WO2015197286A1

WO2015197286A1 - Checking the authenticity of a balise

Info

Publication number: WO2015197286A1
Application number: PCT/EP2015/061697
Authority: WO
Inventors: Uwe Deichmann; Werner Friedrichs; Norbert Geduhn; Udo GOLEBNIAK; Jochen KÄPPEL; Dirk Schulz
Original assignee: Siemens Aktiengesellschaft
Priority date: 2014-06-27
Filing date: 2015-05-27
Publication date: 2015-12-30
Also published as: EP3137363A1; ES2773437T3; EP3137363B1; DE102014212516A1; ZA201607726B

Abstract

The invention relates to checking the authenticity of a balise. For this purpose, an identifier is provided by the balise, which is transmitted as part of the telegram from the balise to the vehicle computer of the rail vehicle. The authenticity of the balise can be verified by the vehicle computer, based on the identifier. The identifier is advantageously transmitted in the ETCS packet 44 according to UNISIG. In addition, a hash value of a cryptographic hash function can be used as an identifier. Furthermore, it is advantageous that any tampering with the telegrams provided by the balise can be detected.

Description

description

The invention relates to a method for operating a rail vehicle, a method for checking a tag provided by a balise, a method for providing a tag by a balise, an ETCS track equipment and a rail vehicle.

The European Train Control System (ETCS) is a component of a single European rail traffic control system, developed under the abbreviation ERTMS. The second technical component of this digital railway technology is the GSM-R railway mobile radio system. ETCS is intended to replace the large number of train control systems used in the countries, to be used in high-speed traffic in the medium term, and to be implemented in the long term throughout the European rail traffic.

An ETCS vehicle device includes e.g. an ETCS computer (EVC, also referred to as On-Board Unit (OBU)), a Driver Machine Interface (DMI), a pathway meter, a GSM-R transmission facility (including Euroradio), a Baiisen reader and a brake access

(http://en.wikipedia.org/wiki/EETS).

ETCS Level 1 uses balises as transmission medium. The information conveyed by the balises are line gradients, maximum line speeds and the point at which the vehicle should stop. Together with an ETCS mode, these form the Movement Authority (MA), translated as "permission to move" or "driving license". Thus, the on-board ETCS equipment continuously the

Monitor compliance with the permitted speed (and direction) and initiate emergency braking in good time. At the end of the MA ("End of Authority", EoA) - for example, a HALT pointing signal - the rail vehicle is to come to a halt.

In addition to ETCS levels, ETCS modes are also defined. The modes describe the states in which the EVC can be located (see also: http://en.wikipedia.org/wiki/ETCS). At ETCS Level 2, almost all information is transmitted via Euroradio from the radio control center (RBC) to the vehicle. In addition, it is possible to transfer information from the train to the route and the information can also be exchanged at standstill. Thus, the track utilization compared to Level 1 can be increased slightly. Before the RBC can calculate the information necessary for a driving license (MA), the RBC must know exactly where the train is and in which direction it is traveling. The determination of position and direction is the responsibility of the vehicle computer, which transmits this regularly via GSM-R to the route. For the determination, however, reference points on the route are needed. For this purpose Eurobaiisen are used, which are installed, for example, in railway sidings and in (for example, irregular) free-distance distances. Between these reference points the position is determined odometrically by means of double radar on the traction vehicle floor and Radimpulsgebern on the traction vehicle axles. Partial acceleration sensors are also used.

As in ETCS Level 1, the information about free track sections is determined via the stationary track release signal from the signal box and transferred to the line center: The section is divided into sections ("blocks") as in conventional safety technology, and the train is allowed to enter the retract next section only if this is not from another Train occupied, but is reported as 'free'. (Source:

htt: // en. wikipedia. org / wiki / European_Train_Control_System. )

The correct transmission of a telegram of the ETCS-Balise is ensured by means of a cyclic redundancy check (CRC, "Cyclic Redundancy Check"). In this case, a check value (also referred to as CRC code) is determined for data in order to be able to detect errors in the transmission (cf.

http: // en. wikipedia. org / wiki / cyclic_redundancy check).

