o1js/src/examples/simple-zkapp-berkeley.ts

TypeScript framework for zk-SNARKs and zkApps

/**
 * This is an example for interacting with the Berkeley QANet, directly from o1js.
 *
 * At a high level, it does the following:
 * -) try fetching the account corresponding to the `zkappAddress` from chain
 * -) if the account doesn't exist or is not a zkapp account yet, deploy a zkapp to it and initialize on-chain state
 * -) if the zkapp is already deployed, send a state-updating transaction which proves execution of the "update" method
 */

import {
  Field,
  state,
  State,
  method,
  PrivateKey,
  SmartContract,
  Mina,
  AccountUpdate,
  fetchAccount,
} from 'o1js';

// a very simple SmartContract
class SimpleZkapp extends SmartContract {
  @state(Field) x = State<Field>();

  init() {
    super.init();
    this.x.set(initialState);
  }

  @method async update(y: Field) {
    let x = this.x.getAndRequireEquals();
    y.assertGreaterThan(0);
    this.x.set(x.add(y));
  }
}

// you can use this with any spec-compliant graphql endpoint
let Berkeley = Mina.Network('https://proxy.berkeley.minaexplorer.com/graphql');
Mina.setActiveInstance(Berkeley);

// to use this test, change this private key to an account which has enough MINA to pay fees
let feePayerKey = PrivateKey.fromBase58('EKEQc95PPQZnMY9d9p1vq1MWLeDJKtvKj4V75UDG3rjnf32BerWD');
let feePayerAddress = feePayerKey.toPublicKey();
let response = await fetchAccount({ publicKey: feePayerAddress });
if (response.error) throw Error(response.error.statusText);
let { nonce, balance } = response.account;
console.log(`Using fee payer account with nonce ${nonce}, balance ${balance}`);

// this used to be an actual zkapp that was deployed and updated with this script:
// https://berkeley.minaexplorer.com/wallet/B62qpRzFVjd56FiHnNfxokVbcHMQLT119My1FEdSq8ss7KomLiSZcan
// replace this with a new zkapp key if you want to deploy another zkapp
// and please never expose actual private keys in public code repositories like this!
let zkappKey = PrivateKey.fromBase58('EKFQZG2RuLMYyDsC9RGE5Y8gQGefkbUUUyEhFbgRRMHGgoF9eKpY');
let zkappAddress = zkappKey.toPublicKey();

let transactionFee = 100_000_000;
let initialState = Field(1);

// compile the SmartContract to get the verification key (if deploying) or cache the provers (if updating)
// this can take a while...
console.log('Compiling smart contract...');
let { verificationKey } = await SimpleZkapp.compile();

// check if the zkapp is already deployed, based on whether the account exists and its first zkapp state is !== 0
let zkapp = new SimpleZkapp(zkappAddress);
let x = await zkapp.x.fetch();
let isDeployed = x?.equals(0).not().toBoolean() ?? false;

// if the zkapp is not deployed yet, create a deploy transaction
if (!isDeployed) {
  console.log(`Deploying zkapp for public key ${zkappAddress.toBase58()}.`);
  // the `transaction()` interface is the same as when testing with a local blockchain
  let transaction = await Mina.transaction(
    { sender: feePayerAddress, fee: transactionFee },
    async () => {
      AccountUpdate.fundNewAccount(feePayerAddress);
      await zkapp.deploy({ verificationKey });
    }
  );
  // if you want to inspect the transaction, you can print it out:
  // console.log(transaction.toGraphqlQuery());

  // send the transaction to the graphql endpoint
  console.log('Sending the transaction...');
  await transaction.sign([feePayerKey, zkappKey]).send();
}

// if the zkapp is not deployed yet, create an update transaction
if (isDeployed) {
  let x = zkapp.x.get();
  console.log(`Found deployed zkapp, updating state ${x} -> ${x.add(10)}.`);
  let transaction = await Mina.transaction({ sender: feePayerAddress, fee: transactionFee }, () =>
    zkapp.update(Field(10))
  );
  // fill in the proof - this can take a while...
  console.log('Creating an execution proof...');
  await transaction.prove();

  // if you want to inspect the transaction, you can print it out:
  // console.log(transaction.toGraphqlQuery());

  // send the transaction to the graphql endpoint
  console.log('Sending the transaction...');
  await transaction.sign([feePayerKey]).send();
}