Author: Peter Todd 2015-12-20 11:24:54
Published on: 2015-12-20T11:24:54+00:00
On December 13, 2015, Gregory Maxwell via bitcoin-dev responded to Vincent Truong's post regarding the discarded UTXO. Maxwell clarifies that the outputs are still spendable but transactions must carry membership proof to spend them, which can be obtained from archive nodes that serve this purpose. Peter Todd has proposed a similar approach with "TXO commitments," which is also known as (U)TXO commitments. The primary argument against this kind of approach is that membership proofs get pretty big and if too aggressive, it trades bandwidth for storage. However, the membership proofs could be omitted when transmitting to a node that has signaled it has kept the historical data. Todd has proposed that a consensus-critical maximum UTXO age be part of the protocol, where UTXOs younger than that age are expected to be cached. For UTXOs older than that age, they can be dropped from the cache, but to spend them, users are required to provide the proof, which counts as blockchain space to account for the fact that they do need to be broadcast on the network. The proofs are relatively large but not so much larger than a CTxIn as to make paying for that data infeasible.
Updated on: 2023-06-11T02:04:28.070616+00:00