Stopping a transaction

[knightkon]

I have been searching the forum and I can not find a solid answer to this question:  Is there a way that anyone can stop a transaction before the confirmations have been made.  For example; I pay Joe Dip 1.1 BTC for a domain name.  I can see that the transaction is waiting confirmation in the block chain, however there are no confirmations yet.  The seller can also see that the transaction is waiting for confirmations to come through.  Once we are at this point is there anyway that I could stop the transaction? 

[shorena]

I have been searching the forum and I can not find a solid answer to this question:  Is there a way that anyone can stop a transaction before the confirmations have been made.  For example; I pay Joe Dip 1.1 BTC for a domain name.  I can see that the transaction is waiting confirmation in the block chain, however there are no confirmations yet.  The seller can also see that the transaction is waiting for confirmations to come through.  Once we are at this point is there anyway that I could stop the transaction?  

Not if the transaction is valid (signed) and the receiver has already seen it. Lets assume Im Joe Dip here and you send me 1.1 BTC without a fee. Currently thats a bad idea, but you say you are sorry and I believe you.

Now it would take a long time for the transaction to get a confirmation. I could also happen, that the entire network forgets about the transaction and it essentially never happened. I can however - and would in this case - remind the network about your transaction. For 1.1 BTC worth I would probably write a small script that does this every 30-60 minutes. You can now remove the transaction from your own wallet, but I will keep reminding the rest of the network until its confirmed. This will make it almost impossible for you to issue a different transaction that sends the coins elsewhere.

If we both agree that the TX should be removed and redone. I would not write nor start the script. You remove the TX from your wallet and we both wait a few days until the network forgot about it. This essentially "stops" the transaction, unless someone else rebroadcasts it for some reason (or none at all).

If the transaction pays a reasonable high fee, you can remove it from your wallet all you want. Chances are it gets confirmed anyway.

[knightkon]

I have been searching the forum and I can not find a solid answer to this question:  Is there a way that anyone can stop a transaction before the confirmations have been made.  For example; I pay Joe Dip 1.1 BTC for a domain name.  I can see that the transaction is waiting confirmation in the block chain, however there are no confirmations yet.  The seller can also see that the transaction is waiting for confirmations to come through.  Once we are at this point is there anyway that I could stop the transaction?  

Not if the transaction is valid (signed) and the receiver has already seen it. Lets assume Im Joe Dip here and you send me 1.1 BTC without a fee. Currently thats a bad idea, but you say you are sorry and I believe you.

Now it would take a long time for the transaction to get a confirmation. I could also happen, that the entire network forgets about the transaction and it essentially never happened. I can however - and would in this case - remind the network about your transaction. For 1.1 BTC worth I would probably write a small script that does this every 30-60 minutes. You can now remove the transaction from your own wallet, but I will keep reminding the rest of the network until its confirmed. This will make it almost impossible for you to issue a different transaction that sends the coins elsewhere.

If we both agree that the TX should be removed and redone. I would not write nor start the script. You remove the TX from your wallet and we both wait a few days until the network forgot about it. This essentially "stops" the transaction, unless someone else rebroadcasts it for some reason (or none at all).

If the transaction pays a reasonable high fee, you can remove it from your wallet all you want. Chances are it gets confirmed anyway.

I am sorry, but this makes sense to me, but I do not understand the jargon of it all.  What do you mean I should write a script?  I am thinking about taking Bitcoin as a form of payment in my local store, but I do not want the customers to have to wait forever to leave and I want to make sure that if I let them leave with the product before the transaction is confirmed, they can not try to take it back.  Are you saying that is a fee such as .00001 is paid as a fee it will be completed faster?

[mocacinno]

I have been searching the forum and I can not find a solid answer to this question:  Is there a way that anyone can stop a transaction before the confirmations have been made.  For example; I pay Joe Dip 1.1 BTC for a domain name.  I can see that the transaction is waiting confirmation in the block chain, however there are no confirmations yet.  The seller can also see that the transaction is waiting for confirmations to come through.  Once we are at this point is there anyway that I could stop the transaction?  

Not if the transaction is valid (signed) and the receiver has already seen it. Lets assume Im Joe Dip here and you send me 1.1 BTC without a fee. Currently thats a bad idea, but you say you are sorry and I believe you.

Now it would take a long time for the transaction to get a confirmation. I could also happen, that the entire network forgets about the transaction and it essentially never happened. I can however - and would in this case - remind the network about your transaction. For 1.1 BTC worth I would probably write a small script that does this every 30-60 minutes. You can now remove the transaction from your own wallet, but I will keep reminding the rest of the network until its confirmed. This will make it almost impossible for you to issue a different transaction that sends the coins elsewhere.

