📅 Original date posted:2016-11-16
📝 Original message:On Thu, Nov 17, 2016 at 12:10 AM, Eric Voskuil via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:
> Both of these cases resulted from exact duplicate txs, which BIP34 now
> precludes. However nothing precludes different txs from having the same
> hash.
>
The only way to have two transactions have the same txid is if their
parents are identical, since the txids of the parents are included in a
transaction.
Coinbases have no parents, so it used to be possible for two of them to be
identical.
Duplicate outputs weren't possible in the database, so the later coinbase
transaction effectively overwrote the earlier one.
The happened for two coinbases. That is what the exceptions are for.
Neither of the those coinbases were spent before the overwrite happened. I
don't even think those coinbases were spent at all.
This means that every activate coinbase transaction has a unique hash and
all new coinbases will be unique.
This means that all future transactions will have different txids.
There might not be an explicit rule that says that txids have to be unique,
but barring a break of the hash function, they rules do guarantee it.
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Tier Nolan [ARCHIVE] /
npub1g6…sl5wd
2023-06-07 17:54:25
in reply to nevent1q…uvh2
Author Public Key
npub1g6vxlp4e0nyhs2dqxxcryztyf5f5hyuaq93nw4r87zcnv0sdsa0qqsl5wdPublished at
2023-06-07 17:54:25Event JSON
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"pubkey": "46986f86b97cc97829a031b03209644d134b939d0163375467f0b1363e0d875e",
"created_at": 1686160465,
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"content": "📅 Original date posted:2016-11-16\n📝 Original message:On Thu, Nov 17, 2016 at 12:10 AM, Eric Voskuil via bitcoin-dev \u003c\nbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\n\u003e Both of these cases resulted from exact duplicate txs, which BIP34 now\n\u003e precludes. However nothing precludes different txs from having the same\n\u003e hash.\n\u003e\n\nThe only way to have two transactions have the same txid is if their\nparents are identical, since the txids of the parents are included in a\ntransaction.\n\nCoinbases have no parents, so it used to be possible for two of them to be\nidentical.\n\nDuplicate outputs weren't possible in the database, so the later coinbase\ntransaction effectively overwrote the earlier one.\n\nThe happened for two coinbases. That is what the exceptions are for.\n\nNeither of the those coinbases were spent before the overwrite happened. I\ndon't even think those coinbases were spent at all.\n\nThis means that every activate coinbase transaction has a unique hash and\nall new coinbases will be unique.\n\nThis means that all future transactions will have different txids.\n\nThere might not be an explicit rule that says that txids have to be unique,\nbut barring a break of the hash function, they rules do guarantee it.\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20161117/55cc4f6a/attachment-0001.html\u003e",
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