Using Quantum Key Distribution to Synchronize Shared State for Secure Messaging

Abstract

Abstract Quantum Key Distribution (QKD) and classical key exchange protocols are conventionally deployed to derive symmetric key material for classical ciphers. In this work, we present an alternative architectural framework in which QKD initializes and synchronizes an endpoint state rather than encrypting payloads directly. By evolving this endpoint state across time, classical payloads can be replaced by non-semantic triggers on the transport wire, where reconstruction occurs entirely locally. We formalize the information-theoretic properties of this state-driven relational messaging framework, detail the complete Alice–Bob protocol exchange, and evaluate its defensive posture against conventional ciphertext transport. We demonstrate that because QKD synchronizes state updates rather than encrypting raw message volume, the required quantum key rate decouples state security from classical payload throughput. Finally, we include three theoretical appendices: Appendix A formalizes Interpretation Secure Key Distribution (ISKD) as a classical state fallback that maintains structural tamper detection; Appendix B provides a formal comparison distinguishing QKD and ISKD from classical public-key exchanges such as Diffie-Hellman; and Appendix C formalizes the theoretical timing dynamics, state transition modes, and the distinction between deterministic ratchets and QKD entropy-injected ratchets.