AWS Diode vs Hardware Diodes
(Waterfall / Owl / Advenica)
In modern cybersecurity architecture, the question of how to reliably transfer data between networks of differing trust levels has risen to strategic importance long ago. Organizations across defense, critical infrastructure, advanced manufacturing, and cloud-native enterprises face the same challenge: enabling data flow without enabling possible attacks and data interception. Among the most significant approaches to solving this problem are cloud-native one-way transfer mechanisms such as AWS Diode and traditional hardware data diodes produced by Waterfall Security, Owl Cyber Defense, and Advenica. Although they serve the same conceptual purpose, the environments they support, the risks they mitigate, and the architectural assumptions they rely upon differ dramatically.
AWS Diode is Amazon's cloud-native implementation of a unidirectional cross-domain solution. Instead of relying on physical one-way optical hardware, AWS uses strictly isolated VPCs, asymmetric routing, IAM boundary enforcement, staging layers such as Amazon S3 with directional read/write policies, and guard components for scanning, validation, and release control. This makes AWS Diode highly suitable for modern mission systems, multi-domain workloads, and DevSecOps pipelines that must promote build artifacts, curated datasets, or sanitized intelligence products from a lower domain to a higher domain. The system is intentionally designed to integrate seamlessly with CodePipeline, Lambda-based sanitization, CloudWatch logging, and region-isolated workloads. Its scalability and automation capabilities enable organizations to maintain security while supporting rapid software-release cycles or multi-environment orchestration strategies.
Hardware diodes from Waterfall, Owl, and Advenica operate in a fundamentally different assurance model. Rather than enforcing directionality through configuration, they enforce it through physics. A physical diode, often implemented as a fiber-optic transmitter on one end and a photodiode receiver on the other, cannot be reversed via misconfiguration, software compromise, or protocol exploitation. Waterfall's products replicate industrial historians, databases, and monitoring servers to IT networks without providing any return path into operational technology. Owl's solutions support structured and unstructured data types across sectors such as defense, utilities, and transportation through multi-layered protocol breaking. Advenica emphasizes high-assurance European-manufactured hardware designed for national security agencies and operators of critical infrastructure. Across these vendors, the consistent theme is high-trust isolation: no matter what happens at the software layer, the reverse direction remains impossible.
While cloud-native and hardware-based diodes share a unidirectional philosophy, they solve different categories of problems. AWS Diode excels in cloud-first architectures, particularly those where unidirectional movement is primarily about reducing cross-domain risk in environments already dependent on cloud services. Its value lies in elasticity, automation, and the ability to embed unidirectional logic inside DevSecOps tooling. Hardware diodes, on the other hand, remain indispensable wherever human safety, industrial continuity, or national defense operations depend on full isolation between control networks and external networks. In nuclear facilities, electric grids, rail signaling, and military command-and-control systems, physically enforced one-way transfer provides a guarantee that software-defined mechanisms cannot match.
The distinction becomes clearer when examining the architectural assumptions behind each solution. AWS Diode assumes that your security domains live inside AWS or can be mirrored there. It assumes that directional boundaries can be enforced through IAM and VPC configuration, and that outbound-only S3 access patterns are operationally acceptable. Meanwhile, hardware diode deployments assume that networks must remain physically segregated, that operational integrity supersedes convenience, and that directional assurance must remain intact even in the face of total software compromise.
Below is the comparison table included within the article
Comparison table
| Dimension | AWS Diode | Hardware Diodes (Waterfall / Owl / Advenica) |
|---|---|---|
| Deployment model | Managed AWS cross-domain service using VPC/IAM/S3 | Physical appliance deployed in OT/secure facilities |
| Assurance mechanism | Logical one-way enforcement with guard layers | Physical one-way link; reverse flow impossible |
| Primary use cases | Classified cloud, DevSecOps, automated pipelines | OT/ICS, defense, critical infrastructure isolation |
| Scaling model | Elastic, cloud-native, automated | Fixed throughput; scale via more appliances |
| Failure mode | Dependent on correct configuration and IAM posture | Even misconfiguration cannot create reverse flow |
Real-world case studies and industry signals
You don't choose between AWS Diode and hardware diodes in a vacuum; you look at how they're already being used.
