Privacy Stewards of Ethereum (PSE) is a research and development lab within the Ethereum Foundation dedicated to integrating privacy-enhancing technologies into the Ethereum ecosystem. Formerly known as the Privacy & Scaling Explorations team, PSE develops open-source cryptographic tools, contributes to standards, and coordinates with projects to make privacy a practical and default feature of Ethereum's application layer. ^{[6] [7] [6] [7]}

Overview

Privacy Stewards of Ethereum (PSE) operates with the mission to deliver usable, scalable, and secure privacy to the Ethereum network. The group's vision is a future where digital infrastructure respects user privacy by default, and any permissions granted by users are purpose-specific, informed, and revocable. PSE functions as a multi-disciplinary team composed of cryptographers, mathematicians, developers, and designers who focus on embedding programmable cryptography into Ethereum's application layer. ^[6]

The organization's work is motivated by the concern that without robust privacy protections, public blockchains like Ethereum could become tools for surveillance, undermining their goal of promoting freedom and decentralization. The PSE team has stated, "Ethereum is on the path to becoming the settlement layer for the world, but without strong privacy, it risks becoming the backbone of global surveillance rather than global freedom." ^{[2] [3] [6]} The inherent transparency of public ledgers is seen as a significant barrier to mainstream adoption by both individuals and institutions. As noted by Petro Golovko of British Gold Trust, the public nature of transactions, which exposes salaries, business deals, and treasury movements, makes crypto "unusable for regular people and impossible for institutions." ^{[8] [3]} PSE aims to solve these challenges by treating privacy as a first-class feature necessary for Ethereum's long-term success and relevance, with the goal of making privacy seamless, cost-effective, and compliant with global standards. ^[7] However, this push for greater privacy is recognized as a "double-edged sword," as it could enhance security and confidentiality while also potentially complicating regulatory compliance and creating avenues for illicit activities. ^[4]

PSE's operating philosophy is grounded in several key principles. All work produced by the team is open source to ensure transparency and community access. The group takes an exploratory and "full stack" approach, investigating foundational concepts, addressing implementation gaps, and pursuing high-risk ideas with transformative potential that may be overlooked by academia or industry. This is guided by a principle of "subtraction by default," meaning the team focuses its efforts on high-impact areas where other ecosystem actors are not present. By maintaining a feedback loop between applied research and real-world needs, PSE aims to provide credible guidance on building private and resilient systems on Ethereum. ^{[6] [7]}

"We focus on areas that are overlooked by academia or industry like foundational concepts that need clarity, implementation gaps that have stalled progress, and risky ideas with uncertain but transformative potential." ^[6]

History

The origins of PSE date back to 2018 when the group was founded within the Ethereum Foundation under the name Applied ZKP. The team's initial mandate was to advance the field of zero-knowledge proofs (ZKPs), transitioning them from theoretical cryptographic concepts into practical and usable applications for the Ethereum ecosystem. ^[6]

In 2021, the group rebranded to Privacy & Scaling Explorations (PSE). This change reflected a significant expansion of its scope beyond just ZKPs to include a wider range of programmable cryptography and privacy-enhancing tools. The team's focus broadened to cover the entire technology stack, from foundational research to end-user applications, while still maintaining its exploratory and research-driven character. ^[6]

A major strategic shift occurred in September 2025, when the team announced its rebranding to Privacy Stewards of Ethereum. This change signaled a move away from being a "cryptography explorations team" that pursued "cool tech" and toward becoming a "problem-first team" focused on concrete ecosystem outcomes. ^{[3] [7]} The new identity came with a refined mission to define and deliver on Ethereum's privacy roadmap, ensuring privacy becomes "the norm rather than the exception." ^[2] The roadmap, released on September 12, 2025, and compiled by team member Sam Richards, was influenced by feedback from key figures such as Ethereum co-founder Vitalik Buterin and other community groups, and it marked a renewed commitment to driving ecosystem-wide impact and solving concrete privacy challenges to enable mass adoption. ^{[7] [8] [6]}

