Proof of Humanity is “a system combining webs of trust, with reverse Turing tests, and dispute resolution to create a sybil-proof list of humans.”. The list of humans is publicized on Ethereum & IPFS.
The first step for users is to “claim” their profile, which costs money because it calls the Kleros smart-contracts. A deposit is needed to create an account. The deposit is reimbursed if the registration succeeds (which should happen if and only the new user is a real new human).
In exchange, users can receive “Universal Basic Income”, in a token minted by the Proof of Humanity team. Users can also use their personal proof of humanity to log in to various dApps such as Democracy Earth, by using the Ethereum address associated with their proof.
Advantages
- This is the only proof-of-personhood option we explored that does not require the need of a trusted third-party issuer, instead it is based on a similar trust assumption as Bitcoin: crypto-incentives based on game theory.
Limitations
- The list of humans being publicly available is not privacy-preserving. Especially, since Ethereum is transparent, the financial details of the Ethereum address used for registering to the proof of humanity is associated with the registered profile.
- Usage of the proof-of-personhood is also not privacy-preserving. There is work undergoing to add privacy by leveraging zero-knowledge-proof and Traceable Ring Signature, but it is still at an early stage.
- The Proof of Humanity network is hard to scale, especially because of its cost. It’s hard to convince users to pay to claim an account.
Could it be useful for our requirements?
PoH could be useful in the future to provide a privacy-preserving yet verifiable authentication protocol, at least for pure proof-of-personhood use-cases, if and only if PoH becomes both widely used and credibly privacy-preserving. In that case, PoH could remove the necessary condition of trusting the centralised issuer, that is currently fundamental to the SSI triangle of trust.
