METHOD FOR THE INITIAL DISTRIBUTION OF PROTECTED DATA IN AN ETCS TRAFFIC GUARD SYSTEM

Description

[0001] The invention relates to a method for the initial distribution of sensitive data, such as at least one key, a certificate, or a password, in an ETCS train protection system between at least one data center and at least one ETCS device, such as a vehicle-side on-board unit (OBU) or a trackside radio block center (RBC). Furthermore, the invention also relates to a corresponding ETCS train protection system.

[0002] In the standardized European Train Control System (ETCS), secret cryptographic keys are used for secure communication between trains with their ETCS on-board units (OBUs) and the trackside ETCS control centers or trackside radio block centers (RBCs). For each of these communication relationships between a vehicle-based on-board unit and a trackside radio block center, a communication key (KMAC) is stored in each on-board unit and each radio block center, from which a secret session key is derived for the duration of a data connection.

[0003] A data center (KMC), also known as a key distribution center, is responsible for generating and distributing the secret cryptographic keys (KMAC) in a secure environment within the railway system. The distribution of the secret keys (KMAC) to the ETCS devices, such as the on-board unit and the radio block center, can be done both online and offline. Offline distribution can be achieved via data carrier exchange, for example, while online transmission can be achieved via a mobile phone connection.

[0004] Precise details, such as associated interfaces and processes, are specified in a standardized set of rules, which is uniformly defined in Europe by UNISIG; in particular, UNISIG SUBSETS 114 and 137 refer to this. UNISIG is a consortium of industrial companies that develop the technical specifications of ETCS.

[0005] During offline key distribution, additional secret transport keys (KTRANS) are used to ensure the confidentiality of the cryptographic keys. These secret transport keys (KTRANS) are used to encrypt the secret keys (KMAC) for transport to the ETCS units. The transport keys are generated and issued by the data center (KMC). The confidentiality of the transport keys (KTRANS) is just as critical to security as the confidentiality of the keys (KMAC). Therefore, the transport keys (KTRANS) must first be stored in the ETCS units to enable offline key distribution.

[0006] Online key distribution, on the other hand, uses root / client certificates and passphrases to securely transmit the secret cryptographic keys. These certificates and passwords must also be kept secret, their authenticity guaranteed, and they must be securely imported into the ETCS facilities to initiate the online key distribution.

[0007] A method for ETCS online key management is known, for example, from WO 2009 / 027380 A1.

[0008] In order to implement the ETCS facilities for the specified ETCS key distribution offline or online, a procedure for the initial distribution of sensitive data, especially keys, is required. One such procedure, according to the state of the art, is to ensure that the secret transport keys (KTRANS) are only introduced by highly trusted individuals within the railway operator. These trusted individuals are also referred to as key managers. Particularly high security requirements are placed on all devices, media, and processes for transporting, storing, and processing the unprotected keys. For example, a special computer must be introduced that is operated exclusively by the key manager. This computer must be specifically secured against cyberattacks, which significantly limits its connectivity.Furthermore, for example, special management and storage requirements are imposed on all data storage devices and computers with unprotected key material in order to prevent the operation of the ETCS train protection system from being jeopardised by key compromise, i.e. by endangering the secret keys.

[0009] However, the problem with the key manager procedure described above is that it can result in considerable technical and organizational effort, particularly for railway operators with larger vehicle fleets, which can also lead to personnel shortages. For example, during the key manager's activities, it must be ensured that no other persons are present at the affected ETCS facility at the same time. This effort increases further if, for example, hardware or software in the ETCS facilities needs to be replaced, for example, after hardware failures or software updates. Therefore, there is a need for simplified or alternative procedures and systems for the initial distribution of sensitive data in the ETCS train control system.

[0010] The invention is therefore based on the object of providing a method and a train protection system of the type mentioned at the outset which are less complex and thus improved.

[0011] According to the invention, the object is achieved by the method according to patent claim 1 and the ETCS train protection system according to patent claim 11.

