Recital 121

The processing of personal data, to the extent necessary and proportionate for the purpose of ensuring security of network and information systems by essential and important entities, could be considered to be lawful on the basis that such processing complies with a legal obligation to which the controller is subject, in accordance with the requirements of Article 6(1), point (c), and Article 6(3) of Regulation (EU) 2016/679. Processing of personal data could also be necessary for legitimate interests pursued by essential and important entities, as well as providers of security technologies and services acting on behalf of those entities, pursuant to Article 6(1), point (f), of Regulation (EU) 2016/679, including where such processing is necessary for cybersecurity information-sharing arrangements or the voluntary notification of relevant information in accordance with this Directive. Measures related to the prevention, detection, identification, containment, analysis and response to incidents, measures to raise awareness in relation to specific cyber threats, exchange of information in the context of vulnerability remediation and coordinated vulnerability disclosure, the voluntary exchange of information about those incidents, and cyber threats and vulnerabilities, indicators of compromise, tactics, techniques and procedures, cybersecurity alerts and configuration tools could require the processing of certain categories of personal data, such as IP addresses, uniform resources locators (URLs), domain names, email addresses and, where they reveal personal data, time stamps. Processing of personal data by the competent authorities, the single points of contact and the CSIRTs, could constitute a legal obligation or be considered to be necessary for carrying out a task in the public interest or in the exercise of official authority vested in the controller pursuant to Article 6(1), point (c) or (e), and Article 6(3) of Regulation (EU) 2016/679, or for pursuing a legitimate interest of the essential and important entities, as referred to in Article 6(1), point (f), of that Regulation. Furthermore, national law could lay down rules allowing the competent authorities, the single points of contact and the CSIRTs, to the extent that is necessary and proportionate for the purpose of ensuring the security of network and information systems of essential and important entities, to process special categories of personal data in accordance with Article 9 of Regulation (EU) 2016/679, in particular by providing for suitable and specific measures to safeguard the fundamental rights and interests of natural persons, including technical limitations on the re-use of such data and the use of state-of-the-art security and privacy-preserving measures, such as pseudonymisation, or encryption where anonymisation may significantly affect the purpose pursued.