Article 21 sets out ten categories of security measure: risk analysis and security policies, incident handling, business continuity and disaster recovery, supply chain security, secure system acquisition and development, effectiveness testing, cyber hygiene and training, cryptography, human resources security and access control, and multi-factor authentication. These are ongoing obligations, not a one-time checklist.
Article 23 adds strict incident notification timelines: a 24-hour early warning to the national CSIRT or competent authority, a fuller notification within 72 hours, and a final report within one month. Article 20 places specific obligations on the management body to approve the security measures and oversee their implementation, with personal liability for those who fail to do so.