Abstract:
A mobile terminal is equipped for SMS payment and service authentication with a remote transaction provider. The remote provider uses common secrets &amp; a seed in a keyed Hash Machine Address Code (HMAC) executing a Message Digest Algorithm to generate a list of authentication token (username-password) for the purchase of services an/or goods. The common secrets and seed are shared with local redemption devices which also generate the list of authentication token. A subscriber conducts payment with the remote transaction provider and receives an authentication token corresponding to the purchased service. The subscriber provides the authentication token to the redemption device which compares the authentication token with sets of valid authentication tokens generated by the redemption terminal. If the comparison indicates a match, the redemption device provides the service to the subscriber.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The present invention relates to transaction and payment systems, methods and program products. More particularly, the invention relates to systems and methods for securing remote authentication/validation of transactions from a transaction provider for use in a local redemption device that does not have continuous connection with the remote transaction provider.  
         [0003]     2. Description of Prior Art  
         [0004]     Electronic payment systems for transportations are already in use today using the messaging service of a ubiquitous telecom network SMS (Short Messaging Service) to authenticate and pay for services in buses and trains, where the communication channel between the train/bus and a data network is not necessarily continuous. The most common technical obstacle that has to be overcome in transportation is that there is necessarily no continuous link between the server where consumption of the services is happening (in the train/bus) and the server that receives information that the short message transaction has been carried out (somewhere in the always-connected data network). The closest existing mechanism is the SMS—ticketing systems of public transportation, but even in that case the ticket checker presumably synchronizes his or her (checking) device periodically, and in those systems there is no need for personalization nor context management.  
         [0005]     What is needed in the art is an e-services payment system which overcomes problems in the transportation payment art, as follows:  
         [0006]     The transportation server can reliably accept the result of an SMS payment even if the server does not have a network connection to any global infrastructure.  
         [0007]     The system can manage the case where payment is time-dependent. and a user changes transportation (from a bus to a train).  
         [0008]     The system can know when, and react to, a given user is repeatedly using the same service.  
         [0009]     The system can protect against fraud where users collude against the system (‘I give you this password for half the price . . . ).  
         [0010]     Prior art related to transportation payment systems and authentication/validation includes:  
         [0011]     1. U.S. Pat. No. 6,386,451 entitled “Travel system and methods utilizing multi-application passport cards”, issued May 14, 2002 discloses a travel system and methods that encompass a plurality of travel service providers and multi-application passport cards for the automated compilation, issuance, and utilization of the passport cards for said plurality of travel services, including the implementation of related application scenarios. The multi-application cards are realized by portable device technologies, such as, smart cards or pocket-sized computer devices, and have the ability to store and activate a traveler&#39;s permit for transportation and other passport services; as well as a monetary value for electronic payment means. Biometrics identification of cardholders, as well as cryptographic certification of card data and travel-related information, can optionally be encoded onto the cards and can be verified, including validated, at various point-of-service locations upon presentation of the card for utilization.  
         [0012]     2. U.S. Pat. No. 5,887,266 entitled “Method for using applications in a mobile station, a mobile station and a system for effecting payments”, issued Mar. 23, 1999 discloses a method for using an application in a mobile station. The application has a first mode of operation and a second mode of operation. The first mode of operation is passive. In the second mode of operation the application controls a master control unit (MCU) of the mobile station. Also provided is a system for making payments, comprising at least one mobile station which has an associated application, a component for using the application, and a first transceiver for providing local data transfer. The system also comprises at least one cash register or the like, which has a second transceiver for providing data transfer. The application has a capability for causing data to be transferred from the first transceiver to the second transceiver.  
