ZK Travel History Management System

Tech Stack

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

Overview

• In the international travel scean, an international traveler would submit and show their passport at the border control at the airport in order for a border protection officer to be able to check their travel history and so on.

  • At this point, the border protection officer would require the international traveler to submit and show their passport. (At this point, If an interanational traveler had stayed in certain countries for a long time beyond the days limit of that these international traveler can stay the country, the border protection officer may refuse that the international traveler enter their country)

  • However, some of information-written in the passport may not be needed for the border protection officer to check the international traveler's travel history and so on.

• This project ("ZK Travel History Management System") can solve this problem by using combination of the ZK (Zero-Knowledge) circuit and the Smart Contract on Blockchain.

  • 1/ Everytime an international traveler would depart from an airport in abroad, the international traveler would generate a travel history ZK proof, which includes information of a country they stayed and an enter/exit date of the country, via the ZK circuit.

  • 2/ When an international traveler would arrived at an airport in abroad and come to the checkpoint of the border control, the international traveler would submit the travel history ZK proof, which was generated when the step 1/, to the TravelHistoryManager contract (TravelHistoryManager.sol) - instead of submitting their passport to the border protection officer.

  • 3/ The border protection officer can validate whether or not the travel history of the international traveler has no problem without seeing all data from the passport. Also, the international traveler can efficiently be approved without revealing all data by submitting the passport.

• The TravelHistoryManager contract (TravelHistoryManager.sol) is supposed to be deployed by the border protection/control authority of each country.

  • Since the requirement of the travel history is different depends on country, a border protection/control authority of an country is supposed to modify the validation in the TravelHistoryManager contract and deploy it on blockchain (Electroneum Testnet).

  • i.e). In the example TravelHistoryManager contract (TravelHistoryManager.sol) deployed on Electroneum Testnet, the validation to check whether or not an international traveler stay in the Schengen Area beyond 90 days limit.

• NOTE:

  • This project would focus on a travel history. In the future, other items should be added.
  • In this project, the Electroneum Testnet would be used as a blockchain where the Smart Contracts for this project are deployed.

Demo Video

• https://youtu.be/qBIm-d0m_LY?si=mHVC4JvtmZgZUPjP

Deployed-smart contracts on Electroneum Testnet

Contract Name	Descripttion	Deployed-contract addresses on Electroneum Testnet
UltraVerifier	The UltraPlonk Verifer contract (./circuits/target/contract.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.	0x0A95E7Fc5c292eCe47893E63A1380f08a061814A
TravelHistoryProofVerifier	The smart contract that enable to validate whether or not a proof-submitted is valid.	0xE82595069b66064345f8EeB162e3c4e2F4cED704
TravelHistoryManager	The example smart contract that enable to validate whether or not a travel history proof-submitted is valid and validate whether or not the traveler breach the days limit of staying a country	0xED169AF4E8d68d167B8c7bf66f241f30B8cA8083

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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

• 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.

ZK circuit - Test

• Run the circuit_test.sh to test the ZK circuit.

cd circuits
sh circuit_test.sh

Smart Contract - Compile

• Compile the smart contracts

sh ./buildContract.sh

Smart Contract - Test on Local Network / Electroneum Testnet

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

sh ./test/runningTest_TravelHistoryProofVerifier.sh

• Run the test of the TravelHistoryProofVerifierOnElectroneumTestnet.t.sol, which is the test file of the TravelHistoryProofVerifier.sol on Electroneum Testnet.

sh ./test/electroneum-testnet/runningTest_TravelHistoryProofVerifierOnElectroneumTestnet.sh

Smart Contract - Script on Electroneum Testnet

• Run the script of the TravelHistoryProofVerifier.s.sol, which is the test file of the TravelHistoryProofVerifier.sol on Electroneum Testnet.

sh ./script/electroneum-testnet/runningScript_TravelHistoryProofVerifier.sh

Smart Contract - Deployment (on Electroneum Testnet)

• NOTE: Each Smart Contract has been deployed on Electroneum 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 ELECTRONEUM_TESTNET_PRIVATE_KEY.

cp .env.example .env

• 2/ Deploy all contracts on Electroneum Testnet by running the script/electroneum-testnet/deployment/DeploymentAllContracts.s.sol

sh ./script/electroneum-testnet/deployment/deployment-on-electroneum-testnet.sh

Or, directly executing the following command:

# [NOTE]: Execute the following at the root directory.

forge script script/electroneum-testnet/deployment/DeploymentAllContracts.s.sol --broadcast --private-key ${ELECTRONEUM_TESTNET_PRIVATE_KEY} \
    ./circuits/target/contract.sol:UltraVerifier \
    ./TravelHistoryProofVerifier.sol:TravelHistoryProofVerifier \
    ./TravelHistoryManager.sol:TravelHistoryManager --skip-simulation --legacy

# [NOTE - Adding the "--legacy" option]: Due to this error - Error: Failed to estimate EIP1559 fees. This chain might not support EIP1559, try adding --legacy to your command.

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

• Electroneum:

  • Block Explorer (on Electroneum Testnet): https://blockexplorer.thesecurityteam.rocks
  • Doc (icl. RPC, etc): https://developer.electroneum.com/electroneum-stack/metamask
  • Fancet: https://faucet.electroneum.com/