DE102016109721A1 - Method of operating a cyber-physical information delivery system - Google Patents

Abstract

The invention relates to a method for operating a cyber-physical information transmission system, which has a virtual end point (α), at least one radio interface (A), at least one radio security token (B) and one or more terminals (C) communicating by radio, in which a potentially unsafe connection (V1) is established between the radio interface (A) and the virtual end point (α), a secure connection (V2) is established between the end point (α) and the radio security token (B) and the terminal (C) is securely coupled to an endpoint (α) by the radio security token (B). The object of the invention is to develop a method which produces a particularly simple, user-friendly, energy-efficient and nevertheless highly secure and authentic connection between the virtual end point (α) and a terminal (C) with minimal administrative and organizational effort. To solve this problem, the invention proposes that the radio safety token (B) in the physical vicinity of the terminal (C) is brought and the end point (α) on the one hand based on the measured physical reception parameters between the terminal (C) and the radio interface (A) On the other hand, between terminal (C) and radio security token (B), the physical proximity of radio security token (B) and terminal (C) is verified.

Description

The invention relates to a method for operating a cyber-physical information transmission system which has a virtual endpoint, at least one radio interface, at least one radio security token and one or more radio-communicating terminals, wherein between the radio interface and the virtual endpoint a potentially unsafe connection a secure connection is established between the endpoint and the wireless security token and the terminal is securely and user-friendly coupled to the endpoint by the wireless security token.

Such cyber-physical information delivery systems are well known. Due to the advancing technical development in many areas of life and industrial processes, especially in "Internet of Things" applications (IoT applications), such as Smart Home, Wearables, E-Health, Smart City, Smart Grid, Connected Cars, Smart Farming, Smart retail, smart supply chain, and especially in "Industry 4.0" applications, the number of these information delivery systems is growing rapidly.

In a method of operating such a cyber-physical information delivery system, a radio link is established between a virtual endpoint, such as a web application or cloud service (application or storage), and one or more terminal-communicating devices, such as sensors, actuators, displays, inputs and Output devices, smartphones, tablets, laptops, implants, machines and tools. The number of these terminals can range from a single to many thousands.

In almost all use cases, it is important that this connection between the virtual endpoint and the terminal be made particularly simple and user-friendly and secure against external attacks, because the interception or manipulation of the connection can cause material damage as well as threats to Body and life of the user arise. Often, however, the security of the connection is subordinated to the operability. In historical approaches, security is only established between the application and the network layer. This approach is no longer sufficient for future cyber-physical systems, as the compromise of the end devices often attacks the network or the application. For this reason end-to-end protection up to the device level is fundamentally important for a secure IoT. Classically, different methods have been established for end-to-end security of the connection.

It often uses asymmetric cryptography. Here, computational and energy-intensive algorithms are used for key generation. Furthermore, cryptographic random number generators are needed in the terminals, which add more complexities to the terminal. Often the terminals are mostly limited for cost reasons but also due to their size in their computational and energy capacity. Therefore, securing the connection by asymmetric encryption is not suitable in many cases. Furthermore, all established key exchange methods are based on mathematical problems that can not be solved in polynomial time. However, once there are solutions to the problems, such as weaknesses found or quantum computers, these techniques are no longer secure.

For this reason, in the operation of information transmission systems in which the terminals are limited in their computing and / or energy capacity, usually only a symmetric encryption is used. This approach is also used, for example, in most WiFi networks. Here, a password must be entered in all terminals. A dynamic key management, for example, to remove the access rights of individual users, is not or only with great effort to implement. This is possible, for example, by regularly entering new passwords. In addition, the keys must be stored or stored in a trusted location, which entails a very complex key management with a high number of terminals. In such cases, therefore, often a single so-called master key is used for a plurality of terminals. However, if this single master key is decrypted or stolen by an attacker, any of the connections to the terminals can be tapped or manipulated. This can cause correspondingly high damage.

