Ethereum zkAPI Anonymizes AI Payments With Privacy Tradeoffs

The Ethereum Foundation has introduced zkAPI, a new privacy-focused solution designed to anonymize AI payments. Launched on October 1, zkAPI allows users to deposit cryptocurrencies like ETH or USDC into an Ethereum vault, enabling them to pay for AI services without revealing their identity to the payment server. The AI provider receives the request but remains unaware of the billing identity behind it.

The system works by separating payment from identity. Users deposit funds into a vault, which generates private notes for spending. Zero-knowledge proofs ensure that payments are authorized without exposing the user’s identity. The AI provider receives a temporary, disposable API key for each session, which expires after use. This ensures that the payment server never sees the content of the AI prompts, and the AI provider never learns the billing identity.

However, zkAPI is not a perfect solution for privacy. While it separates billing identity from API usage, it does not hide the content of the prompts. The AI provider still receives the prompts and responses, and network information could potentially link separate sessions. The Ethereum Foundation acknowledges these limitations and advises users seeking stronger anonymity to use tools like Tor for separate sessions.

Despite these limitations, zkAPI has broader applications beyond AI. It can handle blockchain RPC queries, image and video jobs, VPN bandwidth, and machine-to-machine services. The system aims to ensure that no single entity knows everything about a user’s transactions, providing a narrower but more focused privacy solution.