Ethereum: How to extract addresses from raw transaction input

Extracting Input Addresses from Raw Ethereum Transactions

Ethereum transactions are complex and require multiple inputs, including “vin” addresses (verifiable inputs). In this article, we’ll show you how to extract these addresses from a raw transaction in offline mode.

Gross Transaction Components Overview

A raw Ethereum transaction consists of several components:

• txn ID: A unique identifier for the transaction.

• from: the sender’s “address” (e.g. “0x…”).

• to: the recipient’s “address”.

• **value: the amount sent in the transaction.

• **address: The sender’s address (a hexadecimal string).

• **amount: The amount sent in the transaction.

• **publicKeyHash: The public part of the sender’s address.

Here is an example of a raw transaction:

txn ID: 0x1234567890abcdef
from: 0x... (sender address)
to: 0x...
value: 10 Ether
gas limit: 20000

Extracting input addresses

To extract the input addresses, we need to parse the raw transaction and identify the “vin” component.

In a typical Ethereum implementation, the “vin” component is stored in the “tx.vin” field of the raw transaction. To access this field, we can use the “eth.utils.toBuffer()” function from the Ethers.js library:

const tx = // parse the raw transaction
// get the VIN field as a buffer
const vinBuffer = tx.vin;
//Create an array to store the input addresses
const inputAddresses = [];
// Loop through the VIN entries and extract the address
for (let i = 0; i < vinBuffer.length; i++) {
const entry = vinBuffer[i];
if (entry.index === 0) { // Sender entry
const privateKey = eth.utils.toHex(entry.privateKey);
inputAddresses.push(privateKey); // add the sender address to the array
}
}

Offline Address Extraction

For offline mode, we need to mine addresses without requiring a connection to the Ethereum network. One approach is to use a library like ethers.js, which provides a “from” and “to” function to convert between Ethereum accounts and addresses.

Here is an example of how to extract input addresses from a raw transaction using ethers.js:

const { eth } = require('Ether');
// Create an instance of the Ethereum contract
const contract = new eth.contract("contractAddress", "0x…"); // replace with your contract address
// Load the raw transaction data (e.g. from a file or database)
const txData = // Load raw transaction data here
// Convert the tx.vin field to an array of input addresses
const inputAddresses = await contract.from(txData).get("from").then((address) => {
returnAddress.address;
});
console.log(inputAddresses); // Output: Array([0x...])

Conclusion

In this article, we will show how to extract input addresses from raw Ethereum transactions in offline mode. By analyzing the transaction data and identifying the “vin” component, we can extract the sender addresses as hexadecimal strings.

Please note that this is a simplified example. In real-world scenarios, you may need to handle errors, special cases, and additional requirements (e.g. supporting multiple input types).

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