Commission Implementing Regulation (EU) 2016/799Show full title

13. SECURITY FOR REMOTE COMMUNICATION OVER DSRC U.K.

13.1. General U.K.

As specified in Appendix 14, a VU regularly generates Remote Tachograph Monitoring (RTM) data and sends this data to the (internal or external) Remote Communication Facility (RCF). The remote communication facility is responsible for sending this data over the DSRC interface described in Appendix 14 to the remote interrogator. Appendix 1 specifies that the RTM data is the concatenation of:

Encrypted tachograph payload

the encryption of the plaintext tachograph payload

DSRC security data

described below

The plaintext tachograph payload data format is specified in Appendix 1 and further described in Appendix 14. This section describes the structure of the DSRC security data; the formal specification is in Appendix 1.

CSM_223 The plaintext data communicated by a VU to a Remote Communication Facility (if the RCF is external to the VU) or from the VU to a remote interrogator over the DSRC interface (if the RCF is internal in the VU) shall be protected in encrypt-then-authenticate mode, i.e. the tachograph payload data is encrypted first to ensure message confidentiality, and afterwards a MAC is calculated to ensure data authenticity and integrity. U.K.

CSM_224 The DSRC security data shall consist of the concatenation of the following data elements in the following order; see also Figure 12: U.K.

Current date time

the current date and time of the VU (data type )

Counter

a 3-byte counter, see CSM_225

[F1 VU serial number

the VU’s serial number or certificate request ID (data type VuSerialNumber or CertificateRequestID) – see CSM_123]

DSRC master key version number

the 1-byte version number of the DSRC master key from which the VU-specific DSRC keys were derived, see section 9.2.2.

MAC

the MAC calculated over all previous bytes in the RTM data.

Textual Amendments

F1 Substituted by Commission Implementing Regulation (EU) 2018/502 of 28 February 2018 amending Implementing Regulation (EU) 2016/799 laying down the requirements for the construction, testing, installation, operation and repair of tachographs and their components (Text with EEA relevance).

CSM_225 The 3-byte counter in the DSRC security data shall be in MSB-first format. The first time a VU calculates a set of RTM data after it is taken into production, it shall set the value of the counter to 0. The VU shall increase the value of the counter data by 1, each time before it calculates a next set of RTM data. U.K.

13.2. Tachograph Payload Encryption and MAC Generation U.K.

CSM_226 Given a plaintext data element with data type as described in Appendix 14, a VU shall encrypt this data as shown in Figure 12: the VU's DSRC key for encryption K_VU_DSRC_ENC (see section 9.2.2) shall be used with AES in the Cipher Block Chaining (CBC) mode of operation, as defined in [ISO 10116], with an interleave parameter m = 1. The initialization vector shall be equal to IV = current date time || ‘00 00 00 00 00 00 00 00 00’ || counter, where current date time and counter are specified in CSM_224. The data to be encrypted shall be padded using method 2 defined in [ISO 9797-1]. U.K.

CSM_227 A VU shall calculate the MAC in the DSRC security data as shown in Figure 12: the MAC shall be calculated over all preceding bytes in the RTM data, up to and including the DSRC master key version number, and including the tags and lengths of the data objects. The VU shall use its DSRC key for authenticity K_VU_DSRC_MAC (see section 9.2.2) with the AES algorithm in CMAC mode as specified in [SP 800-38B]. The length of the MAC shall be linked to the length of the VU-specific DSRC keys, as specified in CSM_50. U.K.

Figure 12

Tachograph payload encryption and MAC generation

13.3. Verification and Decryption of Tachograph Payload U.K.

CSM_228 When a remote interrogator receives RTM data from a VU, it shall send the entire RTM data to a control card in the data field of a PROCESS DSRC MESSAGE command, as described in Appendix 2. Then: U.K.

1.

The control card shall inspect the DSRC master key version number in the DSRC security data. If the control card does not know the indicated DSRC master key, it shall return an error specified in Appendix 2 and abort the process.

2.

[F1 The control card shall use the indicated DSRC master key in combination with the VU serial number or the certificate request ID in the DSRC security data to derive the VU-specific DSRC keys K_VU _DSRC _ENC and K_VU _DSRC _MAC, as specified in CSM_124.]

3.

The control card shall use K_VU_DSRC_MAC to verify the MAC in the DSRC security data, as specified in CSM_227. If the MAC is incorrect, the control card shall return an error specified in Appendix 2 and abort the process.

4.

The control card shall use K_VU_DSRC_ENC to decrypt the encrypted tachograph payload, as specified in CSM_226. The control card shall remove the padding and shall return the decrypted tachograph payload data to the remote interrogator.

CSM_229 In order to prevent replay attacks, the remote interrogator shall verify the freshness of the RTM data by verifying that the current date time in the DSRC security data does not deviate too much from the current time of the remote interrogator. U.K.

Notes: U.K.

— This requires the remote interrogator to have an accurate and reliable source of time. U.K.

— Since Appendix 14 requires a VU to calculate a new set of RTM data every 60 seconds, and the clock of the VU is allowed to deviate 1 minute from the real time, a lower limit for the freshness of the RTM data is 2 minutes. The actual freshness to be required also depends on the accuracy of the clock of the remote interrogator. U.K.

CSM_230 When a workshop verifies the correct functioning of the DSRC functionality of a VU, it shall send the entire RTM data received from the VU to a workshop card in the data field of a PROCESS DSRC MESSAGE command, as described in Appendix 2. The workshop card shall perform all checks and actions specified in CSM_228. U.K.