A method of the type mentioned above is known from the publication Kalamandeen et al. [ A. Kalamandeen, A. Scannell, E. de Lara, A. Sheth, A. LaMarca, Ensemble: cooperative proximity-based authentication, in: Proceedings of the 8th International Conference on Mobile Systems, Applications, and Services, ACM, 2010, pp. 331-344. ] known. In the known method, the connection between a virtual endpoint with at least one radio interface and the terminal is authenticated via a radio security token and thus supposedly securely coupled. To authenticate the connection, the wireless security token is placed in the brought physical proximity of the terminal. The similarity of the channel parameters between the terminal and the radio interface on the one hand and the radio security token and the radio interface on the other hand, the connection between the terminal and the radio security token is verified. A radio security token is understood to mean a hardware component for identifying and authenticating subscribers.

The disadvantages of this method are, on the one hand, the use of computational and thus energy-intensive, public-key cryptography on the terminals. Furthermore, this method is only suitable for a few environments. The distance-dependent correlation course of the channel parameters is not given in most cases. To compensate for this problem, multiple radio interfaces are needed in real environments to more likely detect the proximity between the radio security token and the terminal. This increases the hardware costs and thus the costs immensely. In addition, this method is also not secure against relay and MITM (Man In The Middle) attacks. An attacker could forward, for example, the radio communication of terminals and wireless security token to the radio interface via a relay and pretend so the physical proximity of a separate terminal to the radio security token.

It is therefore an object of the invention to develop a method which produces a particularly simple, user-friendly, energy-efficient and nevertheless highly secure and authentic connection between the virtual endpoint and a terminal with minimal administrative and organizational effort.

To solve this problem, the invention proposes, starting from a method of the type mentioned that the radio security token is brought into the physical vicinity of the terminal and the end point based on the measured physical reception parameters between the terminal and the radio interface on the one hand and between terminal and wireless security token verified the physical proximity of wireless security token and terminal. The connection between the radio interface and the terminal takes place via a reciprocal and time-invariant radio channel, which is provided in almost all communication systems. Together with the exchanged application data, the corresponding signal reception parameters (for example the RSSI value) are also made available to the end point. These parameters are available to all base stations and wireless gateways and are already provided to the endpoint in various communication standards. The radio security token, like all radio systems, is capable of receiving signals and measuring the physical reception parameters. This information is provided to the endpoint by the wireless security token over the secured connection. By dependencies of both information, the endpoint is able to verify that the terminal is in the physical vicinity of the radio security token. Based on this information and / or data as a shared secret, the endpoint is able to establish an authentic key with the terminal.

A further development of the invention provides that additionally in a first step the terminal takes influence on the received parameters measured by the radio interface and thereby mask the true channel parameters and that in a second step the true channel parameters are restored from the end point with knowledge of the influencing values , This does not require the radio interface to be trusted. The data connection between the virtual endpoint and the radio interface is considered potentially insecure and the interception or manipulation of that connection is possible. The radio interface can thus be replaced arbitrarily, in particular in mobile applications. In the information transmission system, it serves as an "untrusted relay", which merely forwards data and reception parameters.

It is expedient if the influence values are based on pre-distributed knowledge, which is known to the end point and the terminal. In this way, the masking of the channel parameters based on a symmetric encryption can be realized. Thus, for example, identically constructed terminals that are already connected to the end point can be (re-) identified by a user.

Alternatively, the invention proposes that the radio security token measure the influence values sufficiently accurately when the radio security token is in physical proximity of the terminal and transmit it to the endpoint. The influence values for masking the true channel parameters here consist of secret information that can only be measured in the physical proximity of the terminal. The channel parameters may be affected, for example, by the use of multiple antennas, detuning mechanisms of antennas, or by transmit power adjustment. It is understood that a further embodiment of the method may use a different influence possibility, without departing from the scope of the invention.

