Spending Unconfirmed Transactions?!

[Parham6]

I don't know how it happened but I already did this twice. Normally MultiBit says I don't have enough balance to send before the received coins get at least 1 confirmations but sometimes it doesn't happen. It happened to me twice, I sent the coins instantly after I received them with 0 confirmation. Then I checked on Blockchain and both the income and output of my new address were Unconfirmed until they both received confirmation at the same time.

Now my question is if this is intended in Multbit or a bug? If it's intended why can't I always do it? Is there an option to spent unconfirmed coins in Multbit?

[shorena]

I don't know how it happened but I already did this twice. Normally MultiBit says I don't have enough balance to send before the received coins get at least 1 confirmations but sometimes it doesn't happen. It happened to me twice, I sent the coins instantly after I received them with 0 confirmation. Then I checked on Blockchain and both the income and output of my new address were Unconfirmed until they both received confirmation at the same time.

Now my question is if this is intended in Multbit or a bug? If it's intended why can't I always do it? Is there an option to spent unconfirmed coins in Multbit?

Can you post an example address? Afaik this should not be possible.

[GoofyUK]

I've spent unconfirmed transactions in Bitcoin-QT before and it took like 3 days for all the tx's to confirm even with a fee.


i was moving my stash into 3 diff paper wallets and the tx's took ages

[Soappa]

I've spent unconfirmed transactions in Bitcoin-QT before and it took like 3 days for all the tx's to confirm even with a fee.

In bitcoin-qt version 0.9.0+, you could stop spending unconfirmed changes in option->wallet.

I don't know how it happened but I already did this twice. Normally MultiBit says I don't have enough balance to send before the received coins get at least 1 confirmations but sometimes it doesn't happen. It happened to me twice, I sent the coins instantly after I received them with 0 confirmation. Then I checked on Blockchain and both the income and output of my new address were Unconfirmed until they both received confirmation at the same time.

Now my question is if this is intended in Multbit or a bug? If it's intended why can't I always do it? Is there an option to spent unconfirmed coins in Multbit?

No idea about Multibit.

[Parham6]

I've spent unconfirmed transactions in Bitcoin-QT before and it took like 3 days for all the tx's to confirm even with a fee.
i was moving my stash into 3 diff paper wallets and the tx's took ages

Thanks for clarification.

Can you post an example address? Afaik this should not be possible.

It happened weeks ago, I don't remember now.

[Finchy]

I think I read somewhere you can spent not fully confirmed coins but I'm not 100 sure.

[zetaray]

May be you put a large enough fee on the child transaction to make miners want to confirm both parent and child transactions in the same block. How much fee did you pay?

[ranlo]

I think I read somewhere you can spent not fully confirmed coins but I'm not 100 sure.

He didn't "spend" them, he just broadcast the transaction. A few of you seem to be misreading this. You can broadcast anything you want; it just won't confirm until it is actually able to be sent. In this case, the transaction was broadcast before he was able to actually send it. As soon as all the inputs were confirmed, the transaction became legal and passed through the network.

[Parham6]

He didn't "spend" them, he just broadcast the transaction. A few of you seem to be misreading this. You can broadcast anything you want; it just won't confirm until it is actually able to be sent. In this case, the transaction was broadcast before he was able to actually send it. As soon as all the inputs were confirmed, the transaction became legal and passed through the network.

But how can I do it again? Multbit won't normally allow me to broadcast those transactions, it just simply says Not Enough Balance.

May be you put a large enough fee on the child transaction to make miners want to confirm both parent and child transactions in the same block. How much fee did you pay?

Just the standard 0.0001 (~4 cents) for both the transactions.

[ranlo]

He didn't "spend" them, he just broadcast the transaction. A few of you seem to be misreading this. You can broadcast anything you want; it just won't confirm until it is actually able to be sent. In this case, the transaction was broadcast before he was able to actually send it. As soon as all the inputs were confirmed, the transaction became legal and passed through the network.

But how can I do it again? Multbit won't normally allow me to broadcast those transactions, it just simply says Not Enough Balance.

May be you put a large enough fee on the child transaction to make miners want to confirm both parent and child transactions in the same block. How much fee did you pay?

Just the standard 0.0001 (~4 cents) for both the transactions.

I'm really not sure. My Multibit, as far as I am aware, has no issues with spending transactions that aren't confirmed yet. I don't even see two separate numbers anymore (I did prior to the last update) to separate unconfirmed from confirmed at the top.

[Parham6]

I'm really not sure. My Multibit, as far as I am aware, has no issues with spending transactions that aren't confirmed yet. I don't even see two separate numbers anymore (I did prior to the last update) to separate unconfirmed from confirmed at the top.

Could that be because I used 0.5.17 at the time this happened?

