WO2006089731A1

WO2006089731A1 - Authenticating by means of a chip card

Info

Publication number: WO2006089731A1
Application number: PCT/EP2006/001605
Authority: WO
Inventors: Ullrich Martini; Stephan Beinlich
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2005-02-23
Filing date: 2006-02-22
Publication date: 2006-08-31
Also published as: EP1859386A1; DE102005008257A1

Abstract

According to a first embodiment of the invention, a person who is equipped with a chip card (1) is biometrically authenticated on a testing apparatus (2) using a security application (14) which is separate from the operating system (13) of the chip card (1) in a data-related and functional manner and can be run on the chip card (1) without modifying functions of the operating system, the security application (14) performing all security-relevant operations on the chip card (1). Authentication data errors are corrected by an external correcting device (4). Data communication between the chip card (1) and the correcting device (4) is secured by alienating the authentication data, errors being correctable in the correcting device (4) in spite of the alienation process. According to a second embodiment of the invention, the biometry is compensated by linking the same to biometric authentication data while being secured by means of an alienation process in such a way that a biometrically secured secret can be securely transmitted to the correcting device (4) in order to correct errors when said secret is provided on a storage medium (1').

Description

Authenticate with chip card

The invention relates to methods and systems for authenticating persons to a test apparatus by means of a chip card and in particular a chip card set up for this purpose and a computer program product for setting up such chip cards for these purposes.

Verification of a person's entitlement to access or use a facility, e.g. at a cash or vending machine, can be realized in different ways depending on the respective security requirements.

A common authentication method is the entry of secret access data such as a password or a personal identification number (PIN) at a test terminal. However, this method is relatively uncertain, since PINs are written down frequently and thus can be accessible to unauthorized persons. As a variant, an additional data carrier is often used, which provides the PIN for comparison with the input of the person. Authentication then takes place via the knowledge of the PIN and the ownership of the data carrier, which is usually present as an electronic device, for example as a chip card or other portable storage medium. However, an unauthorized owner of the data carrier can usually read the access data with little technical effort. In this context, biometric characteristics of persons such as fingerprints or iris patterns can be used as access data, since the digitization of these complex patterns leads to the derivation of a suitable number of numerical features by means of a reproducible extraction process, which can be unambiguously and exclusively attributed to the person concerned On the other hand, they can not easily be forged.

One approach to solving the aforementioned problems by means of biometric means is WO 01/15378 A1, which discloses a method for protecting a digital signature key. For this purpose, a biometric feature vector is first extracted on a test terminal from a biometric property as reference authentication data. In a registration process, the signature key with the reference authentication data is encrypted and stored on the chip card as a storage medium, while the reference authentication data remain on the test terminal. In the subsequent use of the signature key, the legitimate user can authenticate in a corresponding authentication process by generating similar biometric authentication data and comparison with the stored reference authentication data on the test terminal. Thereafter, the authentication data are transmitted to the smart card and decrypted with the signature key.

However, due to the unprotected presence of the reference authentication data on the terminal and the transmission of the authentication data to the chip card, such an off-card solution, in which the actual authentication is performed outside of the storage medium on the test terminal, results in considerable attack potential. The process is therefore not secure enough for many purposes. In addition, the porting of all security-related operations and data of the process on the smart card is too expensive.

WO 03/071492 A2 likewise discloses an off-card method for biometric authentication, in which the actual authentication also takes place outside the storage medium on the test terminal. For this purpose, the authentication data are generated on the test terminal and encrypted with a random number generated there. Likewise, the reference authentication data on the chip card are encrypted with the random number which is sent to the test terminal for this purpose. The encrypted reference authentication data is then sent to the test terminal for comparison with the encrypted authentication data. The problem here, however, is that with the random number a cryptographic key is sent in plain text to the smart card and encrypted with this key Ref erenz- authentication data for the actual authentication back to the test terminal are sent back.

In contrast, in on-card solutions, the authentication is performed on the storage medium or on the chip card. In this case, the digitized biometric properties or the refinement authentication data extracted therefrom are stored on the chip card in unencrypted or encrypted form. The realization of an on-card authentication is complicated, however, since a modified authentication strategy necessitates a modification of the authentication or cryptographic functions implemented as part of the chip card operating system. During the authentication of a person, both the on-card and the off-card solution first of all determine exactly those biometric characteristics of the person at the checking device and transformed into a biometric feature vector which already generates the reference authentication data stored in the chip card were used. However, both in the recording and digitization of the biometric properties, as well as in the extraction of a biometric feature vector multiple (meß-) technical and biological-natural noise and error sources, which is why the authentication data determined against the stored on the smart card reference authentication data are faulty and of These differ within the variance of the noise and error processes.

Since the intrinsically error-prone authentication data can only be used for authentication in an error-corrected form, these are expediently transmitted to an error-correcting correction device, which can either be a component of the test device or physically separate, independent component of an authentication system. In the latter case, the correction device is connected to the test apparatus via a suitable communication network.

Accordingly, it is an object of the present invention to propose a secure and easy-to-implement authentication method in which a user is authenticated using a secure storage medium on a test device.

This object is achieved according to a first aspect of the invention by a method and a system, as well as a chip card and a Computer program product for such a chip card having the features of independent claims 1 and 21 solved. In dependent claims advantageous embodiments and developments of the invention are given.

For authentication, a person first approaches a test device with a chip card as a portable storage medium. The smart card stores reference authentication data that is based on one or more of the person's unique biometric characteristics.

In the subsequent authentication process, all security-relevant operations not directly related to the generation of the authentication data, in particular the actual authentication, are executed directly on the chip card. For this purpose, a security application is present on the chip card, which provides such required for carrying out the authentication method security and control functionalities that are not already provided as unmodif icated standard functions of a conventional, commercially used standard smart card operating system. Such smart card operating systems are e.g. STARCOS, STARSIM, Multos, CardOS, JavaCard, etc. In this respect, the security application accesses e.g. to the obligatory authentication or cryptography function of the respective smart card operating system in the standard implemented manner.

