Integrating Quantum Key Distribution into Distribution Ring Main Unit for Secure Power System Communications

The evolution of smart grids necessitates the deployment of highly secure communication protocols, particularly for critical infrastructure such as Distribution Ring Network Cabinets (RMUs). In this work, we present an integrated cryptographic framework that combines Quantum Key Distribution (QKD) with an SM2-based SPEKE protocol to establish a resilient end-to-end secure communication channel. Initially, QKD is employed—using, for instance, the BB84 protocol—to generate a quantum key with information-theoretic security guar- antees. In parallel, an SM2-enhanced SPEKE protocol is used to perform mutual authentication through elliptic curve-based ephemeral key exchange and identity binding, thereby deriving an authentication key. These two independent keys are then combined with a randomly generated salt via a HMAC-based Key Derivation Function (HKDF) to derive a robust session key. The session key is subsequently utilized to secure data transmissions through symmetric encryption, effectively mitigating threats from eavesdropping, man-in-the-middle, replay, and side-channel attacks. Comprehensive theoretical analysis and preliminary evaluations suggest that our layered approach not only bridges quantum and classical cryptographic techniques but also meets the stringent security and performance requirements of modern power system communications. This work provides a promising pathway toward future-proofing secure communication in next-generation smart grids.