A PQC-Based Cyber Resilient and Energy Efficient Framework for Secure Blockchain-Enabled Decentralized Transactions in the BFSI Sector

Elliptic curve cryptography (ECC) serves as the security foundation for decentralized ledger systems that enables transaction authorization and user account control through compact signatures. However, this architectural reliance poses an existential threat due to Shor’s algorithm, which allows a cryptographically relevant quantum computer (CRQC) to reconstruct private keys from publicly recorded transactions. Simply replacing ECDSA with post-quantum signature schemes introduces severe system bottlenecks, as schemes like ML-DSA require signature payloads up to 70 times larger than ECDSA. This leads to transaction bloats, increased propagation delays, high archival storage costs, and heavy CPU/energy consumption on resource-constrained mobile nodes. This paper presents the Quantum Resistant Digital Wallet (QRDW), a full-stack post-quantum blockchain wallet, and ledger architecture. QRDW features the Deterministic Adaptive Post-Quantum Policy Engine (DAPPE), which dynamically selects signing profiles (ML-DSA-44, ML-DSA-65, or ML-DSA-87) based on real-time transaction amounts and a consensus-derived sliding window. DAPPE utilizes a consensus-verified sliding window threshold derived from the ledger’s public state, ensuring that validators independently recompute the required profile deterministically. This research contributes a demonstrable end-to-end PQC wallet architecture that mitigates the storage and network overhead of post quantum migration through adaptive, consensus-safe cryptographic routing.