Ethereum Foundation Launches zkAPI for Anonymity in AI Model Payments
The Ethereum Foundation has launched zkAPI, a system that enables users to pay for AI models without revealing their identity. The system, built with the Open Anonymity Project, implements a design co-authored by Ethereum co-founder Vitalik Buterin and Ethereum Foundation dAI Lead Davide Crapis. zkAPI is live on Ethereum mainnet and allows users to pay for AI models and other metered APIs without exposing their identity.
To use zkAPI, users must first deposit tokens such as ETH or USDC into a vault contract on Ethereum, which records the user's balance as a private note. A zero-knowledge proof is then generated, showing that the request is backed by a funded note, without revealing which note or deposit funds it.
When a user pays for AI usage, a serial number called a 'nullifier' is published. A duplicate nullifier is exposed if a user tries to spend the same balance twice, which can be used to track attempts to reuse a balance.
zkAPI does not provide network anonymity, and users seeking stronger privacy may route traffic through Tor. The system's GitHub repository describes the protocol as experimental.