ZK Mortgage Agreement Manager

Tech Stack

• ZK circuit: Written in Noir powered by Aztec)
• Smart Contract: Written in Solidity (Framework: Foundry)
• Blockchain: Sonic (Testnet)

Overview

• This is the ZK Mortgage Agreement Manager, which is the Zero-Knowledge based mortgage loan agreement management system that consists of the ZK circuits and the smart contracts.

• In the real estate space, when a borrower would borrow a mortgage loan to buy a house via a real estate agency, the following scenario will be proceeded:

  • 1/ A borrower will submit some financial documents (i.e. Employment verification letter) to a real estate agency for showing their finantial profile (i.e income, tax returns, etc).
  • 2/ Also, the real estate company would ask a credit score provider (i.e. FICO) the borrower's credit score and retrieve it as the borrower's finantial profile.
  • 3/ The real estate company would send these finantial profile (i.e. income, credit score) to a lender (i.e. Bank, Morgage Loan company, etc) as a morgage loan request.
  • 4/ Once the borrower's morgage loan request would be approved by the lender, the mortgage agreement would be created through the real estate agency (or the lender).

• The problem of the general mortgage loan process via a real estate agency above is that the real estate agency (and the lender) can see all of the borrower's informations, which includes the sensitive informations or/and unnecessity informations.

  • This project (ZK Mortgage Agreement Manager) can resolve these problem by the combination of the ZK circuits and the smart contracts as a privacy-preserving way.
  • By using this project (ZK Mortgage Agreement Manager), a borrower can submit a mortgate loan request to a lender via a real estate agency without revealing their sensitive informations or/and unnecessity informations.

Deployed-smart contracts on Sonic Testnet

Contract Name	Descripttion	Deployed-contract addresses on Sonic Testnet
UltraVerifier (for the EmploymentVerificationLetterProof)	The UltraPlonk Verifer contract for the EmploymentVerificationLetterProof (./employer/contracts/circuit/plonk_vk.sol), which is generated based on ZK circuit in Noir (./circuits/src/main.nr). FYI: To generated this contract, the way of the Noir's Solidity Verifier generation was used.	0x621dbc8010E0d5Aa2b11a5103c9833eC94a70E39
EmploymentVerificationLetterProofVerifier	The smart contract that enable to validate whether or not a EmploymentVerificationLetterProof-submitted is valid.	0xEd1324385Fe64c83687C3f9576F3210c6B8E309E
UltraVerifier (for the FICOCreditScoreProof)	The UltraPlonk Verifer contract for the EmploymentVerificationLetterProof (./FICO/contracts/circuit/plonk_vk.sol), which is generated based on ZK circuit in Noir (./circuits/src/main.nr). FYI: To generated this contract, the way of the Noir's Solidity Verifier generation was used.	0xEa8EB5CFf49241B39950c31f788AEF8E0d4Df1c1
FICOCreditScoreProofVerifier	The smart contract that enable to validate whether or not a EmploymentVerificationLetterProof-submitted is valid.	0x20a414abEcFe31DD27Aa7FcCC353a505E976D277
UltraVerifier (for the MortgageAffordabilityProof)	The UltraPlonk Verifer contract for the EmploymentVerificationLetterProof (./borrower/contracts/circuit/plonk_vk.sol), which is generated based on ZK circuit in Noir (./circuits/src/main.nr). FYI: To generated this contract, the way of the Noir's Solidity Verifier generation was used.	0x2317106a73E00fc66AB25aD50979CFf140075b2b
MortgageAffordabilityProofVerifier	The smart contract that enable to validate whether or not a MortgageAffordabilityProof-submitted is valid.	0x7a2E68d1d1bB79dBc945801A02Bd6e17d0842457
MortgageAgreementManager	The smart contract that enable a borrower to create a request of the mortgage agreement /w three ZK proofs (EmploymentVerificationLetterProof, FICOCreditScoreProof, MortgageAffordabilityProof) and enable a lender to accept these request	0x0A95E7Fc5c292eCe47893E63A1380f08a061814A

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Installations

Installation - Smart contract

• Install libraries (NOTE: Before this installation, all folders should be removed under the ./lib directory)

forge install OpenZeppelin/openzeppelin-contracts
forge install 0xnonso/foundry-noir-helper

ZK circuit - Generate (Prove) an Ultraplonk Proof in Noir

There are three ZK circuits in total. For three ZK circuits in the three directory (./employer/circuits, ./FICO/circuits, ./borrower/circuits) respectively, the following installation should be done:

• 1/ Move to the ./circuits directory:

cd circuits

• 2/ Create the Prover.toml file by coping the example file (Prover.example.toml) in the ./circuits directory.

cp Prover.example.toml Prover.toml

• 3/ Write the input data should be written in the Prover.toml.