[0012] In particular, the object is achieved in the method according to the invention in that sensitive data intended for the at least one ETCS device is generated in a secure environment in the data center, at least one transport packet intended for the at least one ETCS device is generated in a secure environment using the sensitive data, the transport packet is secured in the secure environment, the secured transport packet is transmitted to the ETCS device, the secured transport packet is de-encrypted in a secure area of ​​the ETCS device, and the sensitive data is stored in the secure area of ​​the ETCS device. The security can consist, for example, in encryption and / or a digital signature. The de-encryption can consist, for example, in decryption and / or a verification of authenticity using a digital signature.

[0013] Furthermore, the solution according to the invention relates to an ETCS train protection system for the initial distribution of sensitive data, such as at least one key, a certificate or a password, between at least one data center and at least one ETCS device, such as a vehicle-side on-board unit (OBU) or a track-side radio block center (RBC), with the at least one data center, which is designed in a secure environment and for generating the sensitive data, with at least one data distribution center, which is also designed in a secure environment and for generating and securing at least one transport package with the sensitive data, and with the at least one ETCS device, which has at least one secure area and is designed to de-encrypt the encrypted transport package and to store the sensitive data in the secure area.

[0014] According to the invention, the sensitive data intended for the at least one ETCS device is generated in a secure environment in the data center. The data center, which is already known from the prior art as a key distribution center (KMC), can be implemented, for example, on a computer in a secure office environment. This is important because in this first phase of the method according to the invention, the sensitive data is still unprotected. The generation of the sensitive data can be done, for example, by a trusted person such as the key manager.

[0015] In this context, the data requiring protection can be, for example, confidential data or non-confidential data whose integrity must be ensured, such as certificates. The initial distribution of the data requiring protection can also include an update.

[0016] In the next step of the method according to the invention, a transport package containing the sensitive data is generated for the ETCS device. The transport package is generated specifically for the ETCS device. Naturally, several transport packages are generated during operation for each of the different ETCS devices.

[0017] Subsequently, according to the method according to the invention, the transport packet is secured in the secure environment, e.g., encrypted or signed. For example, cryptographic encryption and / or a digital signature can be used here.

[0018] In the next step, the secured transport package is transmitted to the relevant ETCS facility. This can be done either online or offline in the usual way. The advantage here is that the sensitive data is now protected, meaning it can be transmitted offline, for example, by any person, or online via any "insecure" means, such as mobile communications, Wi-Fi, 5G, or the internet. The sensitive data is protected against unauthorized access in the transport package.

[0019] In the final step of the method according to the invention, the secured transport package is de-secured in a secure area of ​​the ETCS device, and the sensitive data is stored in the secure area of ​​the ETCS device. The secure area of ​​the ETCS device is a protected storage location in which sensitive data, such as unprotected ETCS keys, can be saved. This secure area can be, for example, special hardware, such as a Trusted Platform Module (TPM) chip, and possibly a special application in the form of firmware that controls access to the data and its processing. Often, the secret keys for security purposes can only be stored but not read. This means that they can only be used in the secure area.During operation, payload data can be transferred to this special hardware and then encrypted and / or decrypted and / or electronically signed and / or verified using the stored secret keys. For example, the transport key (KTRANS) for offline key distribution is stored securely in the secure area of ​​the ETCS facility. For online key distribution, at least the client certificate and passphrase are stored securely.

[0020] The transport packet is secured, for example, with a key (KP ENC ), while a further key (KP SIG ) is used to sign the transport packet. The private key (KP SIG ) is used to generate a digital signature for the transport packet, which can be sent to the ETCS facility in the transport packet. In this case, the signature is also a component of the packet because ensuring authenticity can be just as important as keeping the keys confidential. According to the invention, the key(s) required to encrypt and / or sign the transport packet are stored in the data center or data distribution center and the ETCS facility.

[0021] After the encrypted and signed transport packets are generated in the data distribution center, they are transported to the ETCS facility. The usual unprotected methods can be used for this, such as manual transport via data carrier or transmission via email.

[0022] In this example, upon receipt of the transport packet in the ETCS facility, the authenticity of the packet is verified using the supplied signature with the public key (KP SIG). After successful authentication, the transport packet is decrypted using the private key (KP ENC). The data contained in the transport packet, which may include key requests, for example, is processed sequentially in the ETCS facility, and the key memory, for example, is updated. For each processed key request, the ETCS facility can generate an acknowledgment message (KMC notification). The content and format of this message are also defined in the UNISIG standard and are returned unchanged to the data center.

