METHOD OF PROVIDING A VOUCHER FOR A SERVICE TO BE RENDERED, AS WELL AS A SYSTEM FOR CHECKING VOUCHERS

Abstract: Using an electronic payment card and a payment station, it is possible to carry out a payment transaction. In this connection, the payment station is capable of producing a transaction code (4) comprising the key transaction data, and an authentication code (5) guaranteeing the authenticity of the transaction code (4). In accordance with the invention, the combination of transaction code (4) and authentication code (5) is used as a voucher (3) for a service to be rendered. For this purpose identification data (6) is added to the transaction code, the identification data identifying the service to be rendered, and the combination of the transaction code extended in this manner (4') and authentication code (5) is printed on a substrate (7), in order to form a voucher (3).

Description: Method of providing a voucher for a service to be rendered, as well as a system for checking vouchers. The invention relates to a method of providing a voucher for a service to be rendered, comprising the execution of a payment transaction using an electronic payment card and a payment station, which payment station is arranged for producing a transaction code representative of the transaction, and an authentication code related to the transaction code. Such method is generally known. Electronic payment cards, i.e., cards provided with an electronic circuit for carrying out payment transactions , are increasingly being applied in practice. During a payment transaction, the electronic payment card co-operates with a payment station or terminal, such as a cash register provided with a card reader. Between the electronic payment card and the payment station, there data is exchanged during the transaction. An example of such data exchange is described in the European patent application EP- 0.637.004. Some of these data items, i.e., data characterising the transaction in question, is stored by the payment station as a transaction code or transaction record. Said transaction code, which contains, inter alia, the amount of the payment transaction, serves to be capable of afterwards settling the payment transaction with one or more financial institutions (e.g., banks). The payment station adds an authentication code to the transaction code in order to guarantee the authenticity of the transaction code. Electronic payment cards are used for purchasing vouchers for services to be rendered, such as transportation documents for public transport (bus and train tickets) , admission tickets for theatres, cinemas and museums and the like. The electronic payment card serves to carry out the payment transaction, whereafter a paper voucher (transportation document, admission ticket and the like) is issued. On the voucher, generally identification data identifying the service to be rendered is also printed, such as a date, a point in time, a destination and/or a seat. The Dutch patent application NL 93.01902 discloses a method for paying, using an electronic payment card, for a service to be rendered, the voucher document being stored on the payment card. When purchasing the service (e.g., acquiring access to a theatre), the voucher is electronically read by an access terminal and subsequently erased. In this known method, the voucher consists of an access code, possibly supplemented by an identification code of the payment card. This known method, however, is fraud-sensitive since no provisions have been made to secure the admission code. For swindlers, therefore, it is relatively easy to apply an access code to the card themselves, or to modify an access code once applied. Fraud-resistant techniques for storing, in electronic form, vouchers in a payment card are described in the European patent applications EP 0.823.694 and EP 0.829.828. In this case, however, it concerns specific data structures for storing and using vouchers in electronic form. Furnishing paper vouchers is not provided for. The object of the invention is to eliminate the above and other drawbacks of the prior art, and to offer a method for providing a voucher for a service to be rendered which makes it possible in a very simple manner to generate a safe voucher. A further object of the invention is to offer a method for providing a voucher for a service to be rendered, use being made, in as far as possible, of available means and data. For this purpose, a method of the type referred to in the preamble , is according to the invention characterised by adding to the transaction code identification data identifying the service to be rendered, in order to form an extended transaction code, and printing on a substrate the extended transaction code and the authentication code in order to form a voucher. By printing the combination of the transaction code and the authentication code onto a substrate, in an easy way a voucher is obtained in which the data characteristic of the transaction is included. Here, use is made of data which is generated by the payment station anyway, namely, the transaction code and the associated authentication code. By adding, to the transaction code, identification data identifying the service to be rendered, a further specification of the voucher is provided, if necessary. The identification data may indicate, e.g., a point in time, a destination or a seat. Possibly, however, the identification data may also have a zero value, i.e., be "empty" , as a result of which the addition thereof is actually omitted, such as a function of the service to be delivered. The substrate on which the voucher is printed may be, e.g., a piece of paper, cardboard or synthetic material, or a combination thereof. Basically, it is possible to add the identification data to the transaction code after forming the authentication code. Preferably, however, the method according to the invention is characterised by producing the authentication code after adding the identification data to the transaction code. This