📅 Original date posted:2017-11-07
📝 Original message:A hard-fork is a situation where non-upgraded nodes reject a block mined
and relayed by upgraded nodes. This creates a fork that cannot heal
regardless of what follows.
This proposal is not a hard-fork, because the non-upgraded node *will heal*
if the attack has less than 1/2 of the original-POW power in the long term.
The cost of such an attack is the cost of a normal "51%" attack, multiplied
by the fractional weight of the original POW (e.g. 0.75 or 0.5).
So rather than saying this is a hard-fork, I would say that this is a
soft-fork with reduced security for non-upgraded nodes. I would also say
that the reduction in security is proportional to the reduction in weight
of the original POW at the time of attack.
As mentioned before, the original-POW weight starts at 1.0 and is reduced
over a long period of time. I would set up the transition curve so that
all nodes upgrade by the time the weight is, say, 0.75. In reality, nodes
protecting high economic value would upgrade early.
On Mon, Nov 6, 2017 at 3:55 PM Eric Voskuil via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:
> If a block that would be discarded under previous rules becomes accepted
> after a rule addition, there is no reason to not simply call the new rule a
> hard fork. IOW it's perfectly rational to consider a weaker block as
> "invalid" relative to the strong chain. As such I don't see any reason to
> qualify the term, it's a hard fork. But Peter's observation (the specific
> behavior) is ultimately what matters.
>
> e
>
> On Nov 6, 2017, at 12:30, Paul Sztorc via bitcoin-dev <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>
> +1 to all of Peter Todd's comments
>
> On Nov 6, 2017 11:50 AM, "Peter Todd via bitcoin-dev" <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>
>> On Wed, Nov 01, 2017 at 05:48:27AM +0000, Devrandom via bitcoin-dev wrote:
>>
>> Some quick thoughts...
>>
>> > Hi all,
>> >
>> > Feedback is welcome on the draft below. In particular, I want to see if
>> > there is interest in further development of the idea and also
>> interested in
>> > any attack vectors or undesirable dynamics.
>> >
>> > (Formatted version available here:
>> > https://github.com/devrandom/btc-papers/blob/master/aux-pow.md )
>> >
>> > # Soft-fork Introduction of a New POW
>>
>> First of all, I don't think you can really call this a soft-fork; I'd
>> call it a
>> "pseudo-soft-fork"
>>
>> My reasoning being that after implementation, a chain with less total
>> work than
>> the main chain - but more total SHA256^2 work than the main chain - might
>> be
>> followed by non-supporting clients. It's got some properties of a
>> soft-fork,
>> but it's security model is definitely different.
>>
>> > ### Aux POW intermediate block
>> >
>> > Auxiliary POW blocks are introduced between normal blocks - i.e. the
>> chain
>> > alternates between the two POWs.
>> > Each aux-POW block points to the previous normal block and contains
>> > transactions just like a normal block.
>> > Each normal block points to the previous aux-POW block and must contain
>> all
>> > transactions from the aux-POW block.
>>
>> Note how you're basically proposing for the block interval to be
>> decreased,
>> which has security implications due to increased orphan rates.
>>
>> > ### Heaviest chain rule change
>> >
>> > This is a semi-hard change, because non-upgraded nodes can get on the
>> wrong
>> > chain in case of attack. However,
>>
>> Exactly! Not really a soft-fork.
>>
>> --
>> https://petertodd.org 'peter'[:-1]@petertodd.org
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev at lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20171107/81f53507/attachment.html>;
Devrandom [ARCHIVE] /
npub1j0…w9k8n
2023-06-07 18:07:25
in reply to nevent1q…knaf
Author Public Key
npub1j0js72tmnxzmrtd6j0j5wcvfuhsqwgqxdwkpmw28rmmuy22y3wzsdw9k8nPublished at
2023-06-07 18:07:25Event JSON
{
"id": "0f0f5cb57cbe9b28ff6c4f9bc21c3b3c5f85b505722aa99d6a1292ea45bc5ed2",
"pubkey": "93e50f297b9985b1adba93e5476189e5e00720066bac1db9471ef7c229448b85",
"created_at": 1686161245,
"kind": 1,
"tags": [
[
"e",
"712d2d7becdfc1f327fb6ef0f23f68f1502b313c103dbc4a20a9e4d0fb581029",
"",
"root"
],
[
"e",
"bb8e38ef51c0e604dcdb4904ec56ccfa728ba7f591753ab61691ec0eeb792079",
"",
"reply"
],
[
"p",
"82205f272f995d9be742779a3c19a2ae08522ca14824c3a3b01525fb5459161e"
]
],
