SSenStone OTAC Trusted Access Gateway

SSenStone Inc. is a security company founded in November 2015 and headquartered in Seoul, South Korea, with a UK office for its swIDch authentication line. It develops OTAC, a one-time authentication code technology, and applies it to operational technology (OT) environments where PLCs, HMIs and SCADA equipment often rely on shared or static passwords.

OTAC Trusted Access Gateway (TAG) places an inline gateway in front of OT endpoints such as PLCs, HMIs, RTUs and DCSs. A client agent on the engineer's workstation prompts for a one-time code generated on a smartphone app or smartcard, the gateway verifies it in real time, and an OTAC server and admin portal manage policies and audit logs. No PLC firmware change or vendor support is needed.

• Client Agent: pops up a login prompt on the engineering workstation when an engineering application starts.
• OTAC Authenticator: one-time codes generated on a smartphone app or smartcard, valid offline.
• Inline OTAC Gateway: verifies codes and allows or blocks access to the endpoint in real time.
• Admin Portal: central management of users, authentication media and whitelist or blacklist policies.
• Audit logging: per-user records of which equipment was accessed.
• Flexible topology: 1:1 and 1:N gateway models with redundant configurations.

A factory in Vietnam could place TAG in front of PLCs on a production line so that only authenticated engineers can change programs. Power or water utilities could protect SCADA and HMI stations with auditable access for contractors.

Lower deployment cost because no PLC replacement or manufacturer firmware work is required. Protects critical OT assets from unauthorised operation. Provides per-user audit trails showing who accessed which equipment. Supports a zero-trust approach in air-gapped and isolated industrial networks.

Regulations such as IEC 62443, NIS2 and the EU Cyber Resilience Act push manufacturers and utilities to control human access to industrial controllers. In Vietnam and Southeast Asia, factories with mixed legacy PLCs and growing remote maintenance need access control that does not require replacing equipment.

Founded November 2015, Seoul. Strategic investment from Hyundai Motor Group (2026-06). OTAC TAG launched 2025-02. ISO 9001 (2026-01); KC and CE for TAG (2026-07). Common Criteria certification for OTAC Token v1.0. MoU with MXON (2026-02).