Passwordless identity is now central to Zero Trust resilience

At a glance

What this is: RSA Security argues that passwordless identity is becoming the backbone of Zero Trust for critical services, especially where IT, OT, IoT, and mobile access must be continuously verified.

Why it matters: For IAM teams, this matters because the control problem spans human authentication, device trust, and operational continuity, not just login UX.

👉 Read RSA Security's analysis of passwordless identity in Zero Trust for critical services

Context

Critical infrastructure no longer behaves like a bounded corporate network. IT, OT, IoT devices, and mobile workforces now sit inside one access problem, which means identity becomes the primary control plane for Zero Trust rather than a supporting layer. In that model, passwordless authentication is not just an MFA alternative, it is the mechanism that reduces reliance on shared, reusable secrets.

RSA Security’s framing is straightforward: if every access request must be verified, the quality of identity assurance becomes the difference between resilience and routine compromise. For practitioners, the governance question is whether current IAM and PAM controls can support continuous verification across mixed operational environments without weakening uptime or compliance obligations.

Key questions

Q: How should security teams implement passwordless access in critical infrastructure?

A: Start with the access paths that are most exposed to phishing or credential reuse, then extend passwordless methods to privileged and operational accounts. Pair the rollout with strong recovery, device trust, and lifecycle controls so authentication changes do not create new availability risks. The goal is stronger assurance without weakening continuity.

Q: Why does Zero Trust depend so heavily on identity in OT and IT environments?

A: Zero Trust depends on identity because the perimeter is no longer reliable in distributed critical services. When IT, OT, mobile users, and devices all share the same operational fabric, every access request needs a trustworthy identity decision. Without that, network segmentation alone cannot provide meaningful control.

Q: What breaks when passwordless identity is deployed without lifecycle governance?

A: The authentication layer may be stronger, but the programme still fails if certificates or other credentials are not issued, rotated, revoked, and recovered properly. In practice, poor lifecycle governance turns cryptographic identity into another form of standing trust, which weakens the resilience gains passwordless is supposed to deliver.

Q: Who is accountable when identity controls fail under NIS2 pressure?

A: Accountability sits with the organisation that owns the service and the identity governance process, not with authentication technology alone. Under NIS2, teams need clear ownership for access policy, incident response, and recovery across business and operational environments. If those responsibilities are split, resilience becomes difficult to prove.

Technical breakdown

Passwordless identity as the Zero Trust entry control

Passwordless identity replaces knowledge-based credentials with cryptographic or device-bound proof, such as FIDO2 tokens, mobile biometrics, or certificate-based identity. In Zero Trust terms, that shifts the first trust decision away from secrets that can be phished or reused and toward stronger proof of possession or presence. The model still depends on policy, but the initial attacker path becomes harder because there is no password to steal and replay. That matters most in critical services where a single compromised login can reach both business systems and operational technology.

Practical implication: replace password-dependent entry paths first where they protect privileged or operational access.

Risk-adaptive authentication in mixed IT and OT environments

Risk-adaptive authentication evaluates signals such as role, device posture, location, and session context before granting access. In IT and OT environments, this matters because the same identity may need different access conditions depending on whether it is reaching a control system, a remote administration portal, or a supporting application. The technical challenge is consistency. If policy logic diverges across environments, Zero Trust becomes a patchwork of exceptions rather than a single verification model. Risk scoring only helps when it is tied to enforceable access decisions and not just logging.

Practical implication: align conditional access logic across IT and OT pathways so policy remains enforceable, not advisory.

Certificate-based identity and operational resilience

Certificate-based identity anchors access in PKI rather than user-chosen secrets, which can improve resistance to phishing and credential stuffing. In a Zero Trust architecture, certificates also support stronger machine and user authentication where uptime matters because they can be integrated with device trust and lifecycle controls. The failure mode is not the certificate itself, but poor issuance, rotation, or revocation discipline. Without those controls, cryptographic identity still becomes another standing credential problem, just with a different format.

Practical implication: treat certificate lifecycle management as part of access governance, not as a separate infrastructure task.

NHI Mgmt Group analysis

Passwordless identity is becoming the access control layer Zero Trust actually depends on. RSA Security’s framing shows why password-based assurance no longer matches the threat model in critical services. If phishing, replay, and credential reuse remain viable, every downstream Zero Trust control inherits that weakness. Practitioners should treat passwordless as an identity assurance requirement, not a convenience feature.

