Ethereum developers working on a ZK protocol for on-chain interactions privacy

Ethereum developers are advancing a new zero-knowledge protocol that aims to bring stronger privacy to on-chain interactions, beginning with a cryptographically verified Secret Santa–style matching system.

Though playful in theme, the work reflects a growing push within the Ethereum ecosystem to design practical privacy frameworks that can be deployed across a range of real-world applications.

A push for private coordination in Ethereum

The idea resurfaced recently after Solidity engineer Artem Chystiakov highlighted research he and collaborators first published earlier this year.

Their proposal, known as the ZK Secret Santa (ZKSS) protocol, describes a method for matching participants on-chain without exposing who is assigned to whom.

The challenge is heightened by Ethereum’s fully transparent state, lack of native randomness and the long-standing problem of Sybil resistance.

To address these constraints, the ZKSS design leans heavily on zero-knowledge proofs, transaction relayers and cryptographic nullifiers.

Together, these tools allow participants to prove their place in the game, contribute randomness and receive assignments without revealing the underlying identity linkages that would otherwise be visible on-chain.

The use of a relayer is central to the privacy guarantee. During the matching phase, participants submit their randomness through the relayer, which broadcasts the transactions on their behalf.

Because the relayer masks the origin of each submission, no observer can infer which address contributed which value.

The protocol’s zero-knowledge proofs then verify that each randomness submission is valid, tied to a legitimate participant and not duplicated.

Inside the three-step protocol

The ZKSS system unfolds in three coordinated steps.

First, all participants are registered in a smart contract, which stores their addresses in a sparse Merkle tree.

This setup needs to be done only once, allowing for repeated Secret Santa rounds without rebuilding the participant list.

The registration tree later enables proof-based membership checks without exposing wallet relationships.

The second stage, called signature commitment, requires each participant to commit to a deterministic ECDSA signature.

This commitment prevents them from using signature variability to bypass anti-Sybil protections.

Each signature hash is stored in a separate Merkle tree, with the contract verifying that the sender belongs to the initial participant set.

After committing, players generate and publish a unique randomness value. They do this privately, but their proof shows that the randomness belongs to a legitimate participant and hasn’t been reused.

Players are encouraged to use RSA public keys as their randomness so they can later receive encrypted delivery details from their assigned counterpart.

The final step is the receiver disclosure phase. Here, each participant reveals themselves to the person who drew their randomness.

They provide a proof showing they are not claiming their own slot and that their nullifier does not conflict with the randomness they selected.

With this final verification step, the protocol completes the matching without leaking any sender-receiver mappings to the public chain.

A framework with broader uses

Although framed as a Secret Santa algorithm, the implications reach far beyond seasonal gift exchanges.

Ethereum’s growing intersection with regulated finance, governance, and organisational coordination has amplified the need for permissionless privacy systems.

The same framework can support anonymous voting in DAOs, whistleblower channels where members must prove eligibility without exposing identity, and private airdrops that avoid revealing recipient lists.

Its structure, Merkle trees for membership checking, deterministic signatures for Sybil resistance, and zero-knowledge proofs for correctness, mirrors the backbone of many emerging privacy-first protocols.

Developers expect continued refinement as the community tests the ZKSS design and explores interoperability with existing Ethereum tooling.

The early research suggests that privacy-preserving, verifiable coordination can be achieved without trusted intermediaries, marking a notable step toward more confidential activity on public blockchains.

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