How Hiss Works

A trustless marketplace for World ID verification on Base.

The Problem

AgentBook lets World ID holders register agent wallets as human-backed. Some people need agent registration but don't have a World ID. Others have a World ID but don't need it. Hiss connects them.

The Flow

Seller lists an offer. A World ID holder posts a listing with their price (ETH or USDC). Their World ID nullifier hash is stored onchain as the listing key.

Buyer picks a seller. The buyer browses listings, checks the seller's registration history, and accepts by locking funds in the escrow contract with their agent address.

Seller registers the agent. The seller runs the AgentBook CLI, scans a QR code with World App, and submits a World ID proof that registers the buyer's agent address.

Seller claims payment. The seller calls resolve(). The contract verifies the agent is registered with the correct nullifier, then releases the escrowed funds to the seller.

Trust Model

Neither party needs to trust the other. The escrow contract enforces every guarantee:

-Buyer can't lose funds. Cancel anytime before the seller registers the agent with the correct nullifier.
-Seller can't steal. Payment only releases after onchain verification that the agent was registered by the correct World ID.
-No stuck funds. If a third party griefs by registering the agent with a wrong nullifier, the buyer can still cancel and get a full refund.
-Price is locked. The seller can change their listing price, but existing orders keep the original amount.

Registration Count

Each listing shows how many agents the seller's World ID has registered across all platforms — not just Hiss. This is indexed from AgentRegistered events on the AgentBook contract. Buyers can use this to gauge whether a seller's World ID is "fresh" or heavily used.

Contract

HissEscrow is deployed on Base mainnet and verified on Basescan. No admin, no protocol fee, no upgradability. Not audited — use at your own risk.

Source

Fully open source at github.com/lucadonnoh/hiss.