A meaningful extension of the method provides that the terminal has at least one bidirectional radio connection to the radio interface and the corresponding channel parameters are measured from the radio channel by the terminal, the corresponding Empfangsparamater are authentic for the endpoint. By doing so, the endpoint is able to detect a relay or MITM attack using the reciprocal channel and the influence values.

It is particularly advantageous if the corresponding channel parameters extracted from the reception parameters are used with the aid of the influence values for the common authentic key generation between the terminal and the end point, the generated keys being authentic for the end point. In this way, the original channel parameters can be reconstructed with sufficient accuracy from the endpoint. The endpoint and the terminal can now apply a known key extraction method based on the channel parameters. Due to the secret influence values, the radio interface receives only a masked version of the channel parameters and forwards them to the end point. The radio security token forwards the measured and secret influence values over the secured connection to the virtual endpoint. The endpoint is now able to reconstruct the original channel parameters with sufficient accuracy to establish a secret key with the terminal that measured the true channel parameters. In this case, the endpoint trusts the wireless security token the function of authentication.

An expedient extension of the method according to the invention provides that the radio security token can additionally influence the reception parameters measured by the radio interface and thus additionally mask the true physical channel parameters, but these can be restored with knowledge of the influencing variable. This improves the quality of entropy in key generation.

It is particularly useful if the knowledge concerning the influence values is exchanged via the secured connection between the radio security token and the end point. With the knowledge of these influence values and the masked channel parameters, the endpoint is able to reconstruct the original channel parameters with sufficient accuracy so that the endpoint can communicate with a common and authentic key with the terminal without the radio interface or other terminals outside physical closeness to learn this secret.

It is also advantageous if the data sent by the terminal is used for the common key generation with the endpoint. Thus, for example, a cryptographic key establishment method can be used. In this case, such an existing method, such as TLS (Transport Layer Security), improved by the location-dependent authentication of the terminal using the radio security token.

An additional development of the method provides that the radio security token measures the reception parameters for the radio interface and transmits them to the end point. In this case, the method is improved by the reception parameters additionally measured by the radio security token. For example, the channel parameters of the channel between the radio interface and the radio security token may aid in identifying the terminal by the channel parameters transmitted from the radio interface to the endpoint. This is especially important when there are a large number of terminals that act as a potential partner. The endpoint, for example, determines a subset of potential terminals that it then uses to attempt key establishment.

An alternative development for this purpose provides that the radio security token additionally has at least one bidirectional radio connection to the radio interface. Through this additional connection, the endpoint is able to more quickly detect a relay or MITM attack by using the reciprocal channel and the influence values.

Embodiments of the invention are explained in more detail below with reference to drawings.

1 shows: Schematically the sequence of the method according to the invention with reference to a basic embodiment

2a / b Schematically illustrate the characterizing process step in the method according to the invention

3a / b Schematically, the application of the method with graphical interface in the form of a smartphone

4a / b Schematically, the application of the method for integrating a terminal, here in the form of a tablet PC, which is then used as a radio security token

5 shows schematically the course of the method according to the invention with reference to a first application example in an Industrie 4.0 environment

6 schematically shows the process of the invention according to a second application example in a smarthealth environment

7 schematically shows the process of the invention according to an embodiment in a TrustedElement application

1 shows the basic structure of a cyber-physical information transmission system, which is operated by the method according to the invention.

A virtual endpoint (α) is connected to a radio interface (A). The end point (α) can be assigned to the same device as the radio interface (A) or else be arranged arbitrarily far away from it. The communication between the end point (α) and the radio interface (A) takes place via a potentially unsafe connection (V1), which is hard-wired, implemented via a radio channel or via web applications via the Internet. Since the radio interface (A) in principle must be interchangeable, this is not trusted. Thus, this connection between the endpoint (α) and the radio interface (A) is potentially not secure.

