📅 Original date posted:2021-09-12
📝 Original message:> - 1 block reorgs: these are a regular feature on mainnet, everyone
should cope with them; having them happen multiple times a day to
make testing easier should be great
Anyone can do 1 block reorg, because nonce is not signed, so anyone can replace that with better value. For example, if you have block 00000086d6b2636cb2a392d45edc4ec544a10024d30141c9adf4bfd9de533b53 with 0x0007f4cc nonce, you can replace that with 0x00110241 nonce and get 000000096a1c4239d994547185c80308a552cba85d5bd28a51e9dc583ae5eadb block, where everything is identical, except the nonce.
Sometimes that reorg could be deeper if you would be lucky enough to get a block with more work than N following blocks combined.
On 2021-09-08 09:59:29 user Anthony Towns via bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org> wrote:
> On Tue, Sep 07, 2021 at 06:07:47PM +0200, 0xB10C via bitcoin-dev wrote:
> The reorg-interval X very much depends on the user's needs. One could
> argue that there should be, for example, three reorgs per day, each 48
> blocks apart.
Oh, wow, I think the last suggestion was every 100 blocks (every
~16h40m). Once every ~8h sounds very convenient.
> Such a short reorg interval allows developers in all time
> zones to be awake during one or two reorgs per day.
And also for there to reliably be reorgs when they're not awake, which
might be a useful thing to be able to handle, too :)
> Developers don't
> need to wait for, for example, a week until they can test their reorgs
> next. However, too frequent reorgs could hinder other SigNet users.
Being able to run `bitcoind -signet -signetacceptreorg=0` and never
seeing any reorgs should presumably make this not a problem?
For people who do see reorgs, having an average of 2 or 3 additional
blocks every 48 blocks is perhaps a 6% increase in storage/traffic.
> # Scenario 1: Race between two chains
>
> For this scenario, at least two nodes and miner scripts need to be
> running. An always-miner A continuously produces blocks and rejects
> blocks with the to-be-reorged version bit flag set. And a race-miner R
> that only mines D blocks at the start of each interval and then waits X
> blocks. A and R both have the same hash rate. Assuming both are well
> connected to the network, it's random which miner will first mine and
> propagate a block. In the end, the A miner chain will always win the race.
I think this description is missing that all the blocks R mines have
the to-be-reorged flag set.
> 3. How deep should the reorgs be on average? Do you want to test
> deeper reorgs (10+ blocks) too?
Super interested in input on this -- perhaps we should get optech to
send a survey out to their members, or so?
My feeling is:
- 1 block reorgs: these are a regular feature on mainnet, everyone
should cope with them; having them happen multiple times a day to
make testing easier should be great
- 2-3 block reorgs: good for testing the "your tx didn't get enough
confirms to be credited to your account" case, even though it barely
ever happens on mainnet
- 4-6 block reorgs: likely to violate business assumptions, but
completely technically plausible, especially if there's an attack
against the network
- 7-100 block reorgs: for this to happen on mainnet, it would probably
mean there was a bug and pools/miners agree the chain has to
be immediately reverted -- eg, someone discovers and exploits an
inflation bug, minting themselves free bitcoins and breaking the 21M
limit (eg, the 51 block reorg in Aug 2010); or someone discovers a
bug that splits the chain, and the less compatible chain is reverted
(eg, the 24 block reorg due to the bdb lock limit in Mar 2013);
or something similar. Obviously the bug would have to have been
discovered pretty quickly after it was exploited for the reorg to be
under a day's worth of blocks.
- 100-2000+ block reorgs: severe bug that wasn't found quickly, or where
getting >50% of miners organised took more than a few hours. This will
start breaking protocol assumptions, like pool payouts, lightning's
relative locktimes, or liquid's peg-in confirmation requirements, and
result in hundres of MBs of changes to the utxo set
Maybe it would be good to do reorgs of 15, 150 or 1500 blocks as a
special fire-drill event, perhaps once a month/quarter/year or so,
in some pre-announced window?
I think sticking to 1-6 block reorgs initially is a fine way to start
though.
> After enough testing, the default SigNet can start to do periodical
> reorgs, too.
FWIW, the only thing that concerns me about doing this on the default
signet is making sure that nodes that set -signetacceptreorg=0 don't
end up partitioning the p2p network due to either rejecting a higher
work chain or rejecting txs due to double-spends across the two chains.