• 4/ Run the build.sh to run ZK circuit

sh build.sh

• 5/ The UltraVerifier contract (contract.sol) and proof and vk in Noir would be generated under the ./circuits/target.
  • The UltraVerifier contract (contract.sol) is automatically copied to the /contracts/circuit as the plonk_vk.sol

ZK circuit - Test

• Run the circuit_test.sh to test the ZK circuit in the ./employer/circuits.

cd employer/circuits
sh circuit_test.sh

• Run the circuit_test.sh to test the ZK circuit in the ./FICO/circuits.

cd FICO/circuits
sh circuit_test.sh

• Run the circuit_test.sh to test the ZK circuit in the ./borrower/circuits.

cd borrower/circuits
sh circuit_test.sh

Smart Contract - Compile

There are three components of the smart contracts in total. For three type of the smart contracts in the three directory (./employer/contracts, ./FICO/contracts, ./borrower/contracts) respectively, the following installation should be done:

• Compile the smart contracts

cd employer or FICO or borrower
sh ./buildContract.sh

Smart Contract - Test on Local Network / Sonic Testnet

There are three components of the smart contract tests in total. For three components of the smart contracts in the three directory (./employer/test, ./FICO/test, ./borrower/test) respectively, the following installation should be done:

• Run the test of the EmploymentVerificationLetterProofVerifier.t.sol, which is the test file of the EmploymentVerificationLetterProofVerifier.sol on Local Network.

cd employer
sh ./test/runningTest_EmploymentVerificationLetterProofVerifier.sh

• Run the test of the EmploymentVerificationLetterProofVerifierOnSonicTestnet.t.sol, which is the test file of the EmploymentVerificationLetterProofVerifier.sol on Sonic Testnet.

cd employer
sh ./test/sonic-testnet/runningTest_EmploymentVerificationLetterProofVerifierOnSonicTestnet.sh

• Run the test of the FICOCreditScoreProofVerifier.t.sol, which is the test file of the EFICOCreditScoreProofVerifier.sol on Local Network.

cd FICO
sh ./test/runningTest_FICOCreditScoreProofVerifier.sh

• Run the test of the FICOCreditScoreProofVerifierOnSonicTestnet.t.sol, which is the test file of the FICOCreditScoreProofVerifier.sol on Sonic Testnet.

cd FICO
sh ./test/sonic-testnet/runningTest_EmploymentVerificationLetterProofVerifierOnSonicTestnet.sh

• Run the test of the MortgageAffordabilityProofVerifier.t.sol, which is the test file of the MortgageAffordabilityProofVerifier.sol on Local Network.

cd borrower
sh ./test/runningTest_MortgageAffordabilityProofVerifier.sh

• Run the test of the MortgageAffordabilityProofVerifierOnSonicTestnet.t.sol, which is the test file of the MortgageAffordabilityProofVerifier.sol on Sonic Testnet.

cd borrower
sh ./test/sonic-testnet/runningTest_MortgageAffordabilityProofVerifierOnSonicTestnet.sh

• Run the test of the MortgageAgreementManagerOnSonicTestnet.t.sol, which is the test file of the MortgageAgreementManager.sol on Sonic Testnet.
  (NOTE: This test is still in progress)

cd borrower
sh ./test/sonic-testnet/runningTest_MortgageAgreementManagerOnSonicTestnet.sh

Smart Contract - Script on Sonic Testnet

• Run the script of the EmploymentVerificationLetterProofVerifier.s.sol, which is the test file of the EmploymentVerificationLetterProofVerifier.sol on Sonic Testnet.

cd employer
sh ./script/sonic-testnet/runningScript_EmploymentVerificationLetterProofVerifier.sh

• Run the script of the FICOCreditScoreProofVerifier.s.sol, which is the test file of the UltraVerifier.sol on Sonic Testnet.

cd FICO
sh ./script/sonic-testnet/runningScript_FICOCreditScoreProofVerifier.sh

• Run the script of the MortgageAffordabilityProofVerifier.s.sol, which is the test file of the UltraVerifier.sol on Sonic Testnet.

cd borrower
sh ./script/sonic-testnet/runningScript_MortgageAffordabilityProofVerifier.sh

Smart Contract - Deployment (on Sonic Testnet)

• NOTE: Each Smart Contract has been deployed on Sonic Testnet. See the "Deployed-smart contracts onSonic Testnet" paragraph above in this README.

• 1/ Create the .env file by coping the example file (.env.example) in the root directory.

  • Then, you should add a private key of your deployer address to the SONIC_BLAZE_TESTNET_PRIVATE_KEY /or the ELECTRONEUM_TESTNET_PRIVATE_KEY.

cd employer or FICO or borrower
cp .env.example .env

• 2/ Deploy all contracts on Sonic Testnet by running the script/DeploymentAllContracts.s.sol

cd employer
sh ./script/sonic-testnet/deployment/deployment-on-sonic-testnet.sh

cd FICO
sh ./script/sonic-testnet/deployment/deployment-on-sonic-testnet.sh

cd borrower
sh ./script/sonic-testnet/deployment/deploymentScript_MortgageAffordabilityProofVerifier.sh
sh ./script/sonic-testnet/deployment/deploymentScript_MortgageAgreementManager.sh

References and Resources

• Noir:

  • Doc: https://noir-lang.org/docs/getting_started/quick_start
  • noir-starter (for Foundry): https://github.com/AztecProtocol/noir-starter/tree/main/with-foundry

• Sonic:

  • Block Explorer (on Sonic Testnet): https://testnet.sonicscan.org/
  • Doc (icl. RPC, etc): https://docs.soniclabs.com/sonic/build-on-sonic/getting-started
  • Fancet: https://testnet.soniclabs.com/account