where change goes

[kellrobinson]

Different wallets have different ways of dealing with change.  Some send it to randomly generated addresses, others use deterministically generated addresses.  But you don't have to use a wallet.
What if you use the transactions tab on brainwallet.org to spend from an address, where would the change go?  On that page you can enter source and destination, but not change.

[1715572365]

1715572365

[1715572365]

1715572365

[1715572365]

1715572365

[bitpop]

It should use your existing address.
There's no requirement for a change address, its only done for privacy.
In armory and blockchain you can use coin control to force it back to source.

[kellrobinson]

It should use your existing address.

The way you phrased that doesn't make me supremely confident.

[bitpop]

It should use your existing address.

The way you phrased that doesn't make me supremely confident.

It's the only explanation. Change can't disappear so it must go back to original address since they Don't ask for one.

[bitpop]

I highly suggest making a watch only blockchain account tho and using a custom send. It will then ask for private key

[Rannasha]

The difference between total input value and total output value is used as miner-fee. If you construct a raw transaction that only spends part of the funds, you may end up paying a rather large fee to the miners as there is nothing in the Bitcoin protocol that forces change to be paid back.

So be careful when using third-party tools to craft transactions.

[kellrobinson]

The difference between total input value and total output value is used as miner-fee.

^^^This.
At some point I might do a test transaction, and leave about .001 btc on the table to see what happens.
Supposing the change goes as a mining fee, would that fact be recorded on the blockchain in such a way that it's visible if I check the transaction with a tool like blockchain.info or blockexplorer?

[bitpop]

I HIGHLY doubt brain wallet destroys your change

[DannyHamilton]

This thread is using words incorrectly and therefore causing confusion.

There is no such thing as "change" at the transaction level of bitcoin.

Transactions have 2 parts when it comes to the transfer of value:

• Inputs
• Outputs

When creating a transaction, no matter whether it is a wallet creating it, or brainwallet.org, or you write your own program to create a raw transaction, the thing that creates the transaction specifies inputs to supply value to the transaction, and then specifies outputs to encumber that value with requirements.

"Change" is a word we use for any output that is "sent back to the sender".

If you specify input values that exceed the specified output values, then the difference will ALWAYS be a transaction fee.  There is no other way to specify a transaction fee.  This is the definition of a transaction fee.

So, if the OP is specifically asking about brainwallet.org (and not some other non-wallet method of creating a transaction), then the answer is:

EDIT:  As of 2013 December 29, there is a bug in the brainwallet.org design (see post from Abdussamad below).  If you are not aware of this bug and how to avoid it, then you should not be using brainwallet.org to create bitcoin transactions.


brainwallet.org creates an additional output sending any additional value that is not accounted for in the specified outputs and specified transaction fee back to the "Source Address".

You can see this by looking at the JSON Transaction, without having to even transmit the transaction.

[Abdussamad]

I HIGHLY doubt brain wallet destroys your change

It has a UI bug that causes exorbitant transaction fees to be paid out instead of sending change back to the origin address:

https://bitcointalk.org/index.php?topic=372725.msg3987470#msg3987470

Bottom line if you are going to construct raw transactions you'd better know what you are doing!

[DannyHamilton]

I HIGHLY doubt brain wallet destroys your change

It has a UI bug that causes exorbitant transaction fees to be paid out instead of sending change back to the origin address:

https://bitcointalk.org/index.php?topic=372725.msg3987470#msg3987470

Bottom line if you are going to construct raw transactions you'd better know what you are doing!

Interesting.

Hopefully the creator of brainwallet.org will fix this bug soon.  In the meantime, it is probably a good idea not to use brainwallet.org to create transactions unless you are aware of this bug and how to avoid it.

[bitpop]

Stick to blockchain watch only

[Abdussamad]

BTW Danny you kinda got the date wrong in your big red warning. That bug has been around for at least two weeks.

[DannyHamilton]

BTW Danny you kinda got the date wrong in your big red warning. That bug has been around for at least two weeks.

Certainly, but it may not be around two weeks from now (when someone may come across this post and think, "No, such a bug does not exist?"

As such, my post is pointing out that as of today, the bug still exists, but in the future you should determine for yourself whether or not it has been fixed before deciding to use brainwallet.org to create a transaction.

Obviously it is too late to decide not to use brainwallet.org in the past.

[Abdussamad]

LOL I brought it up and he got a little annoyed but fixed it nevertheless:

https://github.com/brainwallet/brainwallet.github.com/issues/41

Still wouldn't recommend using this site though.

[bitpop]

Never use brain wallet