Proof of Humanity
A Sybil-resistant (=duplicate and bot-proof) registry of humans.
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A Sybil-resistant (=duplicate and bot-proof) registry of humans.
Last updated
Was this helpful?
Proof of Humanity (PoH) is a Sybil-resistant registry of humans, combining social verification with video submission to create a trusted list of real humans. This innovative system serves as a gateway to numerous applications requiring verified human identities, ensuring users are genuine and not fake or duplicate accounts. PoH can be seamlessly integrated into a variety of existing and emerging identity systems, enhancing their security and reliability.
When applying to the list, users need to provide their name, a photo, and a short video, allowing others to verify that they are indeed human.
In 2021, we launched the first version of Proof of Humanity, which successfully registered almost 19,000 users. However, the Ethereum mainnet's high costs and various community challenges, which led to a fork, highlighted the need for improvements, paving the way for Proof of Humanity 2.0.
Proof of Humanity 2.0 has been deployed on Gnosis Chain to reduce the fees associated with registering, making it more accessible for everyone.
Proof of Humanity 2.0 introduces two exciting new features: soulbound IDs and multi-chain expansion.
Soulbound IDs are unique, non-transferable identifiers that link each human to a single ID (PoH ID), ensuring the authenticity and permanence of their digital identity. This feature allows users to recover their reputation and assets even if they lose access to their original wallet, enhancing security and reliability.
Multi-chain expansion allows the system to operate across multiple blockchain networks, including Gnosis Chain, enhancing accessibility and interoperability. This feature enables users to maintain and transfer their verified identity across different chains, ensuring a seamless and versatile digital experience.
Let’s explore some exciting use cases that benefit from Proof of Humanity.
PoH can be used to verify that voters are real people, thus preventing Sybil attacks where a single entity could create multiple fake identities to influence voting outcomes.
PoH can be used to ensure that only verified humans receive UBI payments. This prevents fraud and ensures that the benefits reach those who are genuinely eligible.
PoH can help ensure that users on social media platforms are real individuals, which can reduce spam, trolling, and the influence of bots. This creates a more authentic and trustworthy online community.
In peer-to-peer (P2P) marketplaces, such as those for freelance work, rentals, or second-hand goods, PoH can be used to verify the identity of participants. This increases trust between users, reducing the risk of fraud and enhancing the overall reliability of the platform.
PoH accounts can serve as universal login methods, automatically recognized by dapps without requiring registration.
By applying PoH to Quadratic Voting, we can develop new funding models for community projects. This ensures optimal distribution of funds, as PoH's Sybil-resistance prevents manipulation by multiple fake accounts, supporting the fair allocation of resources in decentralized ecosystems.
Systems often use captchas before allowing a user action in order to prevent spam. These are wasting user time and do not prevent spam from a determined user who would be willing to spend the time to solve them (or outsource the solution). People in the PoH registry could be allowed a number of captcha-free interactions (potentially high enough such that they never have to fill a captcha).
The PoH registry could also be used to create a novel type of sidechain secured by Proof of Identity with a “1 person = 1 vote” principle. This would assume an honest majority of humans in the registry and would work in a way similar to Proof of Authority sidechains.
And many others such as social recovery, inheritance planning...
All of these use cases can be improved upon by building new privacy layers on top of Proof of humanity that will enrich it with new capabilities. A key step for the future would be the creation of anonymous Sybil-resistant identities.
This would allow individuals to prove that they are humans and not bots while not revealing their identity. For example, certifications could be used in the context of privacy-preserving KYC by giving zero-knowledge proof showing that you are a citizen of a specific country or above a specific age without revealing who you are.
Another good use of anonymous identities is being able to prove one’s reputation or scoring without detailing the full history of actions made by one’s account in the past.
Proof of Humanity is an open-source project. You are free to start integrating it into your project or building on top of it as soon as you are ready to do it.
Identities stored in the PoH registry currently are not anonymous. It is however possible to create private Sybil-resistant identities from them. It can be done through the use of or other using zero-knowledge proof mechanisms.
If you need some support, feel free to reach out to Cooperative Kleros at , , .