Transaction Cost Analysis for a High Security Role-Based Access Control Vending Machine Using Blockchain

this paper will present a blockchain-based, high-security, role-based access control (RBAC) vending machine system. The vending machine shall implement stringent role-based permissions wherein only users with the designated `MANAGER_ROLE` can add, update, or restock items. Only the contract owner, led exclusively to his address, has this role and thus is authorized to assure controlled management. Items will be mapped with unique IDs for scalability and organization. Every item shall have its corresponding assigned `purchase limit`, thus limiting the number of units an individual user may buy to prevent customers' exploitation. The smart contract enforces these limits by halting in excess Ether sent accompanying a transaction. It will, however allow the users to buy items by only sending Ether to the contract, so that all purchases will observe set limits. The combination of blockchain and RBAC would provide much-needed security and transparency to vending machine operations, making this solution very robust for decentralized commerce. It will, however, let users easily purchase items just by sending Ether to the contract, ensuring that all purchases observe set limits. This combination of blockchain and RBAC would provide much-required security and transparency to vending machine operations, making this solution very robust for decentralized commerce