zk-STARKs in Action: Real-Time and Post-Quantum Verification for Banking Transactions

Abstract

Zero-knowledge proofs have become an essential component for providing privacy and verifiability in decentralized systems. Existing techniques, such as zk-SNARKs, have intrinsic constraints, including the necessity for a trusted setup and sensitivity to quantum attacks, which make them unsuitable for high-assurance applications such as digital banking. In this paper, we provide a viable zk-STARK-based verification system that eliminates the trusted setup while maintaining long-term post-quantum security. Our system integrates off-chain proof generation using Cairo 0, on-chain verification through Cairo 2 smart contracts on Starknet, and decentralized proof storage via IPFS and Filecoin. Experimental results show that the time users wait from transaction submission to confirmation is approximately 1.15 seconds on average, with Cairo 2 contract verification completing in 0.73 seconds and consuming a gas cost of 0.0158 STRK (equivalent to approximately 0.00229 USD) per first-time execution. End-to-end latency for proof publication to IPFS and Filecoin is evaluated separately, reaching up to 63 minutes and 41 hours, respectively. However, these steps run asynchronously without impacting user responsiveness. Compared to zk-SNARK and Bulletproof-based systems, our hashbased, transparent architecture is more scalable, auditable, and quantum-resistant. These findings show that it is possible to install real-world, privacy-preserving, post-quantum verification pipelines for next-generation financial systems.