The end point (α) can communicate with a terminal (C) via the radio interface (A) and a radio channel (K1). For this communication to be secure against eavesdropping and tampering by an attacker (E), the virtual endpoint (α) and the terminal (C) must be securely paired to provide a secure connection between the two. For this purpose, a radio security token (B), which communicates with the virtual end point (α) via an additional, secure connection (V2), is brought into the physical vicinity of the terminal (C), i. into a so-called approach zone (z), brought. The radius of this approach zone (z) depends on the radio frequency used. For a radio frequency of 2.4 GHz frequently used in WIFI networks, the radius is typically about 6.25 cm. In this case, the higher the frequency and the smaller the design of the antenna, the smaller the approximation zone (z).

The radio security token (B), like most radio communication devices, is capable of measuring the reception parameters of the radio channels used. If the radio security token (B) is in the proximity zone (z), the latter can measure the device- and random-specific influencing parameters of the radio signal from the terminal (C) with sufficient accuracy and transmit this information to the virtual end point (α). Neither the radio interface (A) nor an attacker (E) outside the proximity zone (z) can measure these instrument-specific and random-specific influencing parameters sufficiently accurately, since these are noisy and influenced due to the greater distance through the environment-specific channel parameters of the radio channels (K1, K2) ,

The terminal (C) is additionally able to artificially influence the device- and random-specific influencing parameters and thereby actively mask the original channel parameters. If the radio security token (B) is located in the approach zone (z) of the terminal (C), it can measure these influencing parameters and transmit them via the secured connection (V2) to the virtual end point (α). Thus, the radio interface (A) only receives the masked channel parameters, while the radio security token only experiences the device-specific and random-specific influencing parameters. The endpoint (.alpha.) Can now extract the true physical channel parameters from the masked channel parameters with the knowledge of the device- and random-specific influencing parameters that it has learned from the radio security token (B), and based on this secret, which it can only communicate with the terminal (FIG. C), generate an authentic key with the terminal (C).

By this method, except for the virtual end point (α) and the terminal (C), nobody can extract the secret to be established. Even the wireless security token (B) can not find out the secret alone. This is particularly interesting when the radio security token (B) is considered potentially compromisable. The radio security token (B) has only the possibility of identification and authentication. The radio interface (A) only experiences masked channel parameters and can not extract the secret. Extraction of the secret by third parties is only possible if the influence values measured by the radio security token (B) and the masked channel parameters measured by the radio interface (A) are known.

By virtue of the fact that the key material originates from the reciprocal radio channel (K1), that the channel parameters of terminal (C) are still masked and finally that the radio security token (B) can safely send the masking information to the virtual endpoint (α), the key establishment is automatic safe against MITM and relay attacks. A potential relay attack would end in failure of the authentication.

The virtual endpoint (α) and the terminal (C) have a highly secure connection as a result, the implementation being very low-resource is feasible. Preliminary investigations and pilot projects have shown that the key generation code requires only 1.1 kB. In comparison, a high efficiency ECDH (Elliptic Curve Diffie-Hellman) implementation requires 8.7kB. In addition, the inventive method also has a much lower energy consumption. While the ECDH implementation requires approx. 530 mJ, the channel-based key generation according to the invention requires only 5-208 mJ of energy, although in most cases the required energy does not exceed 8.2 mJ (cf. Zenger et al. [Christian Zenger, Mario Pietersz, Christof Paar, 'Preventing Relay Attacks and Providing Perfect Forward Secrecy Using PHYSEC on 8-bit μC', Proceedings in the IEEE ICC 2016 Conference]).

In 2a and 2 B the step which characterizes the method is shown in more detail. The terminal, here represented as a sensor (C1), is to be newly integrated into the cyber-physical information transmission system. This is done with the help of the radio security token, here shown as a simple security stick (B1) whose function is activated via a push button (PB). In 2a is a user with the security stick (B1) outside the approach zone (z) of the sensor (C1). Even if the radio function is activated, the security stick (B1) is not able to measure the influencing parameters generated by the sensor (C1) with sufficient accuracy. As a result, the sensor can not be securely connected to the cyber-physical information delivery system. If the user brings the security stick (B1) into the proximity zone (z) of the sensor (C1), as in 2 B shown, and activates the user via the push button (PB) the radio function, the security stick (B1) the sensor generated by the sensor (C1) influencing parameters, for example via an artificial adjustment of the transmission power, sufficiently accurate and to the virtual Submit endpoint. On this basis, the sensor (C1) and the virtual endpoint can be securely coupled as described above, and the sensor (C1) is incorporated into the cyber-physical information communication system.