Strategic Roadmap and Key Projects

In September 2025, PSE unveiled a comprehensive roadmap structured around three core tracks designed to address fundamental privacy gaps in the Ethereum ecosystem. This problem-driven approach guides the team's research, development, and coordination efforts, with some measurable goals expected to be rolled out in the following 3 to 6 months. ^{[7] [4] [5] [7]}

Private Writes

The "Private Writes" track aims to "make private onchain actions as cheap and seamless as public ones." ^[6] This involves improving the feasibility, usability, and cost-effectiveness of private transactions, confidential voting, and other application interactions that write data to the blockchain. The long-term research in this area includes exploring advanced cryptographic techniques like Fully Homomorphic Encryption (FHE) and practical obfuscation. ^[7]

Key initiatives within this track include:

• Private Transfers: This initiative focuses on confidential payments. It includes the continued development of PlasmaFold, an experimental Layer 2 solution utilizing Proof-Carrying Data (PCD) and folding schemes to create efficient private transfers. The team is working on a proof of concept for a private transfer feature in PlasmaFold and hopes to debut it by Devconnect in November 2025. ^[6] Another key project is Kohaku, a proof-of-concept privacy wallet that incorporates features like zero-knowledge account recovery and a keystore for stealth addresses. ^{[7] [8] [4]}
• Private Governance: To enable confidential voting in DAOs and other governance systems, PSE collaborates with partners like Aragon on protocol integrations. The team also works on producing educational resources, such as a planned "State of private voting 2025" report. ^[7]
• Confidential DeFi: In collaboration with the Ethereum Foundation's EcoDev Enterprise team, PSE launched the Institutional Privacy Task Force (IPTF). This task force aims to identify and unblock the privacy-related challenges preventing institutional adoption of DeFi by creating specifications, designing protocols that ensure privacy while maintaining compliance, and developing proofs-of-concept for enterprise use cases. ^{[7] [6]}
• Private Computation: This area involves research into programmable privacy. Projects include MachinaIO and oversight of a grant for Phantom Zone, which explores related concepts. ^[7]

Private Reads

The "Private Reads" track is focused on enabling users to "read from Ethereum without revealing identity or intent." ^[6] The goal is to enhance network-level privacy to prevent surveillance and the leakage of metadata when users query the blockchain, browse dApps, or authenticate with wallets. This addresses the vulnerability where even if transactions are private, the act of reading blockchain data can expose user activity, as Remote Procedure Call (RPC) services can leak private data like IP addresses or which accounts a user is interested in. ^{[7] [2] [6]}

Initiatives under this track include:

• Network Privacy: To address data leakage in RPCs, PSE convened a Private RPC working group to evaluate and advance solutions for private Remote Procedure Calls, which are used by wallets to communicate with the blockchain. ^[6]
• Oblivious RAM (ORAM): The team is integrating an ORAM solution into the Kohaku wallet. ORAM is a cryptographic technique that obscures a user's data access patterns, preventing an observer from knowing which specific pieces of state a user is reading.
• Broadcast Privacy: Development includes implementing mixnet protocols like Sphinx to protect the privacy of broadcasted transactions, making it difficult to link a transaction to its originating IP address.
• Research Translation: PSE actively researches state-of-the-art techniques in ORAM and Private Information Retrieval (PIR) with the goal of translating academic findings into practical features for wallets and browsers.

These initiatives aim to create a more surveillance-resistant experience for Ethereum users. ^{[7] [8]}

Private Proving

The "Private Proving" track, also known as "Prove Anywhere," has the goal to "make proving any data private and accessible." This work focuses on enabling fast, private, and accessible generation and verification of zero-knowledge proofs, making it easier and cheaper to generate them on everyday devices. ^[6] These proofs allow users to verify data from on-chain, off-chain, and traditional web sources without revealing the underlying data itself, supporting data portability and verifiable provenance. ^[7]

Key projects in this area are:

