Unidirectional (or Bidirectional) Optical Secure Link
Design and Security Analysis of a Unidirectional (or Bidirectional) Optica Secure Link Abstract This paper presents a design for a unidirectional (or bydirectional) secured optical link intended to transfer data from / to an external network to a high-security internal network (e.g., critical infrastructure) while maintaining strong isolation. Two complementary implementations are examined: a screen–camera free-space optical channel and a compact optocoupler/fiber-optic data diode. Both designs rely on in-house programmed FPGAs (or ASICs) to eliminate software attack surfaces and ensure hardware-level trust. We analyze potential attack vectors—including hardware Trojans, side‑channel emissions (electromagnetic, optical, acoustic), and receiver compromise—and propose practical mitigations grounded in physical security and hardware verification. A comparative evaluation shows that while the screen–camera approach is feasible under stringent installation constraints, the opt...