SmartSupply: Smart contract based validation for supply chain blockchain

Blockchain based supply chain systems benefit from immutability and auditability properties. We develop and implement a blockchain based supply chain system in Ethereum platform. We find and address several challenges both in system design and performance issues. We focus on system design for transaction validation, information retrieval efficiency and fault-tolerant query mechanism. We describe our implementation details to bypass some of the limitations in Ethereum and smart contracts. We design a smart contract to efficiently organize miners' local data structure for transaction validation and information retrieval. We design Ethereum smart contract that allows transaction validation based on a priori knowledge of product life cycle. Our system achieves constant time latency per query independent of the blockchain length. We also consider supply chain systems with malicious miners that respond with false data upon query. We develop a sampling query and majority voting method accordingly. We evaluate our system's performance in emulated setting and show that even with 30% malicious miners, we still achieve reasonable accuracy in only 0.0723 seconds response time on average.