Metamask: How to sign a transaction in metamask (EIP 712) with data instead of sending it normally to save gas cost?
Optimizing Gas Costs in Metamask: Signing Transactions with Data in EIP 712
As a developer working on Ethereum-based projects, you’re probably no stranger to the challenges of managing gas costs. A significant contributor to high gas fees is the need to send large amounts of data via Ethereum’s transaction format. However, there is an alternative approach that can help reduce your gas costs: signing transactions in EIP 712.
In this article, we’ll dive deeper into how to sign a transaction in Metamask using EIP 712 and its benefits for optimizing gas costs.
What is EIP 712?
EIP 712 (Ethereum Improvement Proposal 712) is an updated version of the Ethereum Standard Gas Type ID that allows developers to define custom gas types that can be used across multiple smart contracts. This feature enables more efficient and scalable interaction between applications built on different chains.
Setting up EIP 712 in Metamask
To use EIP 712 in your project, you will need to set it up in your Metamask wallet first. Here are the steps:
- Create or import an Ethereum account: Set up a new Ethereum account in MetaMask or import an existing one.
- Install required packages: Install the
ethers.jsandweb3packages using npm or yarn:npm install ethers@5 web3
- Import the EIP 712 data contract: Import the EIP 712 data contract as a file, for example:
const { GasType } = require('ethers/types'); import '
- Set your custom gas type: Set the gas type you want to use in your transaction, for example:
{
“name”: “MyCustomGasType”,
“description”: “A custom gas type for my NFT project”,
"data": {
"value": 100,
"type": GasType.Bytes32
}
}
Signing transactions with data in EIP 712
Now that you have set your custom gas type, it’s time to sign a transaction using data instead of sending it normally. Here is an example:
async function setAdditionalMetadata(nftCardAddress) {
const tx = {
from: 'your Ethereum address',
nonce: web3.eth.getTransactionCount('your Ethereum address'),
gasPrice: web3.toWei(20, 'gwei'), // Set the gas price to 20 gwei (2.5 ETH)
gas: 2000,
data: [
{
"data": [
{
"type": GasType.Bytes32,
"value": new Uint8Array([1, 2, 3, 4])
},
{
"type": GasType.Uint256,
"value": '1234567890abcdef'
}
]
}
],
for: nftCardAddress
};
const signature = await web3.eth.accounts.signTransaction(tx);
return { ...tx, signed: signature.rawTransaction };
}
// Sign a transaction with data in EIP 712
const tx = setAdditionalMetadata('0xYourNFTCardAddress');
const signedTx = await metamask.sendTransaction(tx);
console.log(signedTx);
In this example, we define a new custom gas type MyCustomGasType` and use it to sign a transaction with data. The data includes two values: a 4-byte integer and a 256-bit unsigned integer.
Benefits of Signing Transactions on EIP 712
Signing transactions using EIP 712 offers several benefits:
- Reduced gas costs
: Since you are not sending large amounts of data via the Ethereum transaction format, you can reduce your gas expenses.
- Improved scalability: By leveraging EIP 712’s custom gas types, you can improve the scalability of your application.
- Increased flexibility: With EIP 712, you can define a wide range of custom gas types for different use cases.
Conclusion
Signing transactions with data on EIP 712 is an efficient way to optimize gas costs while maintaining the benefits of using Ethereum-based applications.