Proof of Humanity

Proof of Humanity is a Sybil-resistant registry of unique humans, implemented as a set of Ethereum smart contracts. Its primary function is to verify that each registered entry corresponds to a real, living person, preventing a single entity from creating multiple fraudulent identities (Sybil attacks). The protocol achieves this through a combination of video submission, social verification by existing members, and a challenge period where submissions can be disputed. Once verified, a person receives a Universal Basic Income (UBI) token stream, incentivizing participation and creating a foundational layer for human-centric applications.

The verification process is a decentralized court system. An applicant submits a short video and deposits a stake. Existing, verified members (vouchers) vouch for the applicant's humanity. The submission then enters a challenge period, where anyone can dispute its validity by depositing a larger stake. Disputes are resolved by the Kleros decentralized arbitration court, where jurors review evidence and vote to determine if the submission is valid. This crowdsourced, game-theoretic mechanism ensures the registry's integrity without relying on a central authority.

Verified status in the Proof of Humanity registry acts as a foundational proof-of-personhood primitive for the Web3 ecosystem. It enables applications that require unique human participation, such as fair airdrops, one-person-one-vote governance models (e.g., Gitcoin Grants quadratic funding), and Sybil-resistant authentication. The associated UBI token provides a continuous, non-transferable basic income stream to verified humans, exploring models for decentralized universal basic income. The protocol's open and permissionless nature allows any dApp to query the registry to confirm a user's unique human status.

Proof of Humanity (PoH) is a sybil-resistant identity verification system built on Ethereum that uses a combination of social verification, video submission, and a challenge period to create a registry of unique human users. A user submits a short video of themselves, a profile, and a deposit to the PoH registry, a smart contract that acts as a curated list. The submission then enters a challenge period, where existing, verified members of the registry can flag it as fraudulent or duplicate. If no successful challenge is made, the applicant is added to the registry and receives a Universal Basic Income (UBI) token stream, funded by fees from the system.

The core mechanism relies on a curated registry and decentralized arbitration. When a submission is challenged, the dispute is escalated to the Kleros decentralized court, where a randomly selected jury of token-holders reviews the evidence. This human-in-the-loop arbitration process is crucial for handling edge cases that algorithms cannot easily resolve, such as verifying the uniqueness of an individual or the authenticity of a video. The requirement for a deposit and the risk of losing it to a successful challenger disincentivizes spam and fraudulent applications.

Once verified, a user's entry in the PoH registry is represented by a non-transferable Ethereum token (an ERC-20 with a transfer function permanently disabled). This token serves as a persistent, on-chain credential that other applications can query to establish a user's verified human status. The primary use case is to prevent sybil attacks—where a single entity creates many fake identities—in governance systems, airdrops, and social networks, ensuring one-person-one-vote principles in decentralized organizations (DAOs).

The protocol is sustained by an internal economic model. Submission and challenge fees fund the Kleros arbitration process and the continuous UBI distribution to all verified humans. This creates a circular economy: new applicants pay to join, and those fees are redistributed to the existing community, aligning incentives for honest participation and careful curation of the registry. The UBI mechanism also provides a foundational, unconditional income layer for participants within the ecosystem.

Proof of Humanity represents a foundational primitive for decentralized society (DeSoc), enabling trust-minimized proof of personhood without relying on centralized authorities. Its open, permissionless, and interoperable design allows any dApp to integrate it, paving the way for more equitable distribution mechanisms, robust democratic governance, and sybil-resistant social graphs across the Web3 landscape.

In DeFi, the pseudonymous nature of blockchain wallets creates a fundamental problem for credit: the inability to assess borrower risk or establish reputation over time. Proof of Humanity solves this by cryptographically linking a wallet to a verified, unique human identity. This creates a Sybil-resistant foundation, preventing a single entity from creating countless fake identities to manipulate systems. With this verified identity, DeFi protocols can move beyond purely collateralized lending to introduce concepts like uncollateralized loans, credit scores, and reputation-based interest rates.

The mechanism enables on-chain credit history. A user's financial behavior—timely repayments, default history, total value locked—can be attributed persistently to their verified identity, not just a disposable address. This data becomes a portable soulbound reputation that can be used across different protocols. For example, a lending platform like Aave or Compound could offer lower collateral requirements or better rates to users with a long, positive PoH-verified credit history, similar to traditional credit bureaus but without centralized control.

Furthermore, PoH facilitates under-collateralized lending and proof-of-personhood grants. Decentralized Autonomous Organizations (DAOs) can distribute resources or loans based on proven human need or merit, as seen with initiatives like Gitcoin Grants. It also enables fair launch mechanisms and anti-bot measures for token distributions, ensuring airdrops and incentives reach real users rather than farmers with thousands of wallets. This builds more equitable and sustainable economic systems within Web3.

Key challenges remain, including privacy concerns, global accessibility of verification, and the legal enforceability of debt for pseudonymous identities. However, by serving as a primitive for decentralized identity (DID), PoH and similar systems like BrightID and Worldcoin are critical infrastructure for evolving DeFi from simple collateral swaps into a full-spectrum, human-centric financial ecosystem with sophisticated credit markets.