PPCA: privacy-preserving conditional actions for IoT environments using smart contracts

Automated tasks play an important role in both consumer and industrial IoT environments. In many scenarios, the IoT tasks are performed given certain conditions. To facilitate the tasks, it is necessary to delegate a third party to listen to events that trigger the conditions and issue commands to the IoT resources accordingly. However, without restriction, the third party may be over-privileged and able to control the resources unconditionally. We define the third party's permission to act under some conditions as a conditional action. We propose PPCA, a privacy-preserving service that allows users to create conditional actions in a decentralized platform using smart contracts. PPCA can guarantee strict privilege at the third party that holds conditional actions. By generalizing a variety of conditions into simple forms of conditional logic, the conditions can be verified in a privacy-preserving manner. We build a prototype of PPCA on Ethereum. The performance shows the feasibility of PPCA in IoT environments.