- AWS Diode in DoD DevSecOps. The US DoD has granted AWS Diode a Cross Domain Solution Authorization, and the Navy's DevSecOps priorities explicitly cite its use in DISA Citadel for secure one-way transfer across security domains. Additional industry presentations describe patterns where AWS Diode is used to push build artifacts and security-scanned packages from lower environments to higher-classified domains as part of cross-domain DevSecOps pipelines.
- Waterfall in energy and industrial sectors. Waterfall highlights deployments in oil & gas and other industrial customers where a unidirectional gateway replicates process historians and other OT data to IT networks, while preventing any network-level access back into the control system. Their "Not Your Grandma's Data Diode" whitepaper describes how the gateway hardware and software together provide real-time server replication and device emulation while preserving one-way security. Multiple writeups on industrial cyber security also point to data diodes and unidirectional gateways as a core pattern for protecting critical infrastructure architecture.
- Owl Cyber Defense in utilities and monitoring. Owl's case studies include OSI PI historian replication where OT historian data is sent one-way through Owl diodes to enterprise networks for analytics, as well as secure file transfer and syslog replication designs that meet regulatory and operational requirements. Their portfolio of use cases across electric utilities, water/wastewater, and defense illustrates how hardware-enforced one-way links fit into complex, regulated environments.
- Advenica in European defense and authorities. Advenica reports recurring orders for data diodes from European defense customers, reinforcing their position in national-security-grade deployments. Their technical papers explain how data diodes help authorities solve issues like preventing intrusions while still allowing outbound reporting and log export, framing them as high-assurance Cross Domain Solutions for sensitive networks.
Taken together, the picture is clear: AWS Diode owns the cloud CDS / DevSecOps niche, while Waterfall, Owl, and Advenica dominate physical, critical-infrastructure and defense networks.
Another Aspect to Consider
Choosing the right diode technology depends entirely on the boundary you are defending. AWS Diode is the right tool when the workflow is inherently cloud-based, when rapid promotion of artifacts is required, and when automated policy enforcement adds more value than physical segregation. It allows organizations to preserve security while leveraging modern development velocity, and it fits naturally into multi-region, multi-domain cloud architectures.
Hardware diodes, however, remain the gold standard for environments where the stakes are existential. A misrouted packet in a cloud workload might cause an outage, but a misrouted packet in an industrial control network might cause physical damage, financial disruption, or safety incidents. In such settings, reversible connections, even if logically blocked, are unacceptable. Physical one-way enforcement is therefore not merely a good practice; it is an operational necessity.
The strongest enterprises increasingly deploy both approaches simultaneously: hardware diodes at the OT boundary to prevent any inbound communication from external networks, and cloud-native diodes within their AWS estate to enforce clean data movement between classification tiers. This layered approach acknowledges that modern systems span both cloud and physical domains, and that no single type of diode can address all threat models or operational requirements.
In designing your own cross-domain architecture, begin with a clear assessment of what you are protecting, what failure modes are acceptable, and how much automation your workflows require. From there, the choice between AWS Diode and hardware diodes becomes straightforward - not a matter of which is better universally, but which is correct for your boundary, your risk model, and your mission.
Quick checklist: choosing between AWS Diode and hardware diodes
And finally, your today's takeaway: Use this as a quick triage tool:
- Are both security domains already in AWS or planned to be? → Bias toward AWS Diode.
- Are you moving CI/CD artifacts, images, or curated data sets between classification levels? → AWS Diode fits DevSecOps better.
- Are you protecting OT/ICS where any inbound connectivity is unacceptable? → Favor Waterfall / Owl / Advenica.
- Do regulations or internal policies require hardware-enforced one-way links or specific diode certifications? → Hardware diodes are mandatory.
- Is there resistance to adding cloud dependencies into your most sensitive environments? → Keep the diode at the physical boundary.
- Do you need elastic, on-demand scaling and deep AWS integration more than you need physical assurance? → AWS Diode is likely the more pragmatic choice.