g., such as secure key exchange) the secure transaction service  701  may open a direct communication channel with the on-premises transaction server  732  (i.e., co-located with the website) or with an off-premises transaction server  733 . 
     The secure transaction servers  732 - 733  are coupled to a secure transaction database  740  for storing user data, authentication device data, keys and other secure information needed to support the secure authentication transactions described below. It should be noted, however, that the underlying principles of the invention do not require the separation of logical components within the secure enterprise or web destination  730  shown in  FIG. 7A . For example, the website  731  and the secure transaction servers  732 - 733  may be implemented within a single physical server or separate physical servers. Moreover, the website  731  and transaction servers  732 - 733  may be implemented within an integrated software module executed on one or more servers for performing the functions described below. 
     As mentioned above, the underlying principles of the invention are not limited to a browser-based architecture shown in  FIG. 7A .  FIG. 7B  illustrates an alternate implementation in which a stand-alone application  754  utilizes the functionality provided by the secure transaction service  701  to authenticate a user over a network. In one embodiment, the application  754  is designed to establish communication sessions with one or more network services  751  which rely on the secure transaction servers  732 - 733  for performing the user/client authentication techniques described in detail below. 
     In either of the embodiments shown in  FIGS. 7A-B , the secure transaction servers  732 - 733  may generate the keys which are then securely transmitted to the secure transaction service  701  and stored into the authentication devices within the secure storage  720 . Additionally, the secure transaction servers  732 - 733  manage the secure transaction database  740  on the server side. 
     Canonical Authentication System 
     Even after many years of IT innovations, passwords are still the most widely used authentication method. However, neither users nor service providers handle passwords appropriately, making this form of authentication inherently insecure. On the other hand, more than 1 billion Trusted Platform Modules (TPMs) and more than 150 million secure elements have been shipped; microphones and cameras are integrated in most smart phones and fingerprint sensors and Trusted Execution Environments (TEEs) are on the rise. There are better ways for authentication than passwords or One-Time-Passwords (OTPs). 
     In 2007, the average user had 25 accounts, used 6.5 passwords and performed logins 8 times a day. Today, things are much worse. An analysis of 6 million accounts showed that 10,000 common passwords would have access to 30% of the accounts (Burnett, 2011). Even when looking at passwords for banking accounts, it can be found that 73% of users shared their online banking password with at least one non-financial site (Trusteer, Inc., 2010), which means that when the non-banking site gets hacked, the banking account is threatened. 
     Several proposals to replace passwords have been made, including silos of authentication, heterogeneous authentication, and trustworthy client environments. 
     Silos of Authentication: Current alternative technologies require their respective proprietary server technology. The current authentication architecture therefore consists of silos comprising the authentication method, the related client implementation and the related server technology. 
     Innovative authentication methods proposed by the research community are not widely deployed, as in addition to the client implementation the complete server software needs to be implemented and deployed. Instead of having a competition for better user verification methods, authentication companies are faced with a battle for the best server technology. 
     Heterogeneous Authentication: Users may authenticate using standalone PCs, tablets or smart phones. The employer may control some devices while others may be controlled by the user (David A. Willis, Gartner, 2013). Increased adoption of mobile devices and the BYOD trend lead to an increasingly heterogeneous authentication landscape. The one authentication method satisfying all needs seems to be out of reach. 
     Trustworthy Client Environment: Client side malware may capture and disclose passwords or OTPs. It may alter transactions to be confirmed after being displayed or it can misuse authenticated communication channels to perform unintended actions. Authentication—even with user name and password—needs at least one trustworthy component at the client side. 
     Today the alternatives to password or OTP-based authentication do not scale. This is primarily due to sub-optimal combinations of authentication building blocks. To address this limitation, one embodiment of the invention identifies canonical building blocks which can be implemented in various different ways and still lead to a well-known and functional authentication system—suitable for integration within existing platform functionality. 
     The recent large-scale attacks on passwords were all focused on the server side. Such attacks are independent from the effort and from the security measures users take. In the attack classification illustrated in  FIG. 8 , these attacks are labelled with ( 1 ). Introducing protection measures against this single threat class will very likely shift the attacker focus to attacks to steal and misuse authentication credentials from user devices ( 2 - 4 ), including stealing and misusing data by impersonating a user ( 2 - 3 ) and misusing authenticated sessions ( 4 ). Items ( 5 ) and ( 6 ) include physical theft of the user&#39;s device and stealing data ( 5 ) and/or misusing the device for impersonating the user. However, it is very likely that attacks will focus on some kind of scalable attack, i.e. an attack with some fixed cost but the potential of a large number of sellable items. Physically attacking individual devices is possible, but less scalable. 
     In one embodiment of the invention, instead of storing hashed passwords having relatively low entropy, asymmetric public keys may be stored on the server and the related private key may be stored in the device. Computing the private key from a given public key is very resource consuming as it requires factoring (RSA) or solving the discrete logarithm problem (DSA/ECDSA). The private key at least should be protected against malware attacks. In one embodiment, this is accomplished using Trusted Execution Environments (TEEs) or Secure Elements (SEs) on the client device. 
     Given that most client devices are always online, instead of extracting the private key, malware may simply attempt to misuse it. In order to protect against such attacks, (a) the access to use the key should be limited to eligible apps and (b) some kind of user interaction which cannot be emulated by malware is required. TrustedUI (GlobalPlatform, 2013) can be used to implement such kind of user interaction. Note that Secure Elements typically do not have a user interface and hence do not provide this kind of protection. 
     When implementing the protection measures as described above, the authentication is secure. However, attackers may then focus on attacking the App which controls the authenticated session. Existing PC infection rates (APWG, 2014) demonstrate the feasibility of these types of attacks. When having an Authenticator with higher protection than current Mobile Apps, this Authenticator can be used for displaying and retrieving a user&#39;s confirmation for a particular transaction. In such a case, infected Apps could lead to (a) malicious transactions being displayed which would be rejected by the user or (b) signed transactions which would be modified after signing, which would be detected by the server. This is the second use-case for the TrustedUI implementation. 
     In one embodiment, Secure Elements are used to protect against physical key extraction. The underlying chip hardware for SE typically implements state-of-the-art protection measures against physical attacks. (Dr. Sergei Skorobogatov, University of Cambridge, 2011). In addition, in one embodiment, TrustedUI or other dedicated user verification hardware such as Fingerprint sensors may be used to meet the need for physical user interaction. 
     If an attacker gains physical access to a device, the attacker could try to misuse the key instead of extracting it. In order to protect against such attacks, an effective user verification method is used which has a low false acceptance rate, good anti-spoofing methods and anti-hammering mechanisms (i.e., to effectively limit the number of potential brute-force attempts). 
     Given that scalable attacks are predominant, one embodiment focuses on counter-measures for physical attacks after implementing the counter-measures for the scalable attacks. 
     Having good protection for attestation on the client side is beneficial, but in reality the remote party (i.e., the server side) is also interested in understanding the security being used. Consequently, one embodiment of the invention “attests” the client-side security properties to the remote server. In order to be effective, these attestation techniques need to be at least as strong as the client side protection. 
     For practical solutions, the privacy of attestation is also important. Methods like direct anonymous attestation (DAA) are a good choice. Unfortunately, the original DAA method was too slow when implemented on standard hardware. The improved pairing-based DAA scheme is much faster. It has been adopted by TCG for TPMv2 (Liqun Chen, HP Laboratories and Jiangtao Li, Intel Corporation, 2013). 
     A typical signature consist of a to-be-signed object controlled by the App and a signature computed using the private key. So to the verifier, any data in the to-be-signed object is only as trustworthy as the App controlling the contents of the to-be-signed object. 
