[Ethereum] How to get raw ethereum transaction hash

raw-transactiontransactions

I searched around for an answer to this question, however couldn't find one.
So let's assume we've a raw ethereum transaction and before broadcasting we'd like to know the transaction hash. Is it possible to find out the hash before it's being broadcasted (i.e. via eth_sendRawTransaction RPC method).

For instance for raw transaction hex:

0xf86c258502540be40083035b609482e041e84074fc5f5947d4d27e3c44f824b7a1a187b1a2bc2ec500008078a04a7db627266fa9a4116e3f6b33f5d245db40983234eb356261f36808909d2848a0166fa098a2ce3bda87af6000ed0083e3bf7cc31c6686b670bd85cbc6da2d6e85

I get this transaction:
https://kovan.etherscan.io/tx/0x58e5a0fc7fbc849eddc100d44e86276168a8c7baaa5604e44ba6f5eb8ba1b7eb

Is it possible to decode raw transaction so that this hash is known before hand?
Note that I am storing private keys outside of applications such as geth/parity.

Best Answer

Ok, so asked it a couple of minutes too soon. As the name implies it's a hash, hash of what? Hash of your raw hex in example:

0xf86c258502540be40083035b609482e041e84074fc5f5947d4d27e3c44f824b7a1a187b1a2bc2ec500008078a04a7db627266fa9a4116e3f6b33f5d245db40983234eb356261f36808909d2848a0166fa098a2ce3bda87af6000ed0083e3bf7cc31c6686b670bd85cbc6da2d6e85

Hashed using keccak256 (for instance can be found here: https://wiki.parity.io/JSONRPC-web3-module#web3_sha3): and the result as expected is:

0x58e5a0fc7fbc849eddc100d44e86276168a8c7baaa5604e44ba6f5eb8ba1b7eb

So ended up being a short rhetorical question. However if someone has similar question... hope this helps!

Related Solutions

[Ethereum] Get raw transaction from hash

There is eth.getRawTransaction(<txhash>) now.

Edit: Please check that you're using an up-to-date version of geth. It's part of the current release (v.1.8.6) and was introduced some time ago. You can also see it in the source code: https://github.com/ethereum/go-ethereum/blob/ca64a122d33008c155c35a9d0e78cfbcafb1820a/internal/web3ext/web3ext.go (look for getRawTransaction)
https://github.com/ethereum/go-ethereum/blob/ec8ee611caefb5c5ad5d796178e94c1919260df4/internal/ethapi/api.go (look for GetRawTransactionByHash)

input: transaction hash
output: bytes of the corresponding transaction

[Ethereum] Given a RAW Transaction – how to get senders address

Here's a full working example of how to decode a raw transaction and read the sender (from) address:

package main

import (
    "encoding/hex"
    "fmt"
    "log"

    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/rlp"
)

func main() {
    rawTx := "f86d8202b28477359400825208944592d8f8d7b001e72cb26a73e4fa1806a51ac79d880de0b6b3a7640000802ca05924bde7ef10aa88db9c66dd4f5fb16b46dff2319b9968be983118b57bb50562a001b24b31010004f13d9a26b320845257a6cfc2bf819a3d55e3fc86263c5f0772"

    tx := new(types.Transaction)
    rawTxBytes, err := hex.DecodeString(rawTx)
    rlp.DecodeBytes(rawTxBytes, &tx)

    msg, err := tx.AsMessage(types.NewEIP155Signer(tx.ChainId()))
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(msg.From().Hex())
    // 0x96216849c49358B10257cb55b28eA603c874b05E
}

See this transaction in etherscan

Best Answer

Related Solutions

[Ethereum] Get raw transaction from hash

[Ethereum] Given a RAW Transaction – how to get senders address

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