Striking a balance between invisibility and traceability is a difficult task for systems that protect privacy. Earlier introduced an legitimate user recognition management system based on group signatures for identifying authentic members. The system has no requirements for how the service provider manages user lists or other personally identifiable data. To automatically transfer deposits from clients who don't pay service fees to the server account, smart contracts are employed. To reduce the requirement for pricey cryptographic techniques for managing smart contracts, we use Elliptic Curve Digital Signature Algorithm (ECDSA) signatures without altering the condition that smart contracts must affirm.