For example, while the authentication and the cryptographic functions are implemented as operating system functionalities, the security application merely makes a separate from it in terms of data technology resettable EEPROM memory of the smart card resident application program, which is executed by the smart card processor and communicates with the operating system via internal interfaces or calls its functions. This results in maximum flexibility in the implementation of smart card authentication procedures, since in the case of a change in the authentication procedure, the chip card operating system does not have to be laboriously modified, but only the separate security application.

In principle, the invention can be implemented with any chip card operating system, in particular with the open platform of the JavaCard. In the case of a JavaCard, the security application implementing the authentication method is located as a Java applet in the EEPROM memory of the card.

In a chip card set up according to the invention, in the non-volatile EEPROM memory of the chip card, on the one hand, the security application and, on the other hand, the reference authentication data used by the authentication function are located. Any cryptographic keys needed by the cryptographic function are also in the EEPROM memory. Since the operating system resides in the permanent ROM memory of the chip card and is therefore immutable in finished smart cards, already personalized and issued to end customers smart cards that use any smart card operating system can be upgraded or retrofitted with the inventive method by loading the security application, without that intervention in the operating system would be necessary. In order to prevent now that the authentication device determined by the test can be spied on the necessary, error correction mentioned above, the authentication data are first transmitted to the smart card, preferably in a secure form, and there subjected to a suitable alienation by the security application, on the one hand can only be reversed by the security application itself and on the other hand is such that the error-prone authentication data despite alienation can be so error-corrected that arise as a result error-corrected alienated authentication data. Due to the alienation, the transmission of the authentication data to an external correction device is technically unproblematic.

For the purposes of this invention, an alienation / (c) of a codeword c is a function which cooperates with the error correction function g such that g (f (c)) ⁼ f (g (c)), ie the order of application of Functions / and g on c is arbitrary. From this commutativity with regard to the function composition, the possibility arises to eliminate the alienation / by applying its inverse (the reconstruction) f ¹ :

S (°) - In this way one obtains the error-corrected, but alienated codeword g (c). In contrast, the much more complex encryption function does not provide this algebraic property. As a result, codewords can not be error-corrected in the encrypted state, but must first be decrypted.

The alienation is preferably individualized by an XOR link (exclusive OR) of the authentication data with one of the security application for each authentication process generated random codeword, such as a random number performed. The authentication data individually alienated in this way can now be transmitted safely via communication networks, since the random code word is used only once and only the smart card or its security application is known. In this respect, a reconstruction of the authentication data from the alienated authentication data is only possible on the security application.

As a rule, it is necessary to coordinate the alienation function with the error correction, since both functions are applied together to the authentication data. Among the binary functions, there is the XOR function that is preferred for alienation and its negation, the NXOR function.

This error correction by means of a special correction device outside the chip card makes sense, since the errors inherent in the authentication data u.a. may depend on the sensors of the test apparatus and the conditions of reception that governed the detection of biometric characteristics. Such error processes can thus be corrected more successfully by a correction device individually matched to the sensor of the respective test device than standardized by a chip card.

The correction functionality of the correction device can be sensibly realized as a software solution that can run on a suitable processor. The correction function then corrects the alienated, error-prone authentication data independently of the alienation, so that the result is error-corrected, but nevertheless alienated authentication data are generated. These are then transmitted back to the chip card via a suitable communication link.

In an advantageous embodiment of the invention, the detected, error-prone authentication data are encrypted by the test device before transmission to the chip card and decrypted before the alienation on the chip card again.

Although the data communication between smart card and correction device can be done in principle unencrypted due to the alienation of the authentication data, it is provided in one embodiment of the invention, in addition to the correction device to transfer the alienated error-prone authentication data to encrypt and decrypt after transmission again. It is also possible to additionally encrypt the retransfer of the error-corrected authentication data from the correction device to the chip card.

In a last step, the chip card receives the encrypted or unencrypted alienated authentication data from the correction device or the test apparatus, reconstructs the authentication data from the encrypted authentication data by means of the security application and finally forwards the error-corrected, unaltered authentication data to the authentication function of the smart card operating system their conformity with the reference authentication data stored in the chip card is checked. If the deviations of the authentication data and the reference authentication data in a given statistical Move frame, the person is considered authenticated and receives the desired access.

Additional security is achieved when the sensor of the tester must additionally authorize prior to the recording of biometric properties at the chip card in contact with the tester at that time. In particular, the secure messaging protocol is suitable for this purpose. The additional authorization of the sensor prevents an attack by deception by means of a manipulated sensor.

In particular, the fingerprints of a person, their iris pattern, their portrait, a frequency pattern of voice and speech samples, or combinations of these and other biometric characteristics can be recorded as biometric characteristics for the present invention.

As far as the individual embodiments encrypt and decrypt data, a symmetric encryption method can be used in which the cryptographic function of the chip card uses a key stored in the memory of the chip card, which is also present on the tester. Since it is not appropriate for security reasons, to deposit the same key on each chip card, in a particularly preferred embodiment of the invention, one of the tester known master key (Masterkey) is used, with a unique, derived smart card key (Derived Key) for the Chip card can be generated. In this way, the consequences of unauthorized reading of the chip card key are minimized. Before a manufactured chip card equipped with an executable standard chip card operating system can be used by its owner for authentication, it must first be prepared by depositing the security application and at least the reference authentication data in the non-volatile EEPROM memory of the chip card. This can be done as part of the personalization of the chip card. If necessary, a cryptography key can also be stored.

Of course, the ref erence authentication data to be written in as part of the preparation of the chip card are in principle generated in the same way as the authentication data from the checking device, so that comparable data records are created within the framework of the error-related variance.

This above object is further achieved according to a second aspect of the invention by a method and system having the features of independent claims 28, 34, 36 and 37. In dependent claims advantageous embodiments and developments of the invention are given.

