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

9.2.2 Keys for Securing DSRC Communication U.K.

9.2.2.1 General U.K.

CSM_119 The authenticity and confidentiality of data communicated from a vehicle unit to a control authority over a DSRC remote communication channel shall be ensured by means of a set of VU-specific AES keys derived from a single DSRC master key, KM_DSRC. U.K.

CSM_120 The DSRC master key KM_DSRC shall be an AES key that is securely generated, stored and distributed by the ERCA. The key length may be 128, 192 or 256 bits and shall be linked to the length of the European root key pair, as described in CSM_50. U.K.

CSM_121 The ERCA shall communicate the DSRC master key to Member State Certificate Authorities upon their request in a secure manner, to allow them to derive VU-specific DSRC keys and to ensure that the DSRC master key is inserted in all control cards and workshop cards issued under their responsibility. U.K.

CSM_122 The ERCA shall assign to each DSRC master key a unique version number. The ERCA shall inform the MSCAs about the version number when sending the DSRC master key to them. U.K.

Note: The version number is used to distinguish different generations of the DSRC master key, as explained in detail in section 9.2.2.2. U.K.

[F1 CSM_123 For every vehicle unit, the vehicle unit manufacturer shall create a unique VU serial number and shall send this number to its Member State Certificate Authority in a request to obtain a set of two VU-specific DSRC keys. The VU serial number shall have data type . U.K.

Note: U.K.

• This VU serial number shall be identical to the vuSerialNumber element of VuIdentification, see Appendix 1 and to the Certificate Holder Reference in the VU’s certificates.

• The VU serial number may not be known at the moment a vehicle unit manufacturer requests the VU-specific DSRC keys. In this case, the VU manufacturer shall send instead the unique certificate request ID it used when requesting the VU’s certificates; see CSM_153. This certificate request ID shall therefore be equal to the Certificate Holder Reference in the VU’s certificates.]

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_124 Upon receiving a request for VU-specific DSRC keys, the MSCA shall derive two AES keys for the vehicle unit, called K_VU_DSRC_ENC and K_VU_DSRC_MAC. These VU-specific keys shall have the same length as the DSRC master key. The MSCA shall use the key derivation function defined in [RFC 5869]. The hash function that is necessary to instantiate the HMAC-Hash function shall be linked to the length of the DSRC master key, as described in CSM_50. The key derivation function in [RFC 5869] shall be used as follows: U.K.

• Step 1 (Extract):

  • PRK = HMAC-Hash (salt, IKM) where salt is an empty string ‘’ and IKM is KM_DSRC.

• Step 2 (Expand):

  • OKM = T(1), where

    T(1) = HMAC-Hash (PRK, T(0) || info || ‘01’) with

    • T(0) = an empty string (‘’)

    • [F1 info = VU serial number or certificate request ID, as specified in CSM_123]

  • K_VU_DSRC_ENC = first L octets of OKM and

    K_VU_DSRC_MAC = last L octets of OKM

    where L is the required length of K_VU_DSRC_ENC and K_VU_DSRC_MAC in octets.

CSM_125 The MSCA shall distribute K_VU_DSRC_ENC and K_VU_DSRC_MAC to the VU manufacturer in a secure manner for insertion in the intended vehicle unit. U.K.

CSM_126 When issued, a vehicle unit shall have stored K_VU_DSRC_ENC and K_VU_DSRC_MAC in its secure memory, in order to be able to ensure the integrity, authenticity and confidentiality of data sent over the remote communication channel. A vehicle unit shall also store the version number of the DSRC master key used to derive these VU-specific keys. U.K.

CSM_127 When issued, control cards and workshop cards shall have stored KM_DSRC in their secure memory, in order to be able to verify the integrity and authenticity of data sent by a VU over the remote communication channel and to decrypt this data. Control cards and workshop cards shall also store the version number of the DSRC master key. U.K.

Note: as explained in section 9.2.2.2, in fact multiple generations of KM_DSRC may have to be inserted in a single workshop card or control card. U.K.

[F1 CSM_128 The MSCA shall keep records of all VU-specific DSRC keys it generated, their version number and the VU serial number or certificate request ID used in deriving them.] U.K.

9.2.2.2 DSRC Master Key Replacement U.K.

CSM_129 Each DSRC master key is associated to a particular generation of the ERCA root key pair. The ERCA shall therefore replace the DSRC master key every 17 years. The validity period of each DSRC master key generation shall begin two years before the associated ERCA root key pair becomes valid and shall end when the associated ERCA root key pair expires. This is depicted in Figure 3. U.K.

Figure 3

Issuance and usage of different generations of the DSRC master key in vehicle units, workshop cards and control cards

CSM_130 At least two years before generating a new European root key pair, as described in CSM_56, the ERCA shall generate a new DSRC master key. The length of the DSRC key shall be linked to the foreseen strength of the new European root key pair, according to CSM_50. The ERCA shall communicate the new DSRC master key to the MSCAs upon their request, together with its version number. U.K.

CSM_131 An MSCA shall ensure that all valid generations of KM_DSRC are stored in every control card issued under its authority, together with their version numbers, as shown in Figure 3. U.K.

Note: this implies that in the last two years of the validity period of an ERCA certificate, control cards will be issued with three different generations of KM_DSRC, as shown in Figure 3. U.K.

CSM_132 An MSCA shall ensure that all generations of KM_DSRC that have been valid for at least a year and are still valid, are stored in every workshop card issued under its authority, together with their version numbers, as shown in Figure 3. U.K.

Note: this implies that in the last year of the validity period of an ERCA certificate, workshop cards will be issued with three different generations of KM_DSRC, as shown in Figure 3. U.K.

CSM_133 Vehicle unit manufacturers shall insert only one set of VU-specific DSRC keys into each vehicle unit, together with its version number. This set of keys shall be derived from the KM_DSRC generation linked to the ERCA certificate upon which the VU's certificates are based. U.K.

Notes: U.K.

— This implies that a vehicle unit based on the generation X ERCA certificate shall only contain the generation X K_VU_DSRC_ENC and K_VU_DSRC_MAC_, even if the VU is issued after the start of the validity period of the generation X+1 ERCA certificate. This is shown in Figure 3. U.K.

— Since workshop cards have a validity period of one year and control cards of two years, the result of CSM_131 — CSM_133 is that all workshop cards and control cards will contain the new DSRC master key at the moment the first VU containing VU-specific keys based on that master key will be issued. U.K.