How does one read whats going on in the Input Data of a Ethereum Transaction?

Question

Function: execute(address _to, uint256 _value, bytes _data) ***

MethodID: 0xb61d27f6 [0]:0000000000000000000000001dba1131000664b884a1ba238464159892252d3a [1]:00000000000000000000000000000000000000000000028b78bf6bd677fe7c17 [2]:0000000000000000000000000000000000000000000000000000000000000060 [3]:0000000000000000000000000000000000000000000000000000000000000000 [4]:0000000000000000000000000000000000000000000000000000000000000000

I am looking at the following data above, i understand that line 0 somehow translates into the reveicing address, can someone show me how the translation is done? The second value is the amount to send i believe, can someone explain how this one translates into the correct amount?

Ive been trying to translate it from hex, but im clearly not understanding it.

Possible duplicate of Decode input data on transaction – Ismael Jul 20 '17 at 16:37 — Ismael, Jul 20 '17 at 16:37

score 2 · Accepted Answer · answered Aug 19 '17 at 19:15

You can use ethereumjs-abi to decode the transaction parameters

const abi = require('ethereumjs-abi');

const data = Buffer.from([
    '0000000000000000000000001dba1131000664b884a1ba238464159892252d3a',
    '00000000000000000000000000000000000000000000028b78bf6bd677fe7c17',
    '0000000000000000000000000000000000000000000000000000000000000060',
    '0000000000000000000000000000000000000000000000000000000000000000',
    '0000000000000000000000000000000000000000000000000000000000000000'].join(''), 'hex');

const decoded = abi.rawDecode(['address', 'uint256', 'bytes'], data);

console.log(`Decoded: ${JSON.stringify(decoded, null, '  ')}`);

The output is

Decoded: [
  "1dba1131000664b884a1ba238464159892252d3a",
  "28b78bf6bd677fe7c17",
  {
    "type": "Buffer",
    "data": []
  }
]

Which means

_to: 0x1dba1131000664b884a1ba238464159892252d3a
_value: 0x28b78bf6bd677fe7c17
_data: [] (empty array)

score -1 · Answer 2 · answered Jul 20 '17 at 14:14

-1

What you're looking at is the transactionObject. You can see how the transactionObject is being used in the following example with web3.js:

transactionObject = {
  from: sender,
  to: receiver,
  value: amount
}

source: https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethsendtransaction

But there are more than just 3 potential variables, as you can see in the link above.

answered Jul 20 '17 at 14:14

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This is contract ABI data - it's completely different from the web3.js transaction object. – benjaminion Aug 19 '17 at 20:27

How does one read whats going on in the Input Data of a Ethereum Transaction?

2 Answers2