In this case, instead of a chip card, any storage medium can be used in which a secret secured by means of biometric reference data is present. The storage medium may be designed as a portable storage device, for example as a USB storage dongle or chip card, or as a stationary storage system, for example in the form of a computer, as well as a conventional storage module of the testing device or the correction device. The basis of the authentication of a person at the checking device in this second aspect of the invention is the secure determination of a secret from a biometrically secured secret present on the storage medium in order to use the secret present in plaintext to authenticate the person at the checking device. For this purpose, biometric authentication data of the person on the test apparatus are first of all collected, as described in the context of the first aspect of the invention.

In a second step of the method, the authorization of the person is checked by compensating for the biometric security of the secret by means of the recorded, necessarily faulty biometric authentication data, so that the result is an alienated secret that no longer contains any biometric information. However, since the compulsory error component of the authentication data is not eliminated in the compensation step, the alienated secret is additionally subject to errors. Therefore, the compensation of the biometric protection is performed such that a later error correction of the alienated secret despite its alienation is possible.

For this purpose, the error-prone, alienated secret is transmitted to the correction device for error correction, where its error component is first eliminated by a suitable algorithm, and then the clear-text secret is reconstructed from the now error-corrected, alienated secret. The clear text secret present on the correction device can be used for the person in the further course for the final authentication of the person. Preferably, the secret of the person is unique so that their authorization can be clearly demonstrated with the presence of the plaintext secret.

The advantage of this method lies in the fact that the clear-text secret can be determined, none without any of the participating instances, the test device, the storage medium or the correction device, the full required for authentication data, and thus a targeted spying one of these instances can not lead to corruption of the authentication method. While the test device only has knowledge of the person's biometry and does not know the secret, the storage medium only knows the secret that has been secured, not biometrics. The correction device finally reconstructs the cleartext secret, but biometrics is unknown to it.

Based on this inventive principle, two embodiments result, which differ in the alienation and the biometric compensation.

In a first embodiment, the authentication data is alienated from a calculation device of the test apparatus and the alienated authentication data is transmitted to the storage medium via corresponding communication interfaces. There, the alienated authentication data and the biometrically secured secret are linked by a computing device of the storage medium such that the biometric authentication data and the biometric reference data used to secure the secret eliminate each other and an erroneous, alienated result results, which is transmitted to the correction device for further processing.

In the second embodiment, the biometrically secured secret is alienated by a computing device of the storage medium and transmitted to the test device via corresponding communication interfaces. There, the alienated, biometrically secured secret is linked to the biometric authentication data by a calculation device of the checking device, so that the biometric reference and authentication data are mutually eliminated and an erroneous, alienated secret results, which is transmitted to the correcting device for further processing.

It is advantageous to biometrically secure the secret by means of an XOR linkage with biometric reference data. In this way, the compensation of the biometric protection can also be carried out by means of an XOR linkage from the test device or from the storage medium, since the biometric authentication data and the biometric reference data eliminate each other in the event of an XOR link.

Likewise, the alienation is preferably realized by an XOR link, so that the reconstruction of the cleartext secret from the alienated secret can also be performed by the correction device by means of an XOR link. The alienation is advantageously carried out by means of a random codeword, for example a random number, which, depending on the embodiment, is generated either by the test device or the storage medium. After this The alienating the random codeword of the test device or the storage medium is transferred to the correction device so that there can take place the final reconstruction of the clear text secret.

While the checking and correcting devices according to the first aspect of the invention may be constructed and arranged, the storage medium comprises, unless it is a chip card according to the first aspect of the invention, at least one calculating means, such as e.g. A processor for performing necessary alienation and linking operations.

Further features and advantages of the invention will become apparent from the following description of various inventive embodiments and alternative embodiments. Reference is made to the figures, which show:

1 shows an inventive authentication system consisting of a chip card and a test device with external correction device;

FIG. 2 shows the sequence of an authentication procedure and, in particular, the interaction of the components involved in it; and

Figures 3A and 3B each show an embodiment of a second. Aspect of the invention show.

According to the first aspect of the invention, the chip card 1 next to the test apparatus 2 and the correction device 4 forms the central component of the authentication system shown in FIG. The chip card 1 is as Commercial chip card formed with a conventional internal structure and includes a communication interface 12 for data communication with the corresponding interface 21 of the test apparatus 2, a central processor (CPU) 11 for program execution, an internal data bus 17 and finally a differentiated memory device 10 consisting of a non-volatile memory ( ROM), a nonvolatile, rewritable EEPROM memory and a RAM memory.

The operating system 13 of the chip card 1 is a specialized chip card operating system which was stored in the ROM memory when the chip card was manufactured. Smart card operating systems are designed as security operating systems that control and secure all operations and in particular data accesses and manipulations on the chip card. Therefore, important safety-relevant algorithms, such as the cryptography function 132 or the authentication function 131 are designed as immediate operating system functionalities, either as real operating system functions or as modular operating system modules. Since the operating system resides in the ROM memory, so far, the above-mentioned security functions over the entire life of the smart card 1 immutable and can be used only in the implemented manner.

In principle, changeable and erasable applications, program components and data are stored in the non-volatile EEPROM memory. Among other things, there are the security application 14, one or more cryptographic keys 15 and the reference authentication data 16. Deviating from this, it is also possible in principle with cryptographic methods with static bowls to deposit them directly in the manufacture of the chip card 1 in the ROM memory. The inventive method illustrated in FIG. 2 is realized by the interaction of the security application 14 with the chip card operating system 13 and its functions 131, 132. In principle, it is of course possible to adapt operating system functions with regard to an authentication strategy to be implemented to the security application 14. However, it is an object of the present invention that the security application 14 just does not require any adapted operating system functions, but can interact with any standard smart card operating system 13, which is unmodified at least in terms of its authentication functionalities.

Such smart card operating systems are e.g. STARSIM, STARCOS, MPCOS, Cyberflex, Multiflex, Payflex, CardOS, but also JavaCard, Multos, BasicCard, Windows for Smart Cards as well as smart card-compatible Linux derivatives. Of course, in all of these operating systems, the security application 14 is adapted to special conventions relating to the programming language, interfaces and data formats. In a particularly preferred embodiment of the chip card 1 as a JavaCard, the security application 14 is accordingly a Java applet.

