Postino

Postino is a secure way to manage document signatures with verified identity through WorldCoin proofs and attestations. It starts with users uploading their documents to IPFS, where they can customize invitations and set the required signatures. Participants then verify their identity using WorldCoin and sign the document through off-chain attestations. Once all signatures are collected, an on-chain attestation is created on Optimism to provide a tamper-proof and verifiable record. This project combines the best of decentralized identity verification and blockchain technology to offer a reliable solution for document signing.

Postino was built using a combination of cutting-edge technologies designed to ensure both security and efficiency while minimizing user friction. The core components include the Ethereum Attestation Service (EAS) for managing attestations, with a designated "attestor" overseeing the attestation process. WorldCoin is used for secure identity verification, setting a Zero-Knowledge (ZK) proof once the identity is verified, allowing for privacy-preserving actions. Documents are uploaded to IPFS (InterPlanetary File System) for decentralized storage, ensuring they are accessible yet tamper-proof. To streamline the user experience, Postino eliminates the need for signatures or gas fees from participants. Instead, once users verify their identity through WorldCoin, a ZK proof is generated, allowing them to sign document attestations seamlessly. This process is facilitated by EAS and managed by the attestor. Additionally, we've implemented an email sign-in option using Alchemy's account kit, further simplifying access without compromising security. Finally, signatures and identity proofs are summarized and recorded on-chain using the Optimism blockchain, leveraging its speed and scalability. This approach ensures a seamless and secure document signing experience while maintaining the integrity and trustworthiness of the Ethereum ecosystem.