DE102008054886B3 - Method for securing transaction data in context of online-applications, involves mapping utilized input values to comparison value that is known to background system by function implemented in multi-functional chip card reader - Google Patents

Abstract

The method involves producing an electronic safety mark by a signature card (7) or chip card. A multi functional chip card reader (5) is utilized in a secure application mode. A utilization of the secure application mode is detected in relation to a background system (2) that is involved in online-applications. The electronic safety mark is utilized as an electronic signature, which is calculated by the signature card. Utilized input values are mapped to a comparison value that is known to the background system by function implemented in a multi-functional chip card reader.

Description

in the In the context of an online application, transaction data is replaced by a electronic signature secured by a signature card the user is generated. The user sets a multifunctional Chip card reader, in addition to an unsecured default mode also at least one secure application mode for generating supported by electronic signatures. Works in default mode the multifunctional smart card reader essentially like a standard one Smart card reader. In this case, malware can be on the machine the user's execution of user's transactions so attack the ones displayed Transaction data of the user is not included in the calculation of electronic Signature, but rather fake transaction data of a Attacker. In contrast, when using the multifunctional Smart card reader in safe application mode ensures that which are displayed on the reader's display and by the user via the Keyboard of the reader confirmed transaction data indeed into the calculation of the electronic signature.

About organizational Regulations such. B. contractually secured customer terms is achieved that the user a suitable multifunctional Chip card reader uses. In which mode the multifunctional Chipcard reader is used concretely, by a the reader using application specified.

The actual transaction is through a background system of the provider the online application after receipt of the transaction data and the associated electronic Signature executed. There is now the problem that the background system does not recognize can, whether the user's multifunctional smart card reader at the calculation of the electronic signature actually in the safe application mode was operated and not insecure Default mode.

For the hedge of transaction data with an electronic signature using a signature card was calculated, became the problem described not solved yet.

For others Methods of securing transaction data, eg. B. at a Payment process with an electronic wallet, is governed by internal filtering rules the multifunctional smart card reader ensures that the needed Functionality of involved chip cards are not used in the default mode of the reader can be.

It is not possible via internal Ensure filter rules of the multifunctional chip card reader that for the calculation of an electronic signature required functionality of the involved Signature card can not be used in the default mode of the reader.

A such solution would prevent that the multifunctional smart card reader in the context of others Signature-based applications also as a universal chip card reader can be used. Signature-based applications that use the secure application mode a multifunctional chip card reader can not use or not want to use then no longer be readily used by the user. A high acceptance of the multifunctional chip card reader in the potential Users would be not reachable any more.

In the from the WO 2008/073606 A2 known method is calculated by a software agent a signature on the relevant software and hardware configuration data of the terminal and sent in the context of the application to the background system (or a dedicated authentication server), then the signature with a previously in the context of a registration of the terminal submitted signature compares. Regardless of the vulnerability of the software agent used and regardless of the complexity of using today's standard PCs as a terminal, this can be demonstrated that at the time of login, the terminal is in the same safe or unsafe condition as when it was registered. However, there is no protection for the specific transaction data, ie attacks on the terminal that already existed at the time of the registration and those that occur only between the login process and the transaction are not recognized or prevented and can thus be carried out without hindrance against specific transactions become.

It Therefore, a security mechanism should be found by the a verifiable proof can be generated that the multifunctional chip card reader at the calculation of a given electronic signature in the safe Application mode was operated.

Is solved This object by the method according to claim 1. Advantageous Embodiments emerge from the subclaims.

It an electronic security stamp is defined, by means of which the correct use of the application mode is demonstrated. An online application is extended so that in addition to the actual electronic signature also an electronic security stamp is generated and sent to the Transfer background system becomes.

One electronic security stamp is a special electronic Signature calculated by the user's signature card. In the calculation of the electronic security stamp flow the same data as in the calculation of the actual electronic Signature. Through a filter rule in the multifunctional chip card reader However, it ensures that the electronic security stamp can only be calculated in application mode. This will then the display of the correct transaction data on the display of the Chipcard reader and its confirmation by ensures the user in the application mode. The possibility, to calculate other electronic signatures in default mode will not significantly limited thereby.

Of the An online application provider can extend this to include, besides the actual hedging of the transaction data is also an electronic one Security stamp created by the user's signature card becomes. This preserves the vendor's background system has a verifiable proof that in the calculation of the actual electronic signature of secure application mode used in multifunctional smart card reader has been. As a result, the provider of the online application then has the security that the user the transaction data securely on the display of the Smart card readers were displayed and these by the user as well approved were.

