Ethereum co-founder Vitalik Buterin has released an experimental anonymous message board built on the Aztec network, demonstrating how zero-knowledge proofs can enable private on-chain communication with built-in moderation. The demo, which Buterin called a “vibe-coded” toy version of a concept he first described in a 2022 blog post, is now public on GitHub.
The application allows users to deposit ETH on Ethereum’s base layer, publish messages completely anonymously on Aztec’s Layer 2, and later withdraw funds — all without any public link between the deposit and the posts. The system relies on ZK-SNARKs, using Aztec’s notes and nullifiers to manage private state: notes store encrypted data, while nullifiers prevent action repetition without revealing identity.
A key innovation is the moderation layer. A designated censor role (set at deployment) can flag posts as “immoral,” hiding them from the default feed and imposing a time-lock penalty on the poster’s next message. Additionally, an automated moderation daemon evaluates each post against an on-chain policy using a locally hosted language model, further filtering content. The moderation policy itself is stored on-chain and visible to all components.
Rate limits are tied to deposit size: a 0.001 ETH deposit allows one post per hour, while 0.01 ETH permits ten. This design, combined with private time locks, helps control spam while preserving anonymity. Buterin noted that Aztec has now reached stage 2 — the highest decentralization tier on the Layer 2 maturity scale.
Though incomplete, the repository already includes formal verification of privacy, rate limits, censorship controls, and deposit safety, with 70 verified theorems and no unproven gaps. The release underscores the rapid evolution of privacy-preserving blockchain tools, extending their potential beyond financial transactions into anonymous online communication.
