In recent years, permissionless blockchains have gained significant attention for their ability to secure and provide transparency in transactions. The development of blockchain technology has shifted from cryptocurrency to decentralized finance, benefiting millions of unbanked individuals, and serving as the foundation of Web3, which aims to provide the next generation of the internet with data ownership for users. The rise of NFTs has also helped artists and creative workers to protect their intellectual property and reap the benefits of their work. However, privacy risks associated with permissionless blockchains have become a major concern for individuals and institutions. The role of blockchain in the transition from Web2 to Web3 is crucial, as it is rapidly evolving. As more individuals, institutions, and organizations adopt this technology, it becomes increasingly important to closely monitor the new risks associated with permissionless blockchains and provide updated solutions to mitigate them. This paper endeavors to examine the privacy risks inherent in permissionless blockchains, including Remote Procedure Call (RPC) issues, Ethereum Name Service (ENS), miner extractable value (MEV) bots, on-chain data analysis, data breaches, transaction linking, transaction metadata, and others. The existing solutions to these privacy risks, such as zero-knowledge proofs, ring signatures, Hyperledger Fabric, and stealth addresses, shall be analyzed. Finally, suggestions for the future improvement of privacy solutions in the permissionless blockchain space shall be put forward.

翻译：近年来，无许可区块链因其在保障交易安全性和透明性方面的能力而备受关注。区块链技术的发展已从加密货币转向去中心化金融，惠及数百万未享受传统银行服务的个人，并成为旨在为用户提供数据所有权的下一代互联网Web3的基础。NFT的兴起也帮助艺术家和创意工作者保护其知识产权并享受劳动成果。然而，与无许可区块链相关的隐私风险已成为个人和机构的主要担忧。区块链在从Web2向Web3过渡中扮演着至关重要的角色，且该领域正快速演变。随着越来越多的个人、机构和组织采用此技术，密切监控与无许可区块链相关的新风险并提供更新的缓解方案变得愈发重要。本文旨在审视无许可区块链中固有的隐私风险，包括远程过程调用（RPC）问题、以太坊名称服务（ENS）、矿工可提取价值（MEV）机器人、链上数据分析、数据泄露、交易关联、交易元数据等。同时，将分析现有应对这些隐私风险的解决方案，如零知识证明、环签名、超级账本Fabric以及隐身地址。最后，提出未来改进无许可区块链领域隐私方案的建议。