         [0013]     3. U.S. Pat. No. 6,615,262 entitled “”Method and apparatus for remotely administered authentication and access control”, issued Sep. 2, 2003 discloses authentication and session management can be used with a system architecture that partitions functionality between a human interface device (HID) and a computational service provider such as a server. An authentication manager executing on a server interacts with the HID to validate the user when the user connects to the system via the HID. The authentication manager interacts with authentication modules. Each authentication module may be configured to authenticate a user based on a different authentication mechanism (e.g., using a smart card, using a login and password, using biometric data, etc.) and may be utilized in connection with one or more sessions. The authentication manager and authentication modules are also responsible for controlling access to services/sessions and may remove/revoke or augment such access. A session manager executing on a server manages services running on computers providing computational services (e.g., programs) on behalf of the user. The session manager notifies each service in a session that the user is attached to the system using a given desktop machine. A service can direct display output to the HID while the user is attached to the system. When a user detaches from the system, each of the service&#39;s executing for the user is notified via the authentication manager and the session manager. Upon notification that the user is detached from the system, a service continues to execute while stopping its display to the desktop machine.  
         [0014]     None of the prior art discloses a mobile terminal equipped for SMS payment and service authentication in a mobile environment with a remote payment and transaction provider (authentication server) wherein common secrets &amp; a seed serve in an algorithm to generate a list of authentication pairs (username-password) for transactions. The common secrets and seed are shared with remote transaction provider and redemption devices (local servers) via a non-continuous communication link, wherein the seed is periodically updated. A subscriber conducts payment with the authentication server and receives an authentication pair in a token or ticket corresponding to the purchased service, the authentication token being generated by the authentication server based on the common secrets and current value of the seed. Upon service redemption, the subscriber provides the authentication token to the local server which compares the authentication token with sets of valid authentication token generated by the local server based on the common secrets and current value of the seed provided by the remote transaction provider. If the comparison indicates a match, the local server provides the service to the subscriber and makes a log record of the transaction.  
       SUMMARY OF THE INVENTION  
       [0015]     In one embodiment, the present invention is applicable in a transportation environment enabling users to purchase local train/bus service from a remote transaction provider. Each user carries a portable terminal, typically a GSM mobile phone enabled for Short Message Service (SMS). The user using SMS messaging can electronically interact with the remote transaction provider via a wireless wide area network (WWAN) or through a local connection, if the transaction provider is represented in a local environment. The remote transaction provider or authentication server stores two (2) secret keys (s 1 ) and (s 2 ) and a seed (x) assigned to a specific future date. Each date is divided into time periods and each time period is assigned a seed x d, P′ , where (d) is a future date and (p) is a time period. The time is taken into account especially in connection with services that are valid for a limited time period. For each time period, a list of username (u)-password (p) pairs (u i   d,p, p i   d,p ) are generated. The user will be identified by the user&#39;s phone number and tied to a given temporary username and password which form an authentication token. The authentication server upon receiving the user SMS request, returns an authentication token and logs the user&#39;s phone number, time and returned authentication token. Previously, the authentication server provided local redemption servers with the seed and the common secrets via a non-continuous communication link, and periodically updates the seed, common secrets and current time. Using the seed, common secrets and current time, the redemption servers calculate a list of authorized authentication token. When the user enters the token into the local redemption server, the local server will check the correctness of the token by comparing it to all possible authentication token for the given time period. If the token is found in the set of possible tokens, the local server will accept the token and tie the media access control (MAC) hardware address of the user device to the authenticated token. Otherwise, the token is rejected and the local server rejects service for the user.  
         [0016]     An aspect of the invention is an electronic payment system securing authentication/validation of transactions remotely from a transaction provider for use in a local redemption device that does not have continuous connection with the remote transaction provider.  
         [0017]     Another aspect is a mechanism allowing a local redemption device to confirm validity of a transaction token/ticket even in the cases where there is no connection available to a remote transaction provider.  
         [0018]     Another aspect is a user interacting with a remote authentication server to obtain authenticated tokens for local transportation service after validation of the token by a local server.  
         [0019]     Another aspect is a time based token for transportation service generated by recursively applying a keyed hash message authentication code (HMAC) to an authentication pair. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0020]      FIG. 1  is a representation a mobile terminal interacting with a remote transaction provider to obtain authenticated token(s) for acceptance/rejection by a local server providing user services wherein the local server is in non-continuous contact with the transaction provider and the transaction provider and local server generate a list of authenticated tokens from common secrets and a seed provided by the remote transaction provider used for authorizing or rejecting service for the user according to an embodiment of the present invention.  
