Topic: Is there an "how to create a double spend"? (Read 1444 times)

What wallet was used to create the original transaction?

Depending on the wallet you used to send the first transaction, it might be possible to generate a a "double-spend" attempt without much technical knowledge.

If with some technical knowledge and, access to the private keys, you can generate a "double-spend attempt" regardless of which wallet created the original transaction.

For the transaction you indicated, the technical way to generate a "double-spend attempt would be to build, sign and broadcast a raw transaction that uses the same inputs.  For example using Bitcoin Core you could build the raw transaction like this:

Broadcasting means that you are relaying the transaction throughout the network. Rebroadcasting means you're doing it again. Transaction usually drops out of mempool in a day or two and to get them in again for chance of miner picking them up, you have to rebroadcast the transaction.

If you do not rebroadcast, the transaction would eventually get forgotten by the network. You can then create a new transaction. Miners and nodes will then relay your transaction and include it into a block. That is unless someone else rebroadcast it again. Nodes can refuse to relay your transaction if any of the output has less than 2730 satoshi or has a very low fee. If that happens, wait for sometime and try to reset blockchain in your wallet. Some wallets rebroadcast it automatically. For Bitcoin Core, you can stop rebroadcasting and delete the transaction from wallet by using -zapwallettx as a flag when starting it up from CMD in windows or terminal in linux. Do still need to wait for network to forget about it though.

Can you explain what you mean?

It now has confirmations. However, I'll just say out the criterias to make a double spend of an unconfirmed transaction. You must find a miner that has forgotten your transactions and relay it OR you need to find a miner which uses RBF (replace by fee) patch which takes the higher fee. You need to relay directly to it. If majority of the network has forgotten about it, you can create a new one to replace it. If you want to create a replacement transaction, go to https://coinb.in/#newTransaction and input your transaction. Go to inputs and select input, at output, place the outputs, one destination and one change if applicable. The remaining will be your change. After that, sign it by going to https://coinb.in/#sign, input unsigned TX, private key and copy the signed TX.
It's going to be a bit tricky after this:

If the majority of network has forgotten about it, go to coinb.in/#broadcast to broadcast your transaction if it doesn't succeed, try others like http://blockr.io/tx/push.

If the miner has forgotten about it or have RBF patch, make sure the new transaction has a higher fee and try to find a place to broadcast to them directly. Alternatively, install Bitcoin Core and add their node to your conf. Next you can relay the transaction to them by going to help, debug window, console and use this: .

To be honest, I would just try to stop the wallet from rebroadcasting and reset the blockchain on wallet afterwards and send it when the transaction drops out from mempool. It's much simpler.

Hey,

I am searching for a way to create a double spend for an existing transaction.
As example let us use this transaction: https://blockchain.info/tx/a22691fce395dc797492944dd0d2dfa454e6d73e3774774648ec30345651b2c2?show_adv=true

For our example the transaction has 0 confirmations at the moment we will do the double spend.
Now we need to raise the fees of the transaction right?

Is there a way to create a double spend with an existing transaction?
Maybe with using https://coinb.in/#newTransaction

And if yes, how to do it?