EP0944027B1 - Franking machine and a method for generating valid data for franking - Google Patents

Description

The invention relates to a franking device and a method for generating valid data for franking imprints according to the preamble of claim 1 or claim 4. The franking device is particularly suitable in the home and for users who send only a few mailpieces.

In DE 40 18 166 C2, a franking module for a personal computer has already been proposed for such users with low mail volume, in whose slot of a drive insert the franking module is arranged, which allows both the franking and the addressing of envelopes. Such a franking module is surrounded by a secured housing and, in terms of circuitry, has the same structure as a franking machine in which the letter transport device is saved. It goes without saying that such a discounted franking module can be offered cheaper than a franking machine.

By using the franking module, the settlement of the franking and the printing of the franking stamp image can not be manipulated externally. The address data are read by a memory managed by the personal computer and fed to the franking module via the internal information network. However, it is not excluded that erroneous address data ultimately lead to the mail carrier, the mailpiece difficult or impossible to deliver to the postal recipient. In a digital printing process, it is difficult to determine whether the printed postage stamp image is not merely an uncollapsed copy of an earlier impression and has been combined with a desired other address. Therefore, special red fluorescent inks are prescribed, which are difficult to copy. With advances in color copiers and color printers, such a move can no longer be considered a serious obstacle to producing counterfeit, unclaimed imprints.

Usually, a printer is connected to the personal computer, with which nowadays not only letters can be printed, but also addresses on envelopes can be printed. In principle, the envelope can also be franked. However, it is difficult to prevent manipulation in such open systems. In fact, over the unsecured links, a forged manipulator might try to inject data into the system by pretending that they came from the authorized site.

The US Postal Authority has published a catalog of requirements for the construction of future secure franking systems published in 1996 (Information-based Indicia Program IBIP). It suggests that certain data be cryptographically closed and printed in the form of a digital signature on the letter to be franked, on the basis of which the postal authority can check the authenticity of franking imprints. At the US Postal Authority arises after estimated Claims by fraud an annual damage of approximately $ 200 million. These requirements have been differentiated according to the type of franking device. Traditional franking machines, which usually print only a franking stamp in red, are also referred to as "closed systems" and, unlike so-called "open systems" (PC frankers), do not need to include the corresponding letter address in the encryption. For open systems, however, a security module with advanced crypto technology and a secure housing is still required, in which data from the data center can be stored.

From US 5,625,839 sending an update information as a data packet to a franking machine is known. Although the accuracy of the data transmission can be checked with a CRC checksum, this does not yet say anything about the correctness of the transmitted data content itself. A problem could arise because of the unsecured connection line, namely, when a forged manipulator tries to store data in the postage meter by pretending that they come from the data center.

In DE 38 40 041 A1, therefore, an arrangement has already been proposed in which a franking device is connected to a central computer via a permanently operating TEMEX dedicated line. The postal customer enters the desired franking value into the franking device. The latter is transmitted to the central computer, which is connected to a Giro computer, in which the customer has a Postgiro account. After a cover check the Giro calculator makes the accounting and the central computer releases the franking function. The franking device itself also has additional postal memory, which can be queried due to the data network and provide additional security against data loss in the event of a computer failure. The central computer triggers an alarm if this leased line is tapped or interrupted without authorization. However, it is complicated and thus not everywhere possible to use such a special secure line.

From EP 373 971 B1 a communication system is known, with a transfer of address data from a local to a central database in a data center, updating the stored address data in the central database of the data center based on the transmitted address data and modifying the address data of the System existing local databases based on the updated data center data. This ensures that the data in each local database is maintained in accordance with a central database. In the case of an unsecured connection line, however, it is not possible to prevent an incorrect address from being stored in the central database of the data center and from there to the respective local database of the further users.

According to EP 663 652 B1, a mailing list containing correct and incorrect address data is generated for preparing packages. This list is sent to the remote data center, generating a digital token and debiting an account.

