As an EPSO exam question, you are in charge of coordinating international missions for the European Commission and are responsible for ensuring the cybersecurity of the communication systems used by the EU's diplomatic representations abroad. According to the EU framework and the guidelines of the European Union Agency for Cybersecurity (ENISA) and the European Union Agency for Network and Information Security (AENSI), which of the following measures constitutes the most critical practice for protecting the integrity of data in high-risk cloud computing environments without relying on a continuous connection to a secure local network? option_A: Implement a local backup system on external hard drives disconnected from the network, as the GDPR explicitly prohibits the storage of sensitive data in public cloud. option_B: Rely on the default security protocols of public cloud providers, as the Network and Information Systems Regulation (NIS2) obliges them to assume full responsibility for the security of the data. option_C: Apply end-to-end encryption (E2EE) to all data before uploading it to the cloud and manage the encryption keys independently, ensuring that neither the service provider nor an external attacker can access the content. option_D: Use exclusively encrypted social media for internal communication, as official EU platforms are vulnerable to social engineering attacks. option_E: Disable two-factor authentication (2FA) on mobile devices to facilitate quick remote access in conflict zones, based on the premise that physical device security is the only necessary barrier. Explanation: 1) **Why the correct answer is correct:** The fundamental measure for protecting the integrity of data in the cloud, especially in high-risk environments where the network may be insecure, is end-to-end encryption (E2EE) with independent key management. According to EU security guidelines and ENISA, the principle of 'privacy by design' and data protection require that data be unreadable to any unauthorized entity (including cloud providers) even if intercepted. This ensures confidentiality and integrity regardless of the underlying infrastructure. This practice aligns with the cybersecurity standards for EU institutions. 2) **Why the incorrect answers are incorrect:** - **Option A (Partially True/False Information):** It is incorrect to state that the GDPR explicitly prohibits the storage of data in public cloud. The GDPR allows cloud storage if the security and responsibility conditions are met. A local backup system is good for resilience, but it does not solve the risk of unauthorized access in the cloud itself and is not the most critical measure for protecting data *in transit* or *at rest* in the cloud. - **Option B (Security Trap):** It is dangerous and false to suggest that official EU platforms are inherently vulnerable or that social media is the solution. EU institutions use certified and secure official tools. Using public social media platforms violates information security protocols. - **Option C (Overgeneralization/Responsibility Trap):** While NIS2 reinforces security, the responsibility for data security is shared (shared responsibility model). The cloud provider protects the infrastructure, but the user (the institution) is responsible for protecting their own data (encryption, access). Relying blindly on default protocols is a weak security practice. - **Option D (Insecure Practice):** Disabling two-factor authentication (2FA) is a critical security practice prohibited by EU standards. 2FA is one of the most effective measures against unauthorized access, especially in remote or high-risk environments. 3) **Quick Tip:** On exam day, always remember: 'Encryption is the last bastion of security; if the data is encrypted correctly, even if the infrastructure is compromised, the content remains secure.'