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Is there any other way besides signing a transaction to verify ownership of utxos?
Verifying ownership of utxos
Answers
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To 'own some bitcoins' is to own the private key that allows a UTXO to be spent, so your question can be refined to "how do you verify ownership of a private key that controls a UTXO?"
There are a few ways you could do this:
- Sign a generic message with the key, such as "I am the owner of bitcoin address 1a5Ag23...."
- Sign a transaction with the key, spending the coins to a new address (you could post the address prior to broadcasting the tx, to prove the coins are not just moving by coincidence)
- You could show off the private key itself (but this is a very bad idea! The bitcoins probably would not remain yours for long...)
1I disagree that owning BTC is equal to having access to private keys. Coinbase certainly does not own all the BTC they have keys for, for example. – Pieter Wuille – 2018-03-23T00:09:42.700
1@PieterWuille I guess it is helpful to differentiate between 'ownership according to the blockchain' and 'ownership according to legal/social contracts'. In any case, the UTXOs Coinbase controls would not map perfectly onto user account balances, so we can't really point to a specific CoinBase-controlled UTXO and say "that one belongs to user x". Coinbase may be reputable and have intent to fulfill their duties as a custodial service, but sketchy exchanges that have exit scammed in the past help prove my point. If someone owes you $5 but hasn't paid it back, you don't own that $5. They do. – chytrik – 2018-03-23T00:24:27.743
2In this sense, perhaps it would be better to say 'Control of the UTXO', rather than 'Ownership of the UTXO'. I think that satisfies both of our arguments. – chytrik – 2018-03-23T00:25:22.277
1I think there's a difference between money owed (a debt) and custodial control. Even the sketchiest exchange doesn't own your money - you're perhaps making a bad business decision to risk having them control it, but it in no way makes the money owned by them. I think ownership is inherently a social construct, and not something described by the blockchain. The latter is just a way to reduce risk of having the wrong parties take control. It's even more complicated with UTXOs controlled by escrow or hashlocked contracts. These don't have a clear identifiable owner key even. – Pieter Wuille – 2018-03-23T00:36:34.593
Nonetheless, the answer does not delve into ownership of BTC. Coinbase certainly has ownership of the private keys needed to sign for each utxo. – Willtech – 2018-03-23T03:33:38.567