OneOfUs: an anonymous survey/voting dApp built on POAP and Semaphore built for DevCon 5

OneOfUs lets you ask questions to attendees of Devcon 5, and lets them, and only them, reply anonymously.

How it works

<img src="./screenshot.png" width=500 />

Each attendee at Devcon 5 will receive a non-fungible Proof of Attendance Token (POAP). We assume that only Devcon 5 attendees own POAP tokens associated with this event.

Attendees can register themselves to the contract as long as they own a Devcon 5 POAP token. When they wish to respond to a question, they can use OneOfUs to generate a proof of their initial registration. This proof does not reveal their identity, but only their membership in the set of registered identities.

For my workshop at Devcon, posting questions and answers are done entirely off-chain, so that participants won't have to pay any gas except for identity registration. The smart contract, however, already supports the ability for registered users to post and answer questions.

Like the smart contract which keeps track of nullifier hashes and rejects double signalling, the off-chain backend prevents double-voting.

The contract requires users to pay extra ETH when they as a question, and these funds are used to pay Surrogeth relayers to submit proofs on behalf of users when they wish to answer questions.

Under the hood, OneOfUs uses Semaphore, a zero-knowledge signalling gadget. Read more about it here.

Please note that the version of Semaphore that OneOfUs uses is outdated. If you wish to implment a voting app in Semaphore, please use the latest version.