As already stated, are in the context of online applications transaction data secured by an electronic signature.

A electronic signature is in the broadest sense a checksum, using cryptographic algorithms using a private key of the User appropriately over the Transaction data is calculated while the verifiability of the transaction data verifiable ensures. Examples are electronic signatures in the sense of the signature law SigG and the cryptographic security of the news in online banking when using HBCI.

• – Die Signaturkarte unterstützt mindestens eine Funktionen zum Erzeugen von elektronischen Signaturen. Sie kann aber auch mehrere verschiedene Funktionen hierfür unterstützen, die im Rahmen von verschiedenen Einsatzzwecken genutzt werden.
• – Diese Funktionen basieren auf dem Einsatz von privaten Signaturschlüsseln des Karteninhabers. In der Signaturkarte können hierfür ein oder mehrere private Signaturschlüssel des Karteninhabers vorhanden sein.
• – Die Funktionen der Signaturkarte für das Erzeugen einer elektronischen Signatur sind wie folgt charakterisiert: Für die Berechnung einer elektronischen Signatur über eine Nachricht M wird entweder der Hashwert über M durch die Anwendung an die Signaturkarte übergeben oder der Hashwert über M wird (ggf. teilweise) durch die Signaturkarte selber bestimmt. In beiden Fällen bestimmt die Signaturkarte intern aufbauend auf dem Hashwert den DSI (digital signature input), in dem sie abhängig von einem vorher ausgewählten Signaturverfahren notwendige Formatierungs- und Paddingschritte durchführt. Über den DSI wird dann intern mit dem hierfür zuständigen privaten Signaturschlüssel die elektronische Signatur durch die Karte berechnet und ausgegeben.
• – Die privaten Signaturschlüssel des Benutzers sind sicher in der Chipkarte gespeichert.
• – Alle Berechnungen mit den privaten Signaturschlüsseln des Benutzers werden nur chipkartenintern durchgeführt.
• – Die Nutzung eines privaten Signaturschlüssels kann durch eine PIN geschützt werden. Ist dies der Fall, muss sich der Benutzer gegenüber der Chipkarte durch Eingabe seiner PIN authentifizieren, bevor der entsprechende private Signaturschlüssel für das Berechnen einer elektronischen Signatur genutzt werden kann. Ob das Verifizieren der PIN vor jedem Erzeugen einer elektronischen Signatur wiederholt werden muss oder nach einem einmaligen Verifizieren der PIN mehrere elektronische Signaturen erzeugt werden können, hängt dabei von der Konfiguration der konkreten Signaturkarte ab.

The user uses a signature card to generate the electronic signature. A signature card is a chip card, for which the following points apply:

• - The signature card supports at least one function for generating electronic signatures. However, it can also support several different functions that are used for different purposes.
• - These functions are based on the use of cardholder private signature keys. In the signature card, one or more of the cardholder's private signature keys may be present.
• The functions of the signature card for generating an electronic signature are characterized as follows: For the calculation of an electronic signature via a message M, either the hash value M is passed through the application to the signature card or the hash value via M becomes (possibly partial). determined by the signature card itself. In both cases, the signature card determines internally based on the hash value the DSI (digital signature input), in which it performs the necessary formatting and padding steps depending on a previously selected signature method. The electronic signature is then internally calculated and output by the card via the DSI using the private signature key responsible for this purpose.
• - The private signature keys of the user are safely stored in the chip card.
• - All calculations with the private signature keys of the user are performed only on-chip card internals.
• - The use of a private signature key can be protected by a PIN. If this is the case, the user must authenticate himself to the chip card by entering his PIN before the corresponding private signature key can be used for calculating an electronic signature. Whether the verification of the PIN must be repeated before each generation of an electronic signature or multiple electronic signatures can be generated after a single verification of the PIN, depends on the configuration of the specific signature card.

to execution In the application the user uses a terminal with mains connection, eg. B. a PC. The user terminal is at a public accessible Network connected, z. For example, the Internet. In particular, this network can a connection to a background system of the provider of the online application getting produced.

