27) Crypto-Agile Post-Quantum Security Architecture for U.S. Critical Infrastructure Optical and IP/MPLS Networks

Abstract

AbstractObjective. Public-key cryptography protects key establishment, authentication, software integrity and trust relationships across the optical transport and IP/MPLS networks that carry U.S. critical-infrastructure communications. A sufficiently capable quantum computer would break the widely deployed algorithms on which these protections rest. This study investigates how such networks can migrate to post-quantum cryptography (PQC) without disrupting operational communications, and how they can be made crypto-agile so that future algorithm changes are routine instead of exceptional.Method. The study follows a Design Science Research (DSR) approach and proposes the Crypto-Agile Post-Quantum Transition Architecture (CAPTA), a nine-layer architecture combining cryptographic inventory, quantum-risk prioritization, a crypto-agility abstraction, PKI and identity migration, optical-layer and IP/MPLS security, management and supply-chain security, staged migration orchestration, and governance. A mathematical model expresses confidentiality and trust exposure over time, handshake size and latency effects of PQC algorithms, hybrid-scheme security, the value of crypto-agility, and a multi-objective migration-scheduling problem with precedence, resource, performance, interoperability and rollback constraints. The evaluation is analytical and scenario-based; no measurements, lab results or numerical performance results are reported.Results. Six analytical propositions are derived: an exposure integral and its marginal cost of delay; an ordering rule for a single migration team and the complexity of the precedence-constrained case; a bound on the extra round trips caused by larger handshakes under TCP slow start; the probability that fragmented UDP-based key exchange completes without retransmission; a condition under which hybrid key establishment is preferable to PQ-only operation; and a break-even condition for investing in crypto-agility. Ten scenarios, six testable hypotheses, four baselines, an ablation plan and a reproducible simulation and laboratory protocol are specified.Significance. The work offers a design pattern, an analytical basis and an evaluation protocol for quantum-safe transition of critical communications infrastructure, and it treats transition as an engineering-risk problem in which operational continuity is a first-class constraint.