sismo-core/sismo-badges

Sismo Badges is a set of smart contracts, self-executing programs that live on a blockchain, that implement the Sismo Badge Minting Protocol. The protocol allows users to prove things about themselves without revealing private information, using a technique called Zero-Knowledge Proofs (ZKP). A zero-knowledge proof lets you demonstrate that you know or own something (like a wallet address or membership in a group) without exposing the underlying data. The system has three core pieces. The Attestations Registry is a shared database on Ethereum (a blockchain platform) that stores verified claims, called attestations, about users. Attesters are contracts that verify a user's request and write attestations into that registry. Badges are a read-only view of those attestations presented as non-transferable tokens, meaning they are digital badges tied to a specific wallet that cannot be sold or moved. Two specific attester implementations are included. The Hydra S1 Simple Attester requires users to submit a zero-knowledge proof to receive an attestation, using a system called nullifiers to prevent the same proof from being used twice. The Accountbound version lets users later update which wallet address holds their attestation. Developers can extend the protocol by building new custom attesters that inherit from the base Attester contract and implement their own verification logic. Written in TypeScript and Solidity, intended for use on Ethereum.