The terminal may contain malicious software (Trojans, viruses, etc.) that interfere with the proper execution of applications. As a result, it is possible, in particular, for the transaction data displayed on the monitor of the terminal not to be included in the calculation of the electronic signature in the online application under consideration, but rather fake transaction data predefined by an attacker. As a result, the provider of the online application does not execute the transaction intended by the user, but rather the counterfeit transaction specified by the attacker. The presence of appropriate malware can also be through the use of firewalls and virus scanners not be completely excluded.

• – Die interne Software des Chipkartenlesers kann entweder gar nicht geändert werden oder nur durch den Hersteller, wobei ein kryptographisch abgesichertes Verfahren eingesetzt wird, das die Authentizität der neuen Software sicherstellt.
• – Der Chipkartenleser unterstützt einen Defaultmodus und einen oder mehrere Anwendungsmodi. In welchem Modus der Chipkartenleser arbeitet, wird durch die den Leser nutzenden Anwendung durch Aufruf eines spezifischen Leserkommandos vorgegeben.
• – In der internen Software des Chipkartenlesers sind Filteregeln enthalten, die u. a. vorgeben, ob ein Chipkartenkommando im gerade aktiven Modus entweder generell oder zusammen mit bestimmten Parameter des Kommandos an die Signaturkarte gegeben werden darf oder nicht.
• – Im Defaultmodus arbeitet der multifunktionale Chipkartenleser im Wesentlichen wie ein normaler Chipkartenleser. Von der den Leser nutzenden Anwendung vorgegebene Chipkartenkommandos werden, sofern dies nicht einer Filterregel widerspricht, ohne Änderung an die Signaturkarte weitergeleitet. Antworten der Signaturkarte werden wiederum unverändert an die Anwendung zurückgegeben.
• – Im Defaultmodus unterstützt der multifunktionale Chipkartenleser eine sichere PIN-Eingabe. Dabei gibt der Benutzer eine PIN (bzw. eine PUK) über die Tastatur des Chipkartenlesers ein. Diese wird leserintern zum Verifizieren an die Signaturkarte übergeben. Es ist sichergestellt, dass der vom Benutzer eingegebene Wert niemals an eine den Leser nutzende Anwendung gegeben wird.
• – Im Defaultmodus werden auf dem Display des multifunktionalen Chipkartenlesers nur solche Texte angezeigt, die in der Software des Lesers fest gespeichert sind. Diese Texte dienen im Wesentlichen der Benutzerführung. Es ist sichergestellt, dass eine den Leser nutzende Anwendung im Defaultmodus keine eigenen Texte auf dem Display des Lesers anzeigen lassen kann.
• – Im Defaultmodus kann die den Leser nutzende Anwendung die Funktionen der Signaturkarte für das Erzeugen von elektronischen Signaturen wie üblich nutzen, d. h. in dem multifunktionalen Chipkartenleser gibt es keine Filterregeln, die die Nutzung dieser Funktionalität der Signaturkarte im Defaultmodus des Lesers verhindern bzw. einschränken.
• – In einem Anwendungsmodus hat die den Leser nutzende Anwendung die Möglichkeit, Daten auf dem Display des Lesers anzeigen zu lassen und diese durch den Benutzer über die Tastatur des Lesers bestätigen zu lassen.
• – Der Anwendungsmodus kann durch eine den Leser nutzende Anwendung eingesetzt werden, um über eine Nachricht N eine elektronische Signatur berechnen zu lassen, wobei die in der Nachricht enthaltenen relevanten Transaktionsdaten TD1 bis TDn auf dem Display des Lesers angezeigt werden und durch den Benutzer über die Tastatur des Lesers bestätigt werden. Durch die Ablaufkontrolle des multifunktionalen Chipkartenlesers wird dann im Anwendungsmodus sichergestellt, dass genau die auf dem Display des Lesers angezeigten und bestätigten Transaktionsdaten TD1 bis TDn in die Berechnung der elektronischen Signatur eingehen.

