Ethereum's zkAPI Brings Anonymity to A.I. Model Payments

The Ethereum Foundation has launched a new system called zkAPI, which allows users to pay for artificial intelligence (A.I.) models without revealing their identity. This system is part of the Open Anonymity Project, an open-source A.I. privacy initiative that aims to develop infrastructure where privacy and sovereignty are foundational and people are in control.

To use the zkAPI system, users first deposit tokens such as Ethereum into a vault contract on the ETH network, which records the user's balance as a private note. The user then generates a zero-knowledge proof, which shows that its request is backed by a funded note, without revealing which note or funds. A zkAPI server checks the zero-knowledge proof and issues a temporary API key with a spending cap.

The user then sends their prompts directly to the A.I. model provider along with the key, and when it expires, the server deducts the usage from the user's private balance. A serial number called a 'nullifier' is also published each time a user pays for A.I. usage. The Ethereum Foundation says that A.I. chat and agents are the first use cases for the system, with other listed applications including blockchain queries, image and video generation, VPN bandwidth, and machine-to-machine payments between A.I. agents.