[0023] In the ETCS system, the transport packet is read in, for example, using a service computer. The transport packet is checked and decrypted only in the secure area of ​​the ETCS system, ensuring that no unsecured, sensitive data ever exists outside of the secure area of ​​the ETCS system. The secure area within the ETCS system can be created, for example, by a special hardware module or a suitable chip card. After the transport packet has been successfully checked, its contents are accepted and further processed.

[0024] To enable the inventive securing and un-securing of the transport package, additional tools, such as keys and / or certificates, are already available in the data distribution center and the ETCS facility. In the case of private keys, their confidentiality is also permanently ensured. Since the data distribution center is located in a secure environment, no new security requirements arise. Secure areas are also available in the known ETCS facilities, so the additional effort is minimal.

[0025] The method and train protection system according to the invention have the advantage of simplifying the distribution of the protected transport package to the ETCS equipment. Instead of a key manager, transmission can be performed by other persons or technical aids without increased security requirements. For example, this can be done by a train's maintenance personnel, who can then install the key. The transport package can also be transmitted to the ETCS equipment via mobile communications. This allows key distribution to be fully automated, eliminating the need for on-site personnel to install the key. Instead of numerous individual transactions, multiple key requests and other sensitive data can be submitted to the ETCS equipment together in a single transport package.Subsequent notifications for completed key requests in the ETCS facilities can also be automatically generated and saved one after the other. This significantly reduces the time required for key management and initial commissioning in the ETCS facilities.

[0026] According to the invention, a large number of sensitive data, including multiple keys, certificates, passwords, and / or key requests, is transmitted in the transport package. This has the advantage that combining the sensitive data in the transport package significantly reduces the workload and the number of transport packages to be sent. In addition to the aforementioned transport key (KTRANS) and the communication key (KMAC), the transport package can also contain other manufacturer-specific ETCS keys. For example, personalization keys (KPERS) or software seals (SEAL) can also be integrated into the transport package as components, further increasing the efficiency of the method according to the invention. Furthermore, key updates can also be included in the transport package.In this case, the new keys are exchanged after the transport package has been successfully verified in the ETCS facility, for example, after a specified cycle. In addition to the keys for offline key management, the transport package can of course also be used to distribute sensitive data for online key management. This could, for example, be the root / client certificates and passphrase commonly used for online key management (OKM). This data is installed and processed in the ETCS facility in a similar way to the offline key management data. Furthermore, in addition to the sensitive key data, other parameters necessary for commissioning the ETCS facility can be stored in the transport package, such as the ETCS ID of the ETCS facility and the corresponding ETCS ID of the data center.When the transport package is processed in the ETCS device, all parameters stored in the transport package are automatically imported into the ETCS device in the correct order.

[0027] The method according to the invention can be further developed by advantageous embodiments as described below.

[0028] In an advantageous embodiment, at least one tool, such as a key or a certificate, can be used to unlock at least one transport package in the ETCS device. This tool was permanently engraved during the manufacture of the ETCS device. This has the advantage that the tool required to unlock the transport package in the ETCS device can be stored particularly easily during the manufacture of the ETCS device, thus eliminating the need to manually store this tool in the railway system. This can be particularly advantageous when the first transport package is received. The tool can then be updated.

[0029] To ensure the highest possible security for the transport packet, symmetric or asymmetric cryptographic encryption, or a combination of these methods, can be used. For example, an asymmetric cryptographic method with public and private keys can be used. The integrity and confidentiality of the protected data are ensured by cryptographic encryption, while a digital signature is generated and verified to protect authenticity. Furthermore, hybrid encryption can also be used, which also uses AES (Advanced Encryption Standard). The AES key, in turn, is encrypted with a public key and stored in the data packet. AES is an advanced encryption standard that includes a symmetric encryption method.

[0030] To reduce the data to be transmitted, especially for online transmission, the transport packet can be compressed before transmission and expanded after transmission.