To ensure that the transaction data desired by the user actually enter into the calculation of the electronic signature, the user uses a multifunctional chip card reader with display and keyboard. This smart card reader has the following features:

• - The internal software of the smart card reader can either not be changed or only by the manufacturer, using a cryptographically secured method that ensures the authenticity of the new software.
• The smart card reader supports a default mode and one or more application modes. The mode in which the chip card reader works is specified by the application using the reader by calling a specific reader command.
• - In the internal software of the chip card reader filter rules are included, which specify, among other things, whether a chip card command in the currently active mode, either in general or together with certain parameters of the command to the signature card may be given or not.
• - In the default mode, the multifunctional smart card reader essentially works like a normal chip card reader. Chip card commands given by the application using the reader are forwarded to the signature card without change, unless this is contrary to a filter rule. Responses of the signature map are in turn returned unchanged to the application.
• - In the default mode, the multifunctional chip card reader supports secure PIN entry. The user enters a PIN (or a PUK) via the keypad of the chip card reader. This is passed to the signature card for verification by the reader. It is ensured that the value entered by the user is never given to an application that uses the reader.
• - In default mode, only texts that are permanently stored in the software of the reader are displayed on the multifunctional smart card reader display. These texts essentially serve the purpose of user guidance. It is ensured that an application that uses the reader in default mode can not display its own texts on the reader's display.
• In the default mode, the application using the reader can use the functions of the signature card for generating electronic signatures as usual, ie in the multifunctional chip card reader there are no filter rules which prevent or limit the use of this functionality of the signature card in the default mode of the reader.
• In an application mode, the application using the reader has the possibility to display data on the display of the reader and to have this confirmed by the user via the keyboard of the reader.
• The application mode can be used by an application using the reader to have an electronic signature calculated via a message N, the relevant transaction data TD1 to TDn contained in the message being displayed on the display of the reader and by the user via the keyboard be confirmed by the reader. In the application mode, the sequence check of the multifunctional chip card reader ensures that exactly the transaction data TD1 to TDn displayed and confirmed on the display of the reader are included in the calculation of the electronic signature.

Next the cited technical characteristics of the initial situation is still required, that the user at all a multifunctional smart card reader with the above characteristic Features. This is governed by organizational regulations achieved, for example, by contractually secured customer conditions.

Even when using a multifunctional smart card reader with the described properties, malicious software can fake a transaction on the user's terminal. This is also possible in particular if the application mode in the chip card reader is used to generate the electronic signature. This is illustrated by the following pattern of an attack on the security by an electronic signature:
The application that controls the execution of the online transaction on the user's terminal is affected by malware as follows. First, the application mode is selected in the multifunctional smart card reader. The correct transaction data TD1 to TDn are then displayed on the reader's display and confirmed by the user via the reader's keyboard. Thereafter, the electronic signature S = sig (TD1, ..., TDn) in the application mode is calculated by the signature card and output. The application mode is then left. The malware then uses the default mode of the smart card reader and can use the forged transaction data TD1 to TDn to calculate the signature S = sig (TD1, ..., TDn) by the signature card. No data will be shown on the display of the reader. The user therefore does not recognize this process. The malware now sends the fake transaction data TD1 to TDn and the associated signature S to the background system. The background system can not recognize that the received transaction data TD1 to TDn have not been confirmed by the user and that the signature S is not in use mode of the user's multifunctional smart card reader.

various Variants are for the described pattern of attacks is conceivable.

Even for the Case that the user before each generating an electronic Signature must reenter his PIN must be against the background experience can be assumed that the described Attack in the vast majority Majority of cases leads to success. For example, the malware can be given to the user under default wrong reasons request to re-enter his PIN and thus the signature card for the Generate another electronic signature release.

The described attack pattern is based on the fact that when using the multifunctional chip card reader the calculation of an electronic Signature also possible in default mode is. However, this is a necessary feature of the smart card reader, to be able to use this in the context of applications that do not want to use the described application modes or not to be able to use. The applicability of the multifunctional chip card reader in default mode As a universal chip card reader is an important requirement its acceptance by the users.

When solution for the Therefore, a method is needed in the described problem its use can detect a background system, whether the smart card reader in generating an existing electronic signature in the application mode was operated.

In The description of the initial situation is based on a function of Signature card for the calculation of an electronic signature always on the use of a hash value as output value for the calculation of the DSI (digital signature input). The hash value can either be determined by the application be specified or (possibly partially) by the signature card be calculated yourself. This characterization of a function to calculate an electronic signature corresponds to the classic Definition.

• – Eine Funktion der Signaturkarte für das Erzeugen einer elektronischen Signatur kann auch die Übergabe eines beliebigen Eingabewertes an die Signaturkarte zulassen, der entweder vom syntaktischen Aufbau her oder von der Bedeutung her nicht unbedingt ein Hashwert sein muss. In diesem Fall bestimmt die Signaturkarte intern aufbauend auf dem vorgegebenen Eingabewert den DSI (digital signature input), in dem sie abhängig von einem vorher ausgewählten Signaturverfahren notwendige Formatierungs- und Paddingschritte durchführt. Über den DSI wird dann intern mit dem hierfür zuständigen privaten Signaturschlüssel die elektronische Signatur durch die Karte berechnet und ausgegeben. Die maximale Länge des Eingabewerts kann dabei für eine konkrete Signaturkarte beschränkt sein.