If we both agree that the TX should be removed and redone. I would not write nor start the script. You remove the TX from your wallet and we both wait a few days until the network forgot about it. This essentially "stops" the transaction, unless someone else rebroadcasts it for some reason (or none at all).

If the transaction pays a reasonable high fee, you can remove it from your wallet all you want. Chances are it gets confirmed anyway.

I am sorry, but this makes sense to me, but I do not understand the jargon of it all.  What do you mean I should write a script?  I am thinking about taking Bitcoin as a form of payment in my local store, but I do not want the customers to have to wait forever to leave and I want to make sure that if I let them leave with the product before the transaction is confirmed, they can not try to take it back.  Are you saying that is a fee such as .00001 is paid as a fee it will be completed faster?

yes... If a transaction contains a fee, it will be an incentive for the miners to include your transaction into a block. A transaction without a fee will usually be confirmed slower than a transaction with a fee (during a spam attack, a fee-less transaction might not be included for a very long time)
Most clients include a fee out-of-the-box.

If you use, for example, blockchain , to look at the transaction, you can easily see if the fee your customer added was large enough.

[filipwx]

if the fee is small the transaction will be long, blockchain originally has a pattern which can be increased fee

[shorena]

I have been searching the forum and I can not find a solid answer to this question:  Is there a way that anyone can stop a transaction before the confirmations have been made.  For example; I pay Joe Dip 1.1 BTC for a domain name.  I can see that the transaction is waiting confirmation in the block chain, however there are no confirmations yet.  The seller can also see that the transaction is waiting for confirmations to come through.  Once we are at this point is there anyway that I could stop the transaction?  

Not if the transaction is valid (signed) and the receiver has already seen it. Lets assume Im Joe Dip here and you send me 1.1 BTC without a fee. Currently thats a bad idea, but you say you are sorry and I believe you.

Now it would take a long time for the transaction to get a confirmation. I could also happen, that the entire network forgets about the transaction and it essentially never happened. I can however - and would in this case - remind the network about your transaction. For 1.1 BTC worth I would probably write a small script that does this every 30-60 minutes. You can now remove the transaction from your own wallet, but I will keep reminding the rest of the network until its confirmed. This will make it almost impossible for you to issue a different transaction that sends the coins elsewhere.

If we both agree that the TX should be removed and redone. I would not write nor start the script. You remove the TX from your wallet and we both wait a few days until the network forgot about it. This essentially "stops" the transaction, unless someone else rebroadcasts it for some reason (or none at all).

If the transaction pays a reasonable high fee, you can remove it from your wallet all you want. Chances are it gets confirmed anyway.

I am sorry, but this makes sense to me, but I do not understand the jargon of it all.  What do you mean I should write a script?  I am thinking about taking Bitcoin as a form of payment in my local store, but I do not want the customers to have to wait forever to leave and I want to make sure that if I let them leave with the product before the transaction is confirmed, they can not try to take it back.  Are you saying that is a fee such as .00001 is paid as a fee it will be completed faster?

I could tell you what a reasonable high fee is for today, but it might be wrong tomorrow. How a high a good fee is greatly depends on the number of transactions that try to get a confirmation as well as the fee they pay.

As someone accepting bitcoin as payment you have essentially 3 options.

#1 you learn the details
#2 you use a service like bitpay as they know the details. They have the scrips ready and AFAIK they also have contracts with mining pools that ensure confirmations.
#3 you accept that a small number of payments might fail.
#4 well, you can wait for a confirmation, but that usually is not acceptable for stores.

-snip-
yes... If a transaction contains a fee, it will be an incentive for the miners to include your transaction into a block. A transaction without a fee will usually be confirmed slower than a transaction with a fee (during a spam attack, a fee-less transaction might not be included for a very long time)
Most clients include a fee out-of-the-box.

This sounds like 1 satoshi is enough of a fee to get a confirmation.

If you use, for example, blockchain , to look at the transaction, you can easily see if the fee your customer added was large enough.

This would require the person accepting the payments to look up the transaction and be able to judge the fee based on the current state of the network. Not typicall what you expect from someone handling the register.

if the fee is small the transaction will be long, blockchain originally has a pattern which can be increased fee

The fee can not be increases once the transaction is broadcasted.

[mocacinno]

I realise now that my explanation might have been a bit confusion as to the size of the fee... Sorry.