The CRC code is suitable for detecting common errors on communication channels. It is disadvantageous here that such CRC codes do not protect against intentional (malicious) manipulation of the data, e.g. in the form of different attacks. For example, the following changes could be made to the telegrams of the balise:

- a change of the driving license (MA);

a change in information provided by the balise, e.g. "Continue" (Proceed) instead of "Stop" (Stop);

a change in speed values, so that, for example, a higher speed is transmitted than the actually intended maximum speed;

a change in a traffic-limiting signaling;

- a change of distance values. Such manipulations are attacks on the data provided by the balise, which can not be detected by the CRC code. For example, the manipulated data (with the appropriate CRC codes for it) may be provided by an attacker as the rail vehicle passes over the balise. This is undesirable especially for security-relevant data. The object of the invention is to avoid the disadvantages mentioned above and in particular to provide a possibility for a secure and reliable transmission of the data from the balise to the vehicle computer of a rail vehicle.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

To achieve the object, a method for operating a rail vehicle is proposed,

in which information for operating the rail vehicle and an identifier from a balise is transmitted to a vehicle computer of the rail vehicle,

in which the identifier is checked by the vehicle computer,

- in which the information is used on successful verification of the identifier.

For example, information and identifier together in a telegram from the balise to the vehicle computer of

Rail vehicle transferred.

The information provided is used in particular by e.g. The information contained in the information for the operation of the rail vehicle are complied with. In particular, the rail vehicle is controlled based on the information, provided that the identifier could be successfully verified.

It should be noted that the successful verification of the identifier comprises, in particular, a verification of the identifier. By verifying the identifier, the authenticity of the balise can thus be ensured. This ensures that the information obtained also comes from the Balise and it is prevented that an attacker - disguised as a balise - unknowingly transmits the information to the rail vehicle. A development is that the identifier is not checked by the vehicle computer, if it is determined that no identifier is present or if the identifier has a predetermined value. For example, a check may be omitted if there is no identifier. This can be determined by the identifier having a predetermined value, eg the field in which the identifier is transmitted is empty or has or contains a specific value.

It is also possible to disregard the check if the identifier does not have a predefined value. In this case, the check is only performed if the identifier is recognized as such. For this, it is possible for the identifier to have an additional value, e.g. in the form of a bit pattern, for example, which is part of the identifier and / or is present in addition to this. Thus, the additional value of the identifier can be prefixed or attached.

If, for example, a data field in which the identifier could be transmitted is used for another purpose and if there is no identifier in it, this is recognized and the verification of the identifier can be dispensed with.

Another development is that the information is not used if the verification of the identifier was unsuccessful. Unless the identifier (existing and recognized as such) could not be verified, it is assumed, for example, that the information from the balise is invalid. It can then a suitable action, such as a check of the balise and / or the transfer of the system in a safe state, such as braking or stopping the rail vehicle, initiated.

In particular, it is a development that the information is not used if the identifier was detected and the verification of the identifier was unsuccessful. It is also a development that the rail vehicle is transferred to a safe state, if the verification of the identifier was unsuccessful.

Furthermore, it is a further development that the identifier comprises at least one of the following options:

- encrypted data;

- unencrypted data;

Data that has been determined based on a hash function, in particular a cryptographic hash function;

- data determined based on an MD4 algorithm;

- a signature;

- a certificate;

a value for identifying the identifier;

a value for identifying a type of the identifier.

As part of an additional development, the identifier is transmitted in a block 44 of the ETCS implementation according to UNISIG.

A next development is that

the identifier is checked by the vehicle computer by determining a further identifier on the basis of the information and by comparing the identifier with the further identifier, the verification of the identifier was successful if the identifier and the other identifier are identical.