In EP 782 296 A2, although a public key method was proposed for retrieving a certificate from an address book memory via an unsecured communication connection, it can only be used to ensure that the transmitted message is authentic. Thus, as well as a fake message could be transmitted, but whose certificate is genuine.

In franking systems, in addition to the correctness and authenticity of a message, it is also important to have the right billing. Therefore, a postage box has already been proposed in a terminal (US 5,233,657) or a secure module (US 5,625,694) in which the accounting data are stored.
The terminal according to the solution proposed in US 5,233,657 is used as a facsimile and franking machine, wherein essential franking image data is requested from a data center and then with other image data, which are stored in the terminal, completed as a franking imprint to be printed. The communication between terminal and data center is secured by a cryptographic method, eg according to the known RSA method. From the data characterizing the terminal, a security code is generated by the central processing unit of the terminal and printed together with the franking value. A disadvantage is the tedious computing work that the central processing unit would have to perform, on the one hand when image data is decrypted according to the RSA method and on the other hand when the security code is generated.

In US 5,625,694 a computer is equipped with a secure module. In a request for a digital signature to such a secure module, wherein the request is made in response to a change in the input franking value and a recipient address, the secure module then generates a corresponding digital signature and transmits it to the microprocessor of the computer, but on the other hand leads also the billing through. The microprocessor of the computer then generates a printed image corresponding to the franking value and the recipient address and the transmitted signature. A signature is not requested by the secure module unless neither the franking value nor the address is changed. A copy of the same impression will not be included in the secure module. The postal carrier is responsible for the authenticity check for each individual item of mail. Even the smallest differences in the address affect the signature. However, it is not certain that the user will enter a valid recipient address. A postal item provided with an invalid recipient address may possibly not be delivered, even though it has been franked with a valid postage and the postage has been properly settled in the secure module because the address can not subsequently be corrected. Expensive in all the above solutions, the need for the arrangement of a secure module in the terminal.

The object is to provide a low-end franking device with a local database, wherein valid addresses are stored in the local database of the franking device. Furthermore, a method for generating valid data for franking imprints is to be specified so that as a result valid franking values with valid addresses can be printed together with a signature on the mailpiece.

The object is solved with the features of claims 1.

The need for the arrangement of a secure module in the terminal is eliminated. This eliminates the need to recharge a credit in the terminal and to make the communication accordingly safe from manipulation of the balance. According to the invention, a digital signature is generated in a data center of a manufacturer of franking systems or of a mail carrier. The communication with the data center is relatively short, since the transmitted clear data neither image data include nor all data is encrypted, but in addition to the clear data only a relatively short signature is returned. Furthermore, the service of the data center with regard to a correction of a wrongly entered postal recipient address is advantageous. Thus, false frankings can be avoided. In one variant, a postage calculation according to the valid tariff can be made as an additional service by the data center. It is also favorable for the security of manipulation that secret keys and other security-relevant data are stored only in the data center and can not be read externally. The impression of the transmitted data on that piece of mail can also be made at any later time. There are no restrictions for the external image generation from the transmitted data. So different printing methods can be used. The different conditions of use and requirements of the individual postal carriers can best be met in this way.

Fig. 1,

Blockschaltbild für die Frankiereinrichtung und die Datenzentrale,

Fig. 2,

Beispiel für einen Abdruck auf einem Poststück.

An advantageous development of the invention is characterized in claims 2. Show it:

Fig. 1,

Block diagram for the franking device and the data center,

2,

Example of an impression on a mail piece.

In the block diagram according to FIG. 1, a data center 20 is communicatively connected to franking devices 10 and 30 and to a checking station 50, for example in the post office, of the mail carrier via a communication network 40.
The franking device 10 is designed as a digital printer 17 which is controlled by a first computer 11 and which can print at least envelopes of a format. For example, a personal computer PC 1 is connected on the one hand via an unsecured cable 16 to the printer 17 and on the other hand via modem 15 and communication network 40 with the data center 20 on-line record a communication link. To the first computer 11, a hard disk memory 13 for a local database, a keyboard 14 and a display unit 12 are connected. By the latter input / output means 12 and 14 corresponding inputs can be made and made visible or the further program execution monitored. During the on-line connection, a reconciliation of the database of the local database and a storage of the transmitted data takes place. The production of impressions on the basis of the transmitted stored data can take place at a later time.