[0031] Furthermore, the transport packet can be decrypted in the ETCS system if the decryption time falls within a specified time and / or a specified password has been entered. This has the advantage of implementing additional security. This limits the permissible time period for processing the transport packet in the ETCS system; i.e., after expiration or before the start of the validity period, reading and processing in the ETCS system are blocked. The required specified password can be used to restrict the group of people who can initiate processing of the transport packet in the ETCS system. It is assumed here that the specified password is only issued to a limited group of people.Alternatively or additionally, further restrictions can be imposed on the processing of the transport package: For example, the functions can be restricted so that, for example, unsealing the software in the ETCS device is blocked while sealing the software is permitted. Furthermore, the transport package can be used at a given time to temporarily enable certain functionalities, such as allowing the deletion of all keys in the ETCS device. Such configuration specifications can, for example, be integrated into the transport package using an XML file when generating the transport package. These supplied configuration specifications are then evaluated and applied in the ETCS device when processing the transport package.

[0032] To make the processing of sensitive data particularly secure, the generation of the transport package can be initiated by a trusted person. To achieve the same advantage, the generation of the sensitive data can also be initiated by a trusted person. Such a trusted person could, for example, be the key manager described above. Since the generation of the transport package and / or the generation of the sensitive data can take place centrally, for example, in a trusted office environment, the effort required by the key manager is minimal.

[0033] The invention also relates to a computer-implemented method which is designed according to an embodiment mentioned above.

[0034] Furthermore, the invention also relates to a device for data processing which is designed according to the invention to carry out the method according to one of the above-mentioned embodiments.

[0035] In an advantageous embodiment of the ETCS train protection system according to the invention, the data center and the data distribution center can be implemented in the same secure environment, in particular on a computer. This has the advantage that less hardware is required and unprotected, sensitive data is never used outside of the same secure environment. Furthermore, the data center can also implement the data distribution center.

[0036] In the following, the invention is explained with reference to the drawings and the exemplary embodiments shown therein.

[0037] They show: Figure 1 shows a schematic representation of a railway system with an exemplary embodiment of an ETCS train protection system according to the invention; Figure 2 shows a schematic representation of the ETCS train protection system according to the invention from Fig. 1 Figure 3 shows a further schematic representation of the ETCS train protection system according to the invention from Figures 1 and 2.

[0038] In the following, the invention will be described with reference to the exemplary embodiments in the Figures 1 to 3 explained.

[0039] One in Fig. 1 The railway system 1 shown has a vehicle 3 traveling along a track 2 and an ETCS train protection system 4 according to the invention. The ETCS train protection system 4 comprises a control center 8 with a data center 5 and a data distribution center 6 as well as several ETCS devices 7. Even if this is Fig. 1Unless otherwise stated, the data center 5 (KMC) and data distribution center 6 (KDC) may be spatially separated from each other and may be operated by different buildings and / or companies.

[0040] The ETCS devices are in the embodiment in the Figures 1-3 For example, as a Radio Block Center (RBC), which could also be referred to as an ETCS route control center, and as a vehicle-mounted On-Board Unit (OBU), which can also be referred to as a vehicle control unit. The Radio Block Center (RBC) is located along the route 2, and the On-Board Unit (OBU) is located on-board in vehicle 3. For the sake of simplicity, Fig. 1 only one vehicle 3 and one Radio Block Center RBC are shown.

[0041] The control center 8 is located somewhere remote from the ETCS equipment 7, for example, in an office environment. During operation of the railway system 1, which is configured for ETCS, communication keys stored in the ETCS equipment 7 are used for communication between the on-board unit (OBU) in the vehicle 3 and the radio block center (RBC). These secret communication keys and also the necessary transport keys (KTRANS) must initially be stored securely in the ETCS equipment. This is done by the method according to the invention and is described below, in particular with reference to the Figures 2 and 3 explained.

[0042] In the data center 5, which is also referred to as the KMC (Key Management Center) in the figures, sensitive data 9 is first generated. This sensitive or confidential data includes the communication key KMAC, the transport key KTRANS, the root certificate OKM, and an OKM passphrase. After its generation, this sensitive data 9 is forwarded to the data distribution center 6.

[0043] The data distribution center 6 is also referred to in the figures as the KDC - Key Distribution Center. According to the invention, an individual transport package 10 is generated and saved in the data distribution center 6 for each ETCS device 7.

