Secure IoT Data Management in a Private Ethereum Blockchain

IoT has proven valuable in many industries such as Supply Chain, Shipping and Transportation providing updates on the status of shipments in real time. This has resulted in a large amount of data created by IoT devices that require real time processing. Blockchain has also emerged as a trusted common data storage among multiple participants in IoT systems. However, it is essential to verify the authenticity of data before they go in to the blockchain. Some IoT data must be also encrypted in a secure manner. In this paper, we propose a method to collect sensor data from IoT devices and use blockchain to store and retrieve the collected data in a secure and decentralized fashion. A testbed private blockchain system with Ethereum and Raspberry Pi has been developed to test the feasibility and performance of blockchain-based secure IoT system. We employ private PKI for key management and TPM for storing keys, signing, verifying and encrypting data in a trusted way. We describe the structure of the testbed, decentralized storage system based on Ethereum Swarm and IPFS, TPM configuration processes, smart contract codes, and detailed operation sequences. Performance has been measured with 5000 test transactions in 8 different configurations. The result shows that Ethereum blockchain with Swarm can offer about 9 transactions per second. Encryption and decryption is shown to reduce the performance slightly to about 8 transactions per second. The proposed system can provide a secure IoT Blockchain platform for small industrial applications at low cost.