Ethereum: How exactly can I generate a transaction id?

Ethereum: Understanding Transaction IDs and Generating Your Own

As a developer building blockchain applications on the Ethereum network, you’re likely familiar with the importance of a unique identifier for each transaction. In this article, we’ll delve into how to generate a transaction ID (Tx ID) in Ethereum and explore its intricacies.

What is a Transaction ID?

In Ethereum, a transaction ID serves as a unique identifier for each transaction that’s sent across the network. It’s used by the Ethereum Virtual Machine (EVM) to identify and verify the transaction on the blockchain. The Tx ID is typically generated when a transaction is created using the transaction function in Solidity or Ethers.js.

How ​​to Generate a Transaction ID

To generate a transaction ID, you need to create a serialized version of your transaction data, which includes:

• Transaction data: This can include fields such as gas price, gas limit, nonce, and value.

• Encryption keys: You’ll need to encrypt these fields using a key pair (private key and public key).

Here’s an example in Solidity:

pragma solidity ^0.8.0;


import "


contract MyContract {

    function transaction ( ) public payable returns ( uint256 ) { ;

        // Create a new transaction data object

        TransactionData txData = TransactionData(

            bytes4(abi.encodePacked("value", "gasPrice", "gasLimit"))

        );


        // Encrypt the fields using the private key

        memory bytes encryptedTxData = encrypt(txData);


        // Calculate the Tx ID as a double SHA-256 hash of the serialized transaction

        uint256 txId = keccak256(encryptedTxData, 0x6e8738a2a35fcd5b1c9f24d8f3e4dd7bfbe94b1caafec9ceffebf2c44bd51a14);


        return txId ;

    } }

} }


struct TransactionData { .

    bytes value; // The amount to be sent

    uint256 gasPrice; // In wei (the unit for the gas price)

    uint256 gasLimit; // The maximum allowed number of gas units that can be executed in one block

} }


function encrypt ( TransactionData txData ) internal pure returns ( bytes memory ) { ;

    bytes memory encryptedTxData = abi.encodePacked(

        txData.value,

        txData.gasPrice,

        txData.gasLimit

    );


    return keccak256 ( encryptedTxData , 0x6e8738a2a35fcd5b1c9f24d8f3e4dd7bfbe94b1caafec9ceffebf2c44bd51a14 );

} }

In this example, we create a TransactionData struct to hold the transaction data, and an encrypt function that takes in this struct and returns its encrypted version.

The Tx ID

The TX ID is calculated using the keccak256 hash function with the encrypted transaction data as its second argument. The first 128 bits of the resulting hash are a SHA-256 hash of the encrypted transaction data, while the last 64 bits are the timestamp and the nonce (i.e., the current block number).

To generate a Tx ID for your own transactions, you can use the following formula:

TxID = keccak256 ( encryptedTxData , timestamp + nonce )

Here’s an example:

“`solidity

pragma solidity ^0.8.0;

contract MyContract {

function transaction ( ) public payable returns ( uint256 ) { ;

// Create a new transaction data object

TransactionData txData = TransactionData(

sore.