Patent Publication Number: US-8122489-B2

Title: Secure handling of stored-value data objects

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §120 as a divisional of application Ser. No. 11/941,325, filed 16 Nov. 2007, which is a divisional of application Ser. No. 10/008,174, filed 13 Nov. 2001, now U.S. Pat. No. 7,315,944, issued 1 Jan. 2008. The entire contents of each of these related applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to conducting secure transactions, and particularly relates to securely managing wireless device transactions involving stored-value data objects. 
     As portable electronic devices become more fully integrated into the everyday lives of people, these devices will be used in a broader range of transactions. For example, one might integrate payment functions into a portable communication device such as a cellular telephone. A user can then pay for selected goods or services using the phone&#39;s payment functions. 
     Security issues complicate using portable devices in commercial transactions. For example, if the user&#39;s device contains payment information, how is that information conveyed to a vendor system in a manner secure from unwanted eavesdropping or monitoring? In general, significant issues arise in providing end-to-end security for such transactions. 
     Particular challenges arise in securely delivering and retrieving information to and from a portable device. The need for such delivery and subsequent retrieval might arise in the context of delivering a stored-value data object to the device for later redemption by the user. Here, the data object might function analogous to a physical ticket. Indeed, a vendor might issue an electronic ticket or other token for delivery to the user&#39;s device for subsequent redemption. Upon redemption of the electronic ticket, the user gains access to or receives the desired goods or service. 
     However, the use of electronic tickets or other stored-value data objects requires significant security provisions throughout the issuing and redeeming processes. An approach to securely managing the use of stored-value data objects with portable devices requires a solution that addresses these and other security concerns. Yet, any such approach should make the use of such data objects relatively convenient and flexible from the user&#39;s perspective. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides methods and apparatus for securely managing wireless device transactions involving the use of stored-value data objects. In some embodiments, the stored-value data object functions as an electronic ticket or token, and methods and apparatus are provided for securely issuing, storing, and redeeming the electronic ticket. 
     In at least one embodiment, the wireless device requests a desired stored-value data object from a ticket issuing system. The ticket issuing system ensures secure delivery to the requesting device by encrypting the requested data object using a public key provided by the wireless device in association with the request. Only the requesting wireless device has the corresponding private key, and thus only that device can decrypt and subsequently use the data object. The wireless device may include a security element, which offers tamper-resistant, secure decrypting and storage for the data object, and secure storage of the private key. 
     The ticket issuing system may offer local access, in which case the wireless device might use RF or optical (e.g., infrared) signaling to communicate with the ticket issuing system. In at least one embodiment, the ticket issuing system is a remote server or other system accessible through the Internet, and the wireless device accesses it through a wireless communication network. For example, the device might incorporate a RF transceiver adapted to communicate with a cellular communication network. Communication between the internet-based ticket issuing system and the wireless device might use the Wireless Application Protocol (WAP). If WAP is used, the wireless device might provide its associated public key to the ticket issuing system in a user certificate, in accordance with WAP Public Key Infrastructure (WPKI) methods. 
     After receiving the stored-value data object (e.g., electronic ticket) in encrypted form from the ticket issuing system, the wireless device transfers the encrypted data object to its security element, which may be integrated in the wireless device or removeably connected therewith. In any case, the security element provides for secure storage of the data object and does not permit viewing, retrieving, or otherwise modifying the stored data object except in accordance with its security rules. As noted, the security element also may provide secure storage of the private key used to decrypt the data object as received from the ticket issuing system. Additionally, the security element may allow a user of the wireless device to browse or view selected fields or portions of the stored data object, but prevents unauthorized copying of the stored data object by not allowing unencrypted access to the full data object. 
     Once the security element contains a stored data object, such as an electronic ticket, the wireless device user can redeem the data object for associated goods or services at a compatible ticket redeeming system. The ticket redeeming system ensures that the data object being redeemed is valid, and cooperates with the security element in the redeeming wireless device to ensure that unauthorized copies of the stored data object cannot be extracted by eavesdropping on the communication between the wireless device and the ticket redeeming system. Further, the security element in the wireless device ensures that unauthorized copies of the stored-value data object are deleted or otherwise not retained. Communication between the wireless device and the ticket redeeming system may use RF, infrared, or other wireless signaling. In at least one embodiment, the wireless device includes an RF interface, such as a Bluetooth interface, for communicating with the ticket redeeming system. Communication between the ticket redeeming system and the wireless device may be based on WAP, or on other standardized or proprietary protocols. 