         [0021]      FIG. 2  is an exemplary algorithm according to an embodiment of the present invention for the construction of a username-password (UN/PW) from the common secrets and seed used in generating tokens for use in the system of  FIG. 1 .  
         [0022]      FIG. 2A  is a representation of time periods for a seed used in the algorithm of  FIG. 2  in generating a username-password according to an embodiment of the present invention.  
         [0023]      FIG. 3  is a signaling diagram between the user and the remote transaction provider and local server in  FIG. 1  for obtaining and using an authorized token for service under the control of the local server according to an embodiment of the present invention.  
         [0024]      FIG. 3A  is a representation of an electronic ticket for use in the system of  FIG. 3 .  
         [0025]      FIG. 4  is a representation of the state of  FIG. 1  for a user making a transaction request/payment according to an embodiment of the present invention.  
         [0026]      FIG. 5  is a representation of the state of  FIG. 1  for a user receiving a transaction token calculated by the transaction provider from the common secrets and seed according to an embodiment of the present invention  
         [0027]      FIG. 6  is a representation of the state of  FIG. 1  for a user negotiating a transaction token/ticket with the local server for service according to an embodiment of the present invention.  
         [0028]      FIG. 7  is a representation of the state of  FIG. 1  for the local server accepting/rejecting the token for service according to an embodiment of the present invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0029]     As an overview, the present invention is designed to be applicable especially in connection with public transportation systems, wherein the subscribers may purchase tokens or ticket(s) for services from a remote service provider by sending a request for a ticket via a wide area network, e.g. using SMS. The remote service provider can charge the subscribers e.g. by way of adding the value of the ticket to subscriber&#39;s phone bill. In an alternative embodiment the subscribers may buy the tickets locally from a dedicated purchase place through local area connection. In any case, after necessary payment procedures are completed, the subscriber is provided with a ticket authenticated for acceptance by a local server for transportation services after validation. In an alternative embodiment, the object of the purchase may be e.g. a token representing an amount of money that the subscriber is allowed to use for a certain services (e.g. pre-paid systems).  
         [0030]     In  FIG. 1 , a transaction and payment system  100 , according to an embodiment of the present invention includes a transaction provider (authentication server)  102  linked to redemption/service terminals (local server)  104   1 ,  104   2  via non-continuous wireless connections  106   1  and  106   2 , respectively through  a wireless wide-area network  108 . The connection may be secure and mutually authenticated. The local servers may be stationary at a train station or mobile when installed in a vehicle. A plurality of mobile terminals interacts with the local servers  104   1  and  104   2  to obtain transportation services. For purposes of illustration, mobile terminals  110   1 ,  110   2  and  110   N  interact with server  104   1  and mobile terminals  112   1 ,  112   2  and  112   N  interact with server  104   2  for obtaining goods or services, after payment to the transaction provider  102  and validation of a token or ticket for service issued by the provider  102 . It should be understood, however, that any mobile terminal is free to interact with any local server, wherever, for obtaining services. The mobile terminal is SMS enabled and the subscriber/user is assumed to have a working knowledge regarding how to use short messages. A SMS telephone system is described in U.S. Pat. No. 6,665,531 assigned to the assignee of the present invention and fully incorporated herein by reference.  
         [0031]     The transaction provider  102  (Authentication server) is a conventional server linked to the network  108  and including storage  114 , typically non-volatile, for storing programs and processes interacting with the mobile terminals for payment of services and executing algorithms in an authentication system for issuing tickets/tokens for the services requested by the subscribers. The authentication system uses keyed message digests for providing security. In one embodiment, keyed Hashing for Message Authentication Codes (HMAC) is used with a cryptographic hash function, typically MD5. HMAC is described in IETF RFC 2104 and MD5 is described in IETF RFC 1321. HMAC requires a secret key for the calculation and verification of the message authentication values. To this end, keys (s 1 ) and (s 2 ), e.g. 128 bit random strings are stored in the storage device  114  along with a similarly constructed seed (x) that serves as the base for the authentication value generation (ticket/token) during a designated time-period.  
