{"type":"rich","version":"1.0","author_name":"npub1kc0zulxt7j4a0ayhzhrz7jk84y7tm4026qcky7w97hlfkxxap24qnwjfw4","author_url":"https://nostr.ae/npub1kc0zulxt7j4a0ayhzhrz7jk84y7tm4026qcky7w97hlfkxxap24qnwjfw4","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2015-12-12\n📝 Original message:It is a common practice in commercial banks that a dormant account might \nbe confiscated. Confiscating or deleting dormant UTXOs might be too \ncontroversial, but allowing the UTXOs set growing without any limit \nmight not be a sustainable option. People lose their private keys. \nPeople do stupid things like sending bitcoin to 1BitcoinEater. We \nshouldn’t be obliged to store everything permanently. This is my \nproposal:\n\nDormant UTXOs are those UTXOs with 420000 confirmations. In every block \nX after 420000, it will commit to a hash for all UTXOs generated in \nblock X-420000. The UTXOs are first serialized into the form: \ntxid|index|value|scriptPubKey, then a sorted Merkle hash is calculated. \nAfter some confirmations, nodes may safely delete the UTXO records of \nblock X permanently.\n\nIf a user is trying to redeem a dormant UTXO, in addition the signature, \nthey have to provide the scriptPubKey, height (X), and UTXO value as \npart of the witness. They also need to provide the Merkle path to the \ndormant UTXO commitment.\n\nTo confirm this tx, the miner will calculate a new Merkle hash for the \nblock X, with the hash of the spent UTXO replaced by 1, and commit the \nhash to the current block. All full nodes will keep an index of latest \ndormant UTXO commitments so double spending is not possible. (a \n\"meta-UTXO set\")\n\nIf all dormant UTXOs under a Merkle branch are spent, hash of the branch \nwill become 1. If all dormant UTXOs in a block are spent, the record for \nthis block could be forgotten. Full nodes do not need to remember which \nparticular UTXO is spent or not, since any person trying to redeem a \ndormant UTXO has to provide such information.\n\nIt becomes the responsibility of dormant coin holders to scan the \nblockchain for the current status of the UTXO commitment for their coin. \nThey may also need to pay extra fee for the increased tx size.\n\nThis is a softfork if there is no hash collision but this is a \nfundamental assumption in Bitcoin anyway. The proposal also works \nwithout segregated witness, just by replacing \"witness\" with \"scriptSig\""}