Topic: Canceling a transaction (Read 318 times)

I get that, but in this case the casino is losing unrealized profits as opposed to losing actual funds. That's why they can allow users to gamble with unconfirmed funds at all, because in the case of a malicious spend they are only back where they started.

Yeah, this is another valid option. There are a handful of merchants I shop at in person where I am a long term customer and they are happy to hand over the goods while my RBF-opted-out transaction is still unconfirmed. I imagine my relationship with these merchants will not change once full RBF is commonplace, exactly because I am a long term customer and they are as sure as they can be that I am not suddenly going to start attempting to scam them.

The casino provide a service, the service used by customers, and at the end, the customers scammed the casino is how I see this. Assuming it is $100 transaction that the customer later use full RBF to double-spend, that only just mean that the casino has been scammed $100. Nothing left the casino reserve, but the amount of money that supposed to add to their reserve decreased, but the money can be nothing to them.

There are some people and sites that can still offer zero confirmation for full RBF transaction, example is a loyal customer that a seller know very well and also knowing his family and trust him to an extent and having excellent reputation in his community, another example are platforms that customers will not be able to withdraw his deposit after a long period of time or until the transaction is confirmed while the platform has nothing to lose like the gambling site example above in a way the customer will not be able to use the money at all.

But full RBF transaction supposed not to be accepted on a gambling site until it has at least 1 confirmation, if they accept it, it is just a vulnerability to the gambling site in my opinion. But they may have different ways about this, like not accepting deposit with high amount of money until it is confirmed and accepting deposit of low amount of money which they can afford to lose to their customers if it is double spent, to see if it works out good.

Sure, but the point is you gambled for free and didn't lose any money, while leaving the option to make money open just in case you won. The casino also didn't make any money on your losses, which they should have.

Crypto casinos haven't been the fastest ones in the past to introduce new things, like SegWit for example. I remember it took some popular platforms years before they updated their systems to allow withdrawals to Bech32 addresses.

This time around, it's their profits and their money that's on the line, so they might be somewhat quicker. I still think they will wait to see what happens. And if they realize there are many players that abuse the zero-deposit feature, they will just disable it for new accounts while probably not doing it for longtime and loyal players.

If you deposit, lose, and then double spend your deposit, then the casino/sportsbook in question has only lost potential profits (your deposit), and hasn't actually lost anything from their reserves. So they can simply ban your account, email address, IP address, bitcoin address, and any other details they might hold on you, such as if you've completed KYC. Or if they really want to keep you as a customer despite your theft, they could simply disable zero confirmation deposits for you.

I wonder how many such places will continue to offer zero confirmation deposits after full RBF becomes widespread. Very few, I suspect, since it them become trivial for anyone to double spend a losing deposit.

Casinos have their methods to fight against doublespend attacks. Sportsbet.io, for example, allows instant bitcoin deposits. After a transaction is broadcasted to the network, it literally takes a few seconds for your account balance to be updated. You can then use your coins despite them still being in unconfirmed status to gamble.

But there is a catch. If you win some money and you attempt to make a withdrawal, it won't work unless your deposit transaction was confirmed on-chain. So cheating and doublespending isn't worth it in that particular case. Makes you wonder though if one could make a deposit and pay a low mining fee, quickly gamble, and if you lose, then you double spend the original transaction back to yourself with a much higher fee. Sportsbet surely has to have some security mechanisms in place to battle against this.     

I just want to add this the confirmation time also depends on the network it is sometimes congested which leads to other transactions being stuck on the mempool that is why there is RBF to remake the transaction with a higher fee.
All transaction with high fees is always in high priority.

@sekssonikk actually in Bitcoin you can't cancel the transaction what you can only do is to make/replace another transaction with the same inputs and increase in fee.

You have until the transaction is confirmed to attempt to double spend it back to yourself (i.e. cancel it). It all depends on the fee you pay and the current state of the mempool.