One embodiment is that

- (e.g., from the balise) the identifier is encrypted;

- Decrypts the identifier of the vehicle computer

becomes,

a further identifier is determined by the vehicle computer on the basis of the information and the decrypted identifier is compared with the further identifier,

- the verification of the identifier was successful if the decrypted identifier and the other identifier are identical.

An alternative embodiment is that a symmetric or asymmetric encryption method is used for encryption and decryption.

A next refinement is that it is determined by the vehicle computer based on the identifier

- whether the identifier exists and

- if the identifier exists, what kind of verification of the identifier is to be performed. For example, the identifier can have a value for identification of the identifier, for example in the form of a bit pattern, by means of which it can be determined that it is an identifier. Also, the identifier may have a value for identifying the type of the identifier, so that it can be determined based on which algorithm the identifier can be checked. The value for identifying the identifier and / or the value for identifying the type of identifier may be coded in a bit pattern. The bit pattern can be used, for example, as a header or the like. Be part of the identifier or be transmitted separately from the identifier. The embodiments or features relating to the method explained above apply correspondingly to the following claims, in particular claim categories. The object is also achieved by a method for checking an identifier provided by a balise,

in which the identifier and information from the balise are received by a vehicle computer of a rail vehicle,

- In which the identifier is checked by the vehicle computer.

An embodiment consists in that upon successful verification of the identifier, the information for operating the

Rail vehicle is used.

It is also an embodiment that the identifier is received in a block 44 of the ETCS implementation according to UNISIG.

Furthermore, the object is achieved by means of a method for providing an identifier by a balise,

in which an identifier is created based on information,

in which the identifier and the information when passing the balise are provided to a rail vehicle,

- so that on the basis of the identifier the authenticity of the

Balise of the rail vehicle is verifiable.

In addition, the task is solved by ETCS route equipment

- with at least one balise,

- Wherein the at least one balise is arranged such that it provides an identifier and information when driving over a rail vehicle, wherein the identifier is created based on the information was, so that based on the identifier, the authenticity of the balise of the rail vehicle is verifiable.

A development consists in that the identifier can be determined by means of a cryptographic hash function and that the identifier can be stored in a block 44 of the ETCS implementation according to UNISIG.

The object is also achieved by means of a rail vehicle with a vehicle computer which is set up in such a way that

- the ID and information from the balise

are receivable,

- Based on the identifier, the authenticity of the balise is verifiable by the rail vehicle.

The vehicle computer mentioned here may in particular be embodied as a processor unit and / or an at least partially hard-wired or logical circuit arrangement which is set up, for example, such that the method can be carried out as described herein. Said vehicle computer can be or include any type of processor or computer or computer with correspondingly necessary peripherals (memory, input / output interfaces, input / output devices, etc.). The vehicle computer may be part of a control unit of the rail vehicle.

Also, the above object is achieved by means of a system comprising at least one of the devices described here.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments, which will be described in more detail in conjunction with the drawings. It can for clarity the same or equivalent elements may be provided with the same reference numerals.

Show it:

FIG. 1 shows an exemplary diagram comprising a rail vehicle with a vehicle computer connected to a balise antenna, wherein the rail vehicle moves along a route in the direction of two balises; FIG.

2 shows an example flowchart of a communication between the balise and the vehicle computer of the

Rail vehicle.

It should be noted that the rail vehicle (also referred to as "train") has at least one, in particular at least two cars, wherein the vehicle may be a traction vehicle, a travel car, a freight car or a combination of such parts or functions. The traction unit has a driver's cab (also referred to as an operator station) and can be designed with or without drive. The traction vehicle may in particular be a locomotive. Every car of the

Rail vehicle may be equipped with a vehicle computer; If the vehicle computer (possibly with the mobile communication interface) provides an ETCS function, it may also be called an ETCS car. In principle, it is possible that only the traction vehicles each have a vehicle computer (possibly with the mobile communication interface) or that individual cars that are not traction vehicles have such vehicle computers (possibly with the mobile communication interface).