     As illustrated in  FIG. 9 , in one embodiment, the private key  905  is protected by an attested authenticator  902 , which is more trustworthy than the App  901 . The authenticator may include a transaction confirmation component  909  (e.g., to allow the user to confirm the text of a confirmation as described herein) and a user verification component  906  (e.g., to allow for biometric or other type of user authentication). In one embodiment, an attestation module  903  uses the private key  905  to generate a signature  908  over an object which includes authenticator attributes and application data to generate a signed object  907 . As illustrated, in one embodiment, the object to be signed comprises a concatenation of attested attributes of the authenticator and application data. The attested attributes used in the signed object may include, for example, (a) the Transaction Text as confirmed by the user, (b) the actual personal identification number (PIN) length as opposed to the minimal PIN length, or (c) the firmware version of the authenticator implementation. 
     The illustrated implementation is more secure than existing systems because exclusive control of the key  905  is granted to the Authenticator  902  (instead of being granted to the app  901 ). In one embodiment, the to-be-signed object, exclusively controlled by the Authenticator  902  has a “slot” reserved for data controlled by the App  901  (identified as “App Data” in  FIG. 9 ). As a result, in this embodiment, the App  901  is not permitted to arbitrarily create any form of to-be-signed objects. Each signed object will look similar, so the object verification module  911  of the relying party  910  can trust that the attested attributes were contributed by the trusted Authenticator  902 . In one embodiment, the object verification module  911  uses the public key and metadata  912  associated with the authenticator  902  (e.g., the authenticator type, model and/or version) to verify the signature  908 . 
     In one embodiment, a set of canonical building blocks are defined that can be used to assemble an authentication system such as shown in  FIG. 9 . Once particular set of building blocks include:
         1. Hardware and/or software to generate cryptographic keys and attest to such keys to a remote party.   2. Hardware and/or software to generate attested signatures.   3. Hardware and/or software to verify a user.   4. Hardware and/or software bind keys to an entity (e.g., restrict “use” access of such keys to a defined set of software applications).       

     Not all building blocks need to be present. Authentication systems can be built even using only building block #1. The other building blocks can be added as needed. The overall security and usability characteristic depends on the specific implementations of the building blocks used. 
       FIG. 10  illustrates one particular embodiment which includes a client-side authenticator  1001 , a client side platform  1002  (e.g., a mobile device using Android OS or Windows OS), a remote party  1003 , and metadata  6304 . One embodiment of the authenticator  1001  generates the authentication keys and supports attestation of the authentication keys to a remote party  1003 . Various attestation methods are supported including those described above. See also FIDO Basic Attestation (Rolf Lindemann, Davit Baghdsaryan and Eric Tiffany,  2014 ), DAA (Ernie Brickell, Intel Corporation; Jan Camenisch, IBM Research; Liqun Chen, HP Laboratories,  2004 ), ECDAA (Ernie Brickell, Intel Corporation; Jiangtao Li, Intel Labs). 
     The remote party has access to metadata  1004  which it uses to verify the attestation object. The authenticator may be implemented as a physically separate entity (e.g. crypto SD-card, USB crypto token, etc) , but could also be physically embedded into the client-side platform (e.g. in an embedded secure element, TPM, TEE). 
     The authenticator  1001  may optionally have the capability of verifying a user. However, the underlying principles of the invention are not limited to any specific user verification method. However, the remote party can learn the user verification method by looking into the attestation object and the metadata  1004 . 
     The embodiments of the invention do not rely on any specific wire-protocol or protocol message encoding. The only requirement is that the assertions generated by the authenticator  1001  such as the attestation object and the attested signature object need to be “understood” by the remote party  1003 . The concrete wire format may depend on the specific platform. 
     This section is intended to give a first impression on how these canonical building blocks could be used. 
     In current authentication frameworks such as the FIDO UAF specification, the client is quite “heavy”. With the approaches described herein, the client can easily be split into two parts: (1) an application software development kit (AppSDK) performing all of the protocol related tasks (which are too specific to be implemented in a platform) and (2) a platform functionality that implements the security related tasks such as binding a key to a set of software applications. With this approach, a client such as the FIDO client being a separate entity disappears. 
     The following is an example of a FIDO UAF being implemented on an Android platform extended to support these canonical building blocks. 
     AttestationType: No need to set it explicitly. All Android Apps will know that they can only use the Android-Attestation method (e.g. through a FIDO AppSDK). 
     AAID: A unique identifier for each class of authenticator (e.g., an “authenticator attestation ID” as described above). Essentially the AAID is reduced to some Android KeyStore Implementation using a user verification method specified when creating the key. The Key Store will lookup the AAID based on the user verification method (and the static knowledge about its own KeyStore crypto implementation). 
     Username: One embodiment allows the mobile app (through the AppSDK) set the KeyAlias to the concatenation of the keyID and the username if present. 
     AppID: Is addressed using the appID binding (if supported). 
     In summary, one embodiment of the invention includes a system for authenticating a client-side authenticator to a remote party, that includes:
         (1) a client-side authenticator comprising (i) circuitry and/or program code to generate cryptographic key pairs (“authentication keys”) and (ii) circuitry and/or program code attesting the identity of the key generating entity to a remote party.   (2) data regarding the authenticator which at least contains sufficient information to verify the attestation made available to the remote party. This data is referred to as “metadata” above.   (3) circuity and/or program code to use the generated authentication private key to perform a cryptographic operation to prove possession of the private authentication key to the remote party.       

     Additionally, the authenticator might be known to restrict the use of the authentication private key to perform cryptographic signature operations on well-defined to-be-signed objects only. This well-define to-be-signed object contains data fields controlled by the authenticator and one or more data fields which are clearly marked to contain arbitrary data (not controlled by the authenticator). The authenticator might indicate such objects by starting them with a magic number MN followed by the well-defined data structure. This signature operation is called “attested signing” herein. This magic number MN can be chosen freely, but it needs to be fixed and well known. One example on how to set this magic number is “ATTESTED_SIGNATURE”. 
     In addition, in one embodiment, the client side authenticator has the ability to verify a user using an arbitrary user verification method and in which the properties of this user verification method are static (i.e. they do not change over time for any authenticator) and described in the Metadata. The user verification method may be arbitrarily complex and even consist of multiple biometric and non-biometric modalities (e.g., PIN or fingerprint, speaker recognition in combination with PIN/ Fingerprint, facial recognition, etc.). 
     Moreover, in one embodiment of the system, (a) the key may only be used for attested signing and (b) the authenticator has the ability to verify a user using a user verification method in which the properties of the user verification method are described in the data fields controlled by authenticator (e.g., in the attested signature). Note the user verification method might be arbitrarily complex and even consist of multiple biometric and non-biometric modalities (e.g., PIN or fingerprint, speaker recognition in combination with PIN/ Fingerprint, facial recognition, etc.). 
     In one embodiment, access to the private authentication key  905  is limited to a specified set of applications. In addition, the set may be restricted to applications considered equivalent by the platform (e.g. operating system). As an example, access to the authentication key could be restricted by the operating system to the applications signed using the same package signing key as the application which triggered the key generation. Moreover, the set of applications may include applications considered equivalent by the application developer through a list of application facets which are considered equivalent. 
     In yet another embodiment, the authenticator  902  supports securely displaying a transaction text and asking the user for confirming (or rejecting) this particular transaction. The transaction text may be cryptographically bound to the attested signature (i.e. a cryptographic hash of the transaction text will be included in one of the fields controlled by the authenticator). 
     One embodiment of the invention implements the security related tasks of the FIDO UAF/U2F stack (which do not belong to the authenticator) on a platform (e.g. the OS or the web browser) and leaves the implementation of the other protocol handling tasks to the app and thus removes the need to implement specific protocols in the platform (i.e., removing the need of having a FIDO Client). 
     System and Method for Bootstrapping a User Binding 
     Today, any user may enroll to a new FIDO authenticator or device having a key store that is being shipped/purchased, including both the legitimate owner and a potential attacker. In general, FIDO authenticators and devices having a key store are bound to a user (i.e., the user enrolls to the authenticator/device) once the user first receives physical access to the device. This is in contrast to smartcards (e.g. EMV banking cards and SIM cards) which are personalized for a user before delivery. This personalization typically includes a user specific personal identification number (PIN). 
