Bitcoin Address Missing?

[BitcoinGirl325]

Hi there,

I'm brand new to Bitcoin and I'm slightly confused by this transfer I made between my 2 addresses. I'm using the Bitcoin-QT software on my Mac to manage my wallet, and I've only created 2 addresses so far. Let's call them "My Address A" and "My Address B".

I was involved in 3 transactions where I received a total of 11.50 Bitcoins into my wallet:
Transaction #1: I received 2 BTC to "My Address A"
Transaction #2: I received another 2.5 BTC to "My Address A"
Transaction #3: I received another 7 BTC to "My Address A"
TOTAL: 11.50 BTC in my wallet, all using "My Address A".

Then, using the Bitcoin-QT software, I wanted to see what it would look like if I made a transfer between my 2 addresses, so I transferred .001 BTC from "My Address A" to "My Address B", and I paid a .001 BTC transaction fee.

Bitcoin-QT shows exactly what I would expect: That I have 11.499 BTC (because it deducted the .001 BTC transaction fee from my previous 11.50 total). Furthermore, Bitcoin-QT lists "My Address A" and "My Address B" on the "Receive Coins" screen. So, from a Bitcoin-QT perspective, everything looks exactly how I would expect it to look. Both of my addresses are listed, and my full balance of 11.499 is listed on the "Overview" screen as well.

However, when I type in "My Address A" into blockchain.info, it says that I only have 9.5 BTC in "My Address A", .001 BTC in "My Address B", and 1.998 BTC was sent to a new 3rd address. This still adds up to 11.499 BTC, which is the accurate total, but I'm confused about this new 3rd address.

From reading other threads in the forum, it seems like Bitcoin-QT used my 2 BTC to pay for the .001 BTC transfer, and then it "made change" of 1.98 which it applied to a brand new 3rd address? Is this correct? Did it "make change" to a brand new, 3rd address? If so, how do I see this 3rd address listed within Bitcoin-QT? And how would I transfer money out of this 3rd address if I wanted to send it along to other people? Is this 3rd address still associated with my wallet?

I'm confused because within my Bitcoin-QT software, it seems to not know about this 3rd address at all... it only shows my first 2 addresses, yet it still rightfully understands that my full balance is 11.499 BTC. My expectations would be that if I had 3 addresses associated with my wallet, then all 3 addresses should be showing up within Bitcoin-QT. But apparently, my expectations don't always match reality!

Could anybody please help shed some light on this issue for me?

Thank you!

[whiskers75]

Most likely, this is an effect of Bitcoin-QT's keypool. Bitcoin-QT stores about 100 addresses in your wallet, and every time you need one, it gives you a different receiving address.

I use blockchain.info for my wallet, as it's secure, password-protected, backed up (on blockchain's servers), doesn't require a blockchain download, and gives you control over your addresses. For example, I imported my very nice vanity address easily (found in my signature)

And a tip, my friend - don't go telling everyone that you have 11.50 BTC.

[BitcoinGirl325]

Most likely, this is an effect of Bitcoin-QT's keypool. Bitcoin-QT stores about 100 addresses in your wallet, and every time you need one, it gives you a different receiving address.

I use blockchain.info for my wallet, as it's secure, password-protected, backed up (on blockchain's servers), doesn't require a blockchain download, and gives you control over your addresses. For example, I imported my very nice vanity address easily (found in my signature)

And a tip, my friend - don't go telling everyone that you have 11.50 BTC.

Ha, thanks for the tips! I'm not sure I completely understand your answer. Are you saying that Bitcoin-QT is responsible for assigning me this 3rd address? If so, how come I can't see this 3rd address listed in Bitcoin-Qt? How would I send the bitcoins from that 3rd address to someone else? Very confusing!

[BitcoinGirl325]

I suppose my main questions are:
 
- Do I have control over this 3rd address?
- Why is this 3rd address not showing up in my BitCoin-QT software program?
- Why does my BitCoin-QT software say that I have the proper number of Bitcoins in my wallet of 2 addresses, but blockchain.info only shows the proper number of Bitcoins if you add up 3 separate addresses?

Any insights would be greatly appreciated!

[whiskers75]

I don't think Bitcoin-QT shows you your keypool... 

If you send all your BTC to a listed wallet, what do you get?

[BitcoinGirl325]

Ah, thanks... this thread talks a little bit about keypools: https://bitcointalk.org/index.php?topic=26344.0

So it seems like that 3rd address is probably one of my 100 assigned addresses that I can't currently see. Very interesting.

Thanks for clearing this up. I'm going to assume that as long as my Bitcoin-QT app shows me the right GRAND TOTAL of all my BTC combined, then everything is good.

[whiskers75]

Yes, you're probably right, as the Bitcoin developers don't like having one address, because it can be traced

I would use a wallet like blockchain.info, as it gives you more control.

(And if you felt that I have helped you and somehow want to give back, my address is in my signature.)

[BitcoinGirl325]

Thanks. I just don't trust online wallets... although your custom address is very cool! :p

[whiskers75]

Thanks. I just don't trust online wallets... although your custom address is very cool! :p

Thanks! Want one? Check out the Vanity Pool - a cheap way to get vanity addresses without worrying about security.

[BitcoinGirl325]

The definitive answer to my question is now located in this thread:
https://bitcointalk.org/index.php?topic=171718.msg1786205