4

I think it would be helpful for you to identify your service here, so that I can encourage people to not do business with you. Users generally have no idea if this will work safely or not, so a notice will not be sufficient. If you send users funds to addresses they did not supply you should be prepared to pay them out when they report the funds have gone ...


4

Transactions explicitly refer to which UTXOs they are spending. You can construct a transaction which only spends one of the two 5-BTC UTXOs, and sends 2 BTC to the destination and 3 BTC to a (possibly new) address of yourself. You can also construct a transaction which spends both, and sends 8 BTC back to yourself. Or it could have multiple outputs that ...


3

Assume you are using a unique common address for each customer and at the end of the day/week/month you make payments to your employees, suppliers or partners. When making those payments, if those outgoing amounts exceed the amounts received from one customer, you will have to include inputs coming from other customers. If some of your customer addresses ...


3

You are looking at transactions the wrong way. Bitcoin does not actually use addresses and their balances. The protocol has no concept of what an address is, nor does it need to. It also has no idea of an address or an account balance. Rather how Bitcoin works is with transaction outputs. Transaction outputs are spent as the inputs to other transactions, ...


2

You are right in noticing that the change from a transaction is linked to the previous input. Address reuse is more for receiving payments than spending them - if you have two clients paying you, giving them separate addresses for the payments creates two completely unlinkable outputs on the chain. Naturally, if you make a future transaction that requires ...


1

This is a limitation on the interface used for send many. The address,amount list is a dictionary internally within Bitcoin Core, and cannot have duplicate keys. As many other projects are forks of Bitcoin Core, the limitation applies to them as well. You can work around this by constructing a transaction manually or with a library that doesn't not use the ...


1

None. No wallet that exists discards private keys. That would be superbly idiotic to do because that means that money could be thrown away permanently. No wallet would intentionally do that.


1

You are confusing addresses and UTXOs. What you are talking about are addresses, not UTXOs. The inputs of a transaction have no effect on the outputs. There is no requirement that a transaction must have an output that corresponds to an address that is an input. In fact, what you described first is known as address reuse which is highly discouraged. The ...


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