[0044] The data distribution center 6, like the data center 5, is located in a secure environment, so that sensitive data can be processed here without any risk. The more secure environment 11 is located in Fig. 1shown schematically. In the exemplary embodiment in the figures, a portion of the sensitive data 9 is encrypted. This encrypted data 12 is shown framed by a dashed line. In the exemplary embodiment in the figures, this encrypted data 12 is encrypted with a key KP ENC.

[0045] Each transport packet containing all sensitive data 9 is signed in the transport packet 10 with the KP SIG key, thus securing it. The transport packet is thus signed for security purposes, but not completely encrypted. All confidential data is encrypted in the transport packet 10. Non-confidential data is not encrypted but signed to protect against unauthorized tampering. KP ENC and KP SIG are part of an asymmetric cryptographic algorithm, such as RSA. KP ENC and KP SIG are also referred to below as the transport packet key 15.

[0046] In the data distribution center 6, an individual transport package 10 is created for each ETCS device. This is exemplified in Fig. 2shown, in which the upper transport package 10 is created for the Radio Block Center RBC and the lower transport package 10 for the On-Board Unit OBU. In the exemplary embodiment in the figures, the transport packages 10 comprise additional configuration specifications 13 which specify the further processing of the sensitive data 9 in the ETCS devices 7. This can, for example, relate to the validity of the respective transport package 10. For example, the transport package 10 can only be decrypted in the ETCS device 7 if the time of decryption falls within a predetermined time. Alternatively or additionally, the group of people can be restricted by assigning a password. As a result, the transport package 10 can only be decrypted in the ETCS device if a predetermined password has been entered which is only known to the group of people.Furthermore, additional restrictions or releases of functions are possible as configuration specifications: For example, the processing of transport package 10 in the ETCS device 7 can only be performed for released functions, or, for example, the unsealing of the software of the ETCS device 7 is blocked while the sealing of the software is enabled. Alternatively, the transport package 7 can also be used for a limited time to enable certain functionalities, such as allowing the deletion of keys in the ETCS device.

[0047] In the next step of the method according to the invention, the secured transport packets 10 are transmitted from the data distribution center 6 to the respective ETCS devices 7. This can be done in various ways, as known from the prior art, for example, via online transmission, email, or data connection. Offline transmission is also possible, for example, via a data carrier delivered by a person.

[0048] The ETCS devices 7 each have a secure area 14 in which the received transport packet 10 is decrypted. The transport packet keys KP ENC and KP SIG are again used as tools for this purpose. These transport packet keys 15 are present both in the data distribution center 6 and in the respective ETCS devices. Each ETCS device 7 has an individual transport packet key or individual transport packet keys 15. In the exemplary embodiment shown in the figures, the transport packet keys 15 have already been incorporated into the secure area 14 of the ETCS device 7 by the manufacturer during hardware production. This can be done, for example, using an imprinting process.The transport package keys 15 can be updated and replaced after commissioning of the respective ETCS device 7, but the original inclusion by the manufacturer in the hardware production ensures that a transport package key 15 is always already present on the respective ETCS device 7.

[0049] In the schematic representation in Fig. 3 is in addition to the representation in Fig. 2 A data flow from the data center 5 via the data distribution center 6 to the ETCS equipment 7 and back is also shown by arrows. In the exemplary representation in Fig. 3 are different from the representation in Fig. 2Three different on-board units (OBUs) are shown, but no radio block center (RBC). However, the data flow to the radio block center (RBC) occurs in the same or similar way as with the on-board units (OBUs). The three on-board units (OBUs) are arranged in three different vehicles (3), which are parked at different depot locations in a depot, for example.

[0050] The Fig. 3The data flow depicted begins at the data center 5, which generates the sensitive data 9 and transmits it, for example, using so-called key orders, to the data distribution center 6. Since, in the exemplary embodiment shown in the figures, both the data center 5 and the data distribution center 6 are located in a secure environment, no special security measures are required for the transmission of the sensitive data 9. Alternatively, both can be spatially separated and, for example, managed by different operators. In this case, they would have to agree on a secure transmission method between the data center 5 and the data distribution center 6.

[0051] In the data distribution center 6, as already described above, the transport packages 10 are generated and saved and transmitted to the respective ETCS devices 7.

