AgriChain: Blockchain Syntactic and Semantic Validation for Reducing Information Asymmetry In Agri-Food

Information asymmetry affects the actors of all the segments of the agri-food supply chain and can arise many problems in the market along the production chain. Transactions of agri-food products are asymmetric because suppliers and buyers have different levels of knowledge on the provenance, value, quality, and freshness of food. Collusive relations among the agri-food chain actors, especially between controllers companies and controlled ones, can cause market failures as they influence customers’ purchase decisions and severe health accidents when food safety is compromised. This paper proposes using blockchain technology to combat information asymmetry and collusive relations. In addition to transparency, cryptography and trusts, which are natively provided by the blockchain, our approach provides a twofold mechanism for validating crowd sensed data: first, a lightweight syntax validation is run before writing data in the blockchain (providing accountability also thanks to immutability); then, a dedicated smart contract runs semantic validation in scenarios with multiple data sources. This semantic validation may reveal collusive behaviours, downgrade colluding nodes and exclude or down-weight their data in future validations. The smart contract seals data that pass both validations adding metadata on data quality. Results prove the feasibility of our solution on Hyperledger Fabric under the assumption that the majority of nodes are honest. Experimental results demonstrate that our implementation of the twofold validation using smart contracts scales well with the dimension of the blockchain state. Our mechanism may greatly impact Product Certification and Designation of Origin as it may be applied to check specific requirements for raw materials, products, and production processes and protect from the collusion of controlling consortia and certification bodies