     In at least some embodiments, the wireless device initiates redemption of the stored data object by sending a redemption request to the ticket redeeming system. The wireless device may also provide its associated public key to the ticket redeeming system as part of this request. In response, the ticket redeeming system sends a certificate containing its associated public key to the wireless device. The ticket redeeming system may also send a nonce (“number used once”) or other generated value (e.g. pseudorandom value) to the wireless device. 
     The security element encrypts a combination of the generated value supplied by the redeeming system and the ticket using the public key received from the redeeming system. The wireless device then sends the encrypted data object to the ticket redeeming system using whatever protocols are associated with the particular interface used to communicate with the ticket redeeming system. Generally, these protocols should support transmission verification to insure that the ticket redeeming system successfully receives the encrypted data object. Upon transmitting the data object to the ticket redeeming system, the security element in the wireless device erases or otherwise clears its stored copy of the data object. 
     The ticket redeeming system decrypts the received data object using a private key corresponding to the public key it provided to the wireless device. During decryption, the ticket redeeming system separates the data object from the nonce and verifies that the data object contains an authentic signature or other marking data from a legitimate ticket issuing system, or from a legitimate ticket redeeming system. If the data object is a multi-use object, such as a multi-use electronic ticket, the ticket redeeming system alters the data object as required, signs it with its own private key, and then returns it in encrypted form to the wireless device, where it is decrypted and stored in the security element, ready for subsequent redemption. 
     In any case, the ticket redeeming system may offer or otherwise enable access to the goods or service associated with redeeming the data object, such as by opening a gate or by returning a rapid verification token (RVT), in exchange of the data object, to the wireless device for subsequent use in accessing the goods or service. A RVT as defined herein typically comprises a different type of information than the data object discussed above, and has associated transfer and verification procedures making it amenable to quick verification. 
     A RVT might be used in situations where one or more subsequent rapid verifications are desired after initial redemption of a stored data object using full security. For example, a ticketed passenger might use his or her portable device to perform full redemption of a stored electronic ticket at a ticket redeeming system positioned in advance of the boarding area. Upon redeeming the electronic ticket, the ticket redeeming system returns a RVT to the passenger&#39;s portable device, which may then be rapidly verified immediately prior to boarding the aircraft. Of course, usage of RVTs extends to a broad range of other activities such as enforcing ticketed access at sporting events. 
     In at least some embodiments, the ticket redeeming system returns a seed value to the wireless device, and may optionally return graphical data or pattern generating information. The seed value may be a pseudorandom value. The security element in the wireless device uses the returned seed value to drive some form of pattern or sequence generator. The pattern/sequence generator preferably incorporates time-of-day dependency in its generation function, such that the sequence or pattern generated by it depends on both the seed value and the time-of-day. If a human operator is meant to redeem or authenticate the RVT, the security element can generate an authentication pattern or otherwise manipulate a graphical element that it displays in a manner dependent upon the seed value, and on time-of-day if desired. Thus, only security elements having valid seed values are able to present the proper pattern or graphical manipulation to the verifying human operator at the verification instant. 
     Incorporating time-of-day considerations into sequence/pattern generation functions protects RVT verification against replay attacks. In general, the pattern/sequence generator generates the desired pattern or sequence at the time of verification. In so doing, the time-of-day used in generation is very close to current time. For example, the pattern/sequence might be generated a half-second before actual verification. Verification might then be made to depend on the time-of-generation being within a certain window of time. This dependency prevents a user from outputting an otherwise valid verification pattern or sequence for recording and subsequent playback to a verifying system. 
     Where a subsequent automated system is meant to verify the RVT, the wireless device may simply transmit a verification sequence to the verifying system. Generally, the verification sequence contains at least one pseudorandom element generated in dependence on the seed value, and preferably also in dependence on the time-of-day. The verifying system receives the verification sequence and checks its validity. It does so by locally generating the same pseudorandom element or elements in the verification sequence, which is feasible because the verification system has knowledge of the seed value that was transmitted to the wireless device by the ticket redeeming system. This seed value is used system-wide, that is, it is given to all wireless devices over a moderately long pre-determined period of time. The period of time may be much longer than the typical user delay between redeeming the ticket at the first TRS and subsequently redeeming the RVT. The RVT-checking TRS would allow acceptance of both the present and the previous period seeds over a relatively brief period following a seed-change; this would accommodate users who obtained their seed just prior to a seed change. 