• Data Portability (zkTLS): A major focus is the stabilization and optimization of the TLSNotary protocol. This protocol uses zero-knowledge proofs to verify data from a TLS web session (HTTPS) without compromising privacy. PSE is also building an SDK to make zkTLS integration easier for developers across mobile, server, and browser platforms. ^[7]
• Private Identity: PSE is advancing standards for generic zk-SNARKs and developing a modular, privacy-preserving ZKP wallet. This work is aligned with emerging digital identity standards like the EUDI (EU Digital Identity) wallet framework. The team also researches unlinkable and scalable frameworks for credential revocation. ^[7]
• Client-side Proving: This initiative aims to make it easier for user devices to generate ZK proofs efficiently. It includes applied research on ZK proving systems like Mopro and PPD, establishing credibly neutral benchmarking for ZK proofs, and a joint effort with Aztec and other partners to accelerate the Noir programming language for ZK circuits. ^[7]

Industry Context and Challenges

The Case for Privacy

The push for enhanced privacy on Ethereum is a direct response to growing concerns from industry leaders and developers about the viability of transparent blockchains for widespread use. Ethereum co-founder Vitalik Buterin has been a vocal advocate for stronger privacy, arguing it is essential for protecting individuals against growing state and corporate surveillance and is necessary for Ethereum's survival as a global settlement layer. ^{[3] [5]} Buterin has also argued that private transactions ought to become the default on the network, allowing users to interact with applications without publicly linking their activity. ^[7] In an era of advanced AI and data analysis, the default transparency of blockchains is increasingly seen as a vulnerability rather than a feature. ^[5] Experts argue that without robust encryption and privacy, crypto remains in a vulnerable state, similar to the pre-SSL internet when users were hesitant to share sensitive information online, thereby hindering the scaling necessary for mass adoption. ^[3]

Regulatory and Ethical Considerations

While enhancing privacy is critical for user protection, it introduces significant regulatory and ethical challenges. The development of privacy-preserving technologies on Ethereum is unfolding amid increasing scrutiny from global regulators. For instance, officials in the United States have explored proposals to add government identity checks to smart contracts and DeFi protocols, a move that has drawn backlash from the crypto community for its surveillance implications. ^[5]

Furthermore, the immutable nature of blockchain records presents a direct conflict with data privacy regulations like Europe's GDPR, which enshrines principles such as the "right to be forgotten." Removing sensitive data from an unalterable on-chain history is a significant technical and legal hurdle. ^[4] There is also the concern that enhanced privacy features could be exploited for illicit activities, which could lead to stricter regulatory crackdowns on crypto-friendly businesses. PSE's work attempts to navigate this complex landscape by developing tools like zero-knowledge proofs that can help businesses verify compliance with regulations without compromising sensitive user or commercial data. ^[4]

Ecosystem Engagement and Collaborations

PSE actively engages with the broader Ethereum community to gather feedback, align on standards, and drive adoption of its open-source tools. The team maintains a presence on several key platforms, including a GitHub organization for its projects, a community channel on the ETH R&D Discord server, and the Ethereum Magicians forum for technical discussions and proposals. ^[1]

The group collaborates with numerous projects and teams both inside and outside the Ethereum Foundation.

• Aragon: PSE works with Aragon, a platform for creating and managing DAOs, to integrate private voting protocols.
• Aztec: The team is part of a joint effort with Aztec and other partners to accelerate the development and adoption of Noir, a domain-specific language for writing ZK circuits.
• EF EcoDev Enterprise Team: PSE co-founded the Institutional Privacy Task Force with this internal Ethereum Foundation team to address the needs of enterprise users.
• Intmax: The roadmap identifies a potential integration path for PSE's PlasmaFold project with Intmax.

PSE also participates in major ecosystem events like Devconnect and organizes its own workshops and summits, such as the Ethereum Cypherpunk Congress, zkTLS Day, and Noircon2, to foster collaboration and knowledge sharing on privacy-related topics. ^[7]

Team

PSE is described as a collective, multi-disciplinary team of cryptographers, mathematicians, developers, designers, and coordinators. While the organization does not publicly list a formal leadership hierarchy, the September 2025 roadmap announcement credited several individuals for their significant contributions to its development. These include Andy (the author of the announcement), Sam Richards (@samonchain) for compiling the roadmap, and Oskar (@oskarth), Vitalik Buterin, and the Silviculture Society for providing inspiration and input. ^{[6] [7] [6]}