[Patatas]

This piece of article might be very useful in understanding how transactions work:

After a transaction is broadcast to the Bitcoin network, it may be included in a block that is published to the network. When that happens it is said that the transaction has been mined at a depth of 1 block. With each subsequent block that is found, the number of blocks deep is increased by one. To be secure against double spending, a transaction should not be considered as confirmed until it is a certain number of blocks deep.

The classic bitcoin client will show a transaction as "n/unconfirmed" until the transaction is 6 blocks deep. Merchants and exchanges who accept bitcoins as payment can and should set their own threshold as to how many blocks are required until funds are considered confirmed. When potential loss due to double spending as nominal, as with very inexpensive or non-fungible items, people may choose not to wait for a transaction to be confirmed, and complete the exchange as soon as it is seen on the network. Most exchanges and other merchants who bear the risk from double spending require 6 or more blocks.

There is nothing special about the default, often-cited figure of 6 blocks. It was chosen based on the assumption that an attacker is unlikely to amass more than 10% of the hashrate, and that a negligible risk of less than 0.1% is acceptable. Both these figures are arbitrary, however; 6 blocks are overkill for casual attackers, and at the same time powerless against more dedicated attackers with much more than 10% hashrate.[1]

Coins generated aren't considered valid by the Bitcoin protocol for 100 blocks. It is advisable to wait some additional time for a better chance that the transaction will be propogated by all nodes. Some older bitcoin clients won't show generated coins as confirmed until they are 120 blocks deep.

[calkob]

Fee less transactions can take an age to even be forgot about, i think the last one i sent, it was 2 days before it got forgot about.  what about including a decent fee as part of the price of transaction.

[knightkon]

I am understanding all that is being said; so I have to ask the question as to what is the best way to accept payment and ensure funds.  Someone mentioned that some places have contracts with mining companies in order to ensure that their transactions are confirmed.  How would one get something like this done.  I am just looking for a way to do this so that I can feel safe about receiving my funds.  When I take cash or  credit card, I have complete control to be sure I am getting paid.  I do not want to take BTC as payment if I do not have the same security that I am getting paid and I am sure other merchants feel the same.

[shorena]

I am understanding all that is being said; so I have to ask the question as to what is the best way to accept payment and ensure funds.  Someone mentioned that some places have contracts with mining companies in order to ensure that their transactions are confirmed.  How would one get something like this done.  I am just looking for a way to do this so that I can feel safe about receiving my funds.  When I take cash or  credit card, I have complete control to be sure I am getting paid.  I do not want to take BTC as payment if I do not have the same security that I am getting paid and I am sure other merchants feel the same.

I assume you will not have the volume, but you can try to contact one of the larger pools directly. I think it makes more sense however to get in touch with one of the big payment processors like bitpay[1] or coinbase[2].

[1] https://bitpay.com/bitcoin-for-retail
[2] https://www.coinbase.com/merchants

[LiteCoinGuy]

Only the Blockchain CEO

[QuestionAuthority]

Quote from theymos

Bitcoin-Qt doesn't support anything like that.

Theoretically:

A transaction is canceled by publishing a second transaction which double-spends some of the coins used in the first transaction (this can be a send-to-self). If the second transaction is included in a block before the first one, the first one becomes invalid and can be considered fully cancelled after the second transaction receives 6 confirmations. It's normally not easy to do this. Network nodes won't accept transactions which double-spend coins used in a transaction they already know about. However, nodes gradually forget about transactions if they don't get into blocks, so a transaction could be cancelled if it doesn't make it into a block after several days and both the sender and recipient stop rebroadcasting it.

Bitcoin used to have a feature called transaction replacement. A transaction could be marked as non-final, which prevented this transaction from getting into a block, but allowed the transaction to be cancelled at any time. Satoshi disabled this a while ago, though. Transactions can still be marked as non-final, but they can't be replaced.

[TKeenan]

Only the Blockchain CEO

Actually, the Blockchain CEO has assigned powers to various people who also can stop transactions.  But they almost never do because it is viewed as 'improper' and somewhat annoying.  Nevertheless, if they had a good reason, they could stop them as they like.

[~Bitcoin~]

No be clear bitcoin transaction is meant to be anonymous, non refundable and non reversible transaction so if you do one mistake than your coin is gone for forever.

[knightkon]

No be clear bitcoin transaction is meant to be anonymous, non refundable and non reversible transaction so if you do one mistake than your coin is gone for forever.