     If the pseudorandom element is generated in dependence of time-of-day as well as the seed value, the wireless device may transmit the time-of-day it used in generating the pseudorandom element included in its verification sequence. The verifying system can use this received-time-of-day value and the known seed value to generate its own pseudorandom element for comparison against the pseudorandom element received from the wireless device. Further, the verifying system may qualify the time-of-day received from the wireless device to make sure it is not old (i.e., stale). 
     Alternatively, verifying system may be synchronized to the same time reference as the wireless device, such that the time-of-day maintained by the verifying system closely matches the time-of-day maintained by the wireless device. If such synchronization is not desirable, the verifying system may allow for a defined time variance between it and the wireless device. In any case, the verifying system may also use the time-of-day in determining whether a received verification sequence is valid, thus preventing a given verification sequence from being copied and reused by other wireless devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an exemplary system supporting the secure handling of stored-value data objects in accordance with the present invention. 
         FIG. 2  is a more detailed diagram of an exemplary embodiment of the system of  FIG. 1 . 
         FIG. 3  is a diagram of exemplary embodiments of the ticket issuing system, ticket redeeming system, and personal trusted device shown in  FIGS. 1 and 2 . 
         FIG. 4  is an exemplary call flow diagram detailing the issuance and redemption of electronic tickets or other types of stored-value data objects. 
         FIG. 5  is a diagram of an exemplary environment suited for the use of rapid verification tokens. 
         FIG. 6  is a diagram of an exemplary verification display associated with a rapid verification token. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides systems and methods enabling certain transactions related to wireless e-commerce. The following detailed description and accompanying drawings provides specific, exemplary details regarding implementations for at least some embodiments of the present invention. However, the scope of the present invention extends well beyond these specific details. For example, it should be understood that where wireless communication systems are involved, no particular wireless communication interface standard is necessary for practicing the present invention. 
     Moreover, the discussion below refers specifically to electronic tickets, but this term should be understood to be a particular embodiment of the more general concept of any stored-value data object. Thus, the term “electronic ticket” as used herein encompasses other stored-value data objects, such as electronic cash, electronic tokens, and any other data item or object that may be used as a medium of exchange in e-commerce, and in other for-value transactional activities. 
       FIG. 1  illustrates a simplified, exemplary system  10  for practicing one or more embodiments of the present invention. System  10  comprises a ticket issuing system (TIS)  12 , a ticket redeeming system (TRS)  14 , and a user device  16 . In this context, the user device  16  is referred to herein as a “personal trusted device” (PTD)  16 . The PTD  16  contains a security element  20 , which is adapted to act as a trusted agent of the TIS  12  and TRS  14  in stored-value data object transactions, such that the security element  20  cooperates with the TIS  12  and TRS  14  in securely issuing, storing, and redeeming an electronic ticket  18 . It should be understood that the PTD  16  represents essentially any device type having the appropriate wireless communication capabilities. Thus, PTD  16  might be an appropriately configured radiotelephone or other mobile terminal, personal digital assistant, hand-held, laptop, other personal computer device, or other type of electronic device. 
     In managing the secure transfer, handling, and redemption of electronic tickets, the systems and processes used must ensure reliable and convenient electronic ticket generation, issuance, and redemption, which includes preventing fraud and misuse. In general, the TIS  12 , TRS  14 , and security element  20  cooperate to achieve the following goals:
         The ticket recipient must be assured that the ticket issuer is legitimate.   The ticket must be delivered only to the legitimate user, i.e., it shall not be possible for a person other than the user to receive and make use of the ticket.   The ticket must be prevented from copying by the user, whether such copying might be undertaken legitimately or fraudulently.   The user must be assured that the ticket collector (redeeming system) is legitimate.   The ticket must be delivered only to the legitimate ticket collector, i.e., it shall not be possible for an entity other than the legitimate ticket collector to receive and make use of the ticket.   The ticket collector must have a reliable mechanism for ensuring that the ticket is legitimate.   If the ticket collector returns the ticket to the user, it must ensure that the ticket is delivered only to the legitimate user, i.e., it shall not be possible for a person other than the user to receive and make use of the returned ticket.       

     In addition to the above secure handling requirements, rapid ticket verification is also a requirement in many ticketing services. Rapid verification is especially advantageous in mass transit systems, sports events, concerts, etc. With rapid verification, which is discussed in more detail later, there may be a tradeoff between verification security and verification speed. In general, the concept entails subjecting an electronic ticket to a high level of initial security to insure verification, and then providing the user with a potentially less secure, short-lived, rapid verification object that may be subsequently verified more quickly than the original electronic ticket. 
