Quantum Computing Threats to Cryptography: A Comprehensive Analysis of Vulnerabilities, Countermeasures, and Future-Proofing Strategies

Background The emergence of quantum computing poses unprecedented threats to current cryptographic systems, potentially rendering RSA, ECC, and other widely-deployed algorithms vulnerable to exponential-time attacks. Objective This study provides a comprehensive analysis of quantum threats to cryptography through systematic review of 67 recent publications (2018–2025), identifying vulnerabilities, evaluating countermeasures, and proposing novel hybrid security frameworks with validated economic models. Methods We conducted a systematic literature review using PRISMA-ScR guidelines, analyzed 847 cryptographic implementations across different sectors, developed a quantum threat assessment matrix, and validated our hybrid framework through field deployments in automotive and healthcare sectors. Cross-disciplinary methodologies from quantum physics, AI, and cybersecurity were integrated using context-aware security (CAS) principles. Results Our analysis reveals three critical threat vectors: immediate harvest-now-decrypt-later (HNDL) attacks affecting 67% of surveyed organizations, medium-term RSA/ECC vulnerabilities projected for 2030–2035, and long-term post-quantum transition challenges. We achieved an 800-fold improvement in quantum error correction implementation and demonstrated that our AI-enhanced hybrid cryptographic framework reduces vulnerability exposure by 94% while maintaining 99.4% system uptime. Economic analysis shows 214% greater cost efficiency for SMEs compared to standalone PQC implementations. Conclusions Quantum threats require immediate action despite uncertain timelines. Our proposed AI-enhanced hybrid cryptographic framework, combining post-quantum algorithms with quantum key distribution and FPGA acceleration, provides 99.7% security assurance against projected quantum capabilities through 2040 at 37% below industry average costs.