[0052] Optionally, an assistant 16 can be present in the vehicle, who, for example, supplies the respective transport packages 10 to the ETCS equipment 7 via offline data transmission. However, this assistant 16 never has access to the sensitive data, so they must be less trustworthy than the key manager. The assistant 16 could be, for example, maintenance personnel.

[0053] As a response or confirmation, the ETCS devices 7 each send responses 17 via the data distribution center 6 or directly to the data center 5.

[0054] Optionally, the transport packages 10 can also be created and transmitted by the data center 5, which thereby takes over the tasks of the data distribution center 6 and trains it. This optional implementation is in Figure 3 indicated by the dashed box between data center 5 and data distribution center 6.

[0055] The transmission of the transport packets 10 between the data distribution center 6 and the ETCS devices 7 and the transmission of the responses 17 in the opposite direction can take place via any data channel 18.

Claims

1. Method for initial distribution of protected data (9), such as e.g. at least a key, a certificate or a password, in an ETCS train control system (4) between at least one data control centre (5) and at least one ETCS facility (7), such as, for instance, a vehicle-side on-board unit, OBU, or a track-side radio block centre, RBC, in which protected data specific to the at least one ETCS facility (7) is generated in a secure environment (11) in the data control centre (5), in which with the protected data (9), at least one transport package (10) specific to the at least one ETCS facility (7) is generated in a secure environment (11) in which the transport package (10) is secured in the secure environment (11), in which the secured transport package (10) is transmitted to the ETCS facility (7), in which the secure transport package (10) is unlocked in a secure area (14) of the ETCS facility (7) and the protected data (9) is stored in the secure area (14) of the ETCS facility (7), wherein a plurality of protected data (9) comprising a number of keys, certificates, passwords and / or key queries is transmitted in the transport package (10).

2. Method according to claim 1, characterised in that in order to unlock at least one transport package (10) in the ETCS facility (7), at least one tool is used, which was impressed in a non-volatile manner during production of the ETCS facility (7).

3. Method according to one of the afore-cited claims, characterised in that a symmetrical or asymmetrical cryptographic encryption or a combination of both methods is used for securing the transport package (10).

4. Method according to one of the afore-cited claims, characterised in that the transport package (10) is compressed before transmission and expanded after transmission.

5. Method according to one of the afore-cited claims, characterised in that the transport package (10) is only unlocked in the ETCS facility (7) if the point in time of unlocking occurs in a predetermined time and / or a predetermined password has been entered.

6. Method according to one of the afore-cited claims, characterised in that the generation of the transport package (10) is initiated by a key manager as a trustworthy person.

7. Method according to one of the afore-cited claims, characterised in that the generation of the data (9) is initiated by a key manager as a trustworthy person.

8. Computer-implemented method, characterised in that the method is embodied according to one of the afore-cited claims.

9. Device for data transmission, characterised in that the device is designed to carry out the method according to one of the afore-cited claims.

10. ETCS train control system (4) for initial distribution of protected data (9), such as e.g. at least a key, a certificate or a password, between at least one data control centre (5) and at least one ETCS facility, such as, for instance, a vehicle-side on-board unit, OBU, or a track-side radio block centre, RBC, wherein the ETCS train control system (4) comprises the following: the at least one data control centre (5), which is embodied in a secure environment (11) and for generating the protected data (9), at least one data distribution centre (6), which is likewise embodied in a secure environment and for generating and securing at least one transport package (10) with the protected data (9), and the at least one ETCS facility, which has at least one secure area (14), and is embodied to unlock the secured transport package (10) and to store the protected data (9) in the secure area (14), wherein a plurality of protected data (9) comprising a number of keys, certificates, passwords and / or key queries is transmitted in the transport package (10).

11. ETCS train control system (4) according to claim 10, characterised in that the data control centre (5) and the data distribution centre (6) are embodied in the same secure environment (11).

12. ETCS train control system (4) according to claim 10, characterised in that the data control centre (5) and the data distribution centre (6) are embodied on a computer.

13. ETCS train control system (4) according to claim 10, 11 or 12, characterised in that the data control centre (5) embodies the data distribution centre (6).