     Sometimes the user has already been identified/vetted before a FIDO authenticator (or device having a key store) is shipped. It would be desirable to leverage the identity vetting performed at a shop (or some other place) and to bind the authenticator to a user before the authenticator actually reaches the user. The embodiments of the invention provide techniques to address this desire. 
     In one embodiment, it is assumed that some trusted identification system already has access to (a) the user verification reference data (e.g. biometric templates, or a PIN), or (b) to some data from which the user verification reference data can be derived, or (c) to some data which is tied to the user through some other system. For example a copy of the user&#39;s facial image taken from a photo-ID card verified in some branch office, or a photo of the user&#39;s fingerprint taken from a governmental identification database or through a SIM card tied to the authenticator and bound to the account owner by the mobile network operator (MNO). Approach (a) works for “what-you-know” factors; approach (b) for “what-you-are” factors; and approach (c) works for “what-you-have” factors, as described below. 
     One embodiment includes some form of secure communication channel to the authenticator allowing a single and initial injection of user verification reference data into the authenticator (i.e., in a state in which there is no other user verification reference data being enrolled by someone). The secure communication channel could be a Trusted Service Manager (TSM) securely talking to a SIM-card based authenticator, or the TSM securely talking to the Trusted Execution Environment (TEE)-based authenticator, or it could be implemented by some secret or private key used by the authenticator for decrypting such data. In any case, one embodiment of the authenticator may include a pre-processing engine, which converts the initial reference data to the form required by the authenticator. Note that this pre-processing may also be done by the trusted system. 
       FIG. 11  illustrates one embodiment of an implementation in which a vetted user Uv initially provides verification of his/her identity to a first relying party  1104 . For example, the relying party  1104  may be a brick and mortar store where the user purchases a new mobile device. During this process, a PIN or other identification code may be generated by the relying party  1104  (e.g., generated randomly or selected by the vetted user Uv). This identification code is one form of initial user verification reference data (IUVRD) described herein which is used to verify the identity of the user when registering the user. In addition, the relying party  1114  may store identification data associated with the user and/or client device within an identity database  1120 . 
     Subsequently, at  1101 , the user verification data is securely provided to the user  1112 . For example, the identification code may be mailed to the user in a tamper resistant or tamper evident (e.g. sealed) envelope. Alternatively, the relying party  1114  may provide the identification code to the user  1114  at the store where the user purchases the device. At  1102 , the IUVRD is provided over a secure communication channel from the relying party  1114  to the authenticator  1110  (e.g., at the store and/or encrypted using a key or key pair known by the relying party  1114  and authenticator  1110 ). In one embodiment, the communication may be encrypted to the authenticator model/instance to prevent misuse. At  1103  the authenticator user U A    1111  is prompted to enter the verification data when registering the authenticator  1110  for the first time with a relying party  1115 . In one embodiment, the authenticator  1110  comprises a FIDO authenticator and the relying party  1115  comprises a FIDO server. If the user  1111  enters the correct verification code, then the authenticator  1110  may include this as proof of the identity of the user  1111  in the transactions with the relying party  1115  (e.g., when registering the authenticator  1110  with the relying party). In addition, in one embodiment, the relying party  1115  may perform a lookup in the identity database to confirm the identity of the authenticator  1110  and/or authenticator user U A    1111 . 
       FIG. 12  illustrates another embodiment in which biometric data is initially captured as IUVRD during the KYC process between the vetted user Uv  1112  and the relying party  1114 . For example, at  1201  an image of the user&#39;s face may be captured and facial recognition template may be generated, the user&#39;s fingerprint may be captured, and/or or voice recognition may be performed. At  1202 , the IUVRD is provided to the authenticator  1110  over a secure communication channel. This may be done, for example, at the store and/or may be encrypted and transmitted over a network to the authenticator  1110  (e.g., using a key or key pair known by the relying party  1114  and authenticator  1110 ). At  1203 , the authenticator user U A    1111  is prompted to collect biometric data such as by analyzing a picture of the user&#39;s face, collecting the user&#39;s fingerprint, and/or recording the user&#39;s voice. The authenticator  1110  compares the collected data against the IUVRD biometric data and, if a match is detected, proof of the user&#39;s identify is provided during the registration with the relying party  1115 . In addition, the relying party  1115  may perform a lookup in the identity database  1120  initially populated by the relying party  1114  to further verify the identity of the user  1111 . 
       FIG. 13  illustrates yet another embodiment in which, during or following the KYC process, an identity module  1310  is provided to the user  1111  which may contain symmetric keys known by the relying party  1114 . In one embodiment, the identity module  1310  comprises a subscriber identity module (SIM) card; however, the underlying principles of the invention are not limited to any particular form of identity module. At  1302 , the relying party  1114  provides a challenge to the authenticator  1110  (e.g., a randomly generated nonce). At  1303 , the authenticator verifies the existence of the identity module  1310  by using the symmetric key to generate a signature over the random number. It then provides the signature to the relying party  1115  during registration. The relying party  1115  may then verify the identity of the user  1111  by communicating the signature to the relying party  1114 , which may use the symmetric key to verify the signature. The relying party  1115  may also perform a lookup in the identity database  1120  as previously described. 
     One embodiment of the described authenticator  1110  supports a new IUVRD, a one-time-UVRD, and/or a one-time Identity-Binding-Handle (OT-IBH) extension for FIDO registration. This extension includes the encrypted user verification data (or data from which the user verification data can be derived or the hashed or encrypted identity binding handle). 
     In case of the IUVRD extension, if no user is enrolled already, the authenticator  1110  will use this data as the initial user verification reference data (IUVRD) and treat the user being enrolled with this data. In one embodiment, the authenticator  1110  proceeds as specified in the FIDO specifications (e.g., verifying the user, generating the Uauth key pair specific to the AppID/relying party ID, generating the registration assertion and signing it with the attestation key). Additionally, one embodiment of the authenticator  1110  includes an extension containing a success indicator in the signed registration assertion to indicate that the data has indeed been used by the authenticator (and the relying party  1115  can assume the related user being enrolled to that authenticator). This result indicator could be a simple Boolean value (i.e. extension processed or not) or it could be a cryptographic hash value of the extension passed to the authenticator  1110 . The latter is relevant if the extension includes a value encrypted to the authenticator  1110  but not authenticated by the originator (e.g. asymmetric encryption of a PIN). If some user is already enrolled to the authenticator  1110 , the authenticator will not process the IUVRD extension and consequently also not include it in the response assertion. 
     In case of the One-Time-UVRD extension used in one embodiment, the user verification reference data included in the extension is applicable to exactly the registration operation it belongs to. In the case of the OT-IBH extension, the extension includes the nonce and potentially an additional identifier followed by the hash of the handle H concatenated with some nonce and potentially some additional Identifier ID. Stated more formally: OT-IBH=(Nonce, ID, Hash(H|Nonce|ID)). 
     The embodiment illustrated in  FIG. 13  (sometimes referred to herein as a “what-you-have” implementation) may utilize a One-Time Identity-Binding-Handle Extension (OT-IBH). This concept will be described using the more concrete scenario of a SIM card supporting Extensible Authentication Protocol Authentication and Key Agreement (EAP-AKA, see RFC4187 https://tools.ietf.org/html/rfc4187) authentication to the mobile network operator (MNO). 
     In this example, relying party  1114  may be a mobile network operator which has already vetted the account owner and issued them a SIM (or personalized an embedded SIM; in general, a “what-you-have” token). The MNO also receives (through the mobile network) a device identifier (e.g., an International Mobile Equipment Identity, IMEI) and authenticates the SIM (and hence the International Mobile Subscriber Identity IMSI tied to it). As a result, the MNO already has a good understanding of the account owner tied to a specific mobile device. If the authenticator is bound to such a mobile device, this existing identity binding may be leveraged for the registration of the authenticator  1110 . 
