Hybrid Cryptography: A Framework for Post-Quantum Agility and Resilience

Quantum computing threatens classical cryptography, which has prompted the creation of post-quantum cryptography (PQC) and quantum key distribution (QKD). Hybrid cryptography integrates classical, post-quantum, and quantum techniques for achieving multi-layer security and smooth migration towards quantum-safe infrastructures. In this paper, practical deployment patterns, the employment of cryptographic agility, and integration of PQC with QKD are presented with emphasis on hybrid methods as a key strategy for quantum-secure communication.