The security application 14 includes a random number generator 141 and an alienation function 142 that uses the random numbers generated by the random number generator 141 to alienate authentication data. This type of alienation with individually generated random numbers (so-called dynamic keys) represents a particularly advantageous embodiment of the invention, since it provides high security due to the randomized and only once used alienation key. If the present smart card operating system 13 includes a random generator, the security application 14 does not necessarily have its own random generator 141, but may instead use the standard random number generator of the operating system 13.

The alienation of data from encryption is such that the alienated data can also be systematically manipulated in an alienated form. This makes it possible, for example, to subject alienated authentication data to error correction without the alienation disturbing the error correction or the error correction corrupting the alienation on the one hand.

Although the concrete alienation function is in principle to be matched to the error correction, there is alienation function such as. the binary XOR function which satisfies the requirements for alienation with respect to a correction of noise and error processes. Another suitable alienation function in this context is the binary NXOR function, ie the XOR negation.

Procedural and personal data and components, such as the security application 14 and the reference authentication data 16, are usually written in the personalization of the smart card 1, so their unique assignment to a person in the EEPROM memory. This preparation of the chip card 1 for its intended use by its owner is usually carried out by the smart card manufacturer or the issuing body. Just as well, however, an already personalized chip card 1 with later security application 14 or updated reference authentication data 16.

The reference authentication data 16 to be written into the chip card 1 during personalization are generated in principle in the same way as the authentication data 221 to be prepared by the checking device 2 during an authentication. That is to say, the same biometric characteristics of the person are recorded or digitized and algorithmically converted into numerical reference authentication data 16 as in the authentication by the testing device 2.

In the recording of biometric properties 24, technical errors are indispensable, which are introduced into the biometric data set, for example by noise processes (sensor or quantum noise) or global and local image disturbances (for example, uneven illumination, pixel errors, distortions). Also, the natural biological variance and the usual complexity of biosignals by many factors complicates the measurement data collection and the feature extraction and leads to further statistical inaccuracies.

Since the reference authentication data 16 serve as a basis for comparison each time the chip card 1 is used, it is expedient to use special methods for error correction or for minimizing statistical, technical or biological variances in its creation. In the simplest case, this can be achieved by averaging over a larger sample of authentication data of the same biometric properties. Other suitable methods have been widely documented in the prior art. The loading of the security application 14 into the EEPROM memory at the time of personalization has the advantage that the authentication method realized by the application 14 can on the one hand be tailored individually to the person, for example because the person belongs to a certain security level. On the other hand, the security application 14 and the authentication method implemented by it can be changed or adapted at a later time, for example to a changed biometric data collection, a changed appearance of the person or an altered encryption strategy in the authentication method.

Further details of the construction, production and handling of chip cards can be found, for example, in the "Handbuch der Chipkarten", Rankl, Effing, 4th edition, 2002, Hanser Verlag In any case, it is expedient to use the chip card 1 in ISO In this case, the communication interface 12 for enabling the read-out of the chip card 1 by the test apparatus 2 either the shape of a contact field or, alternatively, in the non-contacting embodiment, the shape of a coil.

The test apparatus 2 is essentially equipped like a conventional computer and therefore includes a program execution CPU 28, a data bus 25, a memory device 27, and other application modules and programs, such as a cryptography device 26 and a computing device 22, both as hardware or software. Components or as stored in the memory 27 and can be configured by the CPU 28 executable software programs. In addition, the test apparatus 2 comprises an interface 21 for a chip card 1, which is advantageously designed as a conventional, contactless or contacting chip card reading device. Furthermore, the test apparatus 2 comprises a sensor 23 which records biometric characteristics 24 of persons who wish to authenticate themselves by means of their chip card 1 on the test apparatus 2. Depending on the biometric properties 24 to be recorded, this may be an optical sensor, for example a CCD camera for digitizing a fingerprint or another digital camera for recording a portrait of the person. Also, acoustic sensors for recording a voice profile, temperature sensors or other biometric sensors, and natural combinations of such sensors for recording multiple biometric characteristics are possible.

In a preferred embodiment, the sensor 23 is arranged to authorize, before it records a biometric characteristic 24, a secure access to the smart card 1, preferably via a secure messaging protocol. This ensures that the biometric data to be processed by the test apparatus 2 actually come from the sensor 23 and thus from the person to be authenticated. After recording the biometric property 24, the computing device 22 calculates therefrom authentication data 221 of the person, which, however, are subject to errors due to technical and biological noise and variance processes.

The correction device 4, whose task is the error correction of the error-prone authentication data 221 recorded by the sensor 23, can either be realized as in FIG. 1 as a separate component from the test device 2 or as an internal component of the test device 2. In the first variant, there is a secure data communication connection 3 between the checking device 2 and the correcting device 4, and the external correcting device 4, which may be a conventional computer, comprises a memory device 43, a CPU 44, a cryptography device 42 and a correction functionality 41 For example, the correction functionality 41 and the cryptography device 42 can each be implemented as software components that reside in the memory 43 and can be executed by the CPU 44. The memory 43 also stores a cryptographic key 431 used for encryption and decryption by the cryptography device 42. In the second variant, however, the correction device 4 is connected directly to the internal data bus 25 of the test apparatus 2 and then does not require its own components, but they can use the corresponding components 26, 27 and 28 of the test apparatus 2.

To secure the data transmission between the chip card 1 and the test device 2 on the one hand and the test device 2 and an external correction device 4 on the other hand, all three components have separate cryptographic functions or devices 132, 26, 43, the data to be transmitted with cryptographic keys 15, 271, Encrypt 431 and decrypt received encrypted data accordingly. The encryption of the data exchange with the correction device 4 is not absolutely necessary because these data are already alienated, but may be useful to increase security.

Since it is risky in smart card-based systems to use a conventional symmetric method with identical keys for all communication partners, is efficient and sufficient Secure variant for the communication between smart card 1 and test device 2, the use of a master key 271 (master key), which is stored in the memory device 27 of the test device 2. The chip card 1 has a counterpart derived from this master key and a chip card-specific information (eg serial number) key 16 (Derived Key). As a cryptographic algorithm can then be used for example Triple-DES or AES.

