zkREX

Problem Statement

zkREX is a privacy-preserving compliance layer for tokenized assets. Users complete zero-knowledge KYC with Self Protocol, proving they are over 18, not sanctioned, and from approved countries; without revealing personal data. Once eligible, users can buy and transfer our T-Rex Token on Oasis Sapphire, where balances and transaction amounts remain fully private thanks to confidential execution. vLayer adds optional zkTLS proofs such as proof of address or proof of funds, giving richer compliance checks without exposing sensitive information. Privy provides seamless wallet onboarding so users can interact with the system instantly.zkREX demonstrates how RWAs can become both compliant and private.

Solution

zkREX combines Self Protocol, Oasis Sapphire, vLayer, and Privy into a single zero-knowledge compliance pipeline. We built a custom eligibility gateway contract on Oasis that verifies Self’s onchain proofs for age, country, and sanctions using their SDK. Once a user passes zkKYC, the contract marks their Privy wallet as eligible to interact with our confidential T-Rex Token. The token itself is deployed on Oasis Sapphire, which gives us private balances and confidential transaction execution out of the box, meaning transfers and holdings are never visible on public state.We integrated vLayer’s zkTLS stack to optionally add proof-of-address and proof-of-funds, using their Web Prover server to generate TLSNotary proofs and compress them into ZKPs we can verify onchain. Privy was used to make onboarding trivial: email login → wallet → zkKYC → private token trading.The “hacky but elegant” part was bridging Self’s onchain verification on Celo with Oasis, and building a lightweight proof-relay pattern so our Sapphire contracts can trust Self’s Merkle tree commitments. Everything runs as modular components, allowing us to stack identity proofs, TLS proofs, and confidential execution into one seamless flow.