A Privacy-preserving Ethereum Lightweight Client Using PIR

By outsourcing most of storage and computational tasks to full nodes, Ethereum lightweight client is able to run on the resource-limited devices such as mobile phones. In the interactions with the lightweight client, the full node obtains considerable information about Ethereum addresses (Ethereum accounts), transactions, and transaction receipts associated with the lightweight client. This behavior obviously violates user privacy. Currently, there is no solution supporting the lightweight client to efficiently retrieve the account state, related transactions, and transaction receipts from the untrust full node without revealing privacy. In this paper, we propose to use private information retrieval (PIR) to design a privacy-preserving Ethereum lightweight client. Since directly using existing PIR scheme significantly increases communication overhead of the lightweight client, we tailor existing PIR schemes to adapt to the lightweight client, which allows the lightweight client to efficiently retrieve account state and transaction data without leaking sensitive query information. Security and performance analysis show that our scheme is capable of efficiently and privately downloading the data of interest to the lightweight client.