The communication between the verifier 2 and the corrector may be symmetric (e.g., DES) or asymmetric (e.g., RSA) encrypted using the appropriate secret or public key, possibly involving a central certificate authority. It is also possible to use dynamic keys, which are regenerated similarly to the random number 141 for each encryption.

In alternative asymmetric encryption, data is encrypted with a secret key that can be decrypted from the receiving site by means of a public counterpart. It is therefore possible to provide each smart card 1 and each test device 2 with its own secret key, the encryption of which can only be decrypted with a public counterpart. The key pairs can then be generated, for example, by a central certification authority and made available to the components of the authentication system during production. Procurement of the required public key could be done via wireless requests to centralized or distributed key servers. 2, the procedural steps to be carried out by the individual components of a preferred embodiment of the authentication method according to the invention are complementary to the authentication system in FIG.

After bringing the chip card 1 into contact with the test apparatus 2, for example by inserting the chip card 1 into a reading device of the test terminal 2 so that data communication can take place via the corresponding interfaces 12, 21, the sensor 23 first authorizes in step S1 This may be done, for example, in accordance with the Secure Messaging Protocol, or with any other secure technology suitable therefor.

After the authorization of the sensor 23, in step S2 those biometric characteristics 24 of the person are recorded which were also used to generate the reference authentication data 16 located in the memory 10 of the chip card 1.

In step S3, the biometric characteristic 24 is transformed by the calculation means 22 of the test terminal 2 by feature extraction into a numerical feature vector PIN *, wherein the feature extraction is performed in the same way as in the generation of the reference authentication data REF. Although among the methods for feature extraction also those are to be found that minimize at least the technical blurring (noise), resulting as the result of step S3 against the reference authentication data REF erroneous authentication data PIN * of the person. In order to preclude a possibility of manipulation during data transmission, the error-prone authentication data PIN * is encrypted by the cryptography device 26 using the key 272 before the transmission in step S4 (resulting in enc [PIN *]), in step S5 for alienation to the chip card 1 and finally decrypted after reception by the interface 12 in step S6 from the cryptographic function 132 of the operating system 13 using the key 15.

For the alienation of the error-prone authentication data PIN * by the security application 14, a random code word RND is first generated by the random generator 141 in step S7. In step S8, the error-prone authentication data PJN * are alienated by the alienation function 142 using the random number RND, resulting in rnd [PΪN *].

In a preferred embodiment, the alienation is performed by an XOR combination of the two number sequences RND and PIN *. For this purpose, it is expedient that the generated random number RND is of the same length as the error-prone authentication data PIN *. The XOR function is suitable for alienation because, on the one hand, it is resource-saving and, on the other hand, it represents its own inverse since its re-use reverses the original effect of first-time use, because rnd [rnd [PIN *]] = PIN CODE*.

Since the reference authentication data REF and the authentication data PIN * can not yet be compared due to the incorrectness of PIN * for this procedural state, the error-prone Authentication data PIN * must be error-corrected before the actual authentication.

However, it is usually not useful to perform the error correction directly on the chip card 1, since the extent of the error depends inter alia on the sensor 23 used. In order to be able to securely send the error-prone authentication data PIN * to a correction device 4, they are so disguised (disguise) in step S8 that they can also be error-corrected in an alienated state, and finally transferred to the correction device 4 in step S9.

As shown in FIG. 1, the authentication data can be transmitted to the correction device 4 via the checking device 2, which forwards the authentication data PIN * to be corrected via a secure network 3 to the correction device 4. Likewise, however, it is also possible for the transmission to establish a direct contact between the chip card 1 and the correction device 4, for example via a corresponding radio link.

In step S10, the correction device 4 corrects the alienated, error-prone authentication data rnd [PIN *] by means of suitable methods and thereby generates alienated, error-corrected authentication data rnd [PIN]. The error correction of step S10 thus pursues the goal of transforming the error-prone authentication data PIN * generated by the checking device 2 so that it is comparable to the reference authentication data REF of the person. To achieve the error correction, it may therefore be useful to match these with the initial generation of the stored on the chip card 1 reference authentication data REP. In addition, the error correction has the combination with the alienation necessary for the inventive authentication property of commutativity with respect to the function composition, because the errors of the authentication data can be corrected so that the alienation is maintained so that it can be reversed by the alienation function 132 of the security application 14 again.

The alienated, error-corrected authentication data rnd [PIN] are now sent back to the chip card 1 in step Sil, possibly by being forwarded through the test terminal 2.

In step S11, the error-corrected authentication data PIN is reconstructed from the received, alienated authentication data rnd [PIN] by the security application 14. If the complementary alienation in step S8 has already been carried out by an XOR combination of the error-prone authentication data PIN * with the random number RND, the alienated authentication data in step S11 are assigned the same random number RND, which in the meantime is stored in the RAM or EEPROM memory of the chip card 1, XOR linked again. The result is an unaltered and error-corrected authentication PIN, which are compared in the final authentication step S13 of the authentication function 131 of the smart card 1 with the stored in the memory reference authentication data REF.

The authentication check in step S13 generally does not consist of a simple equality test, but of a fault-tolerant comparison, which is robust to remaining minimal deviations between the reference authentication data REF and the authentication data PIN within a certain tolerance interval. If the two data sets are identical within the tolerance interval, the transaction intended by the person is finally released in step S14 and this is communicated to the test terminal in a suitable manner.

Depending on the input values of the standard authentication function 131 of the respective operating system 13, there are further variants of the inventive authentication method illustrated in FIG.

- In a variant, the alienated authentication data are not reconstructed after receiving the error-corrected, alienated authentication data by the smart card 1, but the reference authentication data 16 are alienated and these are compared by the authentication function 131 with the alienated authentication data.

