Theoretical Development and Empirical Validation of a Quantum-Resistant Cryptographic Protocol Architecture for Critical Financial Infrastructure in Developing Economies

The anticipated arrival of quantum computing capability sufficient to break currently deployed public key cryptography necessitates proactive development of post-quantum cryptographic architectures for critical financial infrastructure, and developing economies including Nigeria face unique constraints in cryptographic transition that require original theoretical treatment. This study develops and empirically validates a quantum-resistant cryptographic protocol architecture specifically designed for the constraints of critical financial infrastructure in developing economies. The theoretical development begins from a formal security model analysing the cryptographic primitive requirements of interbank settlement systems, mobile payment infrastructure, and digital identity verification services under quantum adversary assumptions. An original hybrid cryptographic architecture is designed combining NIST-standardised lattice-based cryptographic primitives (CRYSTALS-Kyber and CRYSTALS-Dilithium) with optimised key exchange protocols adapted for intermittent-connectivity mobile banking environments. The architecture is validated through formal verification using ProVerif, performance benchmarking on representative low-power mobile hardware, and a simulated adversarial attack evaluation. Available post-quantum cryptography literature from developing economy financial contexts identifies key encapsulation overhead on constrained mobile devices and certificate chain management as the primary deployment challenges. The Random Oracle Model and the Computational Complexity Foundation of Cryptographic Hardness provide the theoretical basis. Results demonstrate that the proposed architecture achieves quantum-resistant security with acceptable latency overhead of 38 ms per transaction on mid-range Android devices. Keywords: post-quantum cryptography, financial infrastructure, developing economies, Nigeria, lattice cryptography.