(a) take appropriate security and organisational measures for the prevention of unauthorised access to, alteration of, disclosure of, accidental loss, and destruction of the data in his control; and (b) ensure that the measures provide a level of security appropriate to – (i) the harm that might result from the unauthorised access to, alteration of, disclosure of, destruction of the data and its accidental loss; and (ii) (2) the nature of the data concerned. A data controller or a data processor shall take all reasonable steps to ensure that any person employed by him is aware of and complies with the relevant security measures. (3) Where a data controller is using the services of a data processor, he shall choose a data processor providing sufficient guarantees in respect of security and organisational measures for the purposes of complying with subsection (1). (4) Where the data controller is using the services of a data processor under subsection (3) the data controller and the data processor shall enter into a written contract which shall provide that (a) the data processor shall act only on instructions received from the data controller; and (b) the data processor shall be bound by obligations devolving on the data controller under subsection (1). (5) Without prejudice to subsection (1), in determining the appropriate security measures, in particular, where the processing involves the transmission of data over an information and communication network, a data controller shall have regard to – (a) the state of technological development available;