     The FIDO specifications carefully avoid exposing any global correlation handle through the authenticator  1110 . So instead of just letting the authenticator add the IMEI or the IMSI as an extension to the registration assertion or the signature assertion, one embodiment of the invention uses a different approach. 
     In the OT-IBH approach, the existence of some handle H is assumed which is tied to the user (e.g., through an IMSI or IMEI or both). Such handle H being cryptographically authenticated or encrypted may even be supported (e.g. H=MAC(IMEI|IMSI) or H=Enc(key,IMEI|IMSI)). This handle H is owned by the Mobile Network Operator issuing the SIM. 
     As this handle H doesn&#39;t depend on any specific relying party (RP) H may be considered a global correlation handle. For privacy reasons such global correlation handles should not be known by multiple relying parties. In order to achieve this, one embodiment derives a relying party specific handle from it: Hd=Hash(H|Nonce|IDrp), where IDrp is a relying party identifier and where the nonce and the IDrp are provided by the owner of H. The nonce is some random value and IDrp is some identifier tied to the relying party wanting to leverage the identity binding performed by the MNO. 
     The derived handle Hd could be issued by the MNO to some RP using a backend service to which the RP would provide some user identifying information IDu (e.g. the MSISDN) which the user could have provided directly or which the RP App could have retrieved through some existing native API on the device. 
       FIG. 14  illustrates one particular embodiment in which a relying party app  1402  transmits user identifying information (IDu) to the relying party  1430  at  1401 . At transaction  1402 , the relying party  1430  transmits the identifying information to the MNO  1431  which responds with the relying party specific handle, Hd, at  1403 . At  1404 , the relying party  1430  transmits a FIDO request to the relying party app  1412 . In response, the relying party app  1412  sends a FIDO registration or authentication request to the authenticator  1410  at  1405  and, at  1406 , the authenticator performs a verification with the SIM  1413  at  1406 . The FIDO transactions at  1407 - 1408  includes the Hd if verification at  1406  was successful. If verification failed, the Hd will not be included in the FIDO response. 
     The embodiment described above is more secure compared to using H as bearer token as the authenticator cryptographically binds H to an assertion generated by a specific authenticator. This protects against man in the middle (MITM) attacks and hence allows the lifetime of H to be extended. 
     This embodiment is also more privacy preserving as the authenticator  1410  will not reveal H; it will just allow an app  1412  to verify H if the app receives access to H through other means such as a contractual relationship to the entity issuing H (e.g., the MNO) or via some API available to the app  1412  on the mobile device  1411  (to which the user grants access permission). 
     The following exemplary use cases may be implemented. It should be noted, however, that the underlying principles of the invention are not limited to these specific use cases. 
     Use Case 1 
     In some branch office/shop a user may be vetted by an identification system using for example an electronic ID card reader, fingerprint scanner, or camera. The identification system verifies the authenticity of the ID card (if ID cards are being used) and then converts the captured data (captured from the user directly or captured from some trusted credential such as a government-issued ID card) into the format required by the authenticator. 
     The identification system encrypts the IUVRD data (as described above) and stores it along with the customer order for the authenticator. The order details are sent to a fulfillment center and the authenticator is shipped to the customer. 
     Once the customer uses the authenticator for the first time, it will automatically trigger the registration of this authenticator to the server providing the order number (or a similar identifier) allowing the server to understand the prospective user. The server will then add the appropriate IUVRD extension to the FIDO registration request and the authenticator will process the registration request as specified above. 
     Use Case 2 
     If the user is at home and orders the authenticator online, the user may provide a scan of his/her photo ID card as proof of identity. The identification system at the server side verifies the integrity of the scan and extracts the IUVRD from it. Proceed as in use Case 1, with the identification system verifying authenticity. 
     Use Case 3 
     Similar to Use Case 2 but using a PIN and a PIN-based authenticator (e.g. based on the SIM) or an authenticator supporting a PIN and some other user verification method(s). 
     Use Case 4 
     Sometimes the device and/or an entity tied to a device (e.g., something the user has such as a SIM card) are already bound to a user (e.g. mobile phone account owner). This binding may already be represented by some generic handle H (e.g., some bearer token, and/or a global correlation handle like the user&#39;s phone number or the device IMEI and potentially even encrypted or hashed like MAC(phone # +IMEI) or HMAC(MSN+IMEI), for example, which is owned by one specific relying party (e.g., the MNO). Instead of revealing such handle H to some relying party directly via the authenticator one embodiment allows the relying party to ask the authenticator in a privacy-friendly way whether the authenticator is somehow tied to this handle H. See section OT-IBH for details. 
     Because at least one embodiment described above works only once for an unused authenticator (unless a reset to factory defaults is performed), it only allows the authenticator vendor (not necessarily the manufacturer) to effectively use it at the beginning. In one common implementation this will be a mobile network operator selling authenticators bound to smartphones. The “One-Time-UVRD” embodiment allows the use of this approach by the authenticator manufacturer at any time and the “Select-UVM” embodiment allows the use of this approach by any RP or potentially limited to specific ones. 
     Cryptographic Details 
     Multiple cryptographic implementation options are possible. In one embodiment, a symmetric encryption key for the IUVRD/One-Time-UVRD/OT-IBH is shared between the authenticator and the identification system. In this case the IUVRD/One-Time-UVRD/OT-IBH would be protected by authenticated encryption. Alternatively, an asymmetric encryption/decryption key may be used inside the authenticator combined with an asymmetric public key as trust anchor. The IUVRD/One-Time-UVRD/OT-IBH may be signed by the identification system and then encrypted using the public encryption/decryption key. In both cases it may be assumed that the key is authenticator specific in order to prevent replay attacks to other authenticators. 
     Privacy Impact 
     The privacy impact is minimal when the RP is enabled to perform identity binding for its own Uauth key. The IUVRD extension allows the first RP to perform an identity binding to the authenticator if it owns cryptographic material specific to the authenticator. 
     The One-Time-UVRD extension allows any RP to do an identity binding to the authenticator if it owns cryptographic material specific to the authenticator. 
     The OT-IBH implementation allows any RP which is provided with access to the handle H through some other existing means (e.g., some native API already available to the App or through some backend-API to the RP “owning” handle H) to cryptographically verify whether the authenticator is indeed bound to it. 
     In one embodiment, one or more of the following privacy policies are followed. At no time are private Uauth keys exposed outside the authenticator boundary. At no time are user verification reference data enrolled by the user to the authenticator revealed by the authenticator. At no time does the authenticator reveal the number or names of relying parties it is registered to. At no time does the authenticator reveal any global correlation handle. At no time is it possible for any RP to modify user verification reference data for existing keys. 
     It is possible for the RP to query the authenticator to determine whether it is tied to some user (specified by the extension). However, the user is involved in such a query (through user verification) and—depending on the authenticator model—might also learn the name of the related RP. 
     System and Method for Sharing Keys Across Authenticators 
     Motivation 
     Current FIDO specifications (UAF, U2F and FIDO2/Web Authentication) expect authentication keys (e.g., Uauth keys) to be dedicated to an individual authenticator instance. Users can register multiple authenticators to each account/relying party. If a user loses any (but the last registered) authenticator, they can simply authenticate with one of the remaining authenticators and then register a new/replacement authenticator. 
     In reality there are two pain points for users. First, if a user loses a last registered authenticator, then the relying parties need to push the user through an account recovery procedure. Account recovery is a painful process, potentially even involving out of band checks. Account recovery is sometimes also a risky process and less secure/trustworthy than FIDO authentication. 
     In addition to registering the new authenticator, a user also must deregister the lost/stolen authenticator at each relying party individually and register a new authenticator at each relying party. The process of registering a new authenticator or deregistering an old authenticator can be painful as users often have multiple accounts. 
     The embodiments of the invention described herein address the above issues using a client-side biometric solution. 