The data center 20 consists of a second computer 21, preferably a personal computer PC 2, with connected input / output means 22 and 24, a hard disk 23 and at least one modem 25. The hard disk 23 stores special service programs and accounting data for services provided to a customer.

On the hard disk 13 of the first personal computer PC 1, a corresponding application program is loaded, which is tailored to the needs of the user for soho (smal office & home office) markets. In such a market, it does not depend on the number of franked letters per unit of time, but only on low expenditure with moderate costs. A mere message could be sent by e-mail. But in practice also unique original images, photos, books, fabrics, etc. are to be sent enveloped in an envelope. The invention is therefore based on the fact that the basic system consisting of a computer and printer is already available to the user. Only then can be dispensed with in the terminal to additional and expensive hardware components, such as a security module, if the franking system is designed according to the invention. The computer must be equipped with a high-speed modern processor and sufficient memory to handle modern cryptographic technologies. The invention further assumes that communication links via the network 40, for example, those via the Internet, WWW (World Wide Web) or ISDN, can be produced inexpensively in the future.

The invention resides in the fact that the data center checks the validity of a mail recipient address on the basis of a central database created on the hard disk 23 and, if necessary, makes sure that the franking device checks the authenticity of a transmitted mail recipient address before storing it in the local database. In this case, a public key is used, which is preferably transmitted together with the valid postal recipient address and the signature of the correct data center. No other than just the right data center can produce the authentic signature.

The checking of the validity of an address requires maintenance of the address files of the central database by a mail carrier or by a service commissioned by the mail carrier. To cover the resulting costs, the use of the address files by external users as a paid service is charged to the user.

To carry out the check at least the postal recipient address to be printed (address) is first transmitted to the aforementioned data center. An incorrect address of the address can be automatically corrected by the postal code or a similar destination code, if there is a corresponding file in the central database for the latter. The same applies vice versa. However, if an automatic correction is not possible, the user is informed and asked to enter the address correctly. After the check, a postal value corresponding to the valid tariff and the valid, possibly previously corrected, postal address postal address are returned to the franking device, whereby the returned data are linked together by means of a signature. As an intermediate step, a message is generated from the data to be transmitted by using a special mathematical function which reduces the amount of data to be encrypted. The signature is generated by encrypting the message with a secret private key according to a known non-symmetric encryption algorithm.

A suitable known asymmetric encryption algorithm is, for example, the Digital Signature Algorithm (DSA), an Elliptic Curve Digital Signature Algorithm (ECDSA) or the ELGamal Algorithm (ELGA). These signature algorithms share a key pair which includes a private and public key. The private key is a secret non-externally readable write key. And the public key acts as a read key for the signature and is accessible to everyone.

In the non-prepublished German application with the title: "Method for a digitally printing postage meter machine for generating and checking a security imprint", asymmetrical encryption algorithms of this type have been explained in more detail on "closed systems". However, in contrast to the solution according to the invention, a postage security device for encryption is used on the franking machine side, which according to the invention can now be dispensed with.

Instead, the hard disk 23 of the second computer 21 of the data center 20 has specially secured storage areas for storing the private key, so that the latter can not be read out externally. Alternatively, a separate memory, for example a semiconductor memory, can be used for the secure storage of the private key, wherein the memory is integrated in the computer and secured against unauthorized reading out.

