Must the register be signed by the Data Controller?

ANSWER

The GDPR does not explicitly require the controller's signature on the record of processing activities. The key requirement is that the register be maintained in written form, including electronic form, contain the elements described in detail in Art. 30(1) GDPR, and be available upon request of the supervisory authority. However, from a practical standpoint, the controller's signature may be useful as a form of confirmation that the register has been verified and approved by the relevant person.