       FIG. 2  is a more detailed illustration of an exemplary embodiment of secure ticket transactions. In this instance, the PTD  16  may be a mobile terminal or other cellular radiotelephone. As such, the PTD  16  wirelessly communicates with the TIS  12  by accessing the wireless communication network  22 , which typically comprises an access network (AN)  26  and a core network (CN)  28 . The wireless communication network  22  provides access to the TIS  12  via the internet  24  or by some other network connection. The wireless communication network  22  may be any one of a number of standardized network implementations, including GSM, CDMA (IS-95, IS-2000), TDMA (TIA/EIA-136), wide band CDMA (W-CDMA), GPRS, or other type of wireless communication network. 
     Any number of end-to-end protocols may be used in supporting ticketing transactions conducted between the PTD  16  and the TIS  12 . For example, the TIS  12  may be a WAP-enabled server, thereby allowing WAP-enabled PTDs  16  to conduct ticketing transactions with the TIS  12  based on WAP standards in conjunction with special MIME types defined for the ticketing messages. In particular, the reader is referred to the standards document entitled “Wireless Application Protocol Public Key Infrastructure Definition,” WAP-271-WPKI, Version 24 Apr. 2001, as promulgated by the WAP Forum. Of course, other protocols may be used, and indeed numerous open and proprietary protocols are available for supporting transactions between the PTD  16  and the TIS  12 . 
     Moreover, it should be understood that while configuring the TIS  12  as an Internet-accessible ticket issuing system is attractive in terms of flexibility and broad access, the TIS  12  might be implemented as part of the wireless communication network  22 . For example, the TIS  12  may be implemented as one of a number of network entities within the core network  28 . In that case, some security concerns associated with the TIS  12  are eliminated, or at least minimized, but access to the TIS  12  may be more restricted. For example, the TIS  12  might be accessible only to subscribers of the wireless communication network  22 . 
     Once the PTD  16  receives an electronic ticket from the TIS  12 , it transfers the ticket  18  to its security element  20 , where it is decrypted and securely held for subsequent redemption. To that end, the PTD  16  further supports wireless communication with the TRS  14  for redemption transactions. The TRS  14  may be linked to other systems via a supporting network  30 , and in fact may be connected to one or more of the Internet  24 , the TIS  12 , and the wireless communication network  22 . While not shown, it should be understood that the TRS  14  may also be linked directly or indirectly to other TRSs  14 , and to other types of equipment associated with ticket redemption, and, optionally, may be linked with rapid verification systems discussed later herein. 
       FIG. 3  provides more detail regarding exemplary embodiments of the TIS  12 , the TRS  14 , and the PTD  16 . Additionally,  FIG. 3  defines exemplary information exchanged between the PTD  16  and the TIS  12  and TRS  14 . 
     Specific embodiments of the PTD  16  will vary significantly because the term “PTD”, as used herein, encompasses a broad range of device types. In an exemplary embodiment, the PTD  16  comprises a functional element  40  and wireless interfaces  40  and  42 , in addition to the security element. As used herein, the term “functional element” essentially describes the whole of the PTD  16  apart from the security element  20 . As will be explained later, the PTD  16  may use the same wireless interface  42  or  44  to communicate with both the TIS  12  and the TRS  14 , but will oftentimes incorporate separate wireless interfaces. Generally, the need for different wireless interfaces is determined based on whether the TIS  12  and the TRS  14  are both local systems, both remote systems, or a mix of remote and local systems. For example, as described earlier, the PTD  16  may communicate with the TIS  12  using WAP services supported by the wireless communication network  22 , while communicating with the TRS  14  at a redemption site via a local communication link. 
     The characteristics of functional element  40  will vary depending upon the nature of the PTD  16 . That is, functional element  40  may be a cellular telephone, a personal digital assistant (PDA), or other type of electronic device dependent on the intended purpose of the PTD  16  in question. Generally, the functional element  40  comprises some type of processor or processors  50 , memory  52 , a user interface  54  and a real-time clock (RTC)  56 . Details of the user interface  54  also vary with the intended purpose of the PTD  16 . For example, if the PTD  16  is a cellular telephone or other mobile terminal, the user interface  54  typically comprise a display screen, keypad, and audio input/out systems. Similarly, if the PTD  16  is a PDA or other mobile computing device, the user interface  54  generally includes display and input/output functions. 