In principle, the alienation provides sufficient protection during the retransmission of the error-corrected authentication data from the correction device 4 to the chip card 1. However, the error-corrected, alienated authentication data can additionally be encrypted by the correction device 4. With appropriate support by the operating system, there are three further variants for this case, which assume that the chip card 1 receives encoded, alienated authentication data from the correction device 4:

- The encrypted, alienated authentication data will not be decrypted, but it will present the chip card 1 Reference authentication data 16 is alienated by the security application 14 with the random number already used for alienating the authentication data, then encrypted by the cryptographic function 132 of the smart card 1 and finally compared by the authentication function 131 with the received encrypted, alienated authentication data;

the encrypted, alienated authentication data are first decrypted by the cryptography function 132 of the chip card 1, reconstructed by the security application 14 and compared by the authentication function 131 with the stored reference authentication data 16; and

- The encrypted, alienated authentication data are decrypted, the reference authentication data 16 are alienated and both records are compared by the authentication function 131. Of course, the security application 14 uses to alienate the reference authentication data 16, the same random number that has already been used to alienate the authentication data.

The embodiment of Figure 2 and the four above variants is common / that all security-related operations are performed by the security application 14 controlled on the smart card 1. No usable information is visible to the outside, which offers an attack potential. In particular, it is not possible to deduce the actual authentication data from the error correction carried out on an external correction device 4, since these are at least alienated outside the chip card 1 at any time. Figures 3 A and 3B show the inventive principle according to the second aspect of the present invention. The method is performed similarly to the above-described first aspect of the invention by three involved instances, a storage medium Y ₁ a test apparatus 2 and a correction apparatus 4, wherein the test apparatus 2 and the correction apparatus 4 correspond to the apparatuses described in connection with FIGS. 1 and 2 ,

The storage medium Y is in principle equipped with a memory device, communication interfaces for data exchange with the test device 2 and the correction device 4 and a calculation device, for example a processor that can execute program files. In this respect, the storage medium Y can also be the chip card 1 described in connection with FIGS. 1 and 2. In addition, however, the storage medium Y can also be an other storage element, for example a portable USB memory card, or a stationary computer, or can be realized as a storage module 27 or 43 of the test device 2 or the correction device 4.

Stored in the storage medium Y is a biometrically secured secret SECΘPIN, the biometric assurance of which is that the secret SEC is XOR-linked with the user's biometric reference data REF. If the user whose biometric reference data REF is stored securely in the storage medium Y approaches the checking device 2 for authentication, in step S21 first authentication data PIN * are determined, which are inherently error-prone. This takes place in the same way as described in FIG. 2 by steps S1 to S3. The embodiments of FIGS. 3A and 3B differ in the alienation step S22, S23; S22 ', S23' to the effect that in the embodiment of FIG. 3A, the faulty authentication data PIN * present on the checking device 2 is alienated by a calculating device of the checking device 2, while in the embodiment of FIG. 3B the biometrically secured one present in the storage medium 1 ' Secret SECΘPIN is alienated by the calculation device of the storage medium V. The alienation is carried out in each case such that the alienated data are suitable for compensating for the biometric security of the secret of the respective other device (ie the storage medium 1 'or the test device 2 when alienated by the test device 2 or the storage medium 1'). to be used.

For this purpose, a random number RND is generated by the test apparatus 2 or the storage medium 1 'in step S22 or S22', which is transmitted to the correction device 4 in step S24 or S24 '. In step S23 or S23 ', the error-prone authentication data PIN * or the biometrically secured secret SECΘPIN are alienated by an XOR operation with the random number RND and the result of this alienation in step S25 or S25' to the storage medium V or the checking device 2 transferred. At this time, in the embodiment of FIG. 3A, on the test apparatus 2 or in the embodiment of FIG. 3B on the storage medium 1 'there is a data record which contains the secret SEC, the biometric reference data REF, the biometric authentication data, in a partially saved or alienated manner PIN * and the random number RND include. In step S26 or S26 ', all these data are linked by means of an XOR link, so that the biometric reference data REF and the authentication data PIN are mutually eliminated by the XOR link. In this way, a secret SEC alienated with the random number RND by means of an XOR link is created, the error component of the biometric authentication data PIN * now acting as an error component of the alienated secret (SECΘRND) *.

That is, by the compensation of the biometric components in steps S26 and S26 ', only the biometric clear data PIN entering the error-prone authentication data PIN * - which correspond exactly to the biometric reference data REF - are eliminated, while the error component is retained for the remainder of the term.

In step S27 or S27 ', the erroneous alienated secret (SECΘRND) * is transmitted from the storage medium V or the checking device 2 to the correction device 4. There, in steps S28 and S29, the cleartext secret SEC is calculated by correcting the error component and reconstructing the secret SEC from the alienated secret SECΘRND by XORing with the random number obtained in steps S24 and S24 ', respectively. As a result of this secure process, the SEC secret now exists in plain text and can be used to authenticate the person concerned.

In addition, it is possible to secure all data transfers between by suitable encryption / decryption, as described in connection with Figures 1 and 2.

Claims

Patent claims

1. A method for authenticating a person to a test device (2) by a chip card (1) with a security application (14) by means of the following steps:

- Determining authentication data (221) of the person by the checking device (2) and transmitting the authentication data (221) to the smart card (1);

- Receiving (S5) of the authentication data (221) by the smart card (1) and alienating (S7, S8) by the security application (14) such that an error correction of the authentication data despite their alienation is possible;

- Transferring (S9) the alienated authentication data to a correction device (4) for error correction outside the smart card

(I);

- Performing the error correction of the alienated authentication data by the correction means (4) for generating (SLO) of error-corrected, still alienated authentication data and transmitting the error-corrected alienated authentication data to the smart card (1);

Receiving (Sil) the error-corrected alienated authentication data by the smart card (1);

- reconstructing (S12) error-corrected, unaltered authentication data from the error-corrected, alienated authentication data by the security application (14); and

Authenticating (S13) the person on the basis of the error-corrected, unaltered authentication data and on the chip card (1) stored, the person uniquely associated Ref erenz- authentication data (16).

2. The method according to claim 1, characterized in that the authentication (S13) of the person by comparing the error-corrected, unaltered authentication data with the reference authentication data (16) by an authentication function (131) of the operating system (13) of the smart card (1 ) he follows.

