Communication for ERTMS

General

To operate on lines with ERTMS level 2, the vehicle must be able to communicate securely with the signalling system. Vehicles use dial-up data connections over GSM-R or GPRS for communication. Onboard equipment (OBU) must have a SIM card with an ETCS profile and encryption keys to ensure communication between the vehicle and the radio block centre (RBC).

The required encryption key is linked to the unique ETCS-ID (NID_ENGINE) assigned to each OBU. The ETCS-ID is assigned by the onboard equipment supplier. The encryption key KMAC is assigned by the Key Management Centre at Bane NOR.

Ordering Encryption Keys

Bane NOR manages encryption keys for RBCs in Norway and vehicles that have Bane NOR’s KMC (Key Management Centre) as their home KMC. Bane NOR supports offline distribution of keys to vehicles via files in the SUBSET-114 format and the UAC format (Bombardier Eastern Line). The SUBSET-38 format is used for other KMCs. Online key distribution uses the SUBSET-137 format.

Two types of encryption keys are used: KMAC and KTRANS. KMAC is used to secure communication between onboard equipment and the RBC and is changed relatively often. To change KMAC without a high risk of compromise, KMAC is encrypted with the KTRANS encryption key. Online key distribution will eventually replace KTRANS with a digital certificate.

Routine for registering vehicle/onboard unit

Vehicles that will receive keys offline or online must be registered in Bane NOR’s KMC. Registration is done by sending contact information for the person responsible for the vehicle’s encryption keys, vehicle data, and ETCS-ID to kmc@banenor.no. Contact details must be kept up to date to ensure that Bane NOR can quickly notify of any irregularities, such as suspected compromise or other issues related to validity and security.

After approved registration, the KTRANS encryption key and a password for ordering the certificate for online key distribution are issued.

Routine for ordering KMAC

Encryption keys (KMAC) can be ordered for:

• Østfoldbanen, eastern line: pilot section for ERTMS
• ETCS Norway: provides access to sections in Norway with ETCS, except for the Eastern Line.
• International sections: the country and section must be specified in the order. Bane NOR will contact the KMC for the area and request the keys.

Keys are ordered by contacting kmc@banenor.no and are usually valid for five years at a time.

Secure Handling of Encryption Keys

Two types of encryption keys are used: KMAC and KTRANS. KMAC is used to secure communication between onboard equipment and the RBC and is changed relatively often. It is encrypted and requires the lowest security level during handling. KTRANS is used for encrypting KMAC. It is not encrypted, and its security is based on procedures that must be followed. Unencrypted keys should only be handled by a limited number of individuals. These individuals must be registered and have undergone training and approval.

Any suspicion that information about the keys may be compromised must be reported to Bane NOR immediately. Bane NOR will, if necessary, revoke the key’s validity.

Ordering Encryption Keys for Visiting Vehicles

Vehicles not based in Bane NOR’s KMC should order keys from their own KMC. Bane NOR will then exchange keys with the KMC where the vehicle is based.

Information Exchange

ERTMS is a distributed system where the driver, traffic controller, onboard equipment, balises, GSM-R, RBC, and interlocking system communicate to ensure safe train operation. To ensure optimal interaction, log files from the onboard equipment must be made available to Bane NOR’s troubleshooting team.

Ordering SIM Cards for ETCS

SIM cards for ETCS are ordered from OPM user support.