Relaying quantum keys across wide-area networks spanning thousands of kilometers without exposing cleartext key material inside intermediate node memories.
When transmitting a key between Node A and Node C via intermediate Node B, Node B receives K_AB and K_BC. Node B computes C = K_target XOR K_AB and sends C to Node C using K_BC as OTP. The target key is never stored in plaintext within non-secure registers, eliminating physical node compromise vulnerabilities.
Each trusted node houses optical transceivers and key processors within an active physical security barrier monitored by micro-wire meshes, pressure sensors, and light detectors. Any drilling or cabinet penetration triggers zeroization of internal cryptographic RAM within 20 nanoseconds.