Take a look at what the mempool looks like here: https://jochen-hoenicke.de/queue/#BTC%20(default%20mempool),8h,weight

If your transaction pays 1 sat/vbyte in fees, and there are many megabytes of transactions which pay higher fee rates sitting in the mempool, then your transaction could take hours or days to confirm, giving you plenty of time to cancel it if you choose.
On the other hand, if the mempool is empty and your transaction pays a high fee putting it near the tip, your transaction could confirm within seconds of you broadcasting it, meaning you have no chance to cancel it at all.

Can't say how much time you have to cancel a transaction.
If your transaction has been flagged as RBF, as long as it is unconfirmed, you can replace it with a new transaction paying higher fee.
It's possible that your transaction is confirmed in a few seconds. It's also possible that it stays unconfirmed even after says.
As mentioned by Charles-Tim above, the higher fee rate you set for your transaction, the faster it can be confirmed.

It is only referring to low, medium and high priority for your transaction to be confirmed. The lower the fee, the lower the chance to include the transaction in the next blocks mined, the longer the time it would take for the transaction to be confirmed. With higher priority fee, your transaction has the probability to be included in the next block, while the chance decreases as the fee decreases in medium and low priority and the longer the time before it is confirmed.

What does this mean?
"Provides you a fee estimation targeting confirmations in 10m, 3h or 1 day. With real time calculation on how much to spend. Ability to Bump and Cancel sent transactions with "Replace-by-fee" (RBF) or with "Child-pays-for-parent" (CPFP)."

Do I always have at least 10 minutes, 3 hours or 1 day to cancel the transaction?

It's true that's why you should be careful when having an online transaction, make sure that the transaction is already confirmed before you send anything or conclude the transaction. This method is used before by cheaters as there are gambling sites before that credit your deposits despite being "unconfirmed", and they have learned their lessons.

Not an off-topic question.

hosseinimr93 has already provided you with one of the wallets canceling unconfirmed bitcoin transaction can be possible which is Bluewallet:


Also you should be able to calcel an unconfirmed bitcoin transaction on Trezor Suite:

You can use bluewallet too. Bluewallet is a non-custodial and open-source wallet that allows you to make RBF-enabled transactions, bump the fee and cancel transactions (Cancel means replace the RBF-enabled transaction with a new one paying higher fee and sending the fund to yourself)

For my general development. What else do wallets exist that have an cancellation option?
I apologise for the off-topic question.

Electrum wallet in mobile RBF is enabled by default you don't need to change anything unless you check the final button after making a transaction.


To make this thing clear I'll add an image below to make sure you won't get lost



As you can see the final is check just uncheck it to enable RBF.

After you tap on "Pay" button on the mobile version of electrum, a new window for confirming the payment pops up.
If "Final" is unchecked in that window, your transaction will be replaceable by fee. If "Final" is checked, your transaction won't be replaceable by fee.
Note that by default, "Final" is unchecked and electrum make RBF-enabled transactions.

I use a mobile app. How do I enable it there?

...
Since each node has their own mempool, the replacement transaction for a transaction (without rbf flag) will be broadcasted to the nodes that enabled full rbf and wont be broadcasted to those who don't.
So if all nodes support it, it definitely can reach a pool or solo miner that supports full-rbf, then "Use Replace-By-Fee" setting wont be necessary.

But from the current stand-point, it may take years to reach a consensus.

But wallets can still be able to have the option to use RBF or not even if all nodes support full RBF, but just that it won't be like before that some transactions are made on those non recommended wallets that do not support RBF by default and the seed phrase or private key can not be imported on wallet like Electrum to pump the fee because RBF is not opted in for. Just that now, if a wallet do not support it, the transaction fee can be pumped using a wallet that support full RBF through seed phrase importation?

Full RBF is not by default on the Bitcoin Core latest release, many node runners are not miners and may consider the option not necessary.

It mainly depends on the setting: "Tools->Preferences->Transactions->Use Replace-By-Fee".
If it's disabled, the option "cancel (double-spend)" wont show up in the unconfirmed transaction's right-click menu.

On a side note, that behavior might change depending on the Electrum servers and bitcoin node users' decision on "Full RBF" which is already available in the latest version of Bitcoin Core.
If most Bitcoin Core nodes enable the option mempoolfullrbf=1 (which is disable by default), the Electrum setting above wont be necessary.