         [0032]     The redemption/service terminals  104   1  and  104   2  (local servers) also include storage units  116  and  118 , respectively storing programs for processing and validating tickets/tokens presented for services by the subscribers. The common secret keys (s 1 ) and (s 2 ) and seed (x) are supplied by the server  102  to servers  104   1  and  104   2  on an intermittent basis due to the non-continuous connection between the server  102  and the server  104 . The communication of the secrets and seed must be done over a protected channel, or alternatively the transmission of the configuration data must be encrypted and integrity protected for the duration of the transfer. The shared secrets and seed are used by the servers  104   1  and  104   2  to calculate lists of authentication tokens, and validating/rejecting the subscriber ticket/token for services, as will be explained hereinafter. The authentication may take a form or authentication token according to one embodiment of the present invention, but that is just one embodiment for the present invention . . . . The seed can be considered to represent a security context for a given time period. Seeds for future time periods can be transmitted to servers  104  ahead of time. More importantly, the seed provides enough randomness to prevent outsiders from hacking the hash codes and misusing the hacked authentication token. The seed can be valid for various time periods e.g. one day. However, in the case of public transportation, a single ticket may be valid for limited time periods, e.g. 2 hours. If further security is required, the validity time period of the seed may be divided into several sub-timing periods, each having separate authentication tokens calculated on the order number or time period of the sub timing period, and to be described further in connection with  FIG. 2A .  
         [0033]      FIG. 2  describes an algorithm  200  for constructing username (UN) and password (PW) pairs for the authentication and local servers according to an embodiment of the present invention. In step  201 , a seed (d) is assigned a specific date and in step  203  combined with secret key (s 1 ) in a HMAC process. Each day is divided into equal time periods in steps  203 ,  205  and  207  and each time period is assigned a seed x d,p′  calculated in step  209  as a reverse (keyed) hash chain over the time periods (l), i.e. x d, p′  (1)=HMAC(s 1 , x(l−1)) 1I  from the expression: 
 1=( y−d )× g +( g−p )  
         [0034]     Where:  
         [0035]     1=remaining time periods.  
         [0036]     y=a specific date in the future.  
         [0037]     p=time period.  
         [0038]     d=date of time period  
         [0039]     g=time periods in day.  
         [0040]     For each time period a number n (currently n=1000) of username-passwords pairs u i   d,p, p i   d,p  are generated again in step  211  by recursively applying the keyed HMAC function, =u i   d,p, p i   d,p =HMAC (S 2 , X D,P ) 1  in steps  213 - 217 . The user will be determined by the user&#39;s phone number and tied to a given temporary username and password only through logs, so actually the username and password together form an authentication token.  
         [0041]     The redemption/service device  104  upon calculating the sub-timing periods  250  of a seed  252 , as shown in  FIG. 2A , maintains a predefined set of the authentication tokens in a valid authentication token list. According to one embodiment of the present invention, the valid list includes the authentication token of the current sub-timing period  254  and one sub-timing period before  256  and after  258  said sub-timing period in order to ensure the correct validity period for the tickets. This can of course be adjusted based on the needs of the current application.  
         [0042]      FIG. 3  taken in conjunction with  FIGS. 4-7  discloses a signaling process  300  between the subscriber and the authentication server  102  and the local server  104  for acquiring services according to an embodiment of the present invention. The process is started by the user sending the server  102  a request and payment for service message  301  via a cellular link/connection using an SMS enabled phone ( FIG. 4 ). The server  102 , upon receiving the SMS, will return an authentication token, and log the user&#39;s phone number, time and the returned authentication token in a message  303  ( FIG. 5 ). The authentication tokens are given out in random order from the set of n tokens generated for the current date and time period (d, p). A given token is given out only once. The token of bit length (x) (currently x= 32 , is presented to the user as two 4-character hex strings, one as a user name and one as a password). The user name and password strings should be user friendly in the sense that an ordinary user should he able to look at the string in the phone display, memorize it, and type it in one setting. Even though the two strings currently contain only 32 bits of randomness, improved versions with a larger character space or longer strings can be taken into use without significant changes in the system. The user name-password pairs can, especially if their length is increased, be mapped into plaintext strings (using a dictionary) to make it easier for the user to memorize and enter the authentication token/ticket.  
