Private DeFi Is Coming: Why Privacy Is Ethereum's Next Frontier | Lean Ethereum

Tomah Teary argues that the decline of privacy due to online surveillance threatens fundamental rights, emphasizing the need for a digital equivalent of cash to enhance financial privacy. He believes Ethereum has the potential to facilitate private decentralized finance (DeFi), which includes opportunities for private lending, borrowing, and swapping, although most on-chain transactions remain trackable.

Teary envisions an ideal privacy scenario in DeFi where user identities, balances, and assets are concealed, predicting that Ethereum will focus on protecting user identities while keeping transaction amounts public in the near future. He warns users to be cautious with private protocols, noting that a large user base is essential to improve the anonymity set.

He highlights that privacy is not stigmatized within the Ethereum community, arguing for its necessity based on security concerns related to financial assets and personal safety. Teary critiques the effectiveness of using multiple wallets for privacy, stating that sophisticated actors can still track these efforts.

Teary predicts that if certain Ethereum Improvement Proposals (EIPs) are implemented, Ethereum could achieve native, trustless, censorship-resistant private transactions within a year. He points out the current system's vulnerability to censorship by a small number of builders, which undermines the network's overall censorship resistance.

The importance of frame transactions for privacy and security is discussed, as they allow for a modular approach to coding transactions without relying on trusted third parties. This modularity could help address significant bottlenecks in privacy protocols, with the Fossil project having broader implications for the Ethereum network beyond just privacy.

Integrating privacy protocols with Ethereum's infrastructure is deemed essential for enabling end-to-end private transaction flows, with users likely needing to opt-in for private transactions through a simple selection process. The unique censorship resistance and reliability of the Ethereum network provide a competitive edge over other Layer 1 solutions.

Puffer Unify is introduced as the first synchronously composable roll-up, facilitating rapid transactions on Ethereum. The current approach aims to obscure transaction details, while Aztec takes it further by hiding the contracts involved, although Aztec's method requires a higher level of trust compared to Ethereum's Layer 1.

The potential for a dominant privacy application to emerge in the coming years is discussed, with privacy seen as beneficial for institutions that need to maintain confidentiality while remaining auditable. However, achieving fully private shared states depends on advancements in cryptography, which are not yet efficient, and there is a shared concern about transitioning to post-quantum cryptography between Ethereum and Zcash.

Teary emphasizes that privacy in DeFi is complex and requires comprehensive solutions to address various vulnerabilities. Full integration of wallets, applications, and protocols is essential for effective user privacy. Many wallets currently log user data and may sell order flow to builders, posing significant risks to user privacy.

Network metadata, including IP addresses, can leak sensitive information if not managed properly, and when wallets query RPC providers for state information, they can inadvertently reveal user intent and transaction details. To enhance privacy, applications should be designed to be immutable, preventing governance changes that could undermine privacy protections.

Reducing reliance on trusted third parties is crucial for maintaining transaction privacy, with the overarching goal being to achieve maximum privacy while minimizing trust in these entities. Users are encouraged to actively participate in Ethereum's governance and discussions surrounding privacy to help shape the future of privacy in the ecosystem.