Quantum-Resilient, Software-Defined Security Framework for Offline Disaster Messaging: Dynamic Crypto-Agility and Policy-Oriented Trust

The increasing large-scale disasters are the major concern in today's current scenario. The use of traditional techniques like centralized communication and quantum computing, on the other hand, are threats to classical cryptography in terms of digital security. This paper will show us how we can deal with the challenges by proposing a novel paradigm. In this paper we have used the Context-Aware Crypto-Agility, realized through a Software-Defined Security (SDS) framework for decentralized networks, which will be helpful in offline communication. We presented a novel architecture in which, beginning at the application layer, the data transmission and the cryptographic policy can function independently. This will in turn help the mobile devices to dynamically select, and it will switch between the classical and post-quantum cryptography based on several real-time factors such as the device battery, message criticality, and the peer trust levels. This framework is represented in “Quantum Messenger,” a fully functional working application built with Flutter. We validate the possibility of attaining quantum resilience and feasibility in zero-infrastructure settings through its execution; this project will serve as a model for the next generation of safe and effective emergency communication systems.