"content": "📅 Original date posted:2017-11-07\n📝 Original message:A hard-fork is a situation where non-upgraded nodes reject a block mined\nand relayed by upgraded nodes. This creates a fork that cannot heal\nregardless of what follows.\n\nThis proposal is not a hard-fork, because the non-upgraded node *will heal*\nif the attack has less than 1/2 of the original-POW power in the long term.\n\nThe cost of such an attack is the cost of a normal \"51%\" attack, multiplied\nby the fractional weight of the original POW (e.g. 0.75 or 0.5).\n\nSo rather than saying this is a hard-fork, I would say that this is a\nsoft-fork with reduced security for non-upgraded nodes. I would also say\nthat the reduction in security is proportional to the reduction in weight\nof the original POW at the time of attack.\n\nAs mentioned before, the original-POW weight starts at 1.0 and is reduced\nover a long period of time. I would set up the transition curve so that\nall nodes upgrade by the time the weight is, say, 0.75. In reality, nodes\nprotecting high economic value would upgrade early.\n\nOn Mon, Nov 6, 2017 at 3:55 PM Eric Voskuil via bitcoin-dev \u003c\nbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\n\u003e If a block that would be discarded under previous rules becomes accepted\n\u003e after a rule addition, there is no reason to not simply call the new rule a\n\u003e hard fork. IOW it's perfectly rational to consider a weaker block as\n\u003e \"invalid\" relative to the strong chain. As such I don't see any reason to\n\u003e qualify the term, it's a hard fork. But Peter's observation (the specific\n\u003e behavior) is ultimately what matters.\n\u003e\n\u003e e\n\u003e\n\u003e On Nov 6, 2017, at 12:30, Paul Sztorc via bitcoin-dev \u003c\n\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\n\u003e +1 to all of Peter Todd's comments\n\u003e\n\u003e On Nov 6, 2017 11:50 AM, \"Peter Todd via bitcoin-dev\" \u003c\n\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\n\u003e\u003e On Wed, Nov 01, 2017 at 05:48:27AM +0000, Devrandom via bitcoin-dev wrote:\n\u003e\u003e\n\u003e\u003e Some quick thoughts...\n\u003e\u003e\n\u003e\u003e \u003e Hi all,\n\u003e\u003e \u003e\n\u003e\u003e \u003e Feedback is welcome on the draft below. In particular, I want to see if\n\u003e\u003e \u003e there is interest in further development of the idea and also\n\u003e\u003e interested in\n\u003e\u003e \u003e any attack vectors or undesirable dynamics.\n\u003e\u003e \u003e\n\u003e\u003e \u003e (Formatted version available here:\n\u003e\u003e \u003e https://github.com/devrandom/btc-papers/blob/master/aux-pow.md )\n\u003e\u003e \u003e\n\u003e\u003e \u003e # Soft-fork Introduction of a New POW\n\u003e\u003e\n\u003e\u003e First of all, I don't think you can really call this a soft-fork; I'd\n\u003e\u003e call it a\n\u003e\u003e \"pseudo-soft-fork\"\n\u003e\u003e\n\u003e\u003e My reasoning being that after implementation, a chain with less total\n\u003e\u003e work than\n\u003e\u003e the main chain - but more total SHA256^2 work than the main chain - might\n\u003e\u003e be\n\u003e\u003e followed by non-supporting clients. It's got some properties of a\n\u003e\u003e soft-fork,\n\u003e\u003e but it's security model is definitely different.\n\u003e\u003e\n\u003e\u003e \u003e ### Aux POW intermediate block\n\u003e\u003e \u003e\n\u003e\u003e \u003e Auxiliary POW blocks are introduced between normal blocks - i.e. the\n\u003e\u003e chain\n\u003e\u003e \u003e alternates between the two POWs.\n\u003e\u003e \u003e Each aux-POW block points to the previous normal block and contains\n\u003e\u003e \u003e transactions just like a normal block.\n\u003e\u003e \u003e Each normal block points to the previous aux-POW block and must contain\n\u003e\u003e all\n\u003e\u003e \u003e transactions from the aux-POW block.\n\u003e\u003e\n\u003e\u003e Note how you're basically proposing for the block interval to be\n\u003e\u003e decreased,\n\u003e\u003e which has security implications due to increased orphan rates.\n\u003e\u003e\n\u003e\u003e \u003e ### Heaviest chain rule change\n\u003e\u003e \u003e\n\u003e\u003e \u003e This is a semi-hard change, because non-upgraded nodes can get on the\n\u003e\u003e wrong\n\u003e\u003e \u003e chain in case of attack. However,\n\u003e\u003e\n\u003e\u003e Exactly! Not really a soft-fork.\n\u003e\u003e\n\u003e\u003e --\n\u003e\u003e https://petertodd.org 'peter'[:-1]@petertodd.org\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20171107/81f53507/attachment.html\u003e",
"sig": "496a5ecbf6ee8703b43b018a3b9af5eb9af5060a9bdc4fda375e9455d7960368df874357d926fd2464fc897f4357063181f10f257becc8f0d2a163d1075165b8"
}