• auf eine gespeicherte bestimmte Postempfängeradresse zuzugreifen oder eine neu eingegebene bestimmte Postempfängeradresse zwischenzuspeichern,
• Anforderungsdaten des Postabsenders per Kommunikationsmittel zur Datenzentrale zu übermitteln, wobei die Anforderungsdaten die Identifikationsdaten des Postabsenders und Postversendungsdaten, einschließlich die bestimmte Postempfängeradresse, umfassen, um die Richtigkeit der Postempfängeradresse mittels eines zweiten Computers zu bestätigen oder anhand einer in der zentralen Datenbank gespeicherten Adreßdatei herzustellen,
• Daten zu empfangen, betreffend eine gültige Postempfängeradresse von einer in der zentralen Datenbank gespeicherten Adreßdatei, einen gültigen Portowert und eine Signatur, wobei der zweite Computer der Datenzentrale die angeforderten Daten nur mit einer Signatur ausstattet, wenn eine gültige Postempfängeradresse in der zentralen Datenbank gespeichert ist, wobei eine Mitteilung erzeugt wird, wenn eine automatische Korrektur einer Postempfängeradresse unmöglich ist,
• die von der zentralen Datenbank empfangenen Daten einschließlich der Signatur zu verarbeiten, um einen authentischen Frankierabdruck auf das Poststück abzudrucken.

Es ist weiterhin vorgesehen, die Authentizität der zur Frankiereinrichtung übermittelten empfangenen Daten anhand der Signatur zu überprüfen und bei Authentizität die Adreßdatei in der lokalen Datenbank bezüglich der bestimmte Postempfängeradresse zu aktualisieren.It is envisaged that the first computer 11 is programmed in memory by means of a user program in order to

• to access a stored particular mail recipient address or to cache a newly entered particular mail recipient address,
• To transmit request data of the mail sender to the data center via communication means, the request data including the mail sender's identification data and mailing data, including the specific mail recipient address, to confirm the correctness of the mail recipient address by a second computer or by using an address file stored in the central database;
• Receiving data relating to a valid mail recipient address from an address file stored in the central database, a valid postage value and a signature, the second computer of the data center providing the requested data with a signature only if a valid mail recipient address in the central database a message is generated, if an automatic correction of a postal recipient address is impossible,
• process the data received from the central database, including the signature, to print an authentic franking imprint on the mailpiece.

It is furthermore provided to check the authenticity of the received data transmitted to the franking device on the basis of the signature and, in the case of authenticity, to update the address file in the local database with regard to the specific mail recipient address.

• Bildung und Übermittlung von Anforderungsdaten, mit welchen ein erster Computer der Frankiereinrichtung von einem zweiten Computer einer Datenzentrale eine Signatur anfordert, wobei die Anforderungsdaten mindestens eine Informationsgruppe mit Postempfängeradressendaten und Identifikationsdaten einschließen,
• Erzeugung einer Signatur auf der Basis verifizierter Daten unter Verwendung eines asymmetrischen Kryptoalgorithmus und geheimen privaten Schlüssels, sowie
• Rückübermittlung der verifizierten Daten und der Signatur zur Frankiereinrichtung, wobei die Authentizität der zurückübermittelten Daten anhand der Signatur unter Verwendung eines öffentlichen Schlüssels überprüfbar ist, sowie
• Speicherung authentischer empfangener Daten in einer lokalen Datenbank.

The method according to the invention for generating a valid database for franking imprints comprises the following steps:

• Formation and transmission of request data with which a first computer of the franking device requests a signature from a second computer of a data center, the request data including at least one information group with mail recipient address data and identification data,
• Generation of a signature based on verified data using an asymmetric crypto algorithm and secret private key, as well
• Returning the verified data and the signature to the franking device, wherein the authenticity of the returned data can be checked on the basis of the signature using a public key, and
• Storing authentic received data in a local database.

It is envisaged that the validity of data is checked by the second computer in the data center and if necessary established that the signature is generated by the second computer in the data center from the requested data. Thus, it is ensured that the data received from the terminal to be returned partially valid data from the second computer in the data center by means of the signature have been linked together. The first computer thus receives valid data according to the request via modem. It is furthermore provided that a comparison is made by the first computer on the basis of data of the information group and data of a received information group transmitted to the data center, an authenticity check being carried out with respect to the received information group by means of the signature, a public key being used during the authenticity check, which is stored in the central or a local database retrievable. In the case of a detected deviation between the transmitted and received data as a result of the comparison, the data in the local database is updated only if the received data is considered authentic. From the first computer is then generated at any later time from the received data, a print image and causes a print accordingly.

