Ethereum is working on a Secret Santa protocol based on ZK proofs

Key points:

• Secret Santa for Ethereum is built on ZK proofs and relays that hide senders and recipients.
• Researchers propose solutions to key problems: lack of privacy, lack of randomness, and the risk of repeat participation.
• ZKSS can be applied to voting, DAOs, whistleblower systems, and private token airdrops.

Ethereum researchers are working on the Secret Santa protocol, which uses zero-knowledge proofs (ZK proofs) and transaction relays to ensure privacy. The protocol should hide connections between users and solve the main problem of public blockchains — the lack of address privacy.

Ethereum developer Artem Chystiakov presented an updated version of the concept at the Ethereum community forum. His work, Zero-Knowledge Secret Santa (ZKSS), describes a three-step gift exchange algorithm that completely hides the identities of participants.

What problems does Secret Santa solve in Ethereum?

Chystiakov identifies three key obstacles that prevent the implementation of classic Secret Santa in a public chain.

1. In Ethereum, all transactions are open, so a mechanism is needed to hide senders and recipients.
2. There is no reliable source of randomness in the blockchain — participants must add their own random values.
3. It is necessary to exclude the possibility of double registration or self-selection.

These limitations formed the basis for ZKSS. The protocol offers a system in which participants confirm their participation with a signature and then anonymously publish their random values through a relay — this way, addresses are not linked to transactions.

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How the ZKSS protocol works

ZKSS consists of three steps:

1. Participant registration.

All addresses are entered into a smart contract and secured in a Merkle tree. Registration is done once and can be used for multiple games.

2. Adding randomness.

Each participant generates their own random value and publishes it through a relay along with a ZK proof of correctness. The sender’s address is hidden.

To prevent manipulation by participants, the protocol uses two key mechanisms: verifiable digital signatures and hidden unique markers that confirm the player’s participation and prevent double registration.

3. Determining the recipient.

In the third step, the participant reveals the ZK proof linking them to the random number they drew from the common list. This determines who they should send the gift to.

If an RSA key is used as the random value, the recipient can encrypt their delivery address and send it to their Secret Santa privately.

These steps together ensure the correctness of the distribution: no one can choose themselves, no one can participate twice, and the connection between users remains hidden.

Where can ZKSS be applied?

Researchers suggest considering ZKSS as a universal mechanism for private interactions on the blockchain. It is suitable for anonymous voting, DAOs, corporate governance, whistleblower channels, and private token airdrops, where it is necessary to confirm the right to participate but hide one’s identity.

As a reminder, the Fusaka upgrade will be one of the key events of December: Ethereum is preparing to activate the fork on December 3 amid growing load on L2 networks and preparations for parallel transaction execution. Developers note that this upgrade opens the next stage of ecosystem scaling.