The solution proposed here makes possible, in particular, a secure transmission of safety-relevant information to the rail vehicle, for example from a balise to the rail vehicle. For this purpose, for example, a so-called packet 44 of the ETCS implementation according to UNISIG (SUBSET-026-7) can be used to transmit a protected message (eg from the balise) to the vehicle computer of the rail vehicle. Thus, the packet 44 allows the transparent transmission of (any) information. The protected message can thus be transmitted in the packet 44. For example, the protected message is an identifier. For example, the identifier may include at least one of the following options (values or data):

- encrypted data;

- unencrypted data;

- data determined based on an MD4 algorithm;

- a signature;

- a certificate;

a value for identifying the identifier;

a value for identifying a type of the identifier. For example, the identifier can be determined based on a cryptographic hash function. Examples of cryptographic hash functions are the so-called message-digest algorithms, e.g. "MD2" or "MD4" (see, e.g., RFC 1320 of the Network Working Group,

http://tools.ietf.org/html/rfcl320).

The identifier can be embedded in the packet 44 and transmitted as part of the balise telegram together with other information from the balise to the vehicle computer of the rail vehicle. Based on the identifier of the vehicle computer can authenticate the balise, ie determine whether the information received from the designated

Balise come.

In this way, the telegrams can additionally be used against deliberate manipulation of data (in particular so-called "man-in-the-middle" attacks, cf.

http: // en. wikipedia. org / wiki / man-in-the-middle attack). The identifier may include the value of a hash function. The

Hash function (also called a scatter function) is an image that maps a large input set (the keys) to a smaller target set (the hash values). The hash function is not necessarily injective. In particular, the input quantity may also contain elements with different lengths, whereas the elements of the target quantity have, in particular, a fixed length. A so-called collision occurs when the same hash value is assigned to different input data.

The identifier may also include the value of a cryptographic hash function (also referred to as a cryptological hash function) (cf.

http: // en. wikipedia. org / wiki / cryptologic_hashfunction). This is a special form of hash function that is collision-resistant and / or a one-way function. The one-way function is complexity-theoretically "easy" to calculate, but "difficult" to reverse. One-way functions are also functions for which no in a reasonable amount of time practically practicable inversion is known.

There are keyless and key-dependent cryptographic hash functions. It is also possible that the identifier comprises a digital signature. A digital signature, also known as a digital signature method, is an asymmetric cryptosystem in which a sensor which uses a secret signature key (the private key) to calculate a value for a digital message (ie for any data), which is also called a digital signature. This value allows anyone to check the integrity of the message using the public verification key (the public key) (cf.

http: // en. wikipedia. org / wiki / digital_signature).

For example, the telegram of the balise (or a part of the telegram of the balise) can be verified by the vehicle computer based on the public key of the balise. For the purpose of encryption, the balise uses its secret signature key, which is preferably stored as secure as possible in the balise and can only be used by the balise itself.

One possibility is that in the packet 44 a hash value of the telegram or a part of the telegram is stored and transmitted to the vehicle computer of the rail vehicle. The vehicle computer now determines a

Hash value based on the telegram or on a part of the telegram and compares this hash value with the hash value obtained in the packet 44. If both hash values are identical, it is assumed that the telegram was not intentionally manipulated.

An alternative possibility is that the hash value of the information to be transmitted is signed by the balise (ie encrypted with the private key of the balise) and stored as an identifier in the packet 44. The information and the identifier are transmitted (eg as a telegram) to the vehicle computer of the rail vehicle. The vehicle computer now determines a hash value based on the information and decodes the identifier based on the public key of the balise (this can optionally be transferred from the balise). The hash value determined by the vehicle computer is compared to the hash value created by the beacon. adjusted; if both are identical, then the identifier is successfully verified, the information provided by the balise can be used or further processed accordingly. For example, in the package 44, a mark may be included, for example in the form of a bit combination, which indicates to the vehicle computer of the rail vehicle whether the packet 44 can be used to check or authenticate the message. If this is the case, for example, one of the above-mentioned checks (verifications) can take place. If, on the other hand, the packet 44 is empty or does not have any of the possibly predetermined number of bit combinations, then no check based on the data of the packet 44 takes place. This approach is therefore also compatible with other uses of package 44.

