Continuing off of this question, Does change appear as an output in a transaction?, can you determine that Alice's change transaction really is a change transaction? Or to put it a different way, can you tell change transactions apart from regular transactions if you have the view key?
1 Answer
There is no such thing as a "change transaction". A transaction has inputs and outputs. When a user sends funds to someone, any change is just destined to one of the transaction outputs. Only the sender can derive which output has any change and how much that output has, and yes, they would be using their view key.
Remember though, there may not actually be any "change". A user could spend all the input(s) to one or more destinations (outputs) that are not theirs, and thus no change output needs creating by the wallet.
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Thanks, perhaps I can rephrase it better now: if there is an output sent back to the sender's wallet as change, can the sender detect that, or does it look different than other transactions?– joeCommented Nov 4, 2018 at 3:41
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2The sender knows already because it created the change output. That aside, when the wallet scans blocks transactions, it is checking every output to see if it is destined for it's wallet. In this case it doesn't need to know if it was change, it only needs to know it's for this wallet. There is nothing that distinguishes an output as being "change". Commented Nov 4, 2018 at 5:19