3a and 3b show an analogous method, wherein the radio security token is represented here by a smartphone (B2). In addition to the function as a radio security token, the smartphone (B2) can also serve here as a graphical interface to a virtual endpoint, for example a web application. If the sensor (C1) is now securely connected to the cyber-physical information transmission system in the same way as described above, it appears as in 3b can be seen on the display of the smartphone (B2), where already more integrated into the information transmission system terminals are shown.

The 4a and 4b show a further variant of the method. In 4a A tablet PC (C2) is securely integrated into the cyber-physical information transmission system using the smartphone (B2). Once this is done, the tablet PC - now called B3 - can serve as a wireless security token for incorporating additional devices, as in 4b shown.

In 5 An application example of a cyber-physical information transmission system in the operational environment of an Industrie 4.0 application using the method according to the invention is shown.

In this application, several terminals (C11, C12, C13, C14) are in a factory 1 (F1) used to capture sensor data and to control machinery. The terminals (C11, C12, C13, C14) communicate via radio, for example by means of radio standards such as LoRAWAN, SIGFOX, NB-IoT, LTE, UMTS, GSM, IEEE 802.11 . IEEE 802.15.1 or IEEE 802.15.4 , with a gateway (A1), which serves as a radio interface here. The gateway (A1) passes the data encoded by the measured and masked channel parameters to an in 5 not shown arbitrary mass storage, such as a cloud database for storing mass data of the terminals (C11, C12, C13, C14), on. This encrypted mass data can later be decrypted by a cloud database application (α1) and checked for previously unknown relationships. For example, processes can be optimized based on these relationships. The gateway (A1) also forwards selected data of the terminals (C11, C12, C13, C14) to a web-based maintenance application (α2).

To prevent industrial espionage and sabotage, the interception and manipulation of this data must be prevented. An authorized technician (T1) can now individually identify each of the terminals (C11, C12, C13, C14) with a mobile radio security token, for example a smartphone (B2), and to the cloud database application (α1) and / or the web-based Authenticate maintenance application (α2), in which he leads the smartphone (B2) in the approach zone (z) of the respective terminal (C11, C12, C13, C14). The Cloud Database Application (α1) or the web-based maintenance application (α2) receives the masked channel parameters of all terminals (C11, C12, C13, C14) in the factory via the gateway 1 (F1) transmitted. Via the smartphone (B2), the random and device-specific influencing parameters of the terminal (C11) are transmitted to the cloud database application (α1) or the web-based maintenance application (α2). By means of this information, the cloud database application (α1) or the web-based maintenance application (α2) now attempts to use the terminals (C11, C12, C13, C14) to share a common secret, namely the true, physical channel parameters between the respective terminal (C11 , C12, C13, C14) and the industrial gateway (A1). This process will logically succeed only with a terminal (C11), in the approach zone, the smartphone (B2) is located. The cloud database application (α1) or the web-based maintenance application (α2) and the respective terminal (C11, C12, C13, C14) can communicate with maximum security after this application of the method according to the invention. Become more terminals in the factory 1 (F1) or replacing one of the existing terminals (C11, C12, C13, C14), the new terminals can be easily and intuitively integrated by the technician (T1) into the cyber-physical information transmission system.

A potential attacker (E) can - even if he comes into the possession of the smartphone (B2) or the process-related data of the device and thus could successfully spend as this or the industrial gateway (A1) manipulated - not get to the information or manipulate them.