Also, it is an option that, depending on the application, it may be required that each balise authenticate itself. In such a case, at least one data field may be provided, which is used for the transmission of the identifier, so that the sending balise can be authenticated on the basis of the identifier. If a balise can not be verified then an appropriate action can be taken, including e.g. one of the following: issuing a warning message; Transferring the system and / or at least one rail vehicle to a safe state (e.g., stoppage); Checking and, if necessary, maintaining the balise; Etc.

Another option is that such a bit combination in the packet 44 may have different values, each of which is associated with a particular type of verification. For example, a given bit combination may indicate that a hash value has been stored in packet 44; it may also be specified by the value of the bit combination which hash function was used to create the hash value. Furthermore, another value of the bit combination may indicate that an electronic signature is stored. chert is or according to which algorithm the electronic signature was generated.

The use of the packet 44 for the transparent transmission of data that can be used for checking the telegram is to be understood merely as an example. In principle, it is possible to use other or additional data fields in order to transmit relevant information from a transmitter to the vehicle computer of the rail vehicle for the check described here. The transmission of the data may, for example, be wireless (e.g., via radio, near field communication, via a telecommunications network, etc.) or wired. FIG. 1 shows an exemplary diagram comprising a rail vehicle 101 with a vehicle computer 102 which is connected to a balise antenna 103. The rail vehicle 101 moves on a route 104 in a direction of travel 105. In the direction of travel 105, the rail vehicle 101 first passes over a balise 106, then a balise 107.

For example, the balises 106 and 107 are euro balises, with the balise 106 exemplifying a

Transparent Data Balise and the Balise 107 a

Fixed data balance is (cf.

http: // en. wikipedia. org / wiki / Eurobaiise).

The Transparent Data Balise or Controllable Balise, for example, is connected by a cable to a trackside electronic unit (LEU, Lineside Electronic Unit). The LEU transmits the respective telegram to the balise.

It should be noted that the term balise here also includes several successively provided balises a so-called Baiisengruppe. The balise 106 and / or the balise 107 sets the rail vehicle 101 when crossing the respective balise by means of the balise antenna 103 and the vehicle computer 102

(Balisen) telegram having a data field (e.g., in the form of packet 44 described above) in which e.g. the identifier is included. On the basis of the data field, a check of the integrity or authenticity of the data obtained is possible. In particular, it can thus be ensured that the information is actually received by the balise 106

and / or 107 and that they have not been corrupted.

Preferably, the respective balise 106 or 107 is designed in such a way that access to a secure storage area from the outside is not possible or only with great effort. In such a secure storage area, a private key used to create the signature may be stored. This key is preferably suitable to secure against external access. One option is that the balises in the telegram (e.g., in the data field or packet 44) are also public

Key of Balise (also referred to as public verification key or certificate) transmitted. Preferably, the rail vehicle can check whether the public key matches the position of the balise. Preferably, only if and only if the verification of the data was successful, the data of the telegram from the vehicle computer of the rail vehicle further processed. 2 shows an exemplary flow diagram of a communication between the balise 106, 107 and the vehicle computer 102 of the rail vehicle 101.

In a step 201, the balise 106, 107 creates the telegram or receives from the LEU the message to be forwarded. In a step 202, the balise generates a hash value by means of a cryptographic hash function (eg MD4) and stores the hash value in the packet 44 of the ETCS implementation according to UNISIG (SUBSET-026-7). In a step 203, the telegram is transmitted from the balise 106, 107 to the vehicle computer 102. The vehicle computer 102 uses the telegram (based on predetermined data of the telegram, eg all data without the packet 44) in a step 204 to determine a hash value by means of a cryptographic hash function which was also used by the balise 106, 107. In a step 205, the vehicle computer 102 compares the determined hash value with that read from the packet 44

Hash. If both hash values are identical, it is assumed that the data of the telegram have not been corrupted and an action (e.g., control of the rail vehicle 101) is made based on this data. If the two hash values are not identical, then an error message can be generated e.g. the rail vehicle and / or a signal box are displayed. In particular, in this case, the rail vehicle operation can be converted into a safe state and it can then be checked whether the balise 106, 107 is defective or whether a manipulation attempt was present.

