Bitcoins sent to hidden addresses?

[jones]

I just found this at blockexplorer.com
http://blockexplorer.com/address/1Mt84HnC635ebTWyu73dfMFtQqEsUQr65b

it says:
Note: While the last "balance" is the accurate number of bitcoins available to this address, it is likely not the balance available to this person. Every time a transaction is sent, some bitcoins are usually sent back to yourself at a new address (not included in the Bitcoin UI), which makes the balance of a single address misleading. See the wiki for more info on transactions.

I cannot found any helpful information on the wiki.

I do not understand what this means. Why whould one send amounts back to new addresses not shown in the UI?

[Blazr]

Lets take a look at one of the trransactions for that address in BC.info:

https://blockchain.info/tx/e37923bc171f74b7bf43ee2c22ed260b80f23b59f9ca38320973f7a73bbc1793

So what happened is, 15BTC was sent to 1LAdprC8a2Y2JrB3qRvEQsX68nZUHC6Nax. Then the owner sent 10BTC to 1LBrdEQgvgxbtaP6ameij3AR1yDoEMYR2U and the remaining amount (after tx fee) 4.995BTC was sent to one of the owners change addresses 1Mt84HnC635ebTWyu73dfMFtQqEsUQr65b

When you send BTC, you are basically spending a transaction that somebody else sent you, and you have to spend ALL of it, so to add anonymity, the change from each new transaction is sent to a new address.

Why aren't they displayed in the UI? No idea, they are displayed in most BTC clients, just not the original for some reason.

[jones]

Thank you for your explanation!

I had expected that it would use the original Bitcoin address as change address.

It's quite intransparent using a hidden change address, though. I hope they will change the behaviour and at least display the address.

[xorglub]

I just had a big scare as the same thing happened to me.
I really hope they change this behavior.
https://bitcointalk.org/index.php?topic=184768.0