A quick draft of code for -signetacceptreorg=0 is available at
https://github.com/ajtowns/bitcoin/commits/202108-signetreorg
Cheers,
aj
_______________________________________________
bitcoin-dev mailing list
bitcoin-dev at lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
vjudeu at gazeta.pl [ARCHIVE] /
npub135…nssga
2023-06-07 22:58:48
in reply to nevent1q…h338
Author Public Key
npub1357006afyypkgz03lmq8fnuvlkyjt0rukx8rt56ck8xv396jaceqmnssgaPublished at
2023-06-07 22:58:48Event JSON
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"content": "📅 Original date posted:2021-09-12\n📝 Original message:\u003e - 1 block reorgs: these are a regular feature on mainnet, everyone\n should cope with them; having them happen multiple times a day to\n make testing easier should be great\n\nAnyone can do 1 block reorg, because nonce is not signed, so anyone can replace that with better value. For example, if you have block 00000086d6b2636cb2a392d45edc4ec544a10024d30141c9adf4bfd9de533b53 with 0x0007f4cc nonce, you can replace that with 0x00110241 nonce and get 000000096a1c4239d994547185c80308a552cba85d5bd28a51e9dc583ae5eadb block, where everything is identical, except the nonce.\n\nSometimes that reorg could be deeper if you would be lucky enough to get a block with more work than N following blocks combined.\n\nOn 2021-09-08 09:59:29 user Anthony Towns via bitcoin-dev \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e On Tue, Sep 07, 2021 at 06:07:47PM +0200, 0xB10C via bitcoin-dev wrote:\n\u003e The reorg-interval X very much depends on the user's needs. One could\n\u003e argue that there should be, for example, three reorgs per day, each 48\n\u003e blocks apart.\n\nOh, wow, I think the last suggestion was every 100 blocks (every\n~16h40m). Once every ~8h sounds very convenient.\n\n\u003e Such a short reorg interval allows developers in all time\n\u003e zones to be awake during one or two reorgs per day.\n\nAnd also for there to reliably be reorgs when they're not awake, which\nmight be a useful thing to be able to handle, too :)\n\n\u003e Developers don't\n\u003e need to wait for, for example, a week until they can test their reorgs\n\u003e next. However, too frequent reorgs could hinder other SigNet users.\n\nBeing able to run `bitcoind -signet -signetacceptreorg=0` and never\nseeing any reorgs should presumably make this not a problem?\n\nFor people who do see reorgs, having an average of 2 or 3 additional\nblocks every 48 blocks is perhaps a 6% increase in storage/traffic.\n\n\u003e # Scenario 1: Race between two chains\n\u003e \n\u003e For this scenario, at least two nodes and miner scripts need to be\n\u003e running. An always-miner A continuously produces blocks and rejects\n\u003e blocks with the to-be-reorged version bit flag set. And a race-miner R\n\u003e that only mines D blocks at the start of each interval and then waits X\n\u003e blocks. A and R both have the same hash rate. Assuming both are well\n\u003e connected to the network, it's random which miner will first mine and\n\u003e propagate a block. In the end, the A miner chain will always win the race.\n\nI think this description is missing that all the blocks R mines have\nthe to-be-reorged flag set.\n\n\u003e 3. How deep should the reorgs be on average? Do you want to test\n\u003e deeper reorgs (10+ blocks) too?\n\nSuper interested in input on this -- perhaps we should get optech to\nsend a survey out to their members, or so?\n\nMy feeling is:\n\n - 1 block reorgs: these are a regular feature on mainnet, everyone\n should cope with them; having them happen multiple times a day to\n make testing easier should be great\n\n - 2-3 block reorgs: good for testing the \"your tx didn't get enough\n confirms to be credited to your account\" case, even though it barely\n ever happens on mainnet\n\n - 4-6 block reorgs: likely to violate business assumptions, but\n completely technically plausible, especially if there's an attack\n against the network\n\n - 7-100 block reorgs: for this to happen on mainnet, it would probably\n mean there was a bug and pools/miners agree the chain has to\n be immediately reverted -- eg, someone discovers and exploits an\n inflation bug, minting themselves free bitcoins and breaking the 21M\n limit (eg, the 51 block reorg in Aug 2010); or someone discovers a\n bug that splits the chain, and the less compatible chain is reverted\n (eg, the 24 block reorg due to the bdb lock limit in Mar 2013);\n or something similar. Obviously the bug would have to have been\n discovered pretty quickly after it was exploited for the reorg to be\n under a day's worth of blocks.\n\n - 100-2000+ block reorgs: severe bug that wasn't found quickly, or where\n getting \u003e50% of miners organised took more than a few hours. This will\n start breaking protocol assumptions, like pool payouts, lightning's\n relative locktimes, or liquid's peg-in confirmation requirements, and\n result in hundres of MBs of changes to the utxo set\n\nMaybe it would be good to do reorgs of 15, 150 or 1500 blocks as a\nspecial fire-drill event, perhaps once a month/quarter/year or so,\nin some pre-announced window?\n\nI think sticking to 1-6 block reorgs initially is a fine way to start\nthough.\n\n\u003e After enough testing, the default SigNet can start to do periodical\n\u003e reorgs, too.\n\nFWIW, the only thing that concerns me about doing this on the default\nsignet is making sure that nodes that set -signetacceptreorg=0 don't\nend up partitioning the p2p network due to either rejecting a higher\nwork chain or rejecting txs due to double-spends across the two chains.\n\nA quick draft of code for -signetacceptreorg=0 is available at \n\n https://github.com/ajtowns/bitcoin/commits/202108-signetreorg\n\nCheers,\naj\n\n_______________________________________________\nbitcoin-dev mailing list\nbitcoin-dev at lists.linuxfoundation.org\nhttps://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev",
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