     Approaches 
     One approach is to keep each Uauth key dedicated to one authenticator and to propose a standardized registration/deregistration API for relying partys for automatically adding/removing authenticators (as described above with respect to certain embodiments). However, standardizing web APIs across relying parties is challenging and requires time. As such, success is not guaranteed. 
     One embodiment of the invention extends the implementations described above to share keys across multiple authenticators. 
     Traditional FIDO Authenticators 
     Registering additional authenticators requires one manual operation per relying party. This manual operation might even include multiple steps (e.g. open app, click on register additional authenticator, perform user verification). This is the traditional FIDO model which is known in the art. 
     Synchronizing Wrapped Uauth Keys via a Cloud Service 
     In one embodiment of the invention, the user uses different authenticator instances of the same model (e.g., identified by the AAID/AAGUID). According to the FIDO specification, such authenticator would have similar security characteristics—no authenticator provides lower security than claimed in the Metadata Statement. So, for example, the class of authenticators could claim Trusted Execution Environment (TEE) security and some implementations may actually even use a secure element for key protection. More specifically, one authenticator may be bound to a smartphone using TEE for key protection, matcher protection and transaction confirmation display and may use a fingerprint as the user verification method. Another authenticator sharing that AAID might be implemented as a smart card with integrated fingerprint sensor and elnk transaction confirmation display and using a secure element for key and matcher protection. 
     Additionally these authenticators may allow the user to: 
     a) Store a copy of the authenticator persistent storage (i.e., private key material and related usernames and AppIDs) in wrapped form on a Cloud service. Only the authenticators belonging to the same user defined group can unwrap these wrapped persistent data blocks. 
     b) The first authenticator defines this group characterized by the symmetric wrapping key. The user can add additional authenticators to that group, by approving the “join” process on the first authenticator. 
     Authenticator Cryptographic Details 
     In one embodiment, the authenticator supports FIDO functions (e.g., it has a FIDO attestation key and supports the generation of FIDO Uauth keys). It should be noted, however, that the underlying principles of the invention are not limited to a FIDO implementation.  FIG. 15  illustrates an exemplary embodiment with a first client device  1518  includes an authenticator which is joining a group Aj and a second client device  1519  includes an authenticator which has already joined the group Ag. Each authenticator in Aj, Ag includes a physical authentication device  1521 - 1522 , an authentication engine  1511 - 1512  with key synchronization logic  1520 - 1521  for implementing the techniques described herein, and a secure storage  1625 - 1626  for storing the various types of cryptographic data described herein. While some of the details are not shown, client device  1519  may store all of the same data as client device  1518 . As illustrated in  FIG. 15 , in one embodiment, each authenticator: 
     a) Has a public Cloud storage access ID encryption key (CSEK)  1501 ,  1511  (e.g., as a trust anchor). 
     b) Has a random Group ID (e.g., UUID)  1502 ,  1512  that is overwritten by each join procedure implemented by key synchronization logic  1520 - 1521  of the authentication engines  3710 - 1511 . 
     c) Has an individual asymmetric wrapping key encryption key (WKEK)  1503 ,  1513 . It may be generated by the authenticator  3710 - 1511  on first use and never made accessible outside the authenticator. 
     d) Has a symmetric wrapping key (WK)  1504 ,  1514  which may be generated on first use and overwritten by each join procedure. 
     e) In one implementation, the key synchronization logic  1520 - 1521  implements the following join process. There is an API function that can ask an authenticator Aj to join an existing authenticator group. The authenticator to join, Aj, generates a nonce value, asks the user for permission (i.e., triggers a user verification displaying the Join process indicator and the Nonce value in the display), appends to the Nonce value its AAID  1505  and public WKEK  1503  and signs it with its attestation key  1506 . This data block is referred to as the “join block” or “trust block.” 
     f) One authenticator in the join group, Ag, receives the join block which is verified by the key synchronization logic  1521 . This is possible because the authenticators all know the acceptable public attestation keys (trust anchors) used for signature verification. The authentication engine  1511  displays the nonce, the AAID  1505  and a Join Request indicator in its display. If the user approves the action (e.g., by normal user verification), the key synchronization logic  1521  will encrypt the wrapping key (WK)  1514  and Group-ID  1512  using the public WKEK  1503  received in the join block. This data block is called in the join response block. 
     g) Aj decrypts the join response block and stores the wrapping key (WK)  1514  and Group-ID  1512 . 
     h) One embodiment supports an API function to retrieve a sync-pull-request (given a Nonce value retrieved from the Cloud service  1550 ) from an authenticator Aj. The key synchronization logic  1520  on the authenticator Aj returns the concatenation of the server provided Nonce, the Group-ID  1502 , and the hash of the internal persistent memory encrypted by the CSEK  1501  (e.g., sync pull request). This function is triggered by an external module (e.g., an ASM, authenticator configuration App). Once the sync-pull-request is received by the Cloud service  1550 , the secure transaction service  4004  decrypts the block and compares the state hash with the hash received along with the latest data block. If it differs it returns the sync pull response, i.e., the latest wrapped data block encrypted by WKEK  1503 , otherwise it returns “no change” code. 
     i) Supports an API function to process the sync-pull-response. The key synchronization logic  1520  decrypts the block using its private WKEK  1503  and then unwraps the data using the symmetric wrapping key (WK)  1504 . It both operations are successful, the authentication engine  3710  updates its internal persistent storage accordingly. Note that this update procedure supports merging various elements (i.e., the key generated on this authenticator which has not yet been synced to the Cloud  1550 ). 
     j) Supports another API function to trigger generation of a sync-push-request in the authenticator. This API function triggers the key synchronization logic  1520  to return a Nonce, the GroupID  1502 , the hash of the internal persistent memory concatenated with the wrapped persistent memory all encrypted with the CSEK  1501  (i.e., so the Cloud service  1550  can read the Nonce, the Group-ID  1502 , and the hash—but it cannot unwrap the persistent memory containing the private key material). Note that the authenticator first needs to perform a sync-pull with the Cloud  1550  in order to merge-in changes before generating the sync-push-request. 
     Characteristics 
     Using the above approach, new authenticators may be readily added to the group with a single operation. The join process can be performed independently from the Cloud service. However, one drawback is that if the user loses his last registered authenticator, a full account recovery needs to be performed, which is burdensome on the user. 
     Synchronizing Password-Protected Uauth Keys via a Cloud Service 
     One embodiment of the invention is similar to the approach described above with one difference being that the symmetric wrapping key (WK) may be derived from a password provided by the user. In particular, step (d) above is supplemented with the ability to overwrite the current WK with a WK derived from a password (e.g., via a dedicated API function). In one embodiment, the password is always entered on the authenticator&#39;s secure display. 
     In addition, in one embodiment, step (h) above is modified as indicated by the bolded portions of the following paragraph. In particular, the key synchronization logic  1520  will return the concatenation of the server provided Nonce, the Group-ID  1502 , the WKEK  1503 , and the hash of the internal persistent memory first signed by the attestation key  1506  and then encrypted by the CSEK  1501  (sync pull request). This function is triggered by an external module (e.g. ASM, authenticator configuration App). Once received by the cloud service, it decrypts the block, verifies the attestation signature and compares the state hash with the hash received along with the latest data block. This method (in combination with encryption to WKEK) allows the cloud service to restrict access to the wrapped memory block to authenticators having the correct model (e.g., protecting against brute force attacks on the password by other authenticators/attackers). If it differs it returns the sync pull response, i.e., the latest wrapped data block encrypted by WKEK  1503 , otherwise it returns “no change” code. 
     Aside from the differences highlighted above, the remaining operations from (a-j) are performed as previously described. 
     Characteristics 
     With the approach described above, it is easy to add a new authenticator to the group with a single operation. If the user loses the last authenticator, he can recover the by providing his password. Brute force attacks on the password are prevented by encrypting the wrapped memory block using the respective authenticated WKEK. However, one drawback is that the Cloud service provider still has access to the wrapped memory block and hence could brute force the password. 