A replacement of the hardware of the industrial gateway (A1) or another industrial gateway (A2) in another position is not a safety problem. Thus, the terminals (C11, C12, C13, C14), originally in the factory 1 (F1) were used in another factory 2 (F2) can be safely used safely. Also the technician (T1) could use the same smartphone (B2) the terminals (C21, C22, C23, C24) in the other factory 2 (F2) securely connect to the cloud database application (α1) or the web-based maintenance application (α2).

Another authorized technician (T2), who already has the terminals (C21, C22, C23, C24) in the other factory via a tablet PC (B3) 2 (F2) has securely connected via another industrial gateway (A2) with a business intelligence application (α3), the terminals (C11, C12, C13, C14) in factory 1 (F1) securely connect to the Business Intelligence application (α3).

It is also possible to operate a mesh network (multi-hop). This means that the radio interface of the terminal (C) can also serve as a radio interface (A).

So it is a decentralized security architecture possible that provides no single point of attack, except those of the endpoint or the terminal. Compromising a terminal (or endpoint) would only be limited to this, bringing a tremendous advantage over the currently used Master-Key based symmetric encryption. By means of the invention, the cloud application (α1) is able to exchange the keys authenticated by individual keys and authenticated by physical proximity with the terminals.

In a state-of-the-art implementation, a secure connection between the radio interfaces and the endpoint is established via a VPN tunnel (SSL, IP-Sec or similar). Thus, here a hedge takes place only at the network level and not at the device level, as in the method according to the invention.

By applying the method according to the invention, a company can now implement, for example, remote monitoring and / or maintenance of their equipment and machines at the device level. This makes it possible to identify possible sources of error from the outset and, if necessary, to evaluate them by specialists. Accordingly, the right measures in terms of personnel, spare parts and tools can be taken directly and thus costs are saved. Furthermore, this minimizes downtime of the machines and systems.

In 6 An exemplary embodiment of a cyber-physical information transmission system in the operational environment of a smarthealth application using the method according to the invention is shown.

One person (P) carries various smarthealth terminals (C3) with him. These smarthealth end devices (C3) can be, for example, motion trackers, implants or medical measuring devices. With these, for example, the blood glucose levels, blood pressure, sleep quality or the function of implants can be observed. The fact that the person (P) these smarthealth devices (C3) in everyday life with them, it will be spared the way to the respective medical facility. In addition, the respective observed values are closer to reality because the person (P) can stay in their usual environment.

The smarthealth terminals (C3) transmit these values via the radio interface to virtual endpoints. In this application example, the radio interface can be, for example, the WLAN router (A3) in the home of the person (P). The virtual endpoints are here Web applications (α4, α5, α6), which for example by the health insurance, the family doctor or by a specialized Specialist anywhere in the world can be used to access the values and evaluate them.

For this it is extremely important that the values can not be manipulated, as wrong values can lead to misdiagnosis and mistreatment and thus pose a danger to the life and limb of the person (P).

In order to securely couple the respective smarthealth terminal (C3) with the web application (α2), the person (P) uses their smartphone (B2) as a radio security token in this application case. The smartphone (B2) has a secure connection to the web application (α2). Bring the person (P) now the smartphone (B2) in the approach zone (z) of the respective terminal (C3), the web applications (α4, α5, α6) and the terminal (C3) can now be securely coupled according to the invention and so establish a secure connection.

It is also clear from this example that the coupling is extremely simple and intuitive. If one of the smarthealth terminals (C3) needs to be replaced, the person (P) can incorporate a new terminal without trouble. It is also clear how important it is that the radio interface (A) does not have to be trusted. This can namely be represented by any mobile tower or any wireless router in the vicinity of the person (P).

In 7 An exemplary embodiment of a cyber-physical information transmission system in the operational environment of a trusted element application using the method according to the invention is shown.

A person carries a smartphone (B2) with him. In today's smartphones are already various types of radio interfaces with multiple antennas. Now one of the radio interfaces of the smartphone (B2) can be used as a radio interface (A) and another function of the radio security token (B) occupy. The separation of the radio interface (A) and the radio security token (B) can be realized by software, one or more secure elements, such as a SIM card, and / or dedicated security cores.