While the invention has been further illustrated and described in detail by the at least one embodiment shown, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Method for operating a rail vehicle (101),

in which information for operating the rail vehicle (101) and an identifier from a balise (106, 107) is transmitted to a vehicle computer (102) of the rail vehicle (101),

- in which the identifier of the vehicle computer (102)

is checked

The method of claim 1, wherein the identifier is not checked by the vehicle computer (102) if it is determined that no identifier is present or if the identifier has a predetermined value.

Method according to one of the preceding claims, in which the information is not used if the verification of the identifier was unsuccessful.

Method according to one of Claims 1 or 2, in which the information is not used if the identifier was detected and the verification of the identifier was unsuccessful.

Method according to one of the preceding claims, in which the rail vehicle is brought into a safe state if the verification of the identifier was unsuccessful.

Method according to one of the preceding claims, in which the identifier comprises at least one of the following possibilities:

- encrypted data;

- unencrypted data; Data that has been determined based on a hash function, in particular a cryptographic hash function;

- data determined based on an MD4 algorithm;

- a signature;

- a certificate;

a value for identifying the identifier;

a value for identifying a type of the identifier.

Method according to one of the preceding claims, wherein the identifier is transmitted in a block 44 of the ETCS implementation according to UNISIG.

Method according to one of the preceding claims,

- In which the identifier is checked by the vehicle computer by using the information, a further identifier is determined and the identifier is compared with the other identifier,

- In which the verification of the identifier was successful, if the identifier and the other identifier are identical.

Method according to one of claims 1 to 7,

- where the identifier is encrypted,

in which the identifier is decrypted by the vehicle computer,

in which a further identifier is determined by the vehicle computer on the basis of the information and the decrypted identifier is compared with the further identifier,

- in which the verification of the identifier was successful, if the decrypted identifier and the other identifiers are identical. Method according to Claim 9, in which a symmetrical or asymetric encryption method is used for encryption and decryption.

Method according to one of the preceding claims, in which the identification is determined by the vehicle computer,

- whether the identifier exists and

- if the identifier exists, what kind of verification of the identifier is to be performed.

Method for checking an identifier provided by a balise (106, 107),

in which the identifier and information from the balise (106, 107) are received by a vehicle computer (102) of a rail vehicle (101),

- In which the identifier is checked by the vehicle computer (102).

The method of claim 12, wherein upon successful verification of the identifier, the information is used to operate the rail vehicle.

Method according to one of claims 12 or 13, wherein the identifier is received in a block 44 of the ETCS implementation according to UNISIG.

Method for providing an identifier by a balise (106, 107),

in which an identifier is created based on information,

in which the identification and the information when passing over the balises (106, 107) are provided to a rail vehicle (102, 101),

- so that on the basis of the identifier the authenticity of the

Balise (106, 107) of the rail vehicle (102, 101) is verifiable.

16. ETCS track equipment

- with at least one balise (106, 107),

- wherein the at least one balise (106, 107) is arranged such that when passing over a rail vehicle (101) provides an identifier and information, wherein the identifier was created based on the information, so that based on the identifier, the authenticity of the balise (106, 107) of the rail vehicle (101) is verifiable.

17. ETCS route equipment according to claim 15, wherein the identifier can be determined by means of a cryptographic hash function and in which the identifier can be stored in a block 44 of the ETCS implementation according to UNISIG.

18. Rail vehicle (101) with a vehicle computer (102), which is set up such that

the identifier and information can be received by the balise (106, 107),

- Based on the identifier, the authenticity of the balise (106, 107) of the rail vehicle (101) is verifiable.