Hybrid Point-of-Sale (POS) Architecture Over Hyperledger Besu QBFT Featuring Fiat-Crypto Transaction Segregation and ERC-4337 Account Abstraction

Integrating cryptocurrency payment options into retail Point-of-Sale (POS) cashier systems remains fundamentally hindered by three major technical bottlenecks: high public network block confirmation latency, dynamic exchange rate volatility, and steep consumer user experience friction involving seed phrase management. To systematically address these hurdles, this research designs, implements, and evaluates POS.FUSION—a novel hybrid enterprise Point-of-Sale architecture that decouples local off-chain Fiat cashier accounting from instant on-chain cryptocurrency settlement using an enterprise Hyperledger Besu Ethereum Virtual Machine (EVM) network. The proposed system incorporates a dual-storage architecture combining Write-Ahead Logging (WAL) relational database execution for high-throughput local Fiat transactions (> 5,000 TPS, latency < 10 ms) with a 4-validator Quorum Byzantine Fault Tolerance (QBFT) consensus network for on-chain settlement, guaranteeing deterministic 1-block finality (< 1 s) without public network gas overhead. To eliminate user experience barriers for non-technical consumers, POS.FUSION implements ERC-4337 Account Abstraction integrated with the hardware-accelerated P256VERIFY EVM precompile (address 0x0100). This enables gasless, seedless WebAuthn/Passkey biometric signature authorization directly from consumer mobile devices. Empirical benchmarks demonstrate that the P256VERIFY precompile reduces signature verification gas consumption from 348,120 gas (standard Solidity ECDSA) to a constant 3,450 gas, achieving a 99.01% execution cost reduction. Furthermore, longitudinal cashier UI evaluations demonstrate seamless multi-asset processing across IDR 1,091,130 Fiat and IDR 1,399,690 Crypto transactions, providing real-time financial auditing transparency, inventory synchronization, and robust resilience against double-spending attacks in high-velocity retail counter environments.