LIST OF REFERENCE NUMBERS

α

endpoint

α1

Cloud database application

α2

Web-based maintenance application

α3

Business Intelligence Application

α4

Web application of the health insurance

α5

Web application of the family doctor

α6

Web application of the specialist

A

Radio interface

A1

industrial gateway

A2

industrial gateway

A3

WLAN router

B

Wireless Security Token

B1

Security stick

B2

Smartphone

C

terminal

C1

sensor

C2

Tablet PC

C1x

Terminal in factory 1

C2x

Terminal in factory 2

C3

SmartHEALTH terminal

e

attacker

F1

factory 1

F2

factory 2

K1

radio channel

K2

radio channel

P

person

T1

authorized technician 1

T2

authorized technician 2

V1

potentially unsafe connection

V2

secured connection

z

approach zone

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• A. Kalamandeen, A. Scannell, E. de Lara, A. Sheth, A. LaMarca, Ensemble: cooperative proximity-based authentication, in: Proceedings of the 8th International Conference on Mobile Systems, Applications, and Services, ACM, 2010, pp. 331-344. [0007]
• IEEE ICC 2016 [0036]
• IEEE 802.11 [0041]
• IEEE 802.15.1 [0041]
• IEEE 802.15.4 [0041]

Claims (11)

Method for the operation of a cyber-physical information transmission system, - which has a virtual end point (α), - at least one radio interface (A), - at least one radio security token (B) - and one or more radio-communicating terminals (C), - at in which a potentially unsafe connection (V1) is established between the radio interface (A) and the virtual end point (α), - a secure connection (V2) is established between the end point (α) and the radio security token (B) and the terminal (C) by the radio safety token (B) is securely coupled to the end point (α), characterized in that - the radio safety token (B) is brought into the physical vicinity of the terminal (C) - and the end point (α) based on the measured physical reception parameters between the terminal (C) and the radio interface (A) on the one hand and between terminal (C) and radio security token (B) ander on the other hand verified the physical proximity of radio security token (B) and terminal (C). Method according to claim 1, characterized in that additionally in a first step the terminal (C) influences influence values on the reception parameters measured by the radio interface (A) and thereby mask the true channel parameters of a radio channel (K1) and in a second step the true channel parameters of endpoint (α) are restored with knowledge of the influence values. A method according to claim 2, characterized in that the influence values are derived from pre-distributed knowledge known to the end point (α) and the terminal (C). A method according to claim 2, characterized in that the radio security token (B) measures the influence values sufficiently accurately when the radio security token (B) is in the physical vicinity of terminal (C) and transmits them to the end point (α). Method according to Claim 1, 2, 3 or 4, characterized in that the terminal (C) has at least one bidirectional radio link to the radio interface (A) and the corresponding channel parameters from the radio channel (K1) are measured by the terminal (C) , where the corresponding channel parameters are authentic for the endpoint (α). A method according to claim 5, characterized in that the corresponding channel parameters from the radio channel (K1) are used for the common key generation between the terminal (C) and the end point (α), wherein the keys thus generated are authentic for the end point (α). Method according to Claim 2, 3 or 4, characterized in that the radio security token (B) can additionally influence the reception parameters measured by the radio interface (A) and thus conceal the true physical channel parameters, but these can be restored with knowledge of the influencing variable. Method according to claims 2, 3, 4 or 7, characterized in that the knowledge about the influence values is exchangeable over the secured connection between the radio safety token (B) and the end point (α). Method according to one of the preceding claims, characterized in that the data sent by the terminal (C) are used for the common authentic key generation with the end point (α). A method according to claim 6, characterized in that the radio security token (B) measures the reception parameters to the radio interface (A) and transmits them to the end point (α). Method according to Claim 6, characterized in that the radio security token (B) additionally has at least one bidirectional radio link to the radio interface (A).

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