Guidelines 07/2020 on the concepts of controller and processor in the GDPR
Paragraph 1.3.2 The processor must ensure that persons authorised to process the personal data have committed themselves to confidentiality or are under an appropriate statutory obligation of confidentiality (Art. 28 (3) (b) GDPR)
119. The contract must say that the processor needs to ensure that anyone it allows to process the personal data is committed to confidentiality. This may occur either via a specific contractual agreement, or due to statutory obligations already in place.
120. The broad concept of “persons authorised to process the personal data ”includes employees and temporary workers. Generally speaking, the processor should make the personal data available only to the employees who actually need them to perform tasks for which processor was hired by the controller.
121. The commitment or obligation of confidentiality must be “appropriate”, i.e. it must effectively forbid the authorised person from disclosing any confidential information without authorisation, and it must be sufficiently broad so as to encompass all the personal data processed on behalf of the controller as well as the details concerning the relationship.