[ranlo]

I'm really not sure. My Multibit, as far as I am aware, has no issues with spending transactions that aren't confirmed yet. I don't even see two separate numbers anymore (I did prior to the last update) to separate unconfirmed from confirmed at the top.

Could that be because I used 0.5.17 at the time this happened?

Maybe. I'm almost positive there used to be two numbers at the top (I'm using 0.5.17 now as well btw), one for confirmed and one (smaller) for unconfirmed. Now I don't see that.

I could be wrong though.

[shorena]

I know its possible to spend unconfirmed change.* Maybe thats what you did? Was it your own transaction?

-snip-
Just the standard 0.0001 (~4 cents) for both the transactions.

sounds like you issued both transactions. In that case it would make sense and almost all clients still allow it, even though it can be a problem.


* You have 1 BTC and send 0.8 to X, you get 0.2 as change to an other address and even though this is a new input and needs confirmation you can make a new transaction 0.2 to Y anyway. The main reason this is possible IIRC is that this is how people imagine a wallet works and having to wait for "ma own moneyz" is counter intuitive

[Parham6]

Maybe. I'm almost positive there used to be two numbers at the top (I'm using 0.5.17 now as well btw), one for confirmed and one (smaller) for unconfirmed. Now I don't see that.

I could be wrong though.

I'm using 0.5.18 now and it stills shows two numbers. I can only spend the confirmed transactions, if I try to spend coins that aren't confirmed yet it says that my balance isn't enough then Help button points me to an article that says I can only spend confirmed transactions.

I know its possible to spend unconfirmed change.* Maybe thats what you did? Was it your own transaction?

-snip-
Just the standard 0.0001 (~4 cents) for both the transactions.

sounds like you issued both transactions. In that case it would make sense and almost all clients still allow it, even though it can be a problem.


* You have 1 BTC and send 0.8 to X, you get 0.2 as change to an other address and even though this is a new input and needs confirmation you can make a new transaction 0.2 to Y anyway. The main reason this is possible IIRC is that this is how people imagine a wallet works and having to wait for "ma own moneyz" is counter intuitive

Yes, both of the transactions was from my own wallets to my own wallets but how can a client detect that? Maybe my wallet was on my android device and completely unlinked with PC (it wasn't in this case), how would the client know it's mine if that happens? In Multbit they were in different wallets, I mean all of those private keys weren't in a single wallet. Each wallet only has a single address (key). I sent from one wallet (with single address) to another wallet (with single address). idk if I'm making sense or not. To put it simple, it wasn't what you're describing, what I did was technically different. It was from my wallet to my other wallet NOT my address to other address.

If anyone can spend unconfirmed transactions then what's the point of getting confirmations? Why do people insist on it? They could just take unconfirmed coins and send them while they're still unconfirmed and they still get there.

[ranlo]

Maybe. I'm almost positive there used to be two numbers at the top (I'm using 0.5.17 now as well btw), one for confirmed and one (smaller) for unconfirmed. Now I don't see that.

I could be wrong though.

I'm using 0.5.18 now and it stills shows two numbers. I can only spend the confirmed transactions, if I try to spend coins that aren't confirmed yet it says that my balance isn't enough then Help button points me to an article that says I can only spend confirmed transactions.

I know its possible to spend unconfirmed change.* Maybe thats what you did? Was it your own transaction?

-snip-
Just the standard 0.0001 (~4 cents) for both the transactions.

sounds like you issued both transactions. In that case it would make sense and almost all clients still allow it, even though it can be a problem.


* You have 1 BTC and send 0.8 to X, you get 0.2 as change to an other address and even though this is a new input and needs confirmation you can make a new transaction 0.2 to Y anyway. The main reason this is possible IIRC is that this is how people imagine a wallet works and having to wait for "ma own moneyz" is counter intuitive

Yes, both of the transactions was from my own wallets to my own wallets but how can a client detect that? Maybe my wallet was on my android device and completely unlinked with PC (it wasn't in this case), how would the client know it's mine if that happens? In Multbit they were in different wallets, I mean all of those private keys weren't in a single wallet. Each wallet only has a single address (key). I sent from one wallet (with single address) to another wallet (with single address). idk if I'm making sense or not. To put it simple, it wasn't what you're describing, what I did was technically different. It was from my wallet to my other wallet NOT my address to other address.

If anyone can spend unconfirmed transactions then what's the point of getting confirmations? Why do people insist on it? They could just take unconfirmed coins and send them while they're still unconfirmed and they still get there.

You can't actually send the coins until they're confirmed. It will pend the payment until the confirmations are completed. It will SEND it to the network as a request, but won't officially go through yet.

[Parham6]

You can't actually send the coins until they're confirmed. It will pend the payment until the confirmations are completed. It will SEND it to the network as a request, but won't officially go through yet.

I sent from Multbit on my PC, totally unrelated to blockchain but both the transactions showed up on blockchain.info and both were unconfirmed. Basically it was a new address with two total transactions, one income and one output and both of them were unconfirmed.

