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Integrate Web3Auth with the StarkEx Blockchain

While using the Web3Auth Web SDK for a non-EVM chain like StarkEx you get a standard provider from which you can get the private key of the user. Using this private key, you can use the corresponding libraries of the blockchain to make blockchain calls like getting the user's account, fetch balance, sign transaction, send transaction, read from and write to the smart contract, etc. We have highlighted a few methods here to get you started quickly on that.

note

This reference is for the Web, however, you can use StarkEx on other Mobile and Gaming Platforms as well. Please follow our reference for EVM Blockchains, and similarly use StarkEx libraries that support the platforms to use the private key and make blockchain calls accordingly.

Installation​

npm install --save web3 bn.js elliptic @starkware-industries/starkex-js @starkware-industries/starkware-crypto-utils

Initializing Provider​

Getting the chainConfig​

const chainConfig = {
  chainNamespace: "other",
  chainId: "0x1", //
  rpcTarget: "https://rpc.ankr.com/eth",
  // Avoid using public rpcTarget in production.
  displayName: "StarkEx Mainnet",
  blockExplorerUrl: "https://etherscan.io",
  ticker: "STARK",
  tickerName: "StarkEx",
};

Initializing and instantiating the Web3Auth SDK​

import { Web3Auth } from "@web3auth/modal";
import { CommonPrivateKeyProvider } from "@web3auth/base-provider";
import { WEB3AUTH_NETWORK } from "@web3auth/base";

const privateKeyProvider = new CommonPrivateKeyProvider({
  config: { chainConfig: chainConfig }
});

const web3auth = new Web3Auth({
  // Get it from Web3Auth Dashboard
  clientId,
  web3AuthNetwork: WEB3AUTH_NETWORK.SAPPHIRE_MAINNET,
  privateKeyProvider: privateKeyProvider,
});

Get User Info​

After logging in, the Web3Auth instance will provide you with information regarding the user that is logged in. This information is obtained directly from the JWT token and is not stored by Web3Auth. Therefore, this information can only be accessed through social logins after the user has logged into your application.

const user = await web3auth.getUserInfo(); // web3auth instance

Get Account and Key​

Once a user logs in, the Web3Auth SDK returns a provider. Even though StarkEx is a layer 2 on Ethereum, it is not EVM compatible. Hence to use it, one cannot use the native EIP1193 provider that Web3Auth gives for EVM blockchains. Hence we need to directly use the private key to make the calls.

Using the function, web3auth.provider.request({method: "private_key"}) from Web3Auth provider, the application can have access to the user's private key. However, we cannot use this key with StarkEx EC Curve specific signing functions, hence, we first derive the Stark Key using the getStarkKey() function.

On the underhood, it uses the starkwareCrypto.ec.keyFromPrivate() function, where we pass our Private key with the hex argument, since it is hex encoded. Further we get the public key from this using the starkwareCrypto.ec.keyFromPublic() function, and we take its X-coordinate using .pub.getX() which is our starkKey. We use this starkKey on StarkEx transactions.

import starkwareCrypto from "@starkware-industries/starkware-crypto-utils";
import { ec as elliptic } from "elliptic";
/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: "private_key" });
const keyPair = starkwareCrypto.ec.keyFromPrivate(privateKey, "hex");
// get the account address from the public key
const account = starkwareCrypto.ec.keyFromPublic(keyPair.getPublic(true, "hex"), "hex");

// Use this key for the StarkEx transactions
const startKey = account.pub.getX().toString("hex");

Mint Request​

import StarkExAPI from "@starkware-industries/starkex-js/dist/browser";
import starkwareCrypto from "@starkware-industries/starkware-crypto-utils";
import { ec as elliptic } from "elliptic";

const starkExAPI = new StarkExAPI({
  endpoint: "https://gw.playground-v2.starkex.co",
});

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: "private_key" });
const keyPair = starkwareCrypto.ec.keyFromPrivate(privateKey, "hex");
// get the account address from the public key
const account = starkwareCrypto.ec.keyFromPublic(keyPair.getPublic(true, "hex"), "hex");

// Use this key for the StarkEx transactions
const startKey = account.pub.getX().toString("hex");

const txId = await starkExAPI.gateway.getFirstUnusedTxId();

const request = {
  txId,
  vaultId: 1654615998,
  amount: "6",
  tokenId: "0x400de4b5a92118719c78df48f4ff31e78de58575487ce1eaf19922ad9b8a714",
  starkKey: `0x${starkKey}`,
};
const response = await starkExAPI.gateway.mint(request);

Deposit Request​

import StarkExAPI from "@starkware-industries/starkex-js/dist/browser";
import starkwareCrypto from "@starkware-industries/starkware-crypto-utils";
import { ec as elliptic } from "elliptic";

const starkExAPI = new StarkExAPI({
  endpoint: "https://gw.playground-v2.starkex.co",
});

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: "private_key" });
const keyPair = starkwareCrypto.ec.keyFromPrivate(privateKey, "hex");
// get the account address from the public key
const account = starkwareCrypto.ec.keyFromPublic(keyPair.getPublic(true, "hex"), "hex");

// Use this key for the StarkEx transactions
const startKey = account.pub.getX().toString("hex");

const txId = await starkExAPI.gateway.getFirstUnusedTxId();

const request = {
  txId,
  amount: 8,
  starkKey: `0x${starkKey}`,
  tokenId: "0x3ef811e040c4bc9f9eee715441cee470f5d5aff69b9cd9aca7884f5a442a890",
  vaultId: 1924014660,
};
const response = await starkExAPI.gateway.deposit(request);

Withdraw Request​

import StarkExAPI from "@starkware-industries/starkex-js/dist/browser";
import starkwareCrypto from "@starkware-industries/starkware-crypto-utils";
import { ec as elliptic } from "elliptic";

const starkExAPI = new StarkExAPI({
  endpoint: "https://gw.playground-v2.starkex.co",
});

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: "private_key" });
const keyPair = starkwareCrypto.ec.keyFromPrivate(privateKey, "hex");
// get the account address from the public key
const account = starkwareCrypto.ec.keyFromPublic(keyPair.getPublic(true, "hex"), "hex");

// Use this key for the StarkEx transactions
const startKey = account.pub.getX().toString("hex");

const txId = await starkExAPI.gateway.getFirstUnusedTxId();

const request = {
  txId,
  amount: 8,
  starkKey: `0x${starkKey}`,
  tokenId: "0x2dd48fd7a024204f7c1bd874da5e709d4713d60c8a70639eb1167b367a9c378",
  vaultId: 612008755,
};
const response = await starkExAPI.gateway.withdrawal(request);