The Quantum Security Stack

The Quantum Security Stack: Roles, Limits, and Use Cases of PQC, QKD, and QRNG provides a practical and technically grounded exploration of the technologies shaping cybersecurity for the quantum era. The book examines Post-Quantum Cryptography (PQC), Quantum Key Distribution (QKD), and Quantum Random Number Generation (QRNG) from the perspective of real-world security requirements, explaining how they work, what threats they address, where they can be deployed, and where their limitations lie. Rather than presenting quantum security as a single universal solution, it distinguishes the roles of each technology and examines their relationship with conventional cryptography, secure communications, critical infrastructure, cloud environments, and emerging digital systems. Designed for cybersecurity professionals, researchers, students, technology leaders, and security architects, the book provides a clear foundation for making informed decisions about what to use, when to use it, and why as organizations move toward quantum-resilient security.