     Fallback Join-Authenticator in the Cloud 
     In one embodiment, to address the above limitation, the wrapped data and the CSEK  1501  private key is protected by a special authentication module  1540  used by the Cloud service  1550 . This authentication module is a unique kind of authenticator with the following features: 
     1. It supports multiple users in one hardware box, similar to bound UAF authenticators used by tablets supporting multiple OS accounts. 
     2. It supports only remote user verification, via another authenticator of exactly that model used at first enrollment. 
     3. It doesn&#39;t allow the user to actually use any Uauth key for authentication, only approving other authenticators joining the group is supported. 
     As a consequence, this Cloud authenticator module  1540  can be joined to the group like any other authenticator can. 
     Authenticator Cryptographic Details 
     One embodiment of the invention is similar to the previous approach but with additional techniques for enrolling with a Cloud service and using a cloud-based join-authenticator. These new techniques are highlighted in bold. In this embodiment, each authenticator:
         a) Has a public Cloud storage access ID encryption key (CSEK)  1501 ,  1511  (e.g., as a trust anchor).   b) Has a random Group ID (e.g., UUID)  1502 ,  1512  that is overwritten by each join procedure implemented by key synchronization logic  1520 - 1521  of the authentication engines  3710 - 1511 .   c) Has an individual asymmetric wrapping key encryption key (WKEK)  1503 ,  1513 . It may be generated by the authenticator  3710 - 1511  on first use and never made accessible outside the authenticator.   d) Has a symmetric wrapping key (WK)  1504 ,  1514  which may be generated on first use and overwritten by each join procedure.       

     e) Can be “enrolled” to the Cloud service  1550  in order to create a new partition. One embodiment of this process may comprise a FIDO registration:
         1. The user takes one authenticator Aj and registers it to the cloud service  1550 . The user additionally provides his email address to identify his partition.   2. The cloud-based join-authenticator  1540  creates a “partition” for the registered authenticator Aj. This partition is identified by the related Uauth public key. Each “partition” has its own set of persistent data (including key material).       

     f) Can be “enrolled” to an existing partition of the cloud service (recovery join):
         1. User enters his/her email address for an existing partition.   2. The user takes one authenticator Aj and registers it to the cloud service.   3. Note that this authenticator is not yet approved. The only action the user can trigger is a join process using this authenticator as Aj (and the cloud-based join-authenticator  1540  as Ag). In one embodiment, this process will only succeed if the AAID  1505  of this authenticator is identical to the AAID of the Authenticator originally creating this partition (e.g., AAID  1515 ).       

     g) Supports the following join process: 
     1. There is an API function that can ask an authenticator to join an existing authenticator group. The authenticator to join (Aj) will generate a nonce value, ask the user for permission (i.e. trigger user verification displaying the Join process indicator and the Nonce value in the display), append to the Nonce value its AAID and public WKEK and sign it with its attestation key. This data block is called “join block” or “trust block.” 
     2. This function is also supported by the cloud-based join-authenticator  1540 .
         a. The user first asks the cloud-based join-authenticator  1540  to join the group (initialized by the authenticator Aj first “enrolled” to the cloud service).   b. In this case, the cloud-based join-authenticator plays the role of Aj and the user&#39;s initial authenticator the role of Ag.   c. Ag authenticates to the cloud service and calls the Aj.join API function. The cloud service  1550  passes the AAID  1515  of Ag to Aj while calling the API function. Aj responds with the join block (see above).   d. Ag performs step h below and sends the join-response block to Aj.   e. Aj stores the Group-ID  1502  and WK  1504  in the related “partition”.       

     h) One authenticator in the join group, Ag, receives the join block and the key synchronization logic  1521  verifies it. This is easily possible as the authenticators all know the acceptable public attestation keys (trust anchors) used for signature verification. Ag displays the nonce, the AAID  1515  and a Join Request indicator in its display. If the user approves the action (by normal user verification), the authenticator will encrypt the wrapping key (WK)  1514  and Group-ID  1512  using the public WKEK  1513  received in the join block. This data block is called in the join response block. 
     i) Aj will decrypt the join response block and store the wrapping key (WK)  1504  and Group-ID  1502 . 
     j) One embodiment supports an API function to retrieve a sync-pull-request (given a Nonce value retrieved from the Cloud service  1550 ) from an authenticator Aj. In particular, the key synchronization logic  1520  will return the concatenation of the server provided Nonce, the Group-ID  1502 , the WKEK  1503 , and the hash of the internal persistent memory first signed by the attestation key  1506  and then encrypted by the CSEK  1501  (sync pull request). This function is triggered by an external module (e.g. ASM, authenticator configuration App). Once received by the cloud service, it decrypts the block, verifies the attestation signature and compares the state hash with the hash received along with the latest data block. This method (in combination with encryption to WKEK) allows the cloud service to restrict access to the wrapped memory block to authenticators having the correct model (e.g., protecting against brute force attacks on the password by other authenticators/attackers). If it differs it returns the sync pull response, i.e., the latest wrapped data block encrypted by WKEK  1503 , otherwise it returns “no change” code. 
     k) Supports an API function to process the sync-pull-response. The key synchronization logic  1520  decrypts the block using its private WKEK  1503  and then unwraps the data using the symmetric wrapping key (WK)  1504 . It both operations are successful, the authentication engine  3710  updates its internal persistent storage accordingly. Note that this update procedure supports merging various elements (i.e., the key generated on this authenticator which has not yet been synced to the Cloud  1550 ). 
     l) Supports another API function to trigger generation of a sync-push-request in the authenticator. This API function triggers the key synchronization logic  1520  to return a Nonce, the GroupID  1502 , the hash of the internal persistent memory concatenated with the wrapped persistent memory all encrypted with the CSEK  1501  (i.e., so the Cloud service  1550  can read the Nonce, the Group-ID  1502 , and the hash—but it cannot unwrap the persistent memory containing the private key material). Note that the authenticator first needs to perform a sync-pull with the Cloud  1550  in order to merge-in changes before generating the sync-push-request. 
     Characteristics 
     With this approach, adding a new authenticator to the group with a single operation is realitvely easy. If the user loses his last authenticator, he can recover the by providing his password. Brute force attacks on the password are prevented by encrypting the wrapped memory block using the respective authenticated WKEK. The cloud service provider would have to break the cloud-based join-authenticator in order to brute force the password. As a consequence the cloud-based join-authenticator should use secure element based security. Its security is reflected by the attestation statement. 
     Unfortunately, the user cannot revoke individual authenticator members of his/her recovery group. 
     Fallback Join-Authenticator in the Cloud and Automatic Key Deletion Policy in Authenticators 
     This approach supplements the previous approach as follows. Each authenticator (except the cloud-based join-authenticator), will delete its persistent private key storage (WK, WKEK, Uauth keys, etc), except the attestation private key after a configurable time period, unless the authenticator persistent storage is re-synchronized to the cloud storage. As a consequence, the authenticator needs a reliable internal clock/ticker. 
     The user has the ability to remove individual authenticators from the group via the cloud storage. If an authenticator has been removed, it cannot be synchronized any longer. 
     Authenticator Cryptographic Details 
     This approach supplements the previous approach as follows (with key feaures highlighted in bold). The authenticator supports another API function to retrieve a sync-pull-request (given a Nonce value retrieved from the cloud service) from an authenticator. The authenticator will return the sync pull response, i.e., the concatenation of the server provided Nonce, the Group-ID  1502 , WKEK  1503  and the hash of the internal persistent memory first signed by the attestation key and then encrypted by the CSEK  1501  (sync pull request). This function is triggered by an external module (e.g. ASM, authenticator configuration App). Once received by the cloud service  1550 , it decrypts the block, verifies the attestation signature and compares the state hash with the hash received along with the latest data block. It returns the sync pull response, i.e. the latest wrapped data block encrypted by WKEK  1503 . In one implementation, the cloud service  1550  increments a mismatch counter if the hash doesn&#39;t match. Very high counter values indicate increased risk. 
