Commission Implementing Regulation (EU) 2016/799 of 18 March 2016 implementing Regulation (EU) No 165/2014 of the European Parliament and of the Council laying down the requirements for the construction, testing, installation, operation and repair of tachographs and their components (Text with EEA relevance) (c. 799)

ANNEX I C U.K. Requirements for construction, testing, installation, and inspection

Appendix 11

COMMON SECURITY MECHANISMS U.K.

PART B U.K. SECOND-GENERATION TACHOGRAPH SYSTEM

10. VU- CARD MUTUAL AUTHENTICATION AND SECURE MESSAGING U.K.

10.5. Secure Messaging U.K.

10.5.1 General U.K.

CSM_181 All commands and responses exchanged between a vehicle unit and a tachograph card after successful Chip Authentication took place and until the end of the session shall be protected by Secure Messaging. U.K.

CSM_182 Except when reading from a file with access condition SM-R-ENC-MAC-G2 (see Appendix 2, section 4), Secure Messaging shall be used in authentication-only mode. In this mode, a cryptographic checksum (a.k.a. MAC) is added to all commands and responses to ensure message authenticity and integrity. U.K.

CSM_183 When reading data from a file with access condition SM-R-ENC-MAC-G2, Secure Messaging shall be used in encrypt-then-authenticate mode, i.e. the response data is encrypted first to ensure message confidentiality, and afterwards a MAC over the formatted encrypted data is calculated to ensure authenticity and integrity. U.K.

CSM_184 Secure Messaging shall use AES as defined in [AES] with the session keys K_MAC and K_ENC that were agreed during Chip Authentication. U.K.

CSM_185 An unsigned integer shall be used as the Send Sequence Counter (SSC) to prevent replay attacks. The size of the SSC shall be equal to the AES block size, i.e. 128 bits. The SSC shall be in MSB-first format. The Send Sequence Counter shall be initialized to zero (i.e. ‘00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00’) when Secure Messaging is started. The SSC shall be increased every time before a command or response APDU is generated, i.e. since the starting value of the SSC in a SM session is 0, in the first command the value of the SSC will be 1. The value of SSC for the first response will be 2. U.K.

CSM_186 For message encryption, K_ENC 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 and an initialization vector SV = E(K_ENC, SSC), i.e. the current value of the Send Sequence Counter encrypted with K_ENC. U.K.

CSM_187 For message authentication, K_MAC shall be used with AES in CMAC mode as specified in [SP 800-38B]. The length of the MAC shall be linked to the length of the AES session keys, as specified in CSM_50. The Send Sequence Counter shall be included in the MAC by prepending it before the datagram to be authenticated. U.K.