NIS2 and secure file sharing: what really changes in 2026

NIS2 and secure file sharing: what really changes in 2026

You encrypted the channel. You defined permissions. You trained your people. Yet every time a document leaves your network, you lose visibility: who actually opens it, from which device, how many times, how long after you sent it.

NIS2 makes that question impossible to defer. And with the ACN Determination of April 13, 2026, the stakes have shifted: declaring compliance is no longer enough. You have to prove it with verifiable data. For secure file sharing, where data leaves the perimeter by definition, this is where most organizations discover they have a gap.

This guide covers what NIS2 actually requires from organizations that share files, where traditional solutions leave a compliance hole, and how to translate those obligations into concrete, operational controls.

Key takeaways

• NIS2 mandates encryption of data in transit and at rest, access control, audit trails, and supply chain security: requirements that secure file sharing stress-tests every day.
• Transposed into Italian law as Legislative Decree 138/2024 (effective October 16, 2024), the directive applies to essential and important entities in critical sectors, not broadly to all SMEs.
• The operational deadline is October 2026: by then, all security measures, including supply chain security, must be fully implemented.
• ACN Determination 127437 of April 13, 2026 shifts the focus from formal compliance to demonstrable resilience: what matters now is data, real processes, and a mapped supplier registry.
• Perimeter-based solutions are not sufficient. Once the transport layer is decrypted, the file is readable at the destination. Protection has to travel with the data.

What NIS2 actually requires from organizations that share files

Italy transposed the NIS2 directive through Legislative Decree 138 of September 4, 2024, which entered into force on October 16, 2024. Article 24 of the decree requires in-scope organizations to adopt cyber risk management measures. Many of those measures apply directly to how documents are protected, shared, and tracked. For anyone building a compliant secure file sharing practice, this is where policy becomes operations.

The requirements cover three dimensions: confidentiality, integrity, and availability of data. This is the CIA Triad, and it is not an academic abstraction. It means you cannot simply prevent unauthorized access to a file. You also have to ensure the file has not been altered, and that it remains available to authorized users when they need it.

Among the ten minimum measures the decree specifies, four carry particular weight for document-sharing workflows:

• encryption policies and procedures;
• access control and identity management;
• operational traceability and incident management;
• supply chain and vendor security.

Anyone familiar with GDPR will recognize this list. Encryption at rest and in transit, multi-factor authentication, log management: these were already adequate measures under Article 32 of Regulation (EU) 2016/679. NIS2 makes them mandatory and auditable. The complete breakdown of which entities and sectors fall in scope is available on the ACN NIS portal.

What changes with the ACN Determination of April 13, 2026

This is the part most compliance guides have not caught up with yet. With Determination 127437 of April 13, 2026, the National Cybersecurity Agency operationalized the NIS Decree framework and changed the ground rules.

Before, you could describe your security measures. Now you have to demonstrate them with data. Security becomes measurable. Supply chain moves to the center, with a formal obligation to map suppliers and critical dependencies. Compliance is grounded in real processes, continuous monitoring, and direct management accountability. We analyzed this shift in detail in our deep dive on the ACN Determination of April 13, 2026.

For secure file sharing, this translates directly: saying "our documents are protected" is no longer sufficient. You need to show who accessed what, when, from which device, and that the protection holds even after the file reaches a third-party vendor. Without granular, exportable audit trails, you cannot produce that data. And if you cannot produce it, you are not meeting the obligation.

What encryption does NIS2 require for shared files?

NIS2 does not prescribe a specific algorithm, but it requires encryption that is adequate to the risk. In practice, that means at least AES-256 for data at rest and TLS 1.3 for data in transit.

There is a distinction worth drawing out. When you send a document by email or upload it to a file-sharing platform, the channel is encrypted. But the file is only protected while it stays in that channel. Once it reaches its destination and the transport layer decrypts, the document is readable. If the recipient is compromised, or forwards the file somewhere it should not go, the channel encryption no longer does anything.

The right question, then, is not how to encrypt the transport better. It is why the data becomes readable the moment it leaves the protected channel.

The answer is a file-centric approach: the document is encrypted at creation and stays encrypted wherever it goes, inside or outside the network. That is the foundation of secure file sharing that holds up beyond the perimeter. CyberGrant FileGrant Enterprise adds quantum-proof encryption based on CRYSTALS-Kyber, the algorithm selected by NIST as the post-quantum standard and published as FIPS 203 (ML-KEM). This is not an academic detail: attackers today are archiving data encrypted with classical algorithms, waiting for quantum computers that will break them tomorrow. That is the "harvest now, decrypt later" logic, and for documents with multi-year value (contracts, patents, health records) it is a concrete threat.

How to implement the audit trails NIS2 requires

Logging every access to your files is not an optional best practice. NIS2, and the April 2026 ACN Determination more specifically, require you to demonstrate who did what, when, and with which data. If an incident occurs, you need to reconstruct the chain of events.

An effective audit trail for secure file sharing captures document opens, edits, third-party shares, downloads, and unauthorized access attempts. Logs must be tamper-resistant and exportable for review.

This is exactly what file-centric protection enables by design. Because the control lives in the file rather than the perimeter, every interaction with that file generates a tracked event: you know who opened a document, from which device, for how long, even after it left the organization.

Where files should reside under NIS2

NIS2 reinforces attention to supply chain security, including cloud service providers. The ACN Determination goes further: each entity must identify relevant suppliers based on criticality and replaceability, and map dependencies.

