Protocol Kit

Protocol Kit

The Protocol Kit (opens in a new tab) enables developers to interact with the Safe contracts (opens in a new tab) using a TypeScript interface. This Kit can be used to create new Safe accounts, update the configuration of existing Safes, propose and execute transactions, among other features.

Quickstart

In this quickstart guide, you will create a 2 of 3 multi-sig Safe and propose and execute a transaction to send some ETH out of this Safe.

For a more detailed guide, including how to integrate with web3.js and more Safe transaction configuration options, see Guide: Integrating the Protocol Kit and API Kit (opens in a new tab) and Protocol Kit Reference (opens in a new tab).

Prerequisites

  1. Node.js and npm (opens in a new tab)
  2. Three externally-owned accounts with Testnet ETH in at least one account

Install dependencies

First, we need to install some dependencies from safe-core-sdk and the ethers library.

To interact with Ethereum and other EVM blockchains in Node, we can either use: web3.js or ethers.js. In this tutorial, we will use the ethers.js library. To use web3js, see Instantiate an EthAdapter section in Guide: Integrating the Safe Core SDK (opens in a new tab).

The Protocol Kit is compatible only with ethers.js v6. Make sure you specify this version when installing the SDK.

You can store your environment variables such as private keys in a .env file. To read easily from .env files, use the dotenv library.

yarn add ethers @safe-global/protocol-kit \
  @safe-global/api-kit \
  @safe-global/safe-core-sdk-types \
  dotenv

Create the .env file:

touch .env

Put your signing account private keys into the .env file you just created.

export OWNER_1_PRIVATE_KEY='<PRIVATE_KEY>'
export OWNER_2_PRIVATE_KEY='<PRIVATE_KEY>'
export OWNER_3_PRIVATE_KEY='<PRIVATE_KEY>'

Create an index.ts file that you will use to run the following code snippets.

touch index.ts

Tip: Use ts-node (opens in a new tab) to run a Typescript file in Node.js.

npx ts-node examples/protocol-kit/index.ts

Initialize Signers, Providers, and EthAdapter

The signers trigger transactions to the Ethereum blockchain or off-chain transactions. The provider connects to the Ethereum blockchain.

You can get a public RPC URL from Chainlist (opens in a new tab), however, public RPC URLs can be unreliable so you can also try a dedicated provider like Infura or Alchemy.

For this tutorial, we will be creating a Safe on the Sepolia Testnet.

import { ethers } from 'ethers'
import { EthersAdapter } from '@safe-global/protocol-kit'
import dotenv from 'dotenv'
 
dotenv.config()
 
// https://chainlist.org/?search=sepolia&testnets=true
const RPC_URL='https://eth-sepolia.public.blastapi.io'
const provider = new ethers.JsonRpcProvider(RPC_URL)
 
// Initialize signers
const owner1Signer = new ethers.Wallet(process.env.OWNER_1_PRIVATE_KEY!, provider)
const owner2Signer = new ethers.Wallet(process.env.OWNER_2_PRIVATE_KEY!, provider)
const owner3Signer = new ethers.Wallet(process.env.OWNER_3_PRIVATE_KEY!, provider)
 
const ethAdapterOwner1 = new EthersAdapter({
  ethers,
  signerOrProvider: owner1Signer
})

Initialize the API Kit

The API Kit (opens in a new tab) consumes the Safe Transaction Service API (opens in a new tab). To use this library, create a new instance of the SafeApiKit class, imported from @safe-global/api-kit. In chains where Safe provides a Transaction Service, it's enough to specify the chainId. You can specify your own service using the optional txServiceUrl parameter.

You will be using Sepolia for this tutorial, however, you can also get service URLs for different networks.

import SafeApiKit from '@safe-global/api-kit'
 
const apiKit = new SafeApiKit({
  chainId: 1n
})
 
 
// or using a custom service
const apiKit = new SafeApiKit({
  chainId: 1n, // set the correct chainId
  txServiceUrl: 'https://url-to-your-custom-service'
})

Initialize the Protocol Kit

Sepolia is a supported network so you don't need to specify the contract addresses, however, to see how to create a safe on a local or unsupported network, see Instantiate an EthAdapter (opens in a new tab).

Safe Factory is used to create Safes. While Safe class represents an instance of a specific Safe account.

import { SafeFactory } from '@safe-global/protocol-kit'
 
const safeFactory = await SafeFactory.create({ ethAdapter: ethAdapterOwner1 })

Deploy a Safe

Calling the deploySafe method will deploy the desired Safe and return a Protocol Kit initialized instance ready to be used. Check the API Reference (opens in a new tab) for more details on additional configuration parameters and callbacks.

import { SafeAccountConfig } from '@safe-global/protocol-kit'
 
const safeAccountConfig: SafeAccountConfig = {
  owners: [
    await owner1Signer.getAddress(),
    await owner2Signer.getAddress(),
    await owner3Signer.getAddress()
  ],
  threshold: 2,
  // ... (Optional params)
}
 