Continuous verification breaks when identity policy is split across IT and OT boundaries. Zero Trust only works when the same access logic can evaluate context consistently across operational and enterprise environments. In critical infrastructure, those environments often use different tooling, different change windows, and different ownership models, which creates governance drift. The implication is that identity policy must be designed for cross-domain enforcement, not just shared terminology.

Certificate-based identity shifts the risk from password theft to lifecycle discipline. Cryptographic identity is stronger only if issuance, rotation, revocation, and recovery are governed as tightly as authentication itself. That changes the control emphasis from user memorisation to identity lifecycle management and privileged access oversight. Practitioners should see this as a lifecycle governance problem, not a pure authentication upgrade.

Zero Trust for critical infrastructure is really an operational continuity question. The value of stronger identity controls is measured not only in reduced compromise probability but in whether essential services can keep running under pressure. That makes identity architecture part of resilience planning, compliance design, and incident containment at the same time. Security teams should align identity controls with continuity objectives, not treat them as separate programmes.

From our research:

• 1.5 out of 10 organisations are highly confident in their ability to secure NHIs, compared to nearly 1 in 4 for securing human identities, according to The State of Non-Human Identity Security.
• Only 85% of organisations lack full visibility into third-party vendors connected via OAuth apps, with 38% reporting no or low visibility and 47% only partial visibility.
• That visibility gap makes Ultimate Guide to NHIs the natural next step for teams mapping identity governance across human, machine, and workload access.

What this signals

Passwordless is becoming less about user experience and more about proving that access can be trusted under pressure. In critical infrastructure, the programme that cannot enforce consistent identity decisions across domains will end up with policy exceptions that quietly defeat Zero Trust.

Credential-bound continuity: The real test is whether cryptographic identity can survive rotation, revocation, and recovery without interrupting essential operations. Teams should watch for places where certificate or device trust is treated as infrastructure plumbing instead of governance.

Identity programmes that stop at authentication will miss the larger shift. The more resilient model is one where access assurance, lifecycle control, and operational continuity are designed together, using Zero Trust as the governance frame rather than a network slogan.

For practitioners

• Prioritise passwordless for high-risk access paths Move privileged, remote, and externally exposed logins away from reusable passwords first. Focus on the access paths that would most disrupt operations if phished or replayed.
• Unify conditional access policy across IT and OT Map where different teams apply different authentication rules and remove exceptions that weaken continuous verification. Zero Trust fails when policy differs by domain more than by risk.
• Govern certificate lifecycle as an access control discipline Track issuance, rotation, revocation, and recovery for certificate-based identities with the same oversight used for privileged accounts. Certificates without lifecycle control become standing trust.

Key takeaways

• Passwordless identity strengthens Zero Trust only when it is tied to enforceable policy across IT and OT access paths.
• Certificate-based trust improves security, but lifecycle governance determines whether it actually reduces operational risk.
• Critical infrastructure teams should measure identity controls by continuity under pressure, not by authentication change alone.

Key terms

• Passwordless identity: An authentication approach that removes reusable passwords and replaces them with stronger proof such as hardware keys, biometrics, or device-bound cryptographic credentials. In identity programmes, the main value is reducing phishing and replay risk while tightening the link between the user, device, and access request.
• Risk-adaptive authentication: A policy model that changes access decisions based on context such as device posture, location, role, or session behaviour. It is more than step-up authentication because it evaluates the access request at runtime, which makes it useful in environments where the same identity can pose different levels of risk.
• Certificate-based identity: An identity method that uses PKI certificates to prove trust instead of shared secrets or memorised passwords. It is commonly used for machines and can also support human access, but its security depends on tight issuance, rotation, revocation, and recovery governance across the full lifecycle.
• Zero Trust Architecture: An operating model that assumes no implicit trust for users, devices, or workloads, even inside the network. Access must be continuously verified, least privilege enforced, and trust conditions re-evaluated as context changes across the session or transaction.

Deepen your knowledge

NHI governance, agentic AI identity, and machine identity lifecycle are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or NHI governance in your organisation, it is worth exploring.

This post draws on content published by RSA Security: Zero Trust NIS2, Identity, IT, and OT: Stay Operational, Stay Resilient. Read the original.