How to decode raw transaction?

Question

I am using @taquito to build and sign a transaction. But before I send it I want to decode it to check my destination address, amount etc like you would normally do for other blockchains.

Not sure how to do it, but I signed a request using my ED25519 signing key. The signing was successful and the sbytes I got in return was

008f1d96e2783258ff663f03dacfe946c026a5d194c73d1987b3da73fadea7d46c008cb5baedee4dc3ec261dfcf57a9600bb0a8e26c0f00bdd85a0018452ac02e0a712000153957451d3cc83a71e26b65ea2391a1b16713d2d009595facf847a72b4c3fe231c0e4185e68e9b2875aa3c639382c86bcf0af23699f47fe66a6550ade936a5b59d5919ad20703885750314e0c368b277de39e7d10a

I've read through some articles but could not find an exact way to do this and whatever I tried did not exactly yield what I wanted, which either means that I do not know how to decode the transaction, or my sbytes are wrong. Can anyone please explain on how do I decode this raw transaction using a Javascript/Typescript library to get stuff like

fromAddress toAddress amount etc. and if my signed transaction is correct. This is for testnet.

Answer 1

Taquito can parse forged bytes using the parse() method in the @taquito/local-forging package.

TypeDocs are here. You can see the unit tests here.

Implementation to decode a signed transaction:

const { localForger } = require('@taquito/local-forging');

const sbytes = '008f1d96e2783258ff663f03dacfe946c026a5d194c73d1987b3da73fadea7d46c008cb5baedee4dc3ec261dfcf57a9600bb0a8e26c0f00bdd85a0018452ac02e0a712000153957451d3cc83a71e26b65ea2391a1b16713d2d009595facf847a72b4c3fe231c0e4185e68e9b2875aa3c639382c86bcf0af23699f47fe66a6550ade936a5b59d5919ad20703885750314e0c368b277de39e7d10a';

async function decode() {
    const unsignedPart = sbytes.substring(0, sbytes.length - 128); // Removing last 128 characters as that is the signature
    const decoded = await localForger.parse(unsignedPart);
    console.log(decoded);
}

decode(); 

Answer 2

You can use the tezos-codec binary to decode this:

tezos-codec decode 006-PsCARTHA.operation from 008f1d96e2783258ff663f03dacfe946c026a5d194c73d1987b3da73fadea7d46c008cb5baedee4dc3ec261dfcf57a9600bb0a8e26c0f00bdd85a0018452ac02e0a712000153957451d3cc83a71e26b65ea2391a1b16713d2d009595facf847a72b4c3fe231c0e4185e68e9b2875aa3c639382c86bcf0af23699f47fe66a6550ade936a5b59d5919ad20703885750314e0c368b277de39e7d10a

which yields

{ "branch": "BKiXcfN1ZTXnNNbTWSRArSWzVFc6om7radWq5mTqGX6rY4P2Uhe",
  "contents":
    [ { "kind": "transaction",
        "source": "tz1YU2zoyCkXPKEA4jknSpCpMs7yUndVNe3S", "fee": "1520",
        "counter": "2622173", "gas_limit": "10500", "storage_limit": "300",
        "amount": "300000",
        "destination": "tz2FwBnXhuXvPAUcr1aF3uX84Z6JELxrdYxD" } ],
  "signature":
    "sighZMqWz5G8drK1VTsmTnQBFEQ9kxQQxL88NFh8UaqDEJ3R3mzgR3g81azadZ9saPwsWga3kEPsyfbzrXm6ueuDvx3pQ5Q9" }

You can get more details about tezos-codec in its manual (tezos-codec man -v 3)

Answer 3

You can use the RPC endpoint: /chains/main/blocks/head/helpers/parse/operations to do that.

Example:

await axios.post(
        `${nodeURL}/chains/main/blocks/head/helpers/parse/operations`,
            parseOperationBytesData,
            {
                headers: {
                    'Content-Type': 'application/json'
                }
            }
        )