Researchers in the Ethereum community are exploring methods to implement a protocol introduced earlier this year that could enhance privacy using zero-knowledge proofs.
Ethereum developer Artem Chystiakov shared his findings on the Ethereum community forum on Monday, presenting “Zero Knowledge Secret Santa (ZKSS),” which proposes a three-step “Secret Santa” algorithm. This paper was initially introduced in January on arXiv.
Secret Santa is a well-known gift-exchanging game typically enjoyed during the holiday season, where individuals anonymously exchange gifts. Each participant buys a gift for another person designated as their “Secret Santa” while also receiving a gift from theirs.
The identities of the gift givers remain unknown to the recipients.
Challenges with playing on Ethereum
Chystiakov identified three primary challenges in executing Secret Santa on Ethereum, which this protocol aims to address.
Transparency on Ethereum means everyone can see everything, necessitating a method to conceal the identity of gift givers to uphold privacy.
Blockchains lack true randomness; thus, participants must generate their own random selections, and the design must prevent double participation or self-gifting.
Potential use cases for Ethereum
With the growing intertwining of crypto and traditional finance, blockchain privacy has gained significant attention.
Privacy protocols could serve in contexts such as anonymous voting and governance processes, including within DAOs or organizations where members need to verify their participation and cast a single private vote.
They could also be employed in whistleblower mechanisms, allowing authorized employees to prove their identity while submitting information anonymously, or in private airdrop situations where token distributions occur without disclosing recipient identities.
When asked about open-source implementations or deployment, Chystiakov responded, “We’re working on it.”
How Zero Knowledge Secret Santa works
The proof-of-concept Solidity protocol employs zero-knowledge proofs to establish the relationships between gift senders and receivers while preserving sender privacy and confidentiality.
ZK-proofs are a cryptographic technique that allows one to prove knowledge without disclosing specific details. The ZKSS protocol further incorporates a transaction relayer, functioning as an intermediary that submits transactions to keep the sender’s identity concealed.
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To join, participants need to register their Ethereum addresses within a smart contract, forming a complete participant list. Each individual must then commit to a specific digital signature.
This design counters cheating attempts where an individual might register multiple times using different signatures.
Participants then secretly input their random numbers into a shared list via the relayer, ensuring anonymity over who contributed what. This allows gift receivers to encrypt their delivery addresses so that only their assigned “Santa” can access it.
Lastly, each participant chooses a random number from the shared list, after which the identity of the receiver becomes apparent.
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