No longer a default: Zero trust and data security at the edge

Once operators, applications, and devices gain access to a system, should they always be trusted? In the architecture known as zero trust, trust is not the default and every access request must be verified and continuously reevaluated. This is especially important at the tactical edge, where deployed systems operate with limited connectivity and face sophisticated cyberthreats.

Imagine a moat surrounding a castle, protecting everything behind its walls. A drawbridge grants or denies access to the castle and its resources depending on the access requester’s trustworthiness. This traditional perimeter-based security is risky because it assumes everyone, once inside, will follow rules and operate with good intentions.

In enterprise cybersecurity, trusting users or privileged processes by default brings the same risks, as insider threats and compromised credentials can breach, expose, or bring down enterprise networks. But for systems at the edge — such as vehicles, aircraft, ships, telecommunications infrastructure, medical devices, and sensors — the challenge is even more complex. In edge systems, the “castle” is distributed across locations, and the people are replaced by privileged processes. Additionally, connectivity is not always ensured at the edge, but adversaries have increased opportunities to access devices physically.

To limit risk to edge systems, a zero-trust approach is critical. 

What is zero trust?

Zero trust is an architecture that assumes risk is present inside and outside a given perimeter boundary, so no device or user is trusted by default. Instead, every access request from operators, applications, services, and devices is verified and authorized before access is granted.

Zero trust’s basic principles are:

·         Microsegmentation, least privilege, platform integrity and continuous monitoring: These fundamentals apply to zero trust generally, not just data security — see our companion piece on the zero-trust security model for how each works across edge systems.

·         Data security: Consider a sensor that receives a firmware update with no connectivity back to a central authority — it can’t phone home to check whether the update is legitimate. Zero trust pushes that verification onto the data itself: a cryptographic signature the sensor can check locally, a chain of trust rooted in hardware, and a default posture that rejects anything it can’t verify rather than assuming good intent. The data has to prove itself, because in that moment, nothing else can.

·         Multifactor authentication: Verifying user and process identities and devices to prevent unauthorized access (e.g., passwords or security tokens for users and digital signatures or other cryptographic approaches for processes).

Benefits of zero trust at the edge

Applying zero-trust principles can reduce what’s known as the attack surface — every vulnerability or digital/physical access point susceptible to attack — and improve security posture. But for edge systems, it is also resilience. By ensuring systems operate as intended in high-threat environments, the operations and the people tasked with its success remain protected.

But applying zero trust takes time and coordination, especially given edge-related realities such as intermittent connectivity, long platform lifecycles, and constraints on size, weight, power, and cooling (SWaP-C).

A practical adoption of zero trust might include:

·         Assessment and planning: Identify critical functions, data flows, and trust boundaries across platforms, tactical networks, and edge compute nodes. Prioritize what must be protected and what must continue operating under attack.

·         Architecture and technology selection: Choose technologies that fit the operational environment — including disconnected, intermittent, and limited (DIL) communications and SWaP-C constraints — and integrate them into a zero-trust architecture aligned to program requirements and applicable standards.

·         Collaboration and sustainment: Coordinate across engineering, cybersecurity, integrators, and mission partners to implement, verify, and sustain zero-trust controls over the platform lifecycle through deployment, updates, and maintenance.

Learn more about zero trust and its role in the zero-trust security model and architecture, and software supply chain security — next in this series.

Zero trust is the architecture that makes cyber resilience possible — it is part of a modern security framework and aligns with government and commercial cybersecurity strategy alike. Mercury Systems is a technology company delivering signal solutions, software applications, networking, storage, and secure processing in support of aerospace, defense and commercial critical infrastructure missions. Mercury’s RelianceOne™ hardens operationally deployed systems and boosts their cyber resilience to protect data and operations.