I agree with this, however I want to start acceptign Bitcoin at my place of business.  In order to do this, I need to be sure that once a transaction is started that the customer has no way to cancel it or reverse it, for if I loose one transaction for .5 btc, that is my profit for a whole days worth of work.

[harrymmmm]

No be clear bitcoin transaction is meant to be anonymous, non refundable and non reversible transaction so if you do one mistake than your coin is gone for forever.

I agree with this, however I want to start acceptign Bitcoin at my place of business.  In order to do this, I need to be sure that once a transaction is started that the customer has no way to cancel it or reverse it, for if I loose one transaction for .5 btc, that is my profit for a whole days worth of work.

I take it you don't accept credit cards then?
Coz if you did, you're exaggerating how sure you need to be that a customer can't cancel the transaction any time within the next 6 months or so.
We're talking 10 mins here, and even that is something bitpay would help with for 1% commission (I think).

Bottom line: you won't ever be sure, but if the extra income/customers beats the averaged/expected loss you need to go ahead, right?

[knightkon]

No be clear bitcoin transaction is meant to be anonymous, non refundable and non reversible transaction so if you do one mistake than your coin is gone for forever.

I agree with this, however I want to start acceptign Bitcoin at my place of business.  In order to do this, I need to be sure that once a transaction is started that the customer has no way to cancel it or reverse it, for if I loose one transaction for .5 btc, that is my profit for a whole days worth of work.

I take it you don't accept credit cards then?
Coz if you did, you're exaggerating how sure you need to be that a customer can't cancel the transaction any time within the next 6 months or so.
We're talking 10 mins here, and even that is something bitpay would help with for 1% commission (I think).

Bottom line: you won't ever be sure, but if the extra income/customers beats the averaged/expected loss you need to go ahead, right?

I understand where you are coming from, but with credit cards, I have a signed receipt from them, so there is always verification that they did authorize this.  I am just more concerned with someone making a large purchase and knowing how to make that transaction stop or such.  With credit cards, I always have a protection where I can prove the validation to the processing company, with BTC it seems I do not, so I want to make sure that the transaction is good before they leave the store.  I understand most of the time it is only 10 minutes or so, but if you ever been shopping with women, they do not want to wait that 10 minutes.

[medUSA]

however I want to start acceptign Bitcoin at my place of business.  In order to do this, I need to be sure that once a transaction is started that the customer has no way to cancel it or reverse it, for if I loose one transaction for .5 btc, that is my profit for a whole days worth of work.

Generally, it is very difficult to double spend. If the input of the transaction is confirmed, the transaction size is small-ish, have adequate fee, there is no reason for the transaction not to confirm. So, the customer has no feasible way to cancel or reverse it.

so I want to make sure that the transaction is good before they leave the store.  I understand most of the time it is only 10 minutes or so, but if you ever been shopping with women, they do not want to wait that 10 minutes.

I have waited a good hour for 1 confirmation before. It's not practical to expect 1 confirmation before customers leave the store. You can ask customers to pay a higher transaction fee to increase your confidence and judge the transaction based on the rules listed above, or don't accept over the counter purchases with bitcoin.

[QuestionAuthority]

No be clear bitcoin transaction is meant to be anonymous, non refundable and non reversible transaction so if you do one mistake than your coin is gone for forever.

I agree with this, however I want to start acceptign Bitcoin at my place of business.  In order to do this, I need to be sure that once a transaction is started that the customer has no way to cancel it or reverse it, for if I loose one transaction for .5 btc, that is my profit for a whole days worth of work.

I take it you don't accept credit cards then?
Coz if you did, you're exaggerating how sure you need to be that a customer can't cancel the transaction any time within the next 6 months or so.
We're talking 10 mins here, and even that is something bitpay would help with for 1% commission (I think).

Bottom line: you won't ever be sure, but if the extra income/customers beats the averaged/expected loss you need to go ahead, right?

I understand where you are coming from, but with credit cards, I have a signed receipt from them, so there is always verification that they did authorize this.  I am just more concerned with someone making a large purchase and knowing how to make that transaction stop or such.  With credit cards, I always have a protection where I can prove the validation to the processing company, with BTC it seems I do not, so I want to make sure that the transaction is good before they leave the store.  I understand most of the time it is only 10 minutes or so, but if you ever been shopping with women, they do not want to wait that 10 minutes.

If that's your concern why don't you just use a payment processor like BitPay? They guarantee payment for small merchants (zero confirmation) and only charge a 1% fee. It would literally be as easy and safe as taking a credit card except your fee is smaller.