     The security element  20  in the PTD  16  may be implemented in any number of ways. For example, the security element  20  may be integrated with the other systems of the PTD  16 , or may be a removable smart card or other modular device. In any case, the security element  20  may be implemented as a tamper-resistant secure module that provides for highly secure storage of electronic tickets and other sensitive data. In an exemplary embodiment, the security element  20  comprises a processor, or other logic  60 , memory  62 , and a sequence/pattern generator  64 . Functions associated with the security element  20  are described in more detail later in association with describing transactions involving the TIS  12  and TRS  14 . 
     In an exemplary embodiment, the TIS  12  comprises a WAP-enabled server, or other network-accessible ticket issuing system. In general, the TIS  12  includes an interface  70  configured for the type of network with which the TIS  12  communicates. In some embodiments, the interface  70  may include wireless communication functionality to support local wireless communication with PTDs  16 . The TIS  12  further comprises a processing/encryption system  72  and memory  74 . 
     Similarly, the TRS  14  comprises an interface  80 , a processing system  82  providing encryption and decryption services, and memory  84 . Of course, both the TIS  12  and the TRS  14  may be implemented differently depending on the specific capabilities and communication methods desired. 
     Independent of the above implementation details, a typical electronic ticket transaction involves a purchase request from the PTD  16  to the TIS  12 , and subsequent delivery of the requested electronic ticket  18  from the TIS  12  to the PTD  16 . Later, a user of the PTD  16  presents the electronic ticket  18  to the TRS  14  for redemption. A number of mechanisms are used within the present invention to ensure end-to-end security for issuing, storing, and redeeming electronic tickets (i.e., stored-value data objects). 
       FIG. 4  illustrates an exemplary call flow that might be practiced in one or more embodiments of the present invention. The overall set of electronic ticket transactions begins with the PTD  16  generating and transmitting a purchase request for receipt by the TIS  12 . A user certificate that includes a public key associated with the PTD  16  is transmitted in conjunction with the purchase request, or is otherwise made available to the TIS  12 . The PTD certificate may be a certificate issued by the operator of the TIS  12  or an associated system, or may come from a trusted third party such as VISA or MASTERCARD. In any case, once the TIS  12  is assured of payment for the electronic ticket  18 , which procedures are not germane to the present invention, it generates the requested electronic ticket  18 . 
     Referring back to  FIG. 3  it might be noted that the ticket  18  may be generated and held in memory  74 . Once the ticket  18  is generated with the desired content and signed or otherwise authenticated by the TIS  12 , it is encrypted using the public key (PTD PuK ) associated with the requesting PTD  16 . Because only the requesting PTD  16  has the corresponding private key, only the requesting PTD  16  will be able to receive and make use of the encrypted ticket  18 . Thus, at Step A in  FIG. 4 , the TIS  12  issues the requested electronic ticket  18  in encrypted format. Note that the ticket  18  consists of data that is digitally signed by the TIS  12 , the digital signature being performed by encrypting the ticket data (TICKET_DATA) with a private key (TIS PrK ) belonging to and securely held by the TIS  12 . 
     The PTD  16  receives the encrypted ticket  18  via the wireless interface  42 , and may pass the encrypted ticket  18  directly to the security element  20 , or indirectly through the functional element  40 . In one embodiment, the TIS  12  sends the encrypted electronic ticket to the PTD  16  as a special Multipurpose Internet Mail Extension (MIME) type, which message type triggers the transfer of the encrypted ticket  18  to the security element  20 . In any case, the security element  20  decrypts the received ticket  18  using its securely held private key. The security element  20  may hold a root certificate (TIS_ROOT_CERT) corresponding to the TIS  12 , which certificate includes the private key needed to decrypt the electronic ticket  18  received from the TIS  12 . 
     The decrypted ticket  18  is held in security element memory  62 . It is noteworthy that the security element&#39;s fixed, pre-defined input/output functions never yield the decrypted electronic ticket  18  to the outside world. Hence, the ticket  18  stored in the security element  20  is inaccessible to would-be copiers, although the security element  20  may make selected fields or portions of the ticket  18  available for browsing by the user of PTD  16 . 
     Subsequent to receiving the ticket  18  from the TIS  12 , the user of the PTD  16  presents the electronic ticket  18  to the TRS  14  for redemption. Ticket redemption typically begins with the PTD  16  issuing a redemption request to the TRS  14 , which might take the form of a WAP Session Protocol (WSP) Get request from the PTD  16  to the TIS  12 , as shown in  FIG. 4  by the Get_Service message. The above Get message may be issued as a result of the user independently navigating to a TIS website, or by the receipt by the PTD  16  of a WAP Push message issued by the TIS  12 , containing the url of the TIS  12 , and the user selecting the said url on his PTD. 