way, the authentication code also guarantees the authenticity of the identification data, as a result of which the identification data is protected against fraud as well. The authentication code is therefore preferably produced cryptographically, as a result of which it is not possible to copy this code. In the event of producing the authentication code cryptographically, use is made, in the method according to the invention, of the fact that the cryptographic means required for that purpose are already present in the payment card and the payment station. It is therefore not required to provide and to manage supplementary cryptographic means . The cryptographic means to be used can therefore be provided and managed by an external party, such as a financial institution. It should be noted that the European patent application EP- 0.294.397 discloses a system in which printing franking values containing franking codes on envelopes is included. The system utilises a physically protected printing unit. In addition, the franking code comprises an encoded marking printed in invisible ink. These measures render the known system relatively complicated and expensive . In the method according to the invention, an unprotected printing unit may be applied, and the printing may be carried out using only visible ink, since the authentication code offers sufficient protection against fraud (applying modifications) . In addition, the method according to the invention is not primarily aimed at postal applications, but rather at access tickets for (public) transport, theatres etc. The method according to the invention is advantageously characterised by printing the transaction code in a form readable to humans. As a result, the voucher can be easily read by a human inspector. The authentication code, however, is preferably printed in machine-readable form, e.g., as a so-called bar code. An embodiment of the method according to the invention is characterised by storing the voucher in the payment card. As a result, to start with, it is possible to print out the voucher only afterwards on a suitable substrate, i.e., not during the transaction in which the service to be rendered is paid for. In this manner, the option of entirely omitting the printing of the voucher is also offered. In this case, the voucher may be offered in electronic form in the event of a check. The invention further offers a device for providing a voucher for a service to be rendered, the device comprising means for carrying out a payment transaction by way of an electronic payment card, which means are arranged for producing a transaction code representative of the transaction and an authentication code related to the transaction code which, according to the invention, is characterised in that the means are further arranged for adding, to the transaction code, identification data identifying the service to be rendered, in order to form an extended transaction code, and printing the extended transaction code and the authentication code onto a substrate in order to form a voucher. In addition, the invention provides a system for checking vouchers, characterised by at least a local checking device, which comprises input means, processor means and communication means, a central checking device comprising a checking module, and a telecommunication connection coupled to the local checking device and the central checking device, cryptographic keys required for the checking being present exclusively in the central checking device. Such a system is preferably characterised by a data file for recording vouchers accommodated in the central checking device, with the central checking device being arranged for giving off an error message if a voucher offered to the data file has already been recorded. As a result, a supplementary protection is obtained against fraud, since repeatedly offering the same voucher will be detected. Such a system is advantageously characterised by recording, in the data file, only part of each voucher, preferably the extended transaction code. As a result, the required storage capacity of the data file is reduced, while the retrieval speed of the recorded vouchers is increased. Below, the invention will be further explained by reference to the figures . FIG. 1 schematically shows a system for providing a voucher to which the invention may be applied. FIG. 2 schematically shows a voucher according to the invention. FIG. 3 schematically shows a payment station for providing a voucher according to the invention. The system for providing a voucher, shown only schematically and by way of example in FIG. 1, comprises an electronic payment card 1 and a payment station 2. The electronic payment card 1 comprises , e.g., a substrate 10, in which an integrated circuit (= IC) 11 is accommodated. The integrated circuit 11 is arranged for, inter alia, carrying out payment transactions. Although in FIG. 1 there is shown a card-shaped substrate 10, it will be understood that the shape, or even the presence, of the substrate 10 is not essential to the invention. The payment station 2 is formed, e.g., by an electronic cash register which is equipped with a card reader 12. The payment station 2 preferably also includes a so-called security module 13 , in which balances, cryptographic keys and the like are securely stored. A security module may be formed by a single special integrated circuit. In the International patent application WO 98/02854, an example of a security module is described, referred to as Secure- Application Module or SAM there. During a payment transaction, an exchange of messages between the payment card 1 and (the security module 13 of) the payment station 2 takes place. In the course of the transaction, (the security module 13 of) the payment station 2 records a number of transaction data items, which together constitute the transaction code 4 (see FIG. 2) . The transaction code 4 may comprise, e.g. : - transaction date and time; - identification of the payment station; - transaction