     In one embodiment, the authenticator supports an API function to process the sync-pull-response. The authenticator decrypts the block using its private WKEK and then unwraps the data using the symmetric wrapping key WK. It both operations are successful, the authenticator updates its internal persistent storage accordingly and resets its internal need-cloud-sync ticker. 
     Characteristics 
     With this approach it is easy to add new authenticator to the group with a single operation. If the user loses his last authenticator, he can recover the by providing his password. Brute force attacks on the password are prevented by encrypting the wrapped memory block using the respective authenticated WKEK. 
     The cloud service provider would have to break the cloud-based join-authenticator in order to brute force the password. As a consequence, the cloud-based join-authenticator should use secure element based security. Its security is reflected by the attestation statement. 
     In addition, in this particular embodiment, the user can “revoke” individual authenticator members of his recovery group by removing them from the group. 
     Sensitive Data Migration Card 
     Instead of using a Cloud service, one embodiment of the invention uses a dedicated chip card (ICC), illustrated in  FIG. 16  as a data migration card (DMC) with secure storage  1626  for storing a protected backup of the all Uauth keys and even all other sensitive data stored in the client device  1518 . To “backup” the sensitive data, the user connects via a secure storage interface  1610  of the DMC  1601  to the client device  1518  containing a bound authenticator Aj (or to the authenticator directly). The user confirms to the authenticator Aj that the data is to be backed-up to the DMC  1601 . This step erases all existing data on the DMC. 
     Depending on the settings, the secure storage interface  1610  may remember the authenticator model (AAID, AAGUID) or a model with similar security characteristics (e.g. keys+matcher TEE protected, etc) and will only restore the data to an identical model or model with comparable security characteristics. 
     In one embodoiment, the authenticator Aj will only backup keys to a DMC  1601  with acceptable security characteristics, e.g., having a model configured in the authenticator. The DMC  1601  will only restore keys into authenticators with acceptable security characteristics, e.g., having the same model as the original authenticator. The security mechanisms may be implemented using authenticator/DMC attestation. 
     In one embodiment, a second authenticator may act as a DMC (e.g. via NFC+BLE). For example, in  FIG. 15 , all keys stored in secure storage  1525  of client device  1518  may be securely migrated into a the secure storage  1526  of client device  1519 . 
     DMC Cryptographic Details 
     In one embodiment, the DMC is like a traditional (external) authenticator. Consequently, the DMC and each authenticator supporting it may perform the same key synchronization techniques described above for joining and managing a join block or trust block. 
     For example, in one embodiment, an authenticator can be “enrolled” to the DMC. This may be accomplished with a FIDO registration in which the user takes one authenticator and registers it to the DMC. The user additionally provides an identifier (e.g. his email address) to identify his partition in the DMC (only required if the DMC supports multiple partitions). Moreover, the DMC may create a “partition” for the registered authenticator (if it supports multiple partitions, otherwise it uses its only pre-configured partition). This partition is identified by the related Uauth public key. Each “partition” has its own set of persistent data (including key material). 
     An authenticator can also be “enrolled” to an existing partition of the DMC (recovery join). The user enters his identifier (e.g. email address) for an existing partition and registers one authenticator to the DMC. Note that this authenticator is not approved yet. The only action the user can trigger is a join process using this authenticator as Aj (and the DMC is a join-authenticator as Ag). This process will only succeed if the AAID of this authenticator is identical to the AAID of the Authenticator originally creating this partition. 
     In addition, one embodiment, there is an API function that can ask an authenticator to join an existing authenticator group. This function is also supported by the DMC join-authenticator. The user first asks the DMC join-authenticator to join the group (initialized by the authenticator first “enrolled” to the cloud service. In this case, the DMC join-authenticator plays the role of Aj and the user&#39;s initial authenticator the role of Ag. Ag authenticates to the DMC and calls Aj.join API function. The DMC passes the AAID of Ag to Aj while calling the API function. Aj responds with the join block (see above). Ag performs step h below and sends the join-response block to Aj. Aj then stores the Group-ID and WK in the related “partition”. 
     Exemplary Data Processing Devices 
       FIG. 17  is a block diagram illustrating an exemplary clients and servers which may be used in some embodiments of the invention. It should be understood that while  FIG. 17  illustrates various components of a computer system, it is not intended to represent any particular architecture or manner of interconnecting the components as such details are not germane to the present invention. It will be appreciated that other computer systems that have fewer components or more components may also be used with the present invention. 
     As illustrated in  FIG. 17 , the computer system  1700 , which is a form of a data processing system, includes the bus(es)  1750  which is coupled with the processing system  1720 , power supply  1725 , memory  1730 , and the nonvolatile memory  1740  (e.g., a hard drive, flash memory, Phase-Change Memory (PCM), etc.). The bus(es)  1750  may be connected to each other through various bridges, controllers, and/or adapters as is well known in the art. The processing system  1720  may retrieve instruction(s) from the memory  1730  and/or the nonvolatile memory  1740 , and execute the instructions to perform operations as described above. The bus  1750  interconnects the above components together and also interconnects those components to the optional dock  1760 , the display controller &amp; display device  1770 , Input/Output devices  1780  (e.g., NIC (Network Interface Card), a cursor control (e.g., mouse, touchscreen, touchpad, etc.), a keyboard, etc.), and the optional wireless transceiver(s)  1790  (e.g., Bluetooth, WiFi, Infrared, etc.). 
       FIG. 18  is a block diagram illustrating an exemplary data processing system which may be used in some embodiments of the invention. For example, the data processing system  1800  may be a handheld computer, a personal digital assistant (PDA), a mobile telephone, a portable gaming system, a portable media player, a tablet or a handheld computing device which may include a mobile telephone, a media player, and/or a gaming system. As another example, the data processing system  1800  may be a network computer or an embedded processing device within another device. 
     According to one embodiment of the invention, the exemplary architecture of the data processing system  1800  may be used for the mobile devices described above. The data processing system  1800  includes the processing system  1820 , which may include one or more microprocessors and/or a system on an integrated circuit. The processing system  1820  is coupled with a memory  1810 , a power supply  1825  (which includes one or more batteries) an audio input/output  1840 , a display controller and display device  1860 , optional input/output  1850 , input device(s)  1870 , and wireless transceiver(s)  1830 . It will be appreciated that additional components, not shown in  FIG. 18 , may also be a part of the data processing system  1800  in certain embodiments of the invention, and in certain embodiments of the invention fewer components than shown in  FIG. 18  may be used. In addition, it will be appreciated that one or more buses, not shown in  FIG. 18 , may be used to interconnect the various components as is well known in the art. 
     The memory  1810  may store data and/or programs for execution by the data processing system  1800 . The audio input/output  1840  may include a microphone and/or a speaker to, for example, play music and/or provide telephony functionality through the speaker and microphone. The display controller and display device  1860  may include a graphical user interface (GUI). The wireless (e.g., RF) transceivers  1830  (e.g., a WiFi transceiver, an infrared transceiver, a Bluetooth transceiver, a wireless cellular telephony transceiver, etc.) may be used to communicate with other data processing systems. The one or more input devices  1870  allow a user to provide input to the system. These input devices may be a keypad, keyboard, touch panel, multi touch panel, etc. The optional other input/output  1850  may be a connector for a dock. 
     System and Method for Authenticator Endorsement 
     In some scenarios, especially those involving electronic payments, apps of multiple merchants need to authenticate payment credentials from a user. Today simple bearer tokens like Primary Account Numbers (PANs) or tokenized PANs are used for that purpose. This approach provides very limited security as such information could be phished and used by malicious actors. 
     Alternatively, a step-up authentication scheme is sometimes used (e.g., Three-Domain Secure or 3DS). Such schemes essentially implement a “decoupled” model which require the issuer to trigger step-up authentication through an out-of-band channel. Today one-time passwords via SMS are primarily used for this step-up authentication, leading to a high cart abandonment rate (e.g., 15% by one estimate). 