However, the new method described below also includes the use of signature cards that support functions for calculating an electronic signature according to the following characterization:

• - A function of the signature card for generating an electronic signature can also allow the transfer of any input value to the signature card, which does not necessarily have to be a hash value either from the syntactic structure or meaning. In this case, the signature card internally determines, based on the given input value, the DSI (digital signature input) in which it performs necessary formatting and padding steps depending on a previously selected signature method. The electronic signature is then internally calculated and output by the card via the DSI using the private signature key responsible for this purpose. The maximum length of the input value can be limited for a specific signature card.

The The invention relates to a method in which by an electronic Safety stamp proved verifiable is that when calculating an electronic signature of the multifunctional chip card reader was operated in application mode and according to the transaction data on the display of the smart card reader were displayed and by the user via the keyboard of the smart card reader approved were.

requirement for the Proof of the electronic security stamp is that by the User a multifunctional chip card reader with display and keyboard is used, which has the characteristics described above Has.

• – Ein elektronischer Sicherheitsstempel im Sinne des Verfahrens ist eine elektronische Signatur, die durch die Signaturkarte berechnet wird, wobei der verwendete Eingabewert sich durch eine geeignete bekannte im multifunktionalen Chipkartenleser implementierte Funktion auf VWERT abgebildet werden kann. VWERT ist dabei ein beliebiger aber fester, allgemein bekannter Vergleichswert. VWERT kann entweder global einheitlich sein oder spezifisch für den einzelnen Chipkartenleser. Beispiele für die im multifunktionalen Chipkartenleser verwendbaren Funktionen sind die Präfix-Funktion, d. h. der Eingabewerte hätte die Form ”VWERT || Rest” oder die Postfix-Funktion, d. h. der Eingabewert hätte die Form ”Rest || VWERT”. Auch die Verwendung der Infix-Funktion ist mit Vorteil möglich.
• – Die Software des multifunktionalen Chipkartenlesers wird um Filterregeln erweitert, die verhindern, dass eine den multifunktionalen Chipkartenleser nutzende Anwendung einen elektronischen Sicherheitsstempel direkt durch die Signaturkarte berechnen lassen kann. Es wird sichergestellt, dass ein elektronischer Sicherheitsstempel nur im Rahmen der Ausführung eines speziellen Kommandos des Chipkartenlesers durch die Signaturkarte berechnet werden kann.
• – Durch die Ablaufkontrolle des multifunktionalen Chipkartenlesers wird gewährleistet, dass ein elektronischer Sicherheitsstempel nur dann durch die Signaturkarte berechnet wird, falls der multifunktionale Chipkartenleser im Anwendungsmodus betrieben wird. Es wird sichergestellt, dass die auf dem Display des Chipkartenlesers angezeigten und durch den Benutzer über die Tastatur des Chipkartenlesers bestätigten Transaktionsdaten in die Berechnung des elektronischen Sicherheitsstempels einfließen. Ferner wird sichergestellt, dass falls im Anwendungsmodus über die angezeigten und bestätigten Transaktionsdaten auch eine elektronische Signatur durch die Signaturkarte berechnet wird, in die Berechnung dieser elektronischen Signatur die gleichen Daten einfließen wie bei der Berechnung des elektronischen Sicherheitsstempels, d. h. bei der Berechnung des elektronischen Sicherheitsstempels wird ein Eingabewert verwendet, der in geeigneter eindeutig nachprüfbarer Weise einen Rückschluss auf H ermöglicht, wobei H der Hashwert ist, der auch in die Berechnung dieser elektronischen Signatur eingeht.
• – Die Online-Anwendung wird so angepasst, dass entweder für die Absicherung der Transaktionsdaten nur ein elektronischer Sicherheitsstempel verwendet wird, oder neben der Absicherung der Transaktionsdaten durch eine elektronische Signatur auch zusätzlich noch der zugehörige elektronische Sicherheitsstempel durch die Signaturkarte berechnet wird. Neben den Transaktionsdaten und ggf. der eigentlichen elektronischen Signatur wird insbesondere auch der zugehörige elektronische Sicherheitsstempel an das Hintergrundsystem übermittelt.
• – Die Anwendung im Hintergrundsystem wird so angepasst, dass entweder nur der elektronische Sicherheitsstempel verifiziert wird, oder neben der Überprüfung der eigentlichen elektronischen Signatur auch der zugehörige elektronische Sicherheitsstempel verifiziert wird.

