ZK-Pal

ZK-Pal - Crypto On/Off-Ramps via PayPal

Reinventing Crypto Access: A Decentralized Peer-to-Peer PayPal Exchange

Access to cryptocurrencies is becoming increasingly restrictive. Users must now go through centralized exchanges, complete KYC procedures, and wait for validation. ZK-Pal aims to restore trustless peer-to-peer exchange using PayPal as a fiat bridge.

Our objective is to offer an alternative aligned with the foundational principles of blockchain: decentralization and peer-to-peer exchange. By leveraging an existing payment system like PayPal, we aimed to enable users to buy and sell crypto without relying on centralized intermediaries. Through this project, we introduce an on-ramp/off-ramp mechanism where users can create and fulfill USDC offers in exchange for PayPal transfers.

The process begins when a user creates an offer on a smart contract deployed on Oasis Sapphire. This contract allows the user to lock a specified amount of USDC and securely store sensitive information, such as their PayPal handle, using Sapphire’s confidential features. Another user, interested in purchasing the USDC, can subscribe to this offer through the contract. After subscribing, the buyer must send the agreed amount via PayPal to the seller and retrieve the confirmation email from PayPal for this transaction.

The buyer forwards the PayPal confirmation email to a dedicated email address, accessible only by ROFL container. This container operates within a trusted execution environment (TEE) using Oasis's ROFL system. Its role is to automatically fetch incoming emails, verify their authenticity, extract the relevant details—such as the PayPal handle and transferred amount—and, upon successful validation, interact with the Sapphire smart contract to release the locked USDC to the buyer.

Issues raised:
https://github.com/oasisprotocol/demo-rofl-chatbot/issues/18
https://github.com/oasisprotocol/oasis-sdk/issues/2211