Electrum change addresses when importing private keys

[deepskydiver]

I want to move a small amount of bitcoin from an address I keep in cold storage by storing a literal private key, because I consider that the most secure and portable.

If I create a wallet for the purpose of importing that private key, where will the change go? To the only address in the wallet? If I import two or more how does it decide which? I figure it's better to ask rather than experiment..

Thanks - and is the official documentation the best reference for Electrum?

[aplistir]

If you import keys, the change address will be one of the keys you imported.
Can't say which one

In the old version of Electrum a new change address was created, which created problems to some users and bitcoins were lost because of that.

Most famous case is the lost 8999BTC in address: 167ZWTT8n6s4ya8cGjqNNQjDwDGY31vmHg
a change address created after moving 1BTC from an address containing 9000BTC

In any case your coins should be safe, if you do your transaction and then check where the BTC went. Even if they would go to a new change address (for some strange reason), you will have a private key to that address unless you delete your wallet.dat file

[TryNinja]

Can someone tell me why there is a need for change addresses? Can't we just send the "change" of the transaction back to ourselves?

I use only one address to receive my signature campaign payments and if I have something like 0.05BTC and want to send 0.03BTC to my local exchange, the remaining 0.02BTC is always sent back to my address. Is there is any issue on doing this?

[Potato Chips]

Can someone tell me why there is a need for change addresses? Can't we just send the "change" of the transaction back to ourselves?

Correct me If I'm wrong but I think its for the anomity which bitcoin promised, although its not completely anonymous even with the help of change addresses, I would call it pseudonymous instead.

Anyways, If there's no change addresses, It'll be easier to track your transactions particularly if you know who's behind a certain address because "change" allows your transactions to be ambigous as it makes the amount sent and the change indistinguishable.

I use only one address to receive my signature campaign payments and if I have something like 0.05BTC and want to send 0.03BTC to my local exchange, the remaining 0.02BTC is always sent back to my address. Is there is any issue on doing this?

In this case, It completely reveals the exact amount you sent as well as where did you sent them [which address]. Now if there is a change address, There will be a number of interpretations. From a strangers POV, you might have sent either .02BTC or .03BTC and at the same time there will be a two addresses (outputs): A). Local exchange B). Change address making him wonder which is which
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If I create a wallet for the purpose of importing that private key, where will the change go? To the only address in the wallet? If I import two or more how does it decide which? I figure it's better to ask rather than experiment..

Importing doesn't create a transaction so there will be no change because you will just be adding private keys to your bitcoin client.

[pooya87]

Can someone tell me why there is a need for change addresses? Can't we just send the "change" of the transaction back to ourselves?

I use only one address to receive my signature campaign payments and if I have something like 0.05BTC and want to send 0.03BTC to my local exchange, the remaining 0.02BTC is always sent back to my address. Is there is any issue on doing this?

i don't know where the notion of "change" address came from since these addresses have no difference with the rest! they are just categorized under another category! but Electrum is designed this way possibly to create a feeling of normal ways like fiat and "change".
and also it is designed this way to prevent address reuse [1]. when you send the change back to the same address you are reusing that address which is not that bad but is not recommended.

[1] https://en.bitcoin.it/wiki/Address_reuse

[HCP]

i don't know where the notion of "change" address came from since these addresses have no difference with the rest! they are just categorized under another category! but Electrum is designed this way possibly to create a feeling of normal ways like fiat and "change".

Under BIP32/44... the addresses actually belong to a slightly different chain on the derivation path... as they have the concept of "External" addresses (ie. receive) and "Internal" addresses (ie. change).

m / purpose' / coin_type' / account' / change / address_index

So for instance... your external addresses are on: m/44'/0'/0'/0 and your internal addresses are on m/44'/0'/0'/1