The method is based on the following points:

• An electronic security stamp in the sense of the method is an electronic signature which is calculated by the signature card, wherein the input value used can be mapped to VWERT by a suitable known function implemented in the multifunctional chip card reader. VWERT is an arbitrary but firm, generally known reference value. VWERT can either be globally uniform or specific to the individual chip card reader. Examples of the functions that can be used in the multifunctional chip card reader are the prefix function, ie the input values would have the form "VWERT || Remainder "or the postfix function, ie the input value would have the form" remainder || VWERT ". The use of the infix function is also possible with advantage.
• - The software of the multifunctional chip card reader is extended by filter rules that prevent an application using the multifunctional chip card reader from having an electronic security stamp calculated directly by the signature card. It is ensured that an electronic security stamp can only be calculated by executing a special command of the chip card reader by the signature card.
• - The flow control of the multifunctional chip card reader ensures that a electronic security stamp is only calculated by the signature card, if the multifunctional chip card reader is operated in the application mode. It is ensured that the transaction data displayed on the display of the chip card reader and confirmed by the user via the keyboard of the chip card reader are included in the calculation of the electronic security stamp. Furthermore, it is ensured that if an electronic signature is calculated by the signature card in the application mode via the displayed and confirmed transaction data, the same data is used in the calculation of this electronic signature as in the calculation of the electronic security stamp, ie in the calculation of the electronic security stamp uses an input value which, in a suitably unambiguously verifiable manner, allows H to be deduced, where H is the hash value which is also included in the calculation of this electronic signature.
• - The online application is adapted so that either only an electronic security stamp is used to secure the transaction data, or in addition to the hedging of the transaction data by an electronic signature also additionally the associated electronic security stamp is calculated by the signature card. In addition to the transaction data and possibly the actual electronic signature, in particular the associated electronic security stamp is also transmitted to the background system.
• - The application in the background system is adjusted so that either only the electronic security stamp is verified, or in addition to the verification of the actual electronic signature and the associated electronic security stamp is verified.

at The method is to secure the transaction data with a electronic signature through an electronic security stamp added. When using a multifunctional chip card reader confirms the Correctness of this electronic security stamp that the Calculation of the actual electronic signature in application mode took place while the transaction data on the display of the smart card reader were displayed and by the user via the keyboard of the smart card reader approved were.

• – Die eigentliche elektronische Signatur ist die anwendungsfachliche Absicherung der Transaktionsdaten. Eine ggf. vorliegende Verbindlichkeit der zugehörigen Transaktion leitet sich nur hieraus ab.
• – Der elektronische Sicherheitsstempel ist ein technischer Sicherheitsmechanismus, durch den überprüfbar nachgewiesen wird, dass beim Erzeugen der eigentlichen elektronischen Signatur der multifunktionale Chipkartenleser im Anwendungsmodus verwendet wurde und dabei die Transaktionsdaten auf dem Display des Chipkartenlesers angezeigt wurden und durch den Benutzer über die Tastatur des Chipkartenlesers bestätigt wurden.

The connection between the actual electronic signature and the associated electronic security stamp is as follows:

• - The actual electronic signature is the application-specific protection of the transaction data. Any liability of the associated transaction is only derived therefrom.
• - The electronic security stamp is a technical security mechanism that verifiably proves that when generating the actual electronic signature of the multifunctional smart card reader was used in the application mode and the transaction data was displayed on the display of the smart card reader and confirmed by the user via the keyboard of the smart card reader were.

By introducing the filter rule mentioned above, the requirement that the multifunctional chip card reader can be used in default mode as a universal chip card reader is only partially met. An electronic signature for an input value can no longer be calculated by the signature card in default mode if it is an electronic security stamp. However, the probability that this leads to a rejection of the calculation of a desired electronic signature in real applications can be reduced as desired by suitably selecting the value VWERT. For VWERT z. For example, if a value of 20 bytes is used, the probability of a random conflict is less than 2 ^-160 .

