OT Remote Access Authentication (OTRAA) for Ships
The OT Authentication Gap
OT Remote Access Authentication (OTRAA) addresses a specific and challenging problem: how to implement strong authentication for access to industrial control systems that were never designed with modern authentication protocols in mind. Standard IT authentication solutions — LDAP, Active Directory, SAML 2.0, OIDC — are often incompatible with shipboard OT systems that run proprietary operating environments, are air-gapped from directory services, or have fixed authentication mechanisms baked into firmware that cannot be changed without OEM involvement.
This gap means that even when a vessel has MFA enforced at the network boundary (jump server, VPN gateway), the final authentication step — logging into the OT workstation or HMI itself — often reverts to a simple username/password or even a shared local account. OTRAA addresses authentication at the OT system level, implementing strong credential controls within the constraints of the OT environment.
The three primary OTRAA approaches — hardware security keys, certificate-based authentication, and OT-native identity federation — each have different applicability depending on the OT system's capabilities, age, and vendor support. Selecting the appropriate approach requires an OT-specific assessment that maps authentication capability against system architecture, not a generic IT security recommendation.
| Approach | How It Works | OT Compatibility | Offline Support |
|---|---|---|---|
| FIDO2 Hardware Key | USB/NFC key plugged into OT workstation at login | Windows OT workstations (W10+) | ✓ Full |
| Smart Card / PIV | Certificate on smart card + PIN for Windows login | Windows OT workstations with card reader | ✓ Full |
| Certificate-Based Auth | Client certificate deployed to OT workstation | Windows, Linux, some embedded OS | ✓ Full |
| OT-Native Federation | PAM proxies authentication; OT system uses its own credential | All OT systems (network-level control) | ~ Partial |
| Biometric Integration | Fingerprint / iris reader at OT workstation | Windows Hello-compatible systems only | ✓ Full |
Regulatory Framework
Requires role-based access control for all computer-based systems. OTRAA implements this at the OT system level — each user authenticates to OT systems with individual credentials rather than shared accounts. Individual authentication is impossible without OTRAA in OT environments that historically used single shared admin accounts for all users.
Requires logging of user access events on computer-based systems. Shared OT accounts make audit logging meaningless — if ten engineers all use the same "admin" account, the log cannot attribute actions to individuals. OTRAA's individual authentication enables meaningful audit logging that satisfies E26's forensic investigation requirements.
IEC 62443 Security Level 2 (SL2) — the target level for most maritime OT zones — requires that all users of industrial control systems be uniquely identified and authenticated. SL2 also requires that authentication mechanisms be resistant to replay attacks — met by hardware tokens and certificates but not by static passwords used for OT system login.
NIST SP 800-82 (Guide to ICS Security), referenced in multiple maritime cybersecurity frameworks, recommends multi-factor authentication for all privileged access to industrial control systems and network-level authentication enforcement where native ICS MFA is not supported — aligning directly with OTRAA objectives and the PAM proxy approach for legacy OT systems.
Architecture & Implementation Patterns
OTRAA implementation follows different patterns depending on OT system capability. Modern OT workstations running supported Windows versions can implement FIDO2 or certificate-based authentication natively. For legacy systems or PLCs with no standard authentication protocol support, network-level authentication enforcement via PAM proxy is the primary option — the OT device retains its local credential, but network access to that device is controlled by the PAM gateway with strong authentication.
Windows 10+ OT HMI and SCADA workstations: Deploy FIDO2 hardware keys (USB-A YubiKey or equivalent). Configure Windows Hello for Business or credential provider for hardware key authentication. Local PKI issues individual certificates stored on keys. No connectivity to cloud identity provider required.
Legacy PLCs, embedded controllers, older Windows XP/7 HMIs: Implement network-level authentication via PAM proxy. Users authenticate to the PAM gateway (with MFA), then the gateway accesses the OT device using its stored local credential — vendor-managed, rotated automatically. The OT device is never directly accessible from outside the PAM boundary.
Mixed environment with modern and legacy OT systems: Deploy hardware keys for modern systems (native integration), PAM network proxy for legacy systems (network-level control), and smart cards for OT workstations with card reader support. Unified identity platform manages all credential types from a single administration interface.
Maritime Implementation Constraints
Many OT systems have authentication mechanisms hard-coded in firmware that cannot be changed without OEM authorisation or firmware update. An AMS console from 2015 may only support username/password authentication with no plugin or extension mechanism. For these systems, network-level PAM proxy is the only available OTRAA option — you cannot change how the OT system authenticates without the vendor.
Certificate-based authentication requires a Public Key Infrastructure (PKI) — a certificate authority (CA), certificate issuance process, and certificate revocation mechanism. On ships, the CA must be reachable when certificates are issued (during onboarding) but certificate validation must work offline. Managing certificate expiry and revocation for crew changes at sea adds operational complexity that must be accounted for in the deployment design.
USB hardware keys inserted into OT workstations in the engine room face vibration, heat, and physical abuse. Keys left permanently plugged in may work loose or be damaged. Key loss in the engine room environment is also more likely than in an office setting. Physical security measures (secure storage, lanyard attachment, spare inventory) must be built into the deployment plan.
In a safety emergency, OT system access must be immediate — a chief engineer cannot wait for authentication if a propulsion emergency occurs. All OTRAA implementations must include an emergency access procedure (break-glass local credential, emergency biometric bypass, or other mechanism) that provides immediate access to OT systems while logging the emergency access event for post-incident review.
Trends & Market Developments
Industry bodies including IMCA and ICS are developing frameworks for seafarer digital identity — a portable credential tied to a seafarer's professional record, usable across multiple vessels. This would eliminate per-vessel credential enrolment at crew changes, as the seafarer's identity and access rights travel with them on their digital certificate.
Newer maritime OT systems from vendors including ABB, Kongsberg, and Wärtsilä are being delivered with embedded Hardware Security Modules (HSMs) that support certificate-based device identity and secure key storage. This enables OT-native strong authentication without retrofitting external hardware keys — a significant improvement for new-build vessels.
Behavioural biometrics — keystroke dynamics, mouse movement patterns, interaction style — are being piloted as a continuous authentication factor for OT workstation sessions. Unlike physical biometrics (affected by environment), behavioural biometrics operate invisibly in the background, providing ongoing authentication confirmation without workflow interruption.
Certificate management automation is reducing the operational burden of certificate-based OTRAA at sea. Automated certificate renewal, crew change credential packages generated shore-side and transferred to vessels pre-arrival, and SCEP (Simple Certificate Enrolment Protocol) integration with OT device management are all emerging as practical solutions to PKI management at sea.
OTRAA fills the authentication gap that network-level controls (PAM, Jump Server) leave open. MFA at the gateway is not sufficient if users share a single OT admin account once inside. Individual, authenticated access at the OT system level is required by IACS UR E26 Clause 4.2 and Clause 5.4.
Assess OT system capability before selecting an approach. FIDO2 hardware keys are ideal for modern OT workstations — but cannot be used with legacy PLCs or embedded HMIs. Deploying a uniform solution across a heterogeneous OT estate will result in gaps. Approach selection must be system-specific.
Emergency access must work without strong authentication factors. Define and test the break-glass procedure before deploying strong authentication. An OT engineer who cannot access a propulsion control system in an emergency because their hardware key is missing is a safety problem, not a security success.
Continue the Ship Solutions series with Security Monitoring — SIEM Integration and Maritime Threat Intelligence deep-dives.
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