WorldCoin is creating a Privacy-Preserving Proof-of-Personhood Protocol (PPPoPP). The project began with the intention of distributing a token to a billion people. However, WorldCoin realized it needed to build major underlying infrastructure-covering both the hardware side (the Orb) and the crypto/protocol layer.

Although many teams are focused on general purpose rollups (such as Arbitrum, Optimism, zksync), WorldCoin encountered Hubble, an open source minimal, application-specific rollup. Hubble supports an extremely efficient approach while remaining permissionless and non-custodial, designed for an airdrop at the scale of one billion people.

With Hubble’s open source contracts already in strong condition, WorldCoin chose to add a high-performance sequencer written in Go, aiming to launch on mainnet as quickly as possible. During this work, WorldCoin improved the sequencer’s performance.

Since the Orb relies on biometrics during initial onboarding, WorldCoin set out to separate this step from the wallet and any later transactions to protect user privacy. To do so, WorldCoin adopted Semaphore, which can provide anonymity for a particular action and also makes the setup straightforward to reuse for new applications, enabling future use cases.