Armory Transaction Newbie Question

[matrix01]

Fellow Forum Members,
Below is a screen capture of the transaction info window for my first Armory transaction I did for testing purposes. It was for the amount of .25 cents USD or 0.001 Bitcoin. I sent 25 cents over to my Armory watchonly wallet as a test and what I do not understand is the  "0.1989 Amount" value shown at the bottom of the screen capture under the "Transaction Outputs (Receiving addresses):" header. Why does Armory display my Blockchain.info wallet public key with a "0.1989" ($53.5 USD) amount when the only amount should logically be for a "0.001" (.26 cents) amount ?  In other words, I never sent "0.1989" ($53.5 USD) from my Blockchain.info wallet to my Armory watchonly wallet therefore this "0.1989" ($53.5 USD) amount does not make sense to me. To gain some understanding I clicked on the question mark next to the "Sum of Outputs" because I don't understand the "0.1999 BTC" value. And the text in the Popup window does not make sense to me.  Any opinion will be greatly appreciated.









Also I'm confused with how Armory shows 0.00000000 BTC for Spendable Funds. However for both Maximum Funds and Unconfirmed it displays: "0.00100000".  36 Confirmations have been processed and Armory for some reason is not seeing my .25 cents as "Spendable Funds".  Any opinion on this will also be welcomed.  Thanks.

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[picobit]

What you see is the "change" part of the transaction.

When you make a bitcoin transaction, you cannot send a partial "coin".  That means that if you have received 0.2 BTC in one transaction, you have to spend 0.2 BTC in one transaction. The way this is handled is by sending 0.001 BTC to the recepient, and 0.199 BTC back to yourself.  Now you have a new "input" of 0.199 that can be used for your next transaction.

Your transaction can combine multiple "inputs" if you send a larger amount, but if an input appears it will be used entirely.  The remainer is change, and is send back to yourself.  Most wallets (including Armory) will create a new bitcoin address for the change instead of reusing the old one as blockchain.info does.  You can see these new addresses labeled "Change received" if you look at the wallet contents.

Experiment.  Transfer another small amount to your armory wallet, send some of it back to blockchain, and look at what happens.  Once you feel you understand what is going on, and are sure you can spend the money again, then you can start using larger amounts.  But it is too stressful to experiment with larger amounts

[dsattler]

I think I've seen a switch to send the change back to the output address (I assume it's hidden in the "coin control" settings). But to create a new address for the change is the better solution security-wise, because using the same bitcoin address in multiple spending transactions makes it vulnerable for hacking it's private key.

[picobit]

I think I've seen a switch to send the change back to the output address (I assume it's hidden in the "coin control" settings). But to create a new address for the change is the better solution security-wise, because using the same bitcoin address in multiple spending transactions makes it vulnerable for hacking it's private key.

No, it doesn't, at least it is not supposed to.  Unless you have a poor RNG in your wallet software, but if you do that then you are lost anyway.  Or until the attacker gets a yet-to-be-invented quantum computer (the real thing, not the d-wave).

But reusing addresses is bad for privacy.  And with a deterministic wallet there is no advantage to reusing addresses, only disadvantages.