Data Diode | One Way Data Flow

What is a data diode?

A data diode is a hardware device that guarantees unidirectional data transfer. It allows information to move from a secure or trusted network to a less-secure environment, or vice versa, while preventing any possibility of reverse communication.

This technology is essential wherever assurance depends on physically enforced separation between networks.

By preventing bidirectional data paths, a data diode eliminates the threat of malware infiltration, data exfiltration, and command-and-control attacks, ensuring that sensitive or classified data remains protected.

Common Criteria–evaluated and aligned to UK and NATO accreditation standards, Nexor Data Diodes provide verified, physical enforcement of security policy, forming the foundation of trusted information exchange architectures.

How the Nexor Data Diode works

Traditional “air gap” methods, such as moving data via portable media, are slow, insecure, and impractical for modern, high-volume systems. Nexor Data Diode replaces these manual approaches with a controlled, high-speed, and physically enforced one-way transfer.

Each Nexor Data Diode is a sealed, tamper-evident hardware unit that links two networks using standard bidirectional cabling. Inside the unit, one half of the optical or electrical connection is physically terminated, allowing information to travel in only one direction. The opposite path does not exist, ensuring that no signal, command, or data can ever return to the source network.

This hardware-enforced unidirectional link cannot be bypassed or altered by software, firmware, or configuration. Even a highly sophisticated attack cannot reverse the data flow or establish a covert return channel.

Every Nexor Data Diode is auditable and accreditable by design. The sealed enclosure and absence of management interfaces prevent remote access or modification, maintaining verifiable integrity and assurance throughout its operational life.

Why organisations trust Nexor Data Diode

Assured separation: Physically enforces one-way transfer, removing any possibility of data returning to the source network.
Trusted heritage: Developed through decades of experience in Defence and Government information-assurance systems.
Sovereign supply chain: Designed, built, and supported in the UK under controlled, accredited engineering processes.
Accreditation alignment: Independently evaluated to Common Criteria EAL7+ and designed to meet NCSC and NATO assurance standards.
Operational simplicity: “Fit and forget” deployment with minimal maintenance and extremely high reliability.

Nexor Data Diode enables secure, policy-controlled information sharing between trusted and untrusted domains, protecting sensitive data while maintaining operational efficiency.

Key benefits

Physically enforced one-way data flow

Guarantees that data moves in only one direction, eliminating any return path for threats or data exfiltration.

Unmatched assurance level

Assured one-way data transfer, certified to Common Criteria EAL7+ or NCSC CAPS for mission-critical success.

Reliability and ease of use

Hardware-only design delivers continuous, maintenance-free operation.

High throughput

Models available for 1 Gbps and 10 Gbps transfer, maintaining consistent performance at wire speed.

Accreditable by design

Trusted in certified environments, enabling straightforward inclusion in accredited architectures.

Low operational cost

No configuration drift or patch management, reducing lifecycle cost compared with software-based controls.

Core features

Unidirectional optical data link

Physical enforcement using a light-emitter and receiver, no electrical or logical return channel.

Physical separation of networks

Maintains complete isolation between domains, eliminating shared resources or attack surfaces.

No IP address or management interface

Invisible on the network and immune to remote exploitation.

Tamper-evident construction

Sealed, auditable hardware enclosure prevents interference or unauthorised modification.

High throughput

Optimised design supports real-time transfer of large data volumes without compromising assurance.

Standards compliance

Designed to meet or exceed UK, NATO, and international data-transfer assurance standards.

Download your free copy of the benefits sheet

Learn about Nexor Data Diode from our free brochure. Simply tell us where to send it and we will email it to your inbox.

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Applications and use cases

Secure integration of legacy systems

In European rail networks, Nexor Data Diodes enable one-way data transfer from legacy signalling systems to central management servers.
This ensures safe, real-time visibility of operational data without introducing any path for remote intrusion, improving efficiency and maintaining safety assurance.

Evidence integrity and secure data archiving

A UK Government agency uses Nexor Data Diodes to safeguard digital evidence by transferring captured information from a restricted domain to a secure storage environment.
The one-way link prevents tampering or deletion, ensuring the integrity and admissibility of data for investigative and legal use.

Critical infrastructure monitoring

Industrial and energy organisations deploy Nexor Data Diodes to send telemetry and sensor data from operational technology (OT) to IT networks.
This enables situational awareness and predictive maintenance while maintaining isolation between control systems and corporate environments.

Military and intelligence operations

Used in command-and-control and intelligence, surveillance, and reconnaissance (ISR) systems to securely disseminate operational data from classified domains to coalition or partner networks without exposing the source network to compromise.

Whether protecting operational data, safeguarding evidence, or enabling infrastructure visibility, each deployment is supported by rigorous engineering control and third-party certification, forming the assurance backbone of Nexor’s offering.

Each deployment is underpinned by the same commitment to verified assurance, ensuring that every Nexor Data Diode installation can be trusted to meet the highest national and international security standards.

Certified assurance for critical national systems

Every Nexor Data Diode deployment is built on proven, independently assured technology.
Through partnerships with trusted manufacturers in the UK and the Netherlands, Nexor delivers a choice of certified hardware platforms, each fully integrated within our sovereign assurance framework and supported through our accredited engineering processes.

Nexor provides two assured data diode options to meet differing operational, regulatory, and accreditation requirements. Both are fully integrated, supported, and accredited within Nexor’s trusted information-exchange frameworks.

Independently evaluated to Common Criteria EAL7+, the highest internationally recognised assurance level for data-diode technologies. This certification confirms that the product’s design, implementation, and testing satisfy the most stringent requirements for hardware-enforced network separation, making it suitable for use in NATO and multi-national environments.

Used in command-and-control and intelligence, surveillance, and reconnaissance (ISR) systems to securely disseminate operational data from classified domains to coalition or partner networks without exposing the source network to compromise.

Both diodes are integrated within Nexor’s sovereign engineering and assurance framework, ensuring consistent configuration control, auditability, and accreditation evidence across all deployments.

Each unit is manufactured within a controlled, traceable supply chain in the UK or the EU, ensuring provenance and compliance throughout the entire production and delivery process.

Together, these options enable customers to select the assurance pathway, UK CAPS or international EAL7+, that best aligns with their operational, policy, and interoperability requirements.

Assured choice, sovereign integration

Nexor’s dual-diode approach combines internationally certified technology with UK assurance oversight, providing trusted options for both domestic and coalition environments.

Why use a data diode

A data diode provides unmatched assurance wherever sensitive or classified systems must exchange information safely:

Prevents external attacks: Eliminates inbound communication paths, stopping malware and ransomware before they reach the protected domain.
Prevents data theft: Guarantees physical break in the return path, blocking exfiltration of sensitive or classified information.
Ensures compliance: Supports regulatory and policy frameworks across Defence, Government, and Critical National Infrastructure.
Supports secure data sharing: Enables controlled, auditable information exchange between domains while maintaining network integrity.
Protects operational integrity: Ensures mission-critical systems receive timely data without risk of contamination or compromise.

Protect your most critical systems with assured one-way data transfer

Nexor Data Diodes provide the physical assurance foundation for secure information exchange across Defence, Government, Law Enforcement and Critical National Infrastructure.
With accredited design, UK manufacturing, and proven performance at scale, they deliver trusted separation for systems where security and reliability cannot be compromised.

Our specialists can advise on deployment, configuration, and accreditation within your environment, from system design to certification support.

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What our customers say

We achieved our primary objective of finding a proof of concept architecture that was technologically feasible and simple to implement.

A European Police Force