3. The method according to claim 1 or 2, characterized in that the determination of the authentication data (221) comprises the following steps:

- recording (S2) at least one biometric characteristic (24) of the person by means of a sensor (23) of the test device (2); and

- Extracting (S3) biometric features from the biometric property (24) as authentication data.

4. The method according to claim 3, characterized in that the sensor (23) records a fingerprint, an iris pattern, a portrait or voice information.

5. The method according to claim 3 or 4, characterized in that the sensor (23) before recording the biometric property (24) in the smart card (1) authorized (SI), in particular by secure messaging.

6. The method according to any one of claims 1 to 5, characterized in that the determined authentication data (221) are encrypted before their transmission (S5) to the smart card (1) and decrypt the encrypted authentication data after their receipt in the smart card (1) again become.

7. The method according to any one of claims 1 to 6, characterized in that the alienated authentication data in the smart card (1) before its transmission (S9) to the correction means (4) are encrypted and the encrypted alienated authentication data in the correction means (4) be decrypted again at their reception.

8. The method according to any one of claims 1 to 7, characterized in that the error-corrected, alienated authentication data before its transmission (Sil) to the smart card (1) are encrypted and decrypt the encrypted alienated authentication data after their receipt in the smart card (1) again become.

9. The method according to any one of claims 6 to 8, characterized in that the encryption takes place symmetrically using a stored on the test device (2) master key.

10. The method according to any one of claims 6 to 9, characterized in that the encrypting or decrypting in the chip card (1) by a cryptographic function (132) of the operating system (13) of the chip card (1).

11. The method according to any one of claims 1 to 10, characterized in that the alienation of the authentication data by generating (S7) a random code word by the security application (14) and by XOR- connections (S8) of the authentication data with the random codeword, and reconstructing (S12) the error-corrected authentication data from the alienated, error-corrected authentication data by XOR links (S12) with that random codeword that has already been used for alienation.

12. The method according to any one of claims 1 to 11, characterized in that the chip card (1) a JavaCard and the security application (14) running on the JavaCard applet.

13. A method for preparing a chip card (1) with a respect to an authentication function (131) unmodified standard chip card operating system (13) for carrying out a method according to one of claims 1 to 14, comprising the steps:

- storing reference authentication data (16) of the person in a memory (10) of the chip card (1); and

- Loading a security application (14) on the smart card (1), which is adapted to the operating system (13) of the smart card (1) so that it can call the authentication function (131) of the operating system (13), and wherein the security application ( 14) is set up to alienate authentication data (221) such that they can be error-corrected despite their alienation, and to reconstruct error-corrected, unaltered authentication data from error-corrected, alienated authentication data.

14. Chip card (1) for authenticating a person to a checking device (2), comprising a memory device (10) in which the person uniquely assigned reference authentication data (16) are stored, and an operating system (13) with an authentication function (131 ) for authenticating the person on the basis of the test device (2) received authentication data and Ref erenz- authentication data (16), characterized in that the chip card (1) further comprises a security application (14), wherein - the security application (14) is arranged to alienate the authentication device (2) received authentication data ( 221), so that an error correction of the alienated authentication data is possible for sending the alienated authentication data to an external correction device (4) and for reconstructing error-corrected, unaltered authentication data from alienated error-corrected authentication data received from the correction device (4).

15. Chip card (1) according to claim 14, characterized in that the chip card (1) with respect to the authentication function (131) unmodified standard chip card operating system (13), wherein the security application (14) separately from the operating system (13) is present and adapted to this, that the security application

(14) can call the authentication function (131) of the standard chip card operating system (13).

16. Chip card (1) according to claim 15, characterized in that in the memory device (10) at least one cryptographic key

(15), and in that the chip card operating system (13) comprises a cryptographic function (132) arranged to decrypt and / or encrypt the encrypted authentication data received from the test apparatus using the at least one cryptographic key (15) Correction device (4) to encrypt transmitted, alienated authentication data and to decrypt encrypted, error-corrected authentication data received by the correction device (4).

17. Chip card (1) according to claim 16, characterized in that the cryptography function (132) is set up for symmetric encryption and decryption.

18. Chip card (1) according to any one of claims 14 to 17, characterized in that the security application (14) is adapted to generate random codewords and alienate the received authentication data (221) by an XOR link with the random codewords and off the alienated, error-corrected authentication data by another XOR link with the random code word to reconstruct the error-corrected, unaltered authentication data.

19. Chip card (1) according to any one of claims 14 to 18, characterized in that the chip card (1) is a JavaCard and the security application (14) is an executable on the JavaCard applet.

20. Computer program product for loading as a security application (14) on a chip card (1) according to one of claims 14 to 19, wherein the computer program product to a respect to an authentication function (131) unmodified standard chip card operating system (13) of the smart card (1) such adapted that the computer program product can call at least the authentication function (131) of the operating system (13), and wherein the computer program product is set up to alienate authentication data (221) such that this despite their alienation be error-corrected, for sending the alienated authentication data to an external correction device (4) and for reconstructing error-corrected, unaltered authentication data received from the correction device (4), error-corrected alienated authentication data.

21. Authentisierungssy system, characterized by a chip card (1) according to any one of claims 14 to 19 and a test device (2) with

- A communication interface (21) for data communication with the smart card (1);

a sensor (23) for recording at least one biometric characteristic (24) of the person;

- a calculation device (22) for extracting biometric features from the at least one biometric characteristic (24) as authentication data (221); and

- A correction device (4) which is adapted to subject the alienated from the chip card (1) authentication data of an error correction such that the error-corrected authentication data are still alienated.

22. Authentication system according to claim 21, characterized in that the sensor (23) of the test device (2) comprises an optical sensor for recording a fingerprint, an iris or a portrait of the person and / or an acoustic sensor for receiving voice information of the person.

23. Authentication system according to claim 22, characterized in that the sensor (23) is set up before recording the to authorize the person's biometric property (24) against the smart card (1), preferably through secure messaging.

