Algorithm 4. Node trust verification rules for smart contract

Require: Node Identification ($node.id$), System Identification ($sys.id$), Gateway Identification ($gt.id$) 1:Parameters: block_chain: Blockchain System: Object Gateway: Object Fog: Object 2:if (fog_system_mapping(sys.id) = fog_address) then 3: if (Node_exist(node.id) = true) then 4:  if (gateway_exist(gt.id) = true) then 5:   if (concerned_gateway(gt.id) = sys.id) then 6:    return node_trust(node.id) 7:   else 8:    return error() 9:   end if 10:  else 11:   return error() 12:  end if 13: else 14:  return error() 15: end if 16:else 17: return error() 18:end if