     Modern authentication concepts like FIDO provide substantially more security and are supported by 3DS v2 for user-to-merchant authentication. Unfortunately, FIDO authentication is designed in a way that the authentication credential is specific to the app and hence leads to the need for a separate authenticator registration step required per merchant which adds undesirable friction. 
     One embodiment of the invention uses a highly secure authentication technology such as FIDO but allows the seamless endorsement of merchant specific authentication credential related to the payment card or account instead of one related to the merchant. Privacy is not an issue in such a scenario as the payment provider by definition will learn that the specific merchant receives a payment from the user. Thus, this embodiment avoids the need for per-app authenticator registration—while still allowing the authenticator to be implemented in the merchant App through an embedded AppSDK. 
     The embodiments of the invention described herein can optionally leverage the techniques described in U.S. Pat. No. 10,091,195 (&#39;195 patent), issued on Oct. 2, 2018 and U.S. Pat. No. 9,413,533 (&#39;533 patent), issued on September 2016. 
     One embodiment of this authenticator-centric implementation extends FIDO authenticators with various new functionalities including secure (initial) sharing of user verification reference data between authenticators tied to the same platform. In addition, one embodiment allows synchronization of user verification reference data between authenticators tied to the same platform. 
     One embodiment will be described with respect to the architecture shown in  FIG. 19  which includes a client device  1930  with a secure key store  1925  for securely storing authentication data (e.g., keys), an old app  1901  associated with authenticator instance  1911 , a first new app  1902  associated with authenticator instance  1912 , and a third new app associated with authenticator instance  1913 . 
     The Apps used in these embodiments may belong to different merchants, but still support the same payment scheme. In order to reduce friction for the user, the Apps want authentication credentials of that user that are seamlessly endorsed to the payment scheme when authenticating to the scheme backend  1940 . 
     In one embodiment, the user initially installs the old App  1901  which checks whether other Apps supporting the same “Scheme” and having a registered authenticator are already installed. If not, then in one embodiment, the user enters his user identifier (e.g. username, or email address, or PAN that might even be tokenized) and also enters a bearer token such as a password or a one-time passcode (e.g. received through SMS). The user is then authenticated by the backend service  1940  which issues a session token to the App  1901 . 
     In one embodiment, the App  1901  triggers registration of its authenticator instance  1911  (e.g., through the AppSDK). This operation may include asking the user for user verification reference data (e.g. a PIN) and generating the authentication key (FIDO credentials). 
     Referring now to  FIG. 20 , in one embodiment, synchronization processor  1921  on an old App  2901  and a synchronization processor  1922  in a new App  1902  implement the techniques described herein. In particular, when the user installs a new app  1902 , the App  1902  checks whether other Apps  1901  supporting the same “Scheme” and having a registered authenticator  1911  are already installed. If so, then the synchronization processor  1922  of the new App  1902  sends an endorsement request  1926  to “endorse” the App&#39;s authenticator instance  1912  to the old App  1901 . The synchronization processors described herein may be implemented in circuitry, program code executed on circuitry, or any combination thereof. 
     This endorsement request  1926  may include the public authentication key(s) and the attestation object generated by the new App&#39;s  1902 &#39;s authenticator instance  1912 . The endorsement request may include a public encryption key for the initial user verification reference data to be used for accessing the private authentication key. 
     In one embodiment, the old App&#39;s  1901 &#39;s authenticator instance  1911 , upon receipt of the request from the synchronization processor  1921 , verifies the source of the request (e.g., using Caller Identification data associated with the request) against a trusted FacetID list. This list may have been retrieved from the backend server  1940  by old App  1911  or it may have been provided by the new App  1902  as a signed object with some version indication in order to protect against attacks replaying outdated FacetID list versions. 
     If the endorsement request is positively verified, the old App&#39;s  1901 &#39;s authenticator instance  1911  generates an endorsement response  1927 . This response  1927  may be a session token retrieved from the “Scheme” backend service  1940  or it could be a signed endorsement object created by the authenticator  1911  without having access to any backend server, but including the public authentication key and potentially parts of the or the entire attestation object as described above. See also  FIGS. 2-6  and associated text. The initial user verification reference data used to gate use access to the related private authentication key may also be included. This data may be encrypted using the public encryption key included in the endorsement request described above. 
     In one embodiment, the endorsement response  1927  is returned to the synchronization processor  1922  of the calling new App  1902  which passes the endorsement response  1927  to the authenticator instance  1912 . The authenticator instance  1912  retrieves the user verification reference data included in the response  1927 , decrypts it using the key store  1925  and updates its own status to require this new user verification reference data before using the private authentication key. 
     Once a network connection to the backend service  1940  is available, the synchronization processor  1922  of the new App  1902  transmits the endorsement response  1927  to the backend service  1940  and retrieves an authenticated session either directly or after proving its possession of the private key related to one or more of the authentication keys generated by the authenticator instance  1912  as described above. 
     The following series of operations, described with respect to  FIG. 21 , are used in one embodiment for synchronizing User Verification Reference Data. In this embodiment, an App&#39;s authenticator instance  1912  receives a request from the user to change the verification reference data. A synchronization processor  1922  sends a synchronization request  2126 A-B to each other App  1901 ,  1903  installed on the same device  1930  that supports the same “Scheme”. 
     Each of the other Apps  1901 ,  1903  include synchronization processors  1921 ,  1923 , respectively, which transmit synchronization responses  2127 A-B with messages indicating interest in receiving the update. These responses  2127 A-B may include an encryption key for the user verification reference data to be updated and may also include the latest version of the Signed FacetID list known to the other App  1901 ,  1903 . 
     The App&#39;s authenticator instance  1912  verifies the source of that message (e.g., using Caller Identification) against a trusted FacetID list. This list may have been freshly retrieved from the server by the App  1902  or it may have been provided by one of the other Apps  1901 ,  1903  as a signed object with some version indication in order to protect against attacks replaying outdated FacetID list versions. 
     At  2128 A-B, the synchronization processor  1922  provides the updated user verification reference data to the other synchronization processors  1921 ,  1923 , making the reference data available to the other authenticator instances  1911 ,  1913 . In one embodiment, this updated user verification reference data might be encrypted using the public encryption key received in the synchronization response(s)  2127 A-B. 
     One embodiment uses an ASM-centric approach based on a FIDO authenticator supporting client-PIN as described in Client to Authenticator Protocol (CTAP) Implementation Draft, Feb. 27, 2018 (see, e.g., https://fidoalliance.org/specs/fido-v2.0-id-20180227/fido-client-to-authenticator-protocol-v2.0-id-20180227.html # authenticatorClientPIN). This may include, for example, a PIN entered into the ASM (or the platform) and send to the authenticator through an API. This embodiment uses an ASM embedded in the App to collect the PIN and to share it with other eligible Apps installed on the same device. 
     The ASM-centric approach may be implemented using the same or similar techniques as those described above. The difference is that it is not the authenticator remembering and sharing the PIN, but the ASM. As a consequence, any FIDO authenticator supporting the client-PIN can be used as long as it is possible to implement an ASM interfacing to the client-PIN specific API. 
     Embodiments of the invention may include various steps as set forth above. The steps may be embodied in machine-executable instructions which cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. 
     Elements of the present invention may also be provided as a machine-readable medium for storing the machine-executable program code. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, or other type of media/machine-readable medium suitable for storing electronic program code. 
     Throughout the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. For example, it will be readily apparent to those of skill in the art that the functional modules and methods described herein may be implemented as software, hardware or any combination thereof. Moreover, although some embodiments of the invention are described herein within the context of a mobile computing environment, the underlying principles of the invention are not limited to a mobile computing implementation. Virtually any type of client or peer data processing devices may be used in some embodiments including, for example, desktop or workstation computers. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow. 
     Embodiments of the invention may include various steps as set forth above. The steps may be embodied in machine-executable instructions which cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components.