The Application of the method according to the invention will be described below by way of example with reference to the single drawing figure explained in more detail.

With the reference number 1 is provided an environment of the user, in particular a user terminal 4 and a multifunctional smart card reader 5 includes. With the reference number 2 is a background system called the provider of the online application.

A user terminal 4 and the background system 2 are connected via a publicly accessible network, for example via the Internet. The user sets a signature card for generating an electronic security stamp or an electronic signature 7 one. At the signature card 7 it is preferably a chip card that supports in particular functions for calculating electronic signatures.

The background system 2 of the provider knows a comparative value VWERT of the multifunctional chip card reader used 5 as well as in this multifunctional chip card reader 5 implemented function for mapping the input value for the calculation of an electronic security stamp to the comparison value VWERT.

The user terminal 4 and the multifunk official chip card reader 5 can now have a connection 6 , for example, communicate via a USB connection. The user terminal 4 has a keyboard 8th , an ad 9 as well as a software 10 that can be attacked by malicious software.

To the multifunctional chip card reader 5 heard a display 13 for displaying transaction data and a keyboard for entering data, in particular a confirmation key 14 which allows the user to confirm the displayed transaction data and a cancel key 15 over which the user can cancel an operation.

In the multifunctional chip card reader is internally between an unsecured default mode 11 and one or more secure application modes 12 distinguished.

The equipment described above is suitable for the implementation the method according to the invention.

1

Surroundings the user

2

Background System the provider of the online application

3

public accessible Network, e.g. Eg internet

4

User terminal

5

multifunctional Smart card reader

6

connection terminal with chip card reader, z. B. USB

7

signature card the user

8th

standard keyboard of the user terminal

9

unsecured Display of the user terminal

10

software of the user terminal

11

internally unsecured default mode of the multifunctional chip card reader

12

internally Secure application mode of the multifunctional smart card reader

13

display of the multifunctional chip card reader

14

confirmation key the keyboard of the multifunctional smart card reader

15

Cancel button the keyboard of the multifunctional smart card reader

Claims (8)

Method for securing transaction data in the context of an online application by means of an electronic security stamp, in which the electronic security stamp is identified by a signature card ( 7 ), wherein a multifunctional chip card reader ( 5 ) is used in a secure application mode, which ensures the secure display and confirmation of the transaction data and their correct influence in the calculation of the electronic security stamp, characterized in that the use of the secure application mode against a background system involved in the online application ( 2 ) is verifiably detected by this electronic security stamp, wherein an electronic security stamp in the sense of this method is an electronic signature, which by the signature card ( 7 ), wherein the input value used is determined by a suitable known in the multifunctional smart card reader ( 5 ) implemented function on any but fixed, the background system ( 2 ) known comparison value VWERT can be mapped. Method according to Claim 1, in which, in addition to an unsecured default mode, one or more secure application modes with display and confirmation of transaction data are internally supported in the multifunctional chip card reader used, and one or more filter rules ensure that one is prevented from causing the reader application can directly initiate the calculation of an electronic security stamp by chip card commands through a signature card, and the calculation of this electronic security stamp only in the context of the execution of a separate command of the chip card reader ( 5 ) in an application mode of the smart card reader ( 5 ). Method according to Claim 2, in which the filter rule is based on the comparison value VWERT having a fixed, the background system ( 2 ), this value being agreed in the context of this method in such a way that the same filter rule is used in several multifunctional smart card readers ( 5 ) is available. Method according to Claim 2, in which the filter rule is based on the comparison value VWERT having a unique value determined by the chip card reader ( 5 ), the background system ( 2 ) has known value. Method according to one of claims 1 to 4, wherein in the chip card reader ( 5 ) function for mapping the input value to VWERT is the function for calculating a postfix of the input value. Method according to one of claims 1 to 4, wherein in the chip card reader ( 5 ) function for mapping the input value to VWERT is the function for calculating a prefix of the input value. Method according to one of claims 1 to 4, wherein in the chip card reader ( 5 ) function for mapping the input value to VWERT is the function for calculating an infix of the input value. Method according to one of Claims 1 to 7, in which the transaction data are additionally secured by an electronic signature which, according to a recognized signature method, is protected by the signature card (Fig. 7 ) is calculated in such a way that by the flow control in the multifunctional smart card reader ( 5 ) ensures that the electronic signature is calculated using the same transaction data as that used to calculate the electronic security stamp.