For Italian companies, maintaining control over where data resides is not just a GDPR requirement. It is operational resilience. If files live on infrastructure outside the EU, a jurisdictional dispute or regulatory shift can strip you of control at the worst possible moment.

Two things matter here: where the data lives, and who holds the keys. CyberGrant offers on-premises deployment for high-confidentiality environments and zero-knowledge key management. The keys stay with you. No one else, including the vendor, can access the content. CyberGrant's R&D and founders are based in Italy, with operations headquartered in Milan: data sovereignty is not a brochure claim, it is a matter of where the data actually lives.

How to protect files shared with vendors and third parties

Supply chain security is one of the pillars of NIS2, and the center of gravity in the April 13 ACN Determination. Every time you share a document with a vendor, consultant, or partner, you extend your organization's attack surface.

The data backs this up. According to the Verizon Data Breach Investigations Report 2025, roughly 30% of breaches involve a third party, double the rate from the previous year. The vulnerability is often not internal: it comes from a compromised partner.

Traditional file-sharing solutions have a structural limitation: once the file is sent, you cannot take it back. A genuinely secure file sharing approach requires the ability to act even after delivery. With a file-centric approach, you can revoke access to any document in real time, even after it has been downloaded. The file becomes unreadable immediately. That is the difference between hoping your vendor is secure and limiting the damage when they are not.

There is a consequence that often goes unnoticed. The real security measure is not preventing a file from being taken. It is making sure that if it is taken, it is useless.

NIS2 compliance checklist for secure file sharing

Translating requirements into operational controls takes a structured approach. Here are the essential controls, organized by category.

Encryption controls

• Encrypt every sensitive file with a robust algorithm (AES-256 or stronger), at rest and in transit.
• Consider persistent encryption that protects content after delivery, not just the channel.
• For documents with multi-year value, evaluate post-quantum cryptography.

Access controls

• Apply least privilege: each person accesses only the files their role requires.
• Require multi-factor authentication on sensitive documents.
• Define granular access policies based on roles (RBAC) and context.

Traceability controls

• Log every file operation: accesses, edits, shares, downloads, denied attempts.
• Protect logs from tampering and make them exportable for audits.
• Configure automatic alerts for anomalous activity.

Supply chain controls

• Map vendors with access to your data and classify them by criticality.
• Embed security requirements in contracts.
• Maintain the ability to revoke vendor access in real time.

Staying compliant without slowing down operations

There is a false tradeoff that derails a lot of compliance projects: either you are secure, or you are productive. NIS2 does not ask you to halt the business in order to become compliant. It asks you to integrate security into the workflows that already exist.

Legacy DLP fed that tradeoff: months of configuration, manual classification, false positives, users circumventing controls just to get work done. The result is security that exists on paper and gets bypassed in practice.

The file-centric approach inverts that logic. The data is protected at creation, classification is automatic, protection follows the file without requiring any action from the user. Security becomes intelligent, persistent, and nearly invisible to the people doing the work. That is what it takes for a NIS2 control to actually hold: when people have no reason to route around it, what you report to the ACN matches what happens every day.

The NIS2 deadlines are not moving. Identify today where your organization leaves gaps in encryption, traceability, and vendor control, and close them before October 2026

Frequently asked questions about NIS2 and secure file sharing

Which Italian companies are subject to NIS2?

NIS2 applies to essential and important entities in the critical sectors listed in Legislative Decree 138/2024: energy, transport, banking, financial infrastructure, healthcare, water, telecommunications, public administration, the digital sector, and others. In general, the directive covers medium and large organizations (above 50 employees or 10 million euros in revenue), though smaller entities may be included if they are deemed critical or if they supply services to a NIS entity. If you operate as a vendor to an essential or important entity, you may be indirectly in scope through supply chain requirements. To verify your position, consult the ACN NIS portal.

When do NIS2 security requirements for file sharing need to be in place?

Security measures, including supply chain security, must be fully operational by October 2026. Registration deadlines on the ACN portal have already passed (January 17, 2025 for cloud, data center, and managed service providers; February 28, 2025 for other entities), and since January 1, 2026 the obligation to report incidents with annual information updates is active. The April 2026 Determination also introduced, for the May-June period, the obligation to submit a categorized list of activities and services.

What encryption does NIS2 require for shared files?

NIS2 does not mandate a specific algorithm, but requires encryption adequate to the risk level: in practice, AES-256 or equivalent at rest and TLS 1.3 in transit. The limitation of traditional solutions is that they protect the channel, not the content: the file becomes readable at the destination. Genuinely compliant secure file sharing maintains persistent encryption on the document itself, and for data with multi-year value, post-quantum cryptography (such as CRYSTALS-Kyber, NIST FIPS 203 standard) protects against the "harvest now, decrypt later" threat.

What happens if a vendor with access to my files is compromised?

You are responsible for security across the entire supply chain. NIS2 and the ACN Determination require you to evaluate and monitor vendor risks and map critical dependencies. If an incident occurs at a vendor, you need to be able to limit the impact on your data. With file-centric protection, you can revoke access to an already-shared document in real time, making it immediately unreadable and minimizing exposure.

How do I demonstrate NIS2 compliance during an audit?

Auditors verify the existence of documented policies, the actual implementation of controls, and the presence of complete audit trails. After the April 13, 2026 Determination, the principle is clear: declaration is not enough; you need to demonstrate with verifiable data. You must be able to show who has access to what, when, and why. A file-centric platform automatically tracks every interaction with protected documents, making it straightforward to demonstrate compliance.