Udacity Blockchain Capstone

The capstone will build upon the knowledge you have gained in the course in order to build a decentralized housing product.

Install

npm install

Compile

cd into eth-contracts/ directory and execute:

truffle compile

Test

Execute:

truffle test test/TestERC721Mintable.js
truffle test test/TestSquareVerifier.js
truffle test test/TestSolnSquareVerifier.js

or

truffle test to run all tests

ZoKrates (generate zk-Snarks Validator)

Step 1: Run ZoKrates in Docker

docker run -v <path to your project folder>:/home/zokrates/code -ti zokrates/zokrates:0.3.0 /bin/bash

Change directory

cd code/zokrates/code/square/

Step 2: Compile the program written in ZoKrates DSL

../../../../zokrates compile -i square.code

Step 3: Generate the Trusted Setup

../../../../zokrates setup

Step 4: Compute Witness

../../../../zokrates compute-witness -a 3 9

Step 5: Generate Proof

../../../../zokrates generate-proof

Step 6: Export Verifier

../../../../zokrates export-verifier

Deploy to Rinkeby

To deploy the contract, get an Infura API key, and deploy with Truffle:

Update <your infura key> and <your metamask seed> in /eth-contracts/truffle-config.js before migrate to Rinkeby Network.

Run:

truffle deploy --network rinkeby

for more information look at: https://docs.opensea.io/docs/1-structuring-your-smart-contract#section-deploying-your-contract

After deploy:

Token: 0x1637C2f66B26EA5e69e25384Dce1c4648BEE8EC0 Verifier: 0xc494d91825b5FA03f10D4B0aa406a17A2543FBF9

ABI's

Contracts ABI's can be found at: eth-contracts/build/contracts/SolnSquareVerifier.json eth-contracts/build/contracts/SquareVerifier.json eth-contracts/build/contracts/Verifier.json

Mint tokens

After deploying to the Rinkeby network, there will be a contract on Rinkeby that will be viewable on Rinkeby Etherscan (0x1637C2f66B26EA5e69e25384Dce1c4648BEE8EC0). You can find the address of the deployed contract in the output of the deployment command and find it on Etherscan by hitting the URL: https://rinkeby.etherscan.io/address/0x1637C2f66B26EA5e69e25384Dce1c4648BEE8EC0.

You should set this contract address and the address of your MetaMask account as environment variables when running the minting script:

export OWNER_ADDRESS="<my_address>"
export NFT_CONTRACT_ADDRESS="<deployed_contract_address>"
node scripts/mint.js

for more information look at: https://docs.opensea.io/docs/1-structuring-your-smart-contract#section-minting-your-tokens

After mint is complete your OpenSea exchange should list items:

https://rinkeby.opensea.io/category/realestateexchangev5

Project Resources

• Remix - Solidity IDE
• Visual Studio Code
• Truffle Framework
• Ganache - One Click Blockchain
• Open Zeppelin
• Interactive zero knowledge 3-colorability demonstration
• Docker
• ZoKrates