Fuse wallet is a great example of how smart accounts can be used to drastically improve UX without giving up security or adding aditional counterparty risk.

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The Problem

  • EOA wallets have a high barrier to entry
  • Users need to store and protect secret recovery phrases
  • Loose your wallet = lose your funds

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The Solution

  • Smart Accounts with multiple signers removes the single point of failure of secret recovery prhases and increases security
  • Smart Accounts add programmable capabilities to wallets to retain security but allow for more complex user flows

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The Implementation

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Onboarding

In order to remove the barrrier to entry, Fuse creates multiple keys on setup thus removing the reliance on a secret recovery phrase. By setting the threshold to 2, Fuse ensures that the user can always access their funds even if the device is lost.

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Signer Setup

  1. On-device key
  2. iCloud backup key
  3. Recovery MPC key

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Security Considerations

  • The threshold of 2 ensures that no single signer can compromise the wallet
  • Users can recover their wallet using any combination of two signers
  • The MPC recovery key adds an additional layer of security while maintaining user-friendly recovery options

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Implementation Guide

Here’s how to implement a wallet similar to Fuse using Squads API v1 endpoints:

In this guide, we’ll:

  1. Create a Smart Account with initial signers (on-device and iCloud backup keys)
  2. Add a recovery MPC key as a third signer for enhanced security
  3. Verify the account setup and check balances
  4. Create and submit a USDC transfer transaction
1

Create Smart Account with Initial Signers

First, create a new Smart Account with the on-device key and iCloud backup key using the create smart account endpoint.

curl -X POST https//developer-api.squads.so/v1/smart-accounts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "x-squads-network: mainnet" \
  -H "Content-Type: application/json" \
  -d '{
    "smart_account_signers": [
      {
        "address": "ON_DEVICE_PUBLIC_KEY",
        "permissions": ["CAN_INITIATE", "CAN_VOTE", "CAN_EXECUTE"]
      },
      {
        "address": "ICLOUD_BACKUP_PUBLIC_KEY",
        "permissions": ["CAN_VOTE"]
      }
    ],
    "threshold": 2
  }'

The returned smart_account_address is your new wallet address. Save this for sending funds to the wallet.

2

Add Recovery MPC Key

Add the MPC recovery key as a third signer using the update smart account endpoint. This provides an additional layer of security and recovery options.

curl -X PATCH https//developer-api.squads.so/v1/smart-accounts/{smart_account_address} \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "x-squads-network: mainnet" \
  -H "Content-Type: application/json" \
  -d '{
    "smart_account_signers": [
      {
        "address": "ON_DEVICE_PUBLIC_KEY",
        "permissions": ["CAN_INITIATE", "CAN_VOTE", "CAN_EXECUTE"]
      },
      {
        "address": "ICLOUD_BACKUP_PUBLIC_KEY",
        "permissions": ["CAN_VOTE"]
      },
      {
        "address": "MPC_RECOVERY_PUBLIC_KEY",
        "permissions": ["CAN_VOTE"]
      }
    ],
    "threshold": 2,
    "transaction_signers": [
      "ON_DEVICE_PUBLIC_KEY",
      "ICLOUD_BACKUP_PUBLIC_KEY"
    ],
    "fee_config": {
      "currency": "usdc",
      "payer_address": "YOUR_SMART_ACCOUNT_ADDRESS"
    }
  }'

Note that we:

  • Keep the threshold at 2, meaning any two signers can approve transactions
  • Include all existing signers in the update
  • Add the new MPC recovery key with CAN_VOTE permission to ensure that the user can always access their funds
  • Include transaction_signers for the update operation
  • Configure the fee to be paid in USDC by the smart account

When submitting this update transaction, remember that:

  • The transaction needs to be signed by the specified transaction_signers
  • Since we’re using the smart account as the fee payer, no additional fee payer signature is needed
  • If using an external fee payer, that account would need to sign the transaction

Learn more about transaction fees and how they work.

3

Verify Account Setup

Verify your Smart Account setup and check the balances using the GET /v1/smart-accounts/ endpoint.

curl -X GET https//developer-api.squads.so/v1/smart-accounts/{smart_account_address} \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "x-squads-network: mainnet"
4

Create your first transfer with your smart account

Now let’s create and submit a USDC transfer transaction. We’ll use the transaction endpoint to submit the transfer.

// Import required dependencies
import { Connection, PublicKey, Transaction } from '@solana/web3.js';
import { Token, TOKEN_PROGRAM_ID } from '@solana/spl-token';

// Initialize connection
const connection = new Connection('https//developer-api.mainnet-beta.solana.com');

// USDC mint address on mainnet
const USDC_MINT = new PublicKey('EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v');
const smartAccountAddress = new PublicKey('YOUR_SMART_ACCOUNT_ADDRESS');
const recipientAddress = new PublicKey('RECIPIENT_ADDRESS');
const amount = 100 * 1e6; // 100 USDC (6 decimals)

// Get the token accounts
const sourceTokenAccount = await Token.getAssociatedTokenAddress(
  TOKEN_PROGRAM_ID,
  USDC_MINT,
  smartAccountAddress
);

const destinationTokenAccount = await Token.getAssociatedTokenAddress(
  TOKEN_PROGRAM_ID,
  USDC_MINT,
  recipientAddress
);

// Create the transfer instruction
const transferInstruction = Token.createTransferInstruction(
  TOKEN_PROGRAM_ID,
  USDC_MINT,
  sourceTokenAccount,
  destinationTokenAccount,
  smartAccountAddress,
  [],
  amount
);

// Create and serialize the transaction
const transaction = new Transaction().add(transferInstruction);
const serializedTransaction = transaction.serialize().toString('base64');

// Submit the transaction through our API
const response = await fetch(
  `https//developer-api.squads.so/v1/smart-accounts/${smartAccountAddress}/transactions`,
  {
    method: 'POST',
    headers: {
      'Authorization': 'Bearer YOUR_API_KEY',
      'x-squads-network': 'mainnet',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      transaction: serializedTransaction,
      transaction_signers: [
        'ON_DEVICE_PUBLIC_KEY',
        'ICLOUD_BACKUP_PUBLIC_KEY'
      ],
      fee_config: {
        currency: 'usdc',
        payer_address: smartAccountAddress.toString()
      }
    })
  }
);

const data = await response.json();

// The response will contain the prepared transaction that needs to be signed
const { transaction: preparedTransaction } = data;

This example shows how to:

  1. Create a USDC transfer instruction using @solana/spl-token
  2. Build and serialize the transaction
  3. Get gas abstaction for the transaction and prepare the transaction for submission using the prepare transaction endpoint
  4. Handle the response which contains the prepared transaction

After receiving the prepared transaction from the API (which includes all necessary fee configurations), you just need to:

  • Sign it with the required signers (matching the transaction_signers you specified)
  • If using an external fee payer (not the smart account), sign with the fee payer
  • Submit the signed transaction to the Solana network
  • Monitor the transaction status until it’s confirmed

Remember to:

  • Handle errors appropriately
  • Implement proper key management for signing
  • Consider adding spending limits for additional security

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Next Steps

Once your Smart Account is set up, you can: