Zero-knowledge repayment certificate
Prove you repaid a Loomzk loan in full and on time, without revealing which loan, how much exactly, or your borrowing wallet. The wallet holding the certificate borrows at 8% a year instead of 12%.
What stays private
- • Which loan, and which wallet borrowed
- • The exact amount borrowed and repaid
- • When the loan was opened and closed
What is proven
- • The loan is in Loomzk's on-chain credit tree, which only fully repaid loans enter
- • Repaid in full: principal + interest for the time borrowed (the tree only accepts full, on-time repayments)
- • Closed ≤ 365 days after opening
- • Principal ≥ your chosen threshold
- • One certificate per loan (nullifier)
How it works
- At borrowing. Your browser creates a secret note and sends only its Poseidon commitment to the program.
- At full repayment. The program hashes (commitment, principal, repaid, start, close) into a leaf of an on-chain Poseidon Merkle tree.
- Any time later. You prove membership plus the repayment statement in a Groth16 circuit; the program verifies it and records a certificate for your chosen wallet.