📅 Original date posted:2015-05-16
📝 Original message:On Sat, May 16, 2015 at 1:22 AM, Rusty Russell <rusty at rustcorp.com.au>
wrote:
> Some tweaks:
>
> 1) Nomenclature: call tx_size "tx_cost" and real_size "tx_bytes"?
>
Fair enough.
>
> 2) If we have a reasonable hard *byte* limit, I don't think that we need
> the MAX(). In fact, it's probably OK to go negative.
>
I agree, we want people to compress the UTXO space and a transaction with
100 inputs and one output is great.
It may have privacy problem though.
>
> 3) ... or maybe not, if any consumed UTXO was generated before the soft
> fork (reducing Tier's perverse incentive).
>
The incentive problem can be fixed by excluding UTXOs from blocks before a
certain count.
UTXOs in blocks before 375000 don't count.
>
> 4) How do we measure UTXO size? There are some constant-ish things in
> there (eg. txid as key, height, outnum, amount). Maybe just add 32
> to scriptlen?
>
They can be stored as a fixed digest. That can be any size, depending on
security requirements.
Gmaxwell's cost proposal is 3-4 bytes per UTXO change. It isn't
4*UXTO.size - 3*UTXO.size
It is only a small nudge. With only 10% of the block space to play with it
can't be massive.
This requires that transactions include scriptPubKey information when
broadcasting them.
>
> 5) Add a CHECKSIG cost. Naively, since we allow 20,000 CHECKSIGs and
> 1MB blocks, that implies a cost of 50 bytes per CHECKSIG (but counted
> correctly, unlike now).
>
> This last one implies that the initial cost limit would be 2M, but in
> practice probably somewhere in the middle.
>
> tx_cost = 50*num-CHECKSIG
> + tx_bytes
> + 4*utxo_created_size
> - 3*utxo_consumed_size
>
> > A 250 byte transaction with 2 inputs and 2 outputs would have an adjusted
> > size of 252 bytes.
>
> Now cost == 352.
>
That is to large a cost for a 10% block change. It could be included in
the block size hard fork though. I think have one combined "cost" for
transactions is good. It means much fewer spread out transaction checks.
The code for the cost formula would be in one place.
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Tier Nolan [ARCHIVE] /
npub1g6…sl5wd
2023-06-07 15:34:02
in reply to nevent1q…g5vu
Author Public Key
npub1g6vxlp4e0nyhs2dqxxcryztyf5f5hyuaq93nw4r87zcnv0sdsa0qqsl5wdPublished at
2023-06-07 15:34:02Event JSON
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"created_at": 1686152042,
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"content": "📅 Original date posted:2015-05-16\n📝 Original message:On Sat, May 16, 2015 at 1:22 AM, Rusty Russell \u003crusty at rustcorp.com.au\u003e\nwrote:\n\n\u003e Some tweaks:\n\u003e\n\u003e 1) Nomenclature: call tx_size \"tx_cost\" and real_size \"tx_bytes\"?\n\u003e\n\nFair enough.\n\n\u003e\n\u003e 2) If we have a reasonable hard *byte* limit, I don't think that we need\n\u003e the MAX(). In fact, it's probably OK to go negative.\n\u003e\n\nI agree, we want people to compress the UTXO space and a transaction with\n100 inputs and one output is great.\n\nIt may have privacy problem though.\n\n\n\u003e\n\u003e 3) ... or maybe not, if any consumed UTXO was generated before the soft\n\u003e fork (reducing Tier's perverse incentive).\n\u003e\n\nThe incentive problem can be fixed by excluding UTXOs from blocks before a\ncertain count.\n\nUTXOs in blocks before 375000 don't count.\n\n\n\u003e\n\u003e 4) How do we measure UTXO size? There are some constant-ish things in\n\u003e there (eg. txid as key, height, outnum, amount). Maybe just add 32\n\u003e to scriptlen?\n\u003e\n\nThey can be stored as a fixed digest. That can be any size, depending on\nsecurity requirements.\n\nGmaxwell's cost proposal is 3-4 bytes per UTXO change. It isn't\n4*UXTO.size - 3*UTXO.size\n\nIt is only a small nudge. With only 10% of the block space to play with it\ncan't be massive.\n\nThis requires that transactions include scriptPubKey information when\nbroadcasting them.\n\n\n\u003e\n\u003e 5) Add a CHECKSIG cost. Naively, since we allow 20,000 CHECKSIGs and\n\u003e 1MB blocks, that implies a cost of 50 bytes per CHECKSIG (but counted\n\u003e correctly, unlike now).\n\u003e\n\u003e This last one implies that the initial cost limit would be 2M, but in\n\u003e practice probably somewhere in the middle.\n\u003e\n\u003e tx_cost = 50*num-CHECKSIG\n\u003e + tx_bytes\n\u003e + 4*utxo_created_size\n\u003e - 3*utxo_consumed_size\n\u003e\n\u003e \u003e A 250 byte transaction with 2 inputs and 2 outputs would have an adjusted\n\u003e \u003e size of 252 bytes.\n\u003e\n\u003e Now cost == 352.\n\u003e\n\nThat is to large a cost for a 10% block change. It could be included in\nthe block size hard fork though. I think have one combined \"cost\" for\ntransactions is good. It means much fewer spread out transaction checks.\nThe code for the cost formula would be in one place.\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20150516/8e5f1099/attachment.html\u003e",
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