     As was mentioned early, the PTD  16  preferably communicates with the TRS  14  wirelessly through wireless interface  42  or  44 . If the TRS  14  is remote, the PTD may access it as it would a remote TIS  12  through the wireless communication network  22 , in which case the PTD  16  uses wireless interface  42 . If the TRS  14  is local, the PTD  16  uses wireless interface  44 , which may comprise a radio frequency interface, an optical interface, some combination thereof, or may be based on some other wireless technology. Wireless technologies of particular interest in this context include Bluetooth and 802.11 wireless networking standards, and additionally include the infrared communications standards promulgated by the Infrared Data Association (IrDA). Of course, it should be understood that communication between the PTD  16  and the TRS  14  might be based on other standards, including proprietary communication protocols. 
     Upon receiving the redemption request from the PTD  16 , the TRS  14  sends a message, B, termed “Request To Show Ticket” to the PTD  16 , which request includes a generated value and a certificate (Cert_TRS n+1 ) associated with the particular TRS  14 . The generated value may be a nonce, for example. The certificate transferred from the TRS  14  to the PTD  16  includes a public encryption key (TRS PuK ) associated with the TRS  14 . 
     In response, the security element  20  within the PTD  16  creates a composite data object, (Nonce, T), comprising the received generated value concatenated with the electronic ticket  18 . This composite data object is then digitally signed by the PTD  16  using the private key of the PTD  16 . Preferably, a standard format such as PKCS  7 , is used, whereby the certificate containing the PTD&#39;s public key, Cert_PTD, is appended to the signed object. The signed composite data object is then encrypted with the public key belonging to the particular TRS  14 , the said public key being contained in the certificate, Cert_TRS n+1 , sent from the TRS  14  to the PTD  16  in message B in the previous step. In this discussion, the present TRS  14  is identified by index number (n+1) and a previous TRS, for multi-use tickets, by (n). 
     Following encryption of the signed composite data object, the PTD  16  returns the encrypted composite object to the TRS  14 . For multi-use tickets described below, the certificate of the previous ticket redeeming system, Cert_TRS n , is also sent as a component of message C. The TRS  14  decrypts the received generated value and electronic ticket  18  using the corresponding private key (TRS PrK ), known only to that TRS  14 , and checks the authenticity and integrity of the received electronic ticket, as well as verifies the returned generated value. 
     In particular, the TRS  14  checks whether the received electronic ticket includes an authentic signature or other verification information from a legitimate TIS  12  and/or from another TRS  14 , which might have signed a multi-use ticket after modifying it, as described below. In so checking, the TRS  14  may use a locally stored copy of the root certificates of one or more TISs  12  and the certificate of the previous TRS received from the PTD  16 . 
     The TRS  14  may also check the PTD&#39;s signature on the composite data object returned by the PTD  16  to verify possession by the PTD  16  of the private key corresponding to the public key contained in the submitted PTD certificate. 
     If the electronic ticket  18  being redeemed at the TRS  14  is a one-time use ticket, the TRS  14  verifies that the ticket is valid and provides a signal or other indication to an associated system that the presenter of the ticket  18  should be granted access to the goods or service corresponding to the received ticket  18 , or that a RVT should be issued. In conjunction with transmitting the ticket  18  from the PTD  16  to the TRS  14  in association with its redemption, the security element  20  erases the secure copy of the ticket  18  that it holds within its memory  62 . This prevents unauthorized duplicate copies of the ticket  18  remaining during or after redemption. 
     In some instances, the electronic ticket  18  is a multiple use ticket. If so, the TRS  14  may return a redeemed ticket  18 ′. The redeemed ticket  18 ′ may comprise a “punched”, that is, an altered copy of the original electronic ticket  18 . For example, the TRS  14  may modify the original electronic ticket  18  to show that it has been redeemed for the nth time, where n is a number from one (1) to the maximum number of times that the ticket  18  may be used. In returning a multi-use ticket  18 ′, the TRS  14  may modify the ticket contents to contain an authentication signature associated with the TRS  14 , which may be used to verify the redeemed ticket  18 ′ at subsequent verification points. 
