PTLC: Protect the Identity Privacy during Cross-Chain Asset Transaction More Effectively

With the continuous development and innovation of blockchain technology, a large number of blockchain networks with various features have emerged to satisfy the needs of differ-ent scenarios. For example, Cross-Chain technologies have been proposed to enable information interaction and value transfer between two blockchains. In Cross-Chain asset transaction, the Hashed Timelock Contract (HTLC for short) algorithm is the most widely used to control asset transaction. However, the HTLC algorithm has a problem of low-level security assurance in practical applications: Attackers can associate the accounts of both parties involved in a Cross-Chain transaction by comparing contract parameters on different chains, which leads to the disclosure of identity privacy information of both relevant parties in the Cross-Chain transactions. In order to protect the identity privacy information of Cross-Chain traders, a new privacy protection method for Cross-Chain asset transaction was proposed based on Paillier homomorphic encryption (PTLC for short) in this paper, which uses Paillier homomorphic encryption to replace hash encryption in privacy protection process. It not only maintains a high security of Cross-Chain asset transaction, but also solves the major problem of identity privacy information leakage during whole asset transaction process. Experiments of cross-chain asset transactions are conducted in two different Ethereum private chains, and experimental results show that the proposed method PTLC can protect the identity privacy information effectively and achieve a low GAS consumption value in the Cross-Chain process.