Complying with the post-recipient address data in the local database thus requires an authenticity check based on the signature in the personal computer PC 1. The authenticity check uses a public key, which can be retrieved from the central or a local database. The public key may be stored in an unsecured storage area along with an associated validation date.

Anyone can use the public key to recover the message from the signature by decrypting it. For comparison, a reference message is generated from the transmitted plain data by using the same aforementioned special mathematical function which reduces the amount of data. In the case of equality of the decrypted message with the reference message formed, the authenticity of the data is given, the validity of which is ensured by the data center at least for the postal recipient address.

In the same way, it is also possible with the authenticity check to check whether a billing has taken place in the data center on the basis of the signature in a post office 50 or in a mail delivery office or an institute of a private mail carrier. For this purpose, a monotonously continuously variable size is entered into the signature, which at the same time is printed in plain text on the mail piece but at least machine-readable. Such a quantity is, for example, the time data at the time of retrieval of the signature from the central database or the number of pieces. At the same time on the basis of the printed time data or number of pieces or another size in the data center, the accounting data can be retrieved and thus the payment of the service in detail verifiable.

The post office 50 or commissioned institute can call the data center via communication link to query data stored in its database.

An example of an impression on a mailpiece will be explained with reference to FIG. 2. For a letter, the address field is arranged centrally. The Postempfängeradersse is in plain text and an associated ZIP code is printed as a barcode. The franking imprint is located in the periphery on the top right. A sender specified in the upper left corner is optional. For the USPS, an approximately 1 inch wide franking imprint is created with a machine readable area. Certain clear data and the signature are, for example, converted to PDF 417 symbolism and printed. The latter is from the company Symbol Technologies, inc. in EP 439 682 B1. Above the machine readable area is the visually (human) readable area and an area for the FIM code according to the US Postal Regulations. To the left of this lies another printing area, which can preferably be used for printing an advertising cliché. Because of the FIM code, a ca. 11 to 14 mm wide visually (human) readable results for an approximately 1 inch wide franking imprint Area. Thus, the remaining width can be used for the machine-readable area.

In a preferred first embodiment variant, the request data transmitted to the data center may additionally include the postal value, further mail dispatch data and a monotone, continuously variable variable. The postal value and other mailing data (EXPRESS, AIR MAIL,...) Are entered by the user via the keyboard 14 of the personal computer PC 1 for each letter.

The storage of the billing or accounting data corresponding to other services takes place in the central database. Since the billing of the mailing in the data center is made customer-specific, a manipulation of the billing data in counterfeit intention can be excluded. A local postage box or one meter is unnecessary for the user of the franking device. The hard disk 23 contains storage areas provided for the booking, according to the agreed billing type and type of service. To increase security against data loss, there is at least one further hard disk 23 '(not shown) in the data center in which redundant storage of all data takes place.

A settlement type for the aforementioned mail service is a cumulative settlement at the end of the month, the cumulative amount being debited from a customer account at a bank or similar credit institution in accordance with the direct debit procedure. It can also be another form of settlement, such as immediate payment or advance payment, agreed. An agreement can be made with the customer on different billing types for different services.

It is provided in a second embodiment that transmission data transmitted and also the service of a Postage calculation is performed in the data center, the cumulated service costs are periodically, for example, at the end of the day, charged to the customer. For this purpose, it is advantageous that the request data, which are transmitted to the data center together with the address data and further dispatch data, also comprise identification data ID. Under identification data ID should be understood an identification number of the customer or the mail sender or the machine serial number, or the sender address. In order to exclude fraud, where another sender is faked, it is further provided that such identification data in the signature also come with. The data center generates a signature from the transmitted request data, such as postal recipient address and identification data, as well as a generated monotone continuously variable size and the postage value using a private key and an asymmetric encryption algorithm.

