📅 Original date posted:2015-12-08
📝 Original message:On Tue, Dec 8, 2015 at 5:41 PM, Mark Friedenbach via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:
> A far better place than the generation transaction (which I assume means
> coinbase transaction?) is the last transaction in the block. That allows
> you to save, on average, half of the hashes in the Merkle tree.
>
This trick can be improved by only using certain tx counts. If the number
of transactions is limited to a power of 2 (other than the extra
transactions), then you get a path of length zero.
The number of non-zero bits in the tx count determings how many digests are
required.
https://github.com/TierNolan/bips/blob/aux_header/bip-aux-header.mediawiki
This gets the benefit of a soft-fork, while also keeping the proof lengths
small. The linked bip has a 105 byte overhead for the path.
The cost is that only certain transaction counts are allowed. In the worst
case, 12.5% of transactions would have to be left in the memory pool. This
means around 7% of transactions would be delayed until the next block.
Blank transactions (or just transactions with low latency requirements)
could be used to increase the count so that it is raised to one of the
valid numbers.
Managing the UTXO set to ensure that there is at least one output that pays
to OP_TRUE is also a hassle.
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Tier Nolan [ARCHIVE] /
npub1g6…sl5wd
2023-06-07 17:45:38
in reply to nevent1q…aue3
Author Public Key
npub1g6vxlp4e0nyhs2dqxxcryztyf5f5hyuaq93nw4r87zcnv0sdsa0qqsl5wdSeen on
wss://relay.noswhere.comPublished at
2023-06-07 17:45:38Event JSON
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"content": "📅 Original date posted:2015-12-08\n📝 Original message:On Tue, Dec 8, 2015 at 5:41 PM, Mark Friedenbach via bitcoin-dev \u003c\nbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\n\u003e A far better place than the generation transaction (which I assume means\n\u003e coinbase transaction?) is the last transaction in the block. That allows\n\u003e you to save, on average, half of the hashes in the Merkle tree.\n\u003e\n\nThis trick can be improved by only using certain tx counts. If the number\nof transactions is limited to a power of 2 (other than the extra\ntransactions), then you get a path of length zero.\n\nThe number of non-zero bits in the tx count determings how many digests are\nrequired.\n\nhttps://github.com/TierNolan/bips/blob/aux_header/bip-aux-header.mediawiki\n\nThis gets the benefit of a soft-fork, while also keeping the proof lengths\nsmall. The linked bip has a 105 byte overhead for the path.\n\nThe cost is that only certain transaction counts are allowed. In the worst\ncase, 12.5% of transactions would have to be left in the memory pool. This\nmeans around 7% of transactions would be delayed until the next block.\n\nBlank transactions (or just transactions with low latency requirements)\ncould be used to increase the count so that it is raised to one of the\nvalid numbers.\n\nManaging the UTXO set to ensure that there is at least one output that pays\nto OP_TRUE is also a hassle.\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151208/99821607/attachment.html\u003e",
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