     In some cases, the result of redeeming a ticket  18  will be the issuance of a rapid verification object by the TRS  14 . The PTD  16  receives the rapid verification object, and later uses it to generate a RVT, which may be quickly validated, albeit with less security, at a subsequent verification point. The rapid verification object sent from the TRS  14  to the PTD  16  itself might comprise the RVT, which is presented by the PTD  16  at a later verification point, but typically, the rapid verification object is a seed value, possibly with other information, from which the PTD  16  generates a valid RVT. Other information sent by the TRS  14  as part of the rapid verification object may include image data, image manipulation information, user-identifying data, etc. In any case, the TRS  14  might, depending on circumstances, return a redeemed ticket  18 ′, a rapid verification object, neither, or both. 
     The use of RVTs might arise in association with tickets  18  issued for sporting events or for use at train stations, for example. In this instance, an original electronic ticket  18  might be subject to verification at a TRS  14  positioned at an open access area, whereupon the TRS  14  returns a rapid verification object to the redeeming PTD  16 , which object, used in generating the RVT, may remain valid only for a defined period of time or a defined number of subsequent RVT validations. 
       FIG. 5  illustrates more specifically an environment where RVTs might be useful. One or more TRSs  14  are available in an open area where users of PTDs  16  may initially redeem their electronic tickets  18 . This initial redemption is typically a high security process, for example, one performed in accordance with the above description. The TRSs  14  return rapid verification objects to PTDs  16  redeeming valid electronic tickets  18 . The PTD users may then present RVTs from their PTDs  16  to gain access to a controlled access area, for example. Arrangements of this sort are particularly useful in circumstances where event attendees or service users arrive at staggered times in advance of the event or service, and then subsequently queue up at a particular time. One might imagine the usefulness of the combination of high security verification followed by a subsequent lower security but faster verification at airport terminals, and at other mass transit facilities. 
     RVTs may be verified by rapid verification systems  100 , but might also be verified by human operators. It should be understood that rapid verification systems  100  might simply be implemented as TRSs  14  but adopting both the secure verification protocols discussed earlier as well as lower-overhead rapid verification protocols. When returning rapid verification information to PTDs  16  from TRSs  14 , the TRSs  14  may include a variety of data elements. In exemplary embodiments, the TRS  14  returns at least a seed value, and may also return visual pattern generating information, image information, and one or more associated scripts, the use of which information is explained below. 
     In one approach, the TRS  14  returns an image and a seed value in encrypted format as the rapid verification object to the PTD  16 . The security element  20  in the PTD  16  includes a sequence/pattern generator  64  capable of generating pseudorandom sequences, or visual pattern information for display on the PTD screen, using the returned seed value. Additionally, the sequence/pattern generator  64  may be adapted to generate pseudorandom sequences based not only on this returned seed value, but on the time of day value that might be obtained from the real-time clock  56 , for example. In many instances, the RTC  56  is itself synchronized to an overall network time or other referenced time, such as a GPS-based reference time. By making the RVT presented by the PTD  16  for verification dependent on time-of-day, the ability to fraudulently replay an earlier-generated RVT is eliminated. 
     In an exemplary scenario, a time-varying image is generated by the security element  20  in the PTD  16  by one of two approaches. A bit-mapped core image, which may be in data-compressed form, is transmitted from the TRS  14  to the PTD  16 ; this image is then manipulated by a program (e.g., computer instructions) native to the security element  20 . This security element program takes as its inputs the output from the sequence/pattern generator  64 , and the time time-of-day output or derived from the RTC  56 . Alternatively, the program for creating and manipulating the time-varying image is itself sent from the TRS  14  to the PTD  16 , possibly in compressed data form. This latter alternative is more suitable when the displayed image is an abstract, computer-generated pattern. It is noteworthy that the verification image displayed by the PTD  16 , regardless of how it is generated, should have the qualities of easy human recognition, including clear discrimination among its various manipulated forms. 
       FIG. 6  illustrates one embodiment of a human-verifiable RVT. The depicted images may be displayed on a display screen included within the user interface  54  in the PTD  16 . In this exemplary embodiment, the displayed image includes (a) the user&#39;s picture, which is typically static; (b) a recognizable pattern that changes at discrete time intervals; and (c) a recognizable pattern changing continuously with time. 
     The user&#39;s picture in (a) above is accessed by the TRS  14  from a server whose location address, as typified by an Internet url, is contained in the PTD certificate sent by the PTD  16  to the TRS  14  in message C in association with signing the composite data object. This image, possibly in compressed form, is forwarded by the TRS  14  to the PTD  16  as a part of the rapid verification object (RVO) in message D. 