24. Authentication system according to one of claims 21 to 23, characterized in that the test device (2) comprises a cryptography device (26) and a memory device (27), wherein

- in the memory device (27) at least one cryptographic key (271) is stored; and

- The cryptographic device (26) for encrypting and decrypting authentication data by means of the at least one cryptographic key (271) is set up.

25. Authentication system according to one of claims 21 to 24, characterized in that the at least one cryptographic key (271) comprises a master key and the cryptography means (26) is arranged for symmetric encryption and decryption by means of the master key.

26. Authentication system according to one of claims 21 to 25, characterized in that the test device (2) is an ATM, a ticket vending machine or another vending machine.

27. Authentication system according to one of claims 21 to 26, characterized in that the correction device (4) of the other components of the test device (2) structurally separated and connected to these via a communication link (3).

28. A method for safely reconstructing a (S20) on a storage medium (1 '), a biometrically secure secret uniquely assigned to a person for authenticating the person to a checking device (2) by means of the following steps:

- determining (S21) biometric authentication data of the person by the checking device (2);

- alienating (S22, S23, S22 ', S23') the biometric authentication data or the secure secret;

- compensating (S26; S26 ') the biometric security of the secret by means of the biometric authentication data to generate an alienated secret such that an error correction of the alienated secret is possible despite its alienation; and

- transferring (S27, S27 ') the alienated secret to a correction device (4) for error correction outside the storage medium (V);

- performing (S28) the error correction of the alienated secret to produce an error-corrected, alienated secret; and

- Reconstructing (S29) by the correction device (4) an error-corrected, unaltered secret from the error-corrected alienated secret.

29. The method according to claim 28, characterized by the following steps:

Alienating (S22, S23) the biometric authentication data by the checking device (2); - transmitting (S25) the alienated authentication data from the checking device (2) to the storage medium (1 '); and

- Compensating (S26) the biometric security of the secret by linking the secure secret and the alienated authentication data.

30. The method according to claim 28, characterized by the following steps:

- alienating (S22 ', S23') the secure secret by the storage medium (1 ');

- transferring (S25 ') the authentication data from the checking device (2) to the storage medium (1'); and

Compensating (S26 ') the biometric security of the secret by linking the alienated, secure secret and the authentication data.

31. The method according to any one of claims 28 to 30, characterized in that the biometrically secured secret is XOR-linked with biometric reference data tes secret, and that the compensation (S26; S26 ') of the biometric protection by means of an XOR linkage takes place in such a way in that the biometric reference data and the biometric authentication data eliminate each other.

32. Method according to one of claims 28 to 31, characterized in that said alienating (S22, S23; S22 ', S23') by generating (S22; S22 ') a random codeword and XOR-combining (S23; S23') with the random codeword is transmitted, the random codeword for reconstruction to the correction device (4) and the reconstructing (S29) is done by XOR linking with the random codeword.

33. The method according to any one of claims 28 to 32, characterized in that the determination (S21) of the authentication data by means of a sensor device of the test apparatus (2) comprises the following steps:

Recording at least one biometric characteristic of the person, in particular a fingerprint, an iris pattern, a portrait or voice information; and

- Extract biometric authentication data of the person from the biometric property.

34. A storage medium (1 ') for authenticating a person to a checking device (2), comprising a storage device, a communication interface and a calculating device, wherein a biometrically secured secret uniquely assigned to the person is stored in the storage device (S20), and the communication interface is arranged to receive alienated, biometric authentication data of the person from a checking device (2) (S25) and to transmit an alienated secret to a correction device (4) (S27), characterized in that the calculating device is set up to provide the biometric security of the To compensate the secret by means of received biometric authentication data for generating the alienated secret (S26) in such a way that an error correction of the alienated secret is possible despite its alienation.

35. The storage medium (1 ') according to claim 34, characterized in that the storage medium (1') is a portable storage medium, such as. B. is a memory card or a smart card, or an internal or external memory module of a computer or even a computer.

36. Test device (2) for authenticating a person, comprising a sensor device, a communication interface and a calculating device, wherein the sensor device is set up to determine biometric authentication data from a biometric characteristic of the person (S21), and the communication interface is set up, an alienated, to receive biometrically secured secret from a storage medium (1 ') (S25') and to transmit an alienated secret to a correction device (4) (S27 '), characterized in that the calculation device is adapted to use the biometric security of the received secret by means of Compensated biometric authentication data for generating the alienated secret to compensate (S26 ') that an error correction of the alienated secret despite its alienation is possible.

37. Authentication system for authenticating a person comprising a storage medium (1 ') with a biometrically secured secret uniquely assigned to the person, a checking device (2) which is set up to determine biometric authentication data from a biometric characteristic of the person (S20), and a correction device (4), characterized in that the storage medium (1 ') is arranged to alienate the biometrically secured secret (S22', S23 '), or the checking device (2) is set up to alienate the biometric authentication data (S22, S23), and

the other, non-alienated means (V, 2) is arranged to compensate for the biometric security of the secret by means of the biometric authentication data for generating an alienated secret (S26; S26 ') such that an error correction (S28) of the alienated Mystery is possible despite its alienation; and

- the correction means (4) is arranged to subject the alienated secret to error correction (S28) such that the error-corrected secret is still alienated, and to reconstruct an error-corrected, unaltered secret from the error-corrected alienated secret (S29).

38. Authentication system according to claim 37 with a storage medium (1 ') according to claim 34 or 35, characterized in that the checking device (2) comprises a communication interface and a calculating device, wherein the calculating device is set up to alienate the biometric authentication data in such a way (S22, S23) that they are adapted to be used by the memory means (1 ') for compensating (S26) the biometric security of the secret, and the communication interface is arranged to transmit the alienated authentication data to the storage medium (S25).

39. Authentication system according to claim 37 with a test device (2) according to claim 36, characterized in that the storage medium (1 ') comprises a communication interface and a calculation device, wherein the calculation device is set up, the to alienate biometrically secured secret (S22 ', S23') such that its biometric protection can be compensated by the checking device (2) (S26 ') and the communication interface is set up to transmit the alienated secret to the checking device (S25'). ).