If, on the other hand, as in the first embodiment variant, the service of a postage calculation is not carried out in the data center but in the franking device, such costs can not be debited to the customer, but rather a discount is to be granted since the computer of the data center is not unnecessary by such calculations is blocked.

In the second embodiment variant, it is provided that the received partially returned data include a postage value calculated in the data center, a recipient address, identification data, data center, a monotonously continuously variable size and a signature, wherein the data center generates the monotonically continuously variable size and from the transmitted request data , As postal recipient address and identification data as well as from other transmitted dispatch data determined the postage value according to a valid tariff. For a maximum variant, the Request data generated equal to several letters that the user has created on his personal computer PC 1, which is also part of the franking device. Corresponding to the number of letters, a number of different signatures are then also assigned to the address and franking data. The returned data can be assigned to the different letters via the address data.

As an alternative dispatching information on the weight, the number and the format and the weight of the individual letter pages per letter can be transmitted. The letter weight can be determined from it in the data center, without the local user a letter scale must be connected to the franking device. Optionally, during communication, the data center opens a user dialog via the display 12 with the user to complete the data required for the postage calculation.

In the case of a minimal variant, only one signature is requested for the following information: postal recipient address, postal value, identification data, piece number value. The piece value is an unencrypted piece number print produced by a numerator. A numerator already provides sufficient protection against copies of the impression. Upon collection of the collected mail by an employee of the mail carrier, the sender identification data and the count reached by the numerator could already be compared with the printed values.

The likelihood is also low that the same date sent a same size and the same weight mail item is sent to the same recipient. The likelihood can be further reduced by requiring that the clock data be additionally printed on the mailpiece. The time data may alternatively be provided by a precise clock - not shown - from the data center.

It is provided in a further variant that all aufzudruckenden on the mail item data are previously stored centrally. In the post office, the delivered mail can be checked with the help of the centrally stored data to see if copies of an imprint are used for forgery purposes. For each mail item delivered, an entry in the central database may be made in a particular area. A duplicate entry in the database indicates a fake print. By linking the postal recipient address with the postal value and number of pieces on the signature, it is impossible separately to copy one of the two postal recipient address or postal value for manipulation purposes.

It is further provided that each key pair, consisting of a private key and a public key, is valid for a limited time and can be changed suddenly to a specific date and time of the data center. The timing of switching occurs according to the current progress made in modern analysis techniques, such as differential cryptanalysis, and is such that an attack on the security of the system is likely to fail.

Claims (2)

1. A franking device having a first computer and a connected printer, said computer comprising a memory with a local database for post receiver address files and a communication means, said first computer being connected via said communication means with a data central having a second computer with a central database,
   characterized in that the first computer is programmed for

   - accessing a certain stored post receiver address or temporarily storing a newly entered certain post receiver address;

   - transmitting request data of the post sender to the data central by means of the communication means, said request data comprising the identification data of the post sender and post sending data, including the certain post receiver address, in order to confirm the correctness of the post receiver address by means of the second computer or create it by means of an address file stored in the central database;

   - receiving data regarding a valid post receiver address from an address file stored in a central database, a valid postage value and a signature, wherein the second computer of the data central provides the requested data with a signature only if a valid post receiver address is stored in the central database, a message being generated when an automatic correction of a post receiver address is impossible;

   - verifying the authenticity of the received data transmitted to the franking device by means of the signature and, if authenticity has been confirmed, updating the address file in the local database with regard to the certain post receiver address; and

   - processing the data, including signature, received from the central database for printing an authentic franking print on the postal item.
2. A franking device according to Claim 1, characterized in that the first computer is equipped with hardware comprising a modern high-speed processor and sufficient memory space for processing modern crypto technology and contains a public key provided for the authenticity check by means of a signature, wherein said public key and a private key form a key pair, and wherein the second computer of the data central generates a message from the transmitted data and the signature by encoding the message with the secret private key according to a known an asymmetrical encoding algorithm.

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