/* This Safe is tied to owner 1 because the factory was initialized with
an adapter that had owner 1 as the signer. */
const protocolKitOwner1 = await safeFactory.deploySafe({ safeAccountConfig })
 
const safeAddress = await protocolKitOwner1.getAddress()
 
console.log('Your Safe has been deployed:')
console.log(`https://sepolia.etherscan.io/address/${safeAddress}`)
console.log(`https://app.safe.global/sep:${safeAddress}`)

Send ETH to the Safe

You will send some ETH to this Safe.

const safeAddress = protocolKit.getAddress()
 
const safeAmount = ethers.parseUnits('0.01', 'ether').toHexString()
 
const transactionParameters = {
  to: safeAddress,
  value: safeAmount
}
 
const tx = await owner1Signer.sendTransaction(transactionParameters)
 
console.log('Fundraising.')
console.log(`Deposit Transaction: https://sepolia.etherscan.io/tx/${tx.hash}`)

Making a transaction from a Safe

The first signer will sign and propose a transaction to send 0.005 ETH out of the Safe. Then, the second signer will add their own proposal and execute the transaction since it meets the 2 of 3 thresholds.

At a high level, making a transaction from the Safe requires the following steps:

Overview

The high-level overview of a multi-sig transaction is PCE: Propose. Confirm. Execute.

  1. First signer proposes a transaction
    1. Create transaction: define the amount, destination, and any additional data
    2. Perform an off-chain signature of the transaction before proposing
    3. Submit the transaction and signature to the Safe Transaction Service
  2. Second signer confirms the transaction
    1. Get pending transactions from the Safe service
    2. Perform an off-chain signature of the transaction
    3. Submit the signature to the service
  3. Anyone executes the transaction
    1. In this example, the first signer executes the transaction
    2. Anyone can get the pending transaction from the Safe service
    3. Account executing the transaction pays the gas fee

Create a transaction

For more details on what to include in a transaction see Create a Transaction in the Safe Core SDK Guide (opens in a new tab).

import { MetaTransactionData } from '@safe-global/safe-core-sdk-types'
 
// Any address can be used. In this example you will use vitalik.eth
const destination = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045'
const amount = ethers.parseUnits('0.005', 'ether').toString()
 
const safeTransactionData: MetaTransactionData = {
  to: destination,
  data: '0x',
  value: amount
}
// Create a Safe transaction with the provided parameters
const safeTransaction = await protocolKitOwner1.createTransaction({ transactions: [safeTransactionData] })

Propose the transaction

To propose a transaction to the Safe Transaction Service we need to call the proposeTransaction method from the API Kit instance.

For a full list and description of the properties that proposeTransaction accepts, see Propose the transaction to the service (opens in a new tab) in the Safe Core SDK guide.

// Deterministic hash based on transaction parameters
const safeTxHash = await protocolKitOwner1.getTransactionHash(safeTransaction)
 
// Sign transaction to verify that the transaction is coming from owner 1
const senderSignature = await protocolKitOwner1.signHash(safeTxHash)
 
await apiKit.proposeTransaction({
  safeAddress,
  safeTransactionData: safeTransaction.data,
  safeTxHash,
  senderAddress: await owner1Signer.getAddress(),
  senderSignature: senderSignature.data,
})

Get pending transactions

Recall that you created the apiKit in Initialize the API Kit.

const pendingTransactions = await apiKit.getPendingTransactions(safeAddress).results

Confirm the transaction: Second confirmation

When owner 2 is connected to the application, the Protocol Kit should be initialized again with the existing Safe address the address of the owner 2 instead of the owner 1.

// Assumes that the first pending transaction is the transaction you want to confirm
const transaction = pendingTransactions[0]
const safeTxHash = transaction.safeTxHash
 
const ethAdapterOwner2 = new EthersAdapter({
  ethers,
  signerOrProvider: owner2Signer
})
 
const protocolKitOwner2 = await Safe.create({
  ethAdapter: ethAdapterOwner2,
  safeAddress
})
 
const signature = await protocolKitOwner2.signHash(safeTxHash)
const response = await apiKit.confirmTransaction(safeTxHash, signature.data)

Execute the transaction

Anyone can execute the Safe transaction once it has the required number of signatures. In this example, owner 1 will execute the transaction and pay for the gas fees.

const safeTransaction = await apiKit.getTransaction(safeTxHash)
const executeTxResponse = await protocolKit.executeTransaction(safeTransaction)
const receipt = await executeTxResponse.transactionResponse?.wait()
 
console.log('Transaction executed:')
console.log(`https://sepolia.etherscan.io/tx/${receipt.transactionHash}`)

Confirm that the transaction was executed

You know that the transaction was executed if the balance in your Safe changes.

const afterBalance = await protocolKit.getBalance()
 
console.log(`The final balance of the Safe: ${ethers.formatUnits(afterBalance, 'ether')} ETH`)
$ node index.js
 
Fundraising.
 
Initial balance of Safe: 0.01 ETH
Buying a car.
The final balance of the Safe: 0.005 ETH

Conclusion

In this quickstart, you learned how to create and deploy a Safe and to propose and then execute a transaction for the Safe.