amount; - identification of the security module; - identification of the payment card. To this transaction code, there may be added, e.g., one or more of the following identification data items identifying the service to be rendered: - service date and time; - identification of the service-rendering agency; - nature of the service. According to the invention, the identification data items are added to the transaction code 4. The combination of the (original) transaction code 4 and identification data 6 forms the extended transaction code 4'. At the end of the transaction, the security module 13 of the payment station 2 determines an authentication code by reference to the transaction code 4' (extended by the identification data 6), a cryptographic algorithm and a cryptographic key. The voucher formed in this way may subsequently be printed on a substrate using a suitable printing unit. In this connection, a non-secured printing unit may be applied and visible ink may be used. The protection of the voucher is provided by the authentication code, which renders unnoticed modification of the extended transaction code impossible. It should be noted that, during a transaction, the transaction code per se is routinely generated by a security module. Such a transaction code, also called transaction record or transaction log, makes it possible to afterwards settle the payment in question with a financial institution. The invention uses the fact that for each transaction there must be generated a transaction code plus authentication code, to provide a voucher in a simple manner. Furthermore, the invention makes use of the fact that the (cryptographic) means for producing the authentication code are already present in the payment card and the payment station. The invention is therefore based on the insight that the combination of transaction code and authentication code, possibly supplemented by the identification data characterising the service, may be used as a voucher. The invention is also based on the further insight that, for protecting vouchers, use may be made of cryptographic means already present (keys, payment cards and payment stations) , so that it is not necessary to provide a separate cryptographic protection for that purpose. The voucher 3 shown in FIG. 2 is printed on a substrate 7. Said substrate 7 preferably is a piece of paper, but may also consist of a piece of synthetic material or cardboard. Printing on paper may be carried out using a normal, non-secured printer. The voucher 3 of FIG. 2 consists of an (extended) transaction code 4' and an authentication code 5. The transaction code 4' is both printed in a form readable to humans, comprising letters and digits, and in machine-readable form, such as a bar code. The authentication code 5 is printed in a machine-readable form and in the example shown also consists of a bar code. It is of course possible to print the authentication code 5 in a form readable to humans as well. In this case, too, the authentication code 5 may possibly be read out by a machine, but a more expensive machine will then be required. For the checking of vouchers provided according to the invention, a local checking device 30 may be provided with a bar-code reader 31 known per se, as is shown in FIG. 3. The reader 31 may possibly be replaced or supplemented by a keyboard for manually feeding the transaction and/or authentication code. The reader 31 reads the authentication code 5 and, if the transaction code 4 is also printed in the form of a bar code, in addition the transaction code 4 including the identification data 6 of the voucher 3. Subsequently, the processor 32 of the device 30 transfers the authentication code 5 and the (extended) transaction code 4' to a central checking device 35 which is connected to the local device 30, e.g., by way of a telephone line 34. For this purpose, the device 30 is provided with a suitable coupling circuit 33, such as a modem, which is connected between the processor 32 and the telephone line 34. The central device 35 is provided with a module 36 (a so-called host security module) which is capable of checking the authentication code 5. The module 36 which by way of a suitable coupling circuit 38 is coupled to the telephone line 34, for the benefit of checking contains a suitable cryptographic process with associated keys . In the event that the authentication code and the (extended) transaction code do not correspond, the voucher is rejected. For this purpose, a suitable message ("not accepted") is given off to the local checking device 30. It is possible for the voucher to be read anew a limited number of times. In the event that the calculated authentication code corresponds to the authentication code read, the transaction code is passed on to a central data file 37, which may also be accommodated in the central checking device 35. By reference to the data file 37, it is verified whether the voucher in question was already recorded earlier. If such is the case, the voucher in question has evidently been used before and a corresponding message (e.g., "not accepted") is given off to the local device 30. If the voucher has not yet been recorded, this is now done for the benefit of a possible later check and, if necessary, a corresponding message (e.g., "accepted") is given off to the local device 30. A supplementary fraud protection is offered through such a check on double offering. The invention may just as well be applied to payment cards which in operation must be introduced into a card reader as for so-called contactless payment cards. Furthermore, the party providing the vouchers (supplier of vouchers) and the party providing the payment cards and payment stations (supplier of payment means) may be two different parties, but also one and the same party. It will therefore be understood by those skilled in the art that the invention is not limited to the embodiments shown, and that many modifications and amendments are possible without departing from the scope of the invention.