         [0043]     The user, when connected to the server  104 , is given instructions to type in an authentication token (username-password) and returns the information in a message  305 . The user may not be aware of the actual data to be transmitted and provided only with e.g. a graphical indication of the ticket that does not reveal the actual authentication pair. Instead of typing the authentication pair, a Bluetooth or RFID connection to the server  104  may be used to transfer an authentication token to the server  104 , as will be described in  FIG. 3A  hereinafter. When the user enters the authentication token into the mobile server via message  305  the server will check the correctness of the token by comparing to all possible tokens  
           ∀     i   ⊄     (       0   ⁢   …n     -   1     )         ⁢       ∀     c   ⊄     (     l   -   r…l   +   r     )         ⁢     u   c   i         ,     p   c   i         
where  1 time period defined by d, p, and r is a factor providing authentication token period overlap compensating an assumed synchronization mismatch between local server and authentication server clocks, where r is currently  1. If the token is found in the set of possible tokens and not used yet, the mobile server will accept the login, and tie the MAC hardware address of the user device (as seen by the mobile server) to the given authentication token. ( FIG. 7 ). A re-authentication operation with a previously accepted authentication token will only be accepted by the redemption local server via a message  307 , if the MAC address has not changed between authentication attempts.  
         [0044]     Alternatively, the user may be requested to feed in an existing authentication token or request a new one with an SMS message to the authentication server  102  at a given SMS number. When the user is presented with the phone number to send his password request to the server  102 , he/she may be requested to input a local server identifier in the SMS message. In such a case, the seed and secret keys may be different for each local server. Furthermore, a password acquired in one local server would not be unconditionally accepted in another when the user switches trains. However, this inconvenience my be remedied in several ways, the easiest being to enlarge the authentication token space; allocate given sets to different local servers, and provide some extra checking if a user “boards” a local server with a token belonging to some other local server. Alternatively, a more elaborate and user friendly protocol can be constructed with a client entity in the user terminal, which gets input from the local server and communicates with the authentication server using the phone as a SMS modem. The solution is OS independent with respect to the client terminal.  
         [0045]     All unsuccessful, as well as successful login attempts are logged, containing the authentication token, time and the perceived MAC address of the user device making the login attempt. In order to prevent possible misuse the usage information of authentication tokens are collected at the local server and merged with the user/terminal identification information related to token purchase. The collected “log” information is then transmitted to periodically to the remote server. If inappropriate usage of tokens is detected, the remote server can provide an alarm containing the user identification and the way the token was misused in order to expel the users behind the misuse.  
         [0046]     In an alternative embodiment, as shown in  FIG. 3A , an authentication token  302  is embedded in an electronic ticket  304  of a data frame  306 , upon purchase, e.g. through SMS. The ticket is sent to the user and stored in a passive RFID device (not shown) included in the user&#39;s mobile device. The ticket is not shown to the user at all. The user may be provided additional information in a message accompanying the ticket, e.g. “One-Day Bus ticket. ID No. 11234XYX123. Please provide the ticket to the redemption machine when entering” . . . . The actual authentication data (authentication pair) is hidden within the ticket. When the ticket is activated in the mobile phone upon entering, e.g. a bus, the redemption device sends an RFID interrogation signal  307  ( FIG. 6 ). The user&#39;s mobile device responds to the signal  307  and sends a RFID response  309  ( FIG. 7 ), including at least the authentication token information and preferably the mobile terminal identification. The redemption device validates the token information by comparing to the valid token list previously calculated by the redemption device from common secret keys and seed, as described in connection with  FIG. 2A . After validation, the purchased services are made available to the user.  
         [0047]     While the invention has been described in a preferred embodiment, various changes can be made therein without departing from the spirit and scope of the invention as defined in the appended claims, in which: