Zac Williamson, co-founder and CEO of Aztec Labs, a well-known Ethereum layer-2 network specializing in privacy solutions, recently shared his views on the profound importance of bringing robust privacy mechanisms to Ethereum. Williamson, who previously earned a PhD in particle physics at Oxford and worked at CERN, is renowned in the blockchain technology sphere as one of the creators of the widely utilized zero-knowledge proof system called PLONK.
According to Williamson, integrating privacy on Ethereum is more than just a technical enhancement; it is crucial for the blockchain’s future expansion and adoption. He identifies three main pillars of blockchain privacy: user privacy (shielding sender and receiver identities), data privacy (concealing transaction amounts), and code privacy (keeping the executed logic hidden). Achieving all three simultaneously, he argues, should be the ultimate goal if developers are serious about constructing fully private blockchain systems.
Williamson believes that misconceptions are stalling wider adoption of privacy technologies; most notably, people drastically oversimplify its purpose. Many erroneously view privacy as limited to tokens or a niche aspect of crypto rather than as something that will inevitably underpin all crypto interactions. He emphasized the concept of composable privacy, where networks such as Aztec Labs allow developers to define tailored private transactions and compliance mechanisms within smart contracts. This model effectively combines transactional privacy with robust regulatory adherence, thus maintaining user protection while satisfying legal and professional standards.
Addressing concerns about privacy’s role in authoritarian contexts, Williamson stressed neutrality and openness as core blockchain principles. He defined legitimate blockchain privacy as enabling users to conduct online activities privately without inadvertently benefiting criminals or malicious actors. He cited Privacy Pools—which offer selective disclosures and compliance-friendly privacy approaches—as a good initial compromise, supported even by Ethereum co-founder Vitalik Buterin, but contended that this should not be the endpoint. Aztec Labs is pushing towards achieving fuller privacy and programmability, enabling applications that utilize zero-knowledge proofs (ZKPs) for sensitive verifications, such as passport-based identity confirmations in DeFi applications without sacrificing privacy.
When asked whether Ethereum ought to become inherently private at its base layer, Williamson argued against this, citing the significant complexity privacy features entail, and suggesting specialized layer-1 or focused layer-2 solutions would better manage these challenges. Existing networks, he explained, would face major disruption if forced into foundational privacy overhauls. Therefore, Layer-2 scaling solutions like Aztec Labs remain ideal for experimentation and integration of advanced privacy.
On whether zero-knowledge proofs alone could fulfill Ethereum’s privacy requirements, Williamson stated clearly that while ZKPs are essential, complementary infrastructure such as private mempools and network-layer protections are also indispensable. Only an end-to-end encrypted blockchain—where sensitive information is known exclusively by the intended recipients—will suffice, especially when transacting sensitive, real-world data, such as mortgage payments or politically sensitive DAO interactions.
Addressing fragmentation within zero-knowledge tooling—such as PLONK, SNARKs, and STARKs—Williamson championed diversity over premature standardization, arguing that the ongoing experimentation with multiple privacy solutions is necessary at this early development stage. He drew on historical analogies, like France’s Minitel, cautioning that adopting the wrong early standards can stifle innovation long-term.
Discussing alternatives such as fully homomorphic encryption (FHE), Williamson recognized its potential but suggested it remains years away due to current computational limitations. He highlighted the present state of FHE as comparable to ZK technologies around 2010—a promising yet still impractical frontier requiring more time and considerable improvements before mainstream adoption.
Finally, Williamson emphasized the pressing need for improved usability in privacy-oriented blockchain technologies. He detailed Aztec Labs’ recent innovations with PLONK and their programming language Noir, intended to reduce complexity for developers and users dramatically. Such enhancements should allow programmers unfamiliar with cryptography to effortlessly build sophisticated privacy-forward blockchain applications in the near future, thereby paving the way for mass-market acceptance of private blockchain transactions.