Claims: CLAIMS 1. Method for providing a voucher (3) for a service to be rendered, comprising the execution of a payment transaction using an electronic payment card (1) and a payment station (2) , which payment station is arranged for producing a transaction code (4) representative of the transaction and an authentication code (5) related to the transaction code (4) , characterised by adding, to the transaction code (4) , identification data (6) identifying the service to be rendered, in order to form an extended transaction code (4') , and printing, on a substrate (7), the extended transaction code (4') and the authentication code (5) in order to form a voucher (3) . 2. Method according to claim 1, characterised by producing the authentication code (5) after adding the identification data (6) to the transaction code (4) . 3. Method according to claim 1 or 2, characterised by cryptographically producing the authentication code (5) . 4. Method according to claim 1 , 2 or 3 , characterised by printing the transaction code (4, 4') in a form readable to humans. 5. Method according to any of the preceding claims, characterised by printing the authentication code (5) in machine-readable form. 6. Method according to any of the preceding claims, characterised by storing the voucher (3) in the payment card (1) . 7. Method according to claim 6 , characterised by securing against overwriting the voucher (3) stored in the payment card (1) . 8. Method according to any of the preceding claims, characterised by the use of, inter alia, a date and a point in time of the service to be rendered, as identification data (6) . 9. Method according to any of the preceding claims, characterised by the use of the amount and the point in time of the transaction, for forming the transaction code (4) . 10. Method according to any of the preceding claims, characterised by checking, when purchasing the service to be rendered, the voucher (3) by reference to the transaction code (4) and identification data (6) , as well as to the authentication code (5) . 11. Method according to claim 10, characterised by reading the voucher (3) , subsequently reproducing the authentication code (5) , and comparing the authentication codes (5) reproduced and read. 12. Method according to claim 10 or 11, characterised by updating checked vouchers (3) in a central system (35) . 13. Device (2) for providing a voucher (3) for a service to be rendered, said device comprising means (12, 13) for carrying out a payment transaction using an electronic payment card (1) , which means are arranged for producing a transaction code (4) representative of the transaction and an authentication code (5) related to the transaction code (4), characterised in that the means (12, 13) are further arranged for adding, to the transaction code (4) , identification data (6) identifying the service to be rendered, in order to form an extended transaction code (4') , and printing the extended transaction code (4') and the authentication code (5) onto a substrate (7) , in order to form a voucher (3) . 14. System for checking vouchers, characterised by at least a local checking device (30) comprising input means (31) , processor means (32) , and communication means (33) , a central checking device (35) , comprising a checking module (36), and a telecommunication link (34) , coupled to the local checking device (30) and the central checking device (35) , the cryptographic keys required for checking being present only in the central checking device (35) . 15. System according to claim 14, characterised by a data file (37) for recording vouchers (3), accommodated in the central checking device (35) , the central checking device (35) being arranged for giving off an error message if a voucher (3) , offered to the data file (37) , has already been recorded. 16. System according to claim 15, characterised by recording, in the data file (37), only part of each voucher (3), preferably the extended transaction code (4'). 17. Central checking device (35) for application in a system according to any of the claims 14-16.

Inventors: GERLOFS JOHANNES FRANCIS, PIETERSE ROB, SCHRAMP RUDI, VAN GOLDEN NIELS ALEXANDER, GERLOFS, JOHANNES, FRANCIS, PIETERSE, ROB, SCHRAMP, RUDI, VAN GOLDEN, NIELS, ALEXANDER
Applicants: GERLOFS JOHANNES FRANCIS, GOLDEN NIELS ALEXANDER VAN, KONINKL KPN NV, PIETERSE ROB, SCHRAMP RUDI, GERLOFS, JOHANNES, FRANCIS, KONINKLIJKE KPN N.V., PIETERSE, ROB, SCHRAMP, RUDI, VAN GOLDEN, NIELS, ALEXANDER
Application year: 1999
Main classification: G07F7
IPC codes: G07F7