[shorena]

-snip-
Yes, both of the transactions was from my own wallets to my own wallets but how can a client detect that? Maybe my wallet was on my android device and completely unlinked with PC (it wasn't in this case), how would the client know it's mine if that happens? In Multbit they were in different wallets, I mean all of those private keys weren't in a single wallet. Each wallet only has a single address (key). I sent from one wallet (with single address) to another wallet (with single address). idk if I'm making sense or not. To put it simple, it wasn't what you're describing, what I did was technically different. It was from my wallet to my other wallet NOT my address to other address.

If anyone can spend unconfirmed transactions then what's the point of getting confirmations? Why do people insist on it? They could just take unconfirmed coins and send them while they're still unconfirmed and they still get there.

Technically speaking there are no wallets, just keys. What you describe is a way the programm you use shows you things, not how they actually are. Did you do this? (or did this happen):

A, B, C refer to public addresses (that allow receiving) and to the coresponding private key (that allows spending)
A holds 1 BTC from 1 input, B holds 0
send A to B (TX1)
before TX1 gets any confirmation send 1 BTC from B to C (TX2)

TX2 should not be possible, because the client has to check whether B has the right to spend 1 BTC. As long as TX1 is not confirmed (single confirmation is enough) B has no right to spend any BTC. It might be that your client allows you to broadcast (!) the transaction anyways, but this makes TX2 invald and it can not confirm until TX1 is confirmed.

-snip-
I sent from Multbit on my PC, totally unrelated to blockchain but both the transactions showed up on blockchain.info and both were unconfirmed. Basically it was a new address with two total transactions, one income and one output and both of them were unconfirmed.

Every transaction has to be included in the blockchain. No transaction can be unrelated to the blockchain. The blockchain is where every transaction is storred, it is where it is written that you actually can spend to coins you want to spend.

[ranlo]

You can't actually send the coins until they're confirmed. It will pend the payment until the confirmations are completed. It will SEND it to the network as a request, but won't officially go through yet.

I sent from Multbit on my PC, totally unrelated to blockchain but both the transactions showed up on blockchain.info and both were unconfirmed. Basically it was a new address with two total transactions, one income and one output and both of them were unconfirmed.

Unconfirmed transactions aren't sent yet, though. You could make the system think you sent someone 25 billion BTC; it'd just remain unconfirmed. You can push anything you want to the blockchain nodes but it won't be added until it meets all of the requirements.

[Parham6]

A, B, C refer to public addresses (that allow receiving) and to the coresponding private key (that allows spending)
A holds 1 BTC from 1 input, B holds 0
send A to B (TX1)
before TX1 gets any confirmation send 1 BTC from B to C (TX2)

TX2 should not be possible, because the client has to check whether B has the right to spend 1 BTC. As long as TX1 is not confirmed (single confirmation is enough) B has no right to spend any BTC. It might be that your client allows you to broadcast (!) the transaction anyways, but this makes TX2 invald and it can not confirm until TX1 is confirmed.

In essence, yes that's what happened:

A has 1 btc from many transactions before, all are confirmed.
A sends 1 btc to B, it's unconfirmed.
B sends the unconfirmed 1 btc from A to C, both are unconfirmed now.
C has an unconfirmed 1 btc

Unconfirmed transactions aren't sent yet, though. You could make the system think you sent someone 25 billion BTC; it'd just remain unconfirmed. You can push anything you want to the blockchain nodes but it won't be added until it meets all of the requirements.

Does that mean I can somehow broadcast that I've sent 25 billion BTC to someone? Will it still show up in their client and remain unconfirmed forever? If I can broadcast unconfirmed transactions, then he can broadcast that unconfirmed 25 billion btc too. This way everyone can make fake unconfirmed transactions out of thin air and just spend all they want. The only downside it that they will never exist and will never get confirmed but if everyone can send unconfirmed transaction, that wouldn't be a problem.

I know what I said above is wrong (because it's not happening), what I don't understand is how or why.

[ranlo]

Does that mean I can somehow broadcast that I've sent 25 billion BTC to someone? Will it still show up in their client and remain unconfirmed forever? If I can broadcast unconfirmed transactions, then he can broadcast that unconfirmed 25 billion btc too. This way everyone can make fake unconfirmed transactions out of thin air and just spend all they want. The only downside it that they will never exist and will never get confirmed but if everyone can send unconfirmed transaction, that wouldn't be a problem.

I know what I said above is wrong (because it's not happening), what I don't understand is how or why.

Why? That's a good question. Maybe someone else can chime in more on that (there may be specifics before the nodes broadcast to the clients themselves).

You can tell that transactions can keep being broadcast, though, because sometimes you'll see double-spend attempts (two transactions will be pending, first one to make it into a block gets accepted and the other is thrown away).