DEF-CRYPT-Q: a quantum-enhanced hybrid encryption framework for privacy-preserving distributed defense communications.

The rapid transformation of defense communication ecosystems into distributed, AI-enabled, and multi-domain operational environments has exposed significant vulnerabilities in existing cryptographic infrastructures. These vulnerabilities are particularly critical in light of the imminent advancement of quantum computing, which threatens conventional public-key encryption schemes, and the operational limitations imposed by lightweight encryption mechanisms deployed on resource-constrained battlefield devices. The traditional public-key algorithm like RSA and ECC, could be exploited by quantum attacks, and the resource-efficient ciphers are not always effective to protect against advanced cyber-warfare, interception, and integrity-compromise in high-mobility tactical networks. This paper suggests DEF-CRYPT-Q (Defense Cryptographic Quantum-Enhanced Privacy-Preserving Hybrid Framework) to secure distributed defense communication data because it is motivated by the requirement of having a single, quantum-resilient, and privacy-preserving security architecture that is suitable in the context of heterogeneous defense settings. The suggested architecture will have four synergistic elements, namely (i) a Context-Aware Lightweight Defense Encryption (CALDE) module that is optimized to support constrained soldier wearables, UAV nodes, and edge sensors; (ii) a Quantum-Resistant Cryptographic Layer (QRCL) that uses lattice-based post-quantum primitives, such as CRYSTALS-Kyber to support the encapsulation of secure keys and CRYSTALS-Dilithium to support the generation of digital signatures, providing long-term quantum safety The experimental assessment of a heterogeneous model of a defense communication demonstrates the shortening of the encryption latency, the limited computational costs of the models of constrained platforms, the high level of integrity, and the resistance to classical and quantum adversarial models, which in turn makes it possible to claim that DEF-CRYPT-Q is a scalable and prospective cryptographic paradigm that is consistent with the strategic goals of modernizing its defense. Simulation results demonstrate that Adaptive DDP-QKA reduces encryption latency to 14.83 ms (vs. 18.21 ms classical and 21.48 ms naïve PQC) and bandwidth overhead to 13.9% (vs. 124.6% PQC), while maintaining moderate energy use (1.14 units). It achieves high quantum resistance (0.92 score), mission adaptability (0.95), and low residual risk (< 0.1 for major threats), verifying appropriateness for latency-sensitive defense communications.