     As an example of (b) and (c), the illustration of  FIG. 6  shows a wine glass and ball in association with the user&#39;s image. The wine glass takes on a series of rotational angles, wherein the sequence of rotational angles assumed by the wine glass are determined by the sequence/pattern generator  64 , based on the seed value provided by the TRS  14  and a time-of-day value. The wine glass image changes at discrete time instants which are sufficiently spaced to allow easy human verification. The exemplary time interval shown in  FIG. 6  is 30 seconds. In this case, the defense against replay attack is the presence of the user&#39;s picture as a component of the verification image displayed by the PTD  16 . 
     Regarding the image component (c), it may be advantageous to pick the ball as following a circular orbit in an essentially continuous motion where the direction of rotation of the ball is determined by a pseudorandom sequence, and the position of the ball in its circular path is determined by the time-of-day. A continuously varying component in the verification image provides a defense against replay attacks comprising real time monitoring and rebroadcast of the image to multiple fraudulent users. 
     The human operator may have a rapid verification system  100 , such as a hand-held device, having a display with similar images following the same pseudorandom sequence or sequences. In this manner, the human operator can look at the PTD&#39;s display and compare the verification image depicted there with the reference image displayed by the rapid verification system  100 . 
     In ensuring that the displayed patterns on the rapid verification system  100  remain in sync with the patterns being generated by PTD  16  having valid RVTs, the rapid verification system  100  may synchronize its time of day to the same time reference used by the security element  20  in the PTD  16 . Thus, the rapid verification system  100  may synchronize its time of day to a network time of day, such as the time maintained by the wireless communication network  22 , or may also have a GPS-based time reference. Alternatively, the rapid verification system  100  may simply maintain a very accurate time of day, and allow for slight variations between its time of day and the times of day in the PTD  16 . Thus, slight discrepancies between the PTD image and the verification image may be tolerated. 
     As mentioned earlier, an alternative approach has the PTD  16  provide the time-of-day to the rapid verification system  100 . This allows the rapid verification system  100  to use the same time-of-day value as was used by the security element  20  in generating pseudorandom data from the seed value. With this approach, the rapid verification system can determine whether the time-of-day value provided by the PTD  16  is recent enough to be deemed legitimate. That is, if the time-of-day value received from the PTD  16  is too old, the rapid verification system  100  can reject the verification sequence or pattern provided to it as being a replay of an earlier verification sequence. 
     Use of a verification sequence is particularly well suited where verification is performed using automated processing. Thus, the RVT generated by the security element  20  and transmitted from the PTD  16  to the rapid verification system  100  might simply be a verification sequence having at least one pseudorandom element generated in dependence on the seed value provided by a legitimate TRS  14  and a PTD time-of-day. The verification sequence can include additional, non-pseudorandom information, such as protocol-defined headers, etc. As with the human-readable version, the rapid verification system  100  may determine whether a sequence is valid based on the known seed value and a synchronized time of day. 
     If the rapid verification system&#39;s time of day is not synchronized to the same reference used by the security element  20 , rapid verification system  100  may compare the received sequence to one of several valid sequences representing a defined time window. In this matter, absolute synchronization of times between PTD  16  and rapid verification system  100  is not necessary; however, by defining the non-discrepancy tolerance to be suitably small (e.g., ±2 seconds), the rapid verification system  100  ensures that an earlier issued seed value has not been redistributed to another PTD  16  for fraudulent reuse. 
     As noted in detail above, the PTD  16  may include the actual time-of-day value used by the security element  20  in generating the pseudorandom element or elements as a preamble in the verification sequence it transmits to the rapid verification system  100 . This technique is useful in that the rapid verification system&#39;s time-of-day may not exactly match the time-of-day reference used by the security element  20 . The rapid verification system  100  will check the received verification sequence against its own reference sequence for the PTD-declared time-of-day (i.e., for the time-of-day value received from the PTD). If the received verification sequence is valid, this proves that the PTD  16  (security element  20 ) had the correct seed value. The rapid verification system  100  will then decide if the PTD-declared time-of-day is within acceptable limits of clock inaccuracy and processing delay. Verification sequences reflecting excessive delays would be rejected as they might result from replay fraud. 
     In an alternate exemplary approach, the rapid verification object returned by the TRS  14  is a paper ticket or other physical token that may be redeemed by the PTD user. In this approach, the TRS  14  may mark the physical token with authentication indicia that may change with time to prevent token reuse. 
     Given the broad scope of the present invention with regard to issuing, managing and redeeming electronic tickets or other stored-value data objects within the realm of e-commerce or in the context of other types of secure transactions, it should be understood that the exemplary details above are not limiting. Indeed, the present invention is limited only by the scope of the following claims, and the reasonable equivalents thereof.