SmartBidPro: A Hybrid Multi-Layered Blockchain Framework for Tamper-Proof Digital Tendering

Contemporary e-tendering infrastructure predominantly relies upon centralized database architectures that expose procurement ecosystems to insider threats, unauthorized bid manipulation, and systemic trust deficits. This paper presents SmartBidPro, a hybrid multi-layered blockchain framework that resolves the fundamental Privacy-Transparency Paradox inherent in monolithic distributed ledger deployments by partitioning procurement data across two cryptographically distinct ledger substrates. Sensitive bid submissions are sequestered within a permissioned Hyperledger Fabric network employing Practical Byzantine Fault Tolerance (PBFT) consensus, ensuring sub-second finality and confidentiality against horizontal competitors. Simultaneously, integrity anchors—comprising SHA-256 commitment hashes, tender deadlines, collateral deposit locks, and definitive award declarations—are persisted on the public Ethereum blockchain via a Solidity-encoded TenderNotary smart contract operating under Proof-of-Stake (PoS) consensus. Mediating between these heterogeneous ledger layers is a decentralized oracle network of Actix Web middleware nodes implemented in Rust, chosen for its deterministic execution and high-concurrency asynchronous I/O, which collectively preclude event-loop blocking during peak bidding traffic. The system frontend provides a role-differentiated dashboard. Empirical evaluation in a distributed multi-region cloud environment demonstrates that the hybrid bridge architecture achieves a mean bid-submission latency of 412 ms on the Fabric channel under enterprise load. Security analysis confirms robust resilience against Sybil attacks, Replay attacks, front-running exploits, and Single Point of Failure (SPOF) vulnerabilities via threshold multi-signatures. SmartBidPro therefore represents a paradigmatic transition from centralized procurement models toward verifiable governance infrastructures.