Proof of personhood is a specific form of sybil-resistance that assigns a single pseudonymous identity to each individual that interacts with a protocol, without requiring a central authority. Essentially, its usage would be similar to a government-issued ID or SSN, except it doesn’t necessarily have to remain consistent between protocols, wouldn’t require citizenship of any kind, and shouldn’t publicly reveal information that could compromise a user’s privacy.
Some protocols get around this by using other forms of identification, such as cell phone numbers, but this just outsources the difficult part without truly solving the problem.
Is it theoretically possible to anonymously identify users in a trustless manner?
Yes, check out https://idena.io
Tldr; Basically, everyone has to solve a set of AI resistant visual puzzles at the same time to prove they are a unique human.
By solving the puzzle, you prove that your are human. You have a limited window in which to solve the puzzle, so you should not be able to manage to complete the puzzle with two identities at once. This proves that your are a *unique* human.
Between validation ceremonies, you must make the puzzles for other humans to solve the next month.
After you solve the puzzles, you verify the quality of a collection of other puzzles that were presented to others for their test. These results are synthesized with other submissions to achieve consensus on who is human.
Anonymous proof of personhood, as long as it remains ai resistant.
I stumbled across this protocol called zkMe. They use zero-knowledge to do anonymous zkKYC and zk proof-of-personhood: http://www.zk.me
No.
At some level, there must be an entity that can write to the state of the blockchain and verify the identity. If you use SSN, there’s a government entity that’s the gatekeeper. If it’s an eyeball scanning orb then there’s a company that has to manufacture and QA them as well as being trusted to have write access to the chain.
It’s a fool’s errand, there’s no way for this to be trustless as much as any vested person would have you believe. Blockchains need to be permissionless