Source: https://vitalik.eth.limo/general/2023/07/24/biometric.html
Proof of personhood, "unique-human problem", to identify a real person without revealing which real person it is.
Related projects:
Sismo(Zero-knowledge),
Worldcoin(co-founded by Sam Altman, using a piece of specialized hardware called "the Orb" to scan user's iris).
Issues:
Privacy issues: technology to solve this, zero knowledge proof
Accessibility issues: Proof of Humanity (using only a smartphone)
Centralization issues:
1,Centralization risks in the system's top-level governance (esp. the system that makes final top-level resolutions if different actors in the system disagree on subjective judgements).
2,Centralization risks unique to systems that use specialized hardware.
3,Centralization risks if proprietary algorithms are used to determine who is an authentic participant.
Security issues:
3D-printed fake people
Possibility of selling IDs
Phone hacking
Government coercion to steal IDs
Others:
Social graph-based verification:
Proponents:
not rely on special-purpose hardware
avoids a permanent arms race
not require collecting biometric data
potentially more friendly to pseudonymity
give a more nuanced numerical score,
weaknesses:
not get lucky in the initial bootstrapping process.
Privacy, leaking info about a person's social relationships
Inequality, a wealthy and socially well-connected person could use their connections to generate many IDs
Risk of collapse into centralization
| Social-graph-based | General-hardware biometric | Specialized-hardware biometric | |
| Privacy | Low | Fairly low | Fairly high |
| Accessibility / scalability | Fairly low | High | Medium |
| Robustness of decentralization | Fairly high | Fairly high | Fairly low |
| Security against "fake people" | High (if done well) | Low | Medium |