Ethereum: How to find the change / sender address given a txid?

Ethereum Transaction Sender Address Search

For a developer creating decentralized applications (dApps) like SatoshiDice, understanding how to access and process transactions is critical to a seamless interaction with your users. One common question arises: “How to find out the address of the sender by the transaction identifier (txid)?”

In this article, we will dive into the world of Ethereum and consider ways to get the sender’s address from txid.

What is a Transaction ID?

A transaction identifier (txid) is a unique identifier for each transaction in the Ethereum network. This is a 64-byte hexadecimal string representing the entire transaction. Each txid corresponds to a certain output in the blockchain, which contains the amount of transferred ether (ETH).

Receiving a transaction with a specific Txid

To find the sender address by txid, you can use the command line bitcoin-cli or a similar utility related to Ethereum. Here is an example of using bitcoin-cli:

bitcoin-cli gettransaction 

Replace with the actual txid of the transaction you are interested in.

For example, to find the sender address for a transaction with txid 0x1234567890abcdef (assumed to be from SatoshiDice):

bitcoin-cli gettransaction 0x1234567890abcdef

Analysis Conclusion

After executing the command, you will get a JSON output containing various fields. One of them is the “From” field, which is the sender’s address.

Here is a snippet of the expected JSON output:

{

    "blockHash": "0x00000000000000000000000000000000000000000000000",

    "blockNumber": 123,

    "timestamp": 1643723400,

    "from": {

        "address": "0x0123456789abcdef", // Address of the sender

        "key": "",

        "sequence": 1,

        "type": "scriptSignature"

    },

    ...

}

Retrieving the address of the sender

From the “From” field, you can extract the sender’s address by looking at the “address” property. In this example, the sender’s address is simply "0x0123456789abcdef".

However, in most cases, you will need to perform additional parsing of the JSON output to extract the necessary information about the transaction and its participants. To analyze JSON data, you can use such tools as jq or echo:

echo "$json" | jq '.from.address'

This will display the sender’s address.

Additional Considerations

Remember that Ethereum transactions involve complex interactions between various stakeholders, including miners, validators, and network participants. The process of finding the sender’s address may require additional steps or refinements, depending on your specific use case.

In conclusion, it should be noted that understanding how to extract the sender’s address from the transaction identifier is crucial for creating reliable and trustworthy decentralized applications on the Ethereum blockchain. Using the `bitcoin-cli’ command line tool and manipulating the JSON output, you will be able to efficiently process transactions and interact with users in a secure and efficient manner.