A Study of the Applicability of Ideal Lattice-Based Fully Homomorphic Encryption Scheme to Ethereum Blockchain

Without the requirement of trusted third parties (TTPs), Blockchain builds an environment where mutual trust among valid members is established. Nevertheless, the associated transparency property caused a hazard to real-world applications because every on-chain information is exposed to the public. That implies those applications involving sensitive data or personal information, which require security and privacy protection, are not suitable to be implemented in Blockchain, directly. Fully homomorphic encryption (FHE) schemes have been treated as one of the end-to-end solutions to data security and privacy protection problems. In this article, we examine the possibility (or cost) of embedding the ideal lattice-based FHE into the Ethereum Blockchain for building up a new trustworthy framework with security and privacy protection capability. Due to the limitations of current Blockchain, the execution of FHE is conducted off-chain; at the same time, on-chain members can call FHE-based functions to directly compute the ciphertext domain operations after their Smart Contracts have been deployed to the Blockchain. To illustrate and benchmark the examining results of our framework, an FHE and Blockchain-based Vickrey auction system is also developed, in which the online bidding prices are kept in secret. Simultaneously, the determination of the winner and the transferring of payments are conducted autonomously by Smart Contracts.