From: Tamas Blummer <tamas.blummer@gmail•com>
To: Pieter Wuille <pieter.wuille@gmail•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] OP_DIFFICULTY to enable difficulty hedges (bets) without an oracle and 3rd party.
Date: Thu, 23 May 2019 22:26:49 +0200 [thread overview]
Message-ID: <8870AC4C-B5E4-491C-8973-8962DEBD39CE@gmail.com> (raw)
In-Reply-To: <CAPg+sBged=ivVLj9tAM6zZdvWdYnG5pj4gozac5EupFPLtwyfA@mail.gmail.com>
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> On May 23, 2019, at 21:45, Pieter Wuille <pieter.wuille@gmail•com> wrote:
>
> On Thu, 23 May 2019 at 11:33, Tamas Blummer via bitcoin-dev
> <bitcoin-dev@lists•linuxfoundation.org> wrote:
>>
>> Difficulty change has profound impact on miner’s production thereby introduce the biggest risk while considering an investment.
>> Commodity markets offer futures and options to hedge risks on traditional trading venues. Some might soon list difficulty futures.
>>
>> I think we could do much better than them natively within Bitcoin.
>>
>> A better solution could be a transaction that uses nLocktime denominated in block height, such that it is valid after the difficulty adjusted block in the future.
>> A new OP_DIFFICULTY opcode would put onto stack the value of difficulty for the block the transaction is included into.
>> The output script may then decide comparing that value with a strike which key can spend it.
>> The input of the transaction would be a multi-sig escrow of those who entered the bet.
>> The winner would broadcast.
>
> If the difficulty can be directly observed by the script language, you
> would need to re-evaluate all scripts in unconfirmed transactions
> whenever the difficulty changes. This complicates implementation of
> mempools, but it also makes reasoning about validity of (chains of)
> unconfirmed transactions harder, as an unconfirmed predecessor may
> have conditions that change over time.
>
> For things like block time/height, this is solved by not having the
> script itself observe the context state directly, but instead having
> an assertion on the state outside of script (nLockTime for absolute
> time/height and nSequence for relative), and then having opcodes
> inside script that observe the assertion (OP_CLTV and OP_CSV). By
> doing so, script validity is a single context-free yes or not that can
> be evaluated once, and the variable part is just transaction-level
> reasoning that doesn't involve a full script interpreter.
> Additionally, the supported assertions are restricted in such a way
> that if they are true within a particular block, they're also true in
> any descendant, removing the complexity of reasoning about validity
> (apart from the inevitable reasoning about possible double-spend
> before confirmation).
>
> I feel a similar construction is needed for observing block
> difficulty. This can be done by either having an opcode that as a side
> effect of execution "posts" an assertion (e.g. "difficulty at block
> height X is at least Y"), instead of putting the difficulty on the
> stack. An alternative is having the assertion be part of the
> transaction structure (for example in the annex we propose in
> bip-taproot), and having an opcode that observes the difficulty
> assertion inside script.
Thanks for these suggestions I will follow up while preparing the BIP.
>
> I don't have a strong opinion either way on the usefulness of having
> difficulty-dependent transaction/scripts.
>
This is the best reception I could have hoped for :)
> Cheers,
>
> --
> Pieter
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next prev parent reply other threads:[~2019-05-23 20:26 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 20:58 [bitcoin-dev] Congestion Control via OP_CHECKOUTPUTSHASHVERIFY proposal Jeremy
2019-05-21 19:41 ` Matt Corallo
2019-05-22 1:47 ` Jeremy
2019-05-22 2:51 ` ZmnSCPxj
2019-05-22 5:11 ` Jeremy
2019-05-22 6:04 ` ZmnSCPxj
2019-05-22 8:10 ` Jeremy
2019-05-23 3:45 ` ZmnSCPxj
2019-05-24 21:15 ` Jeremy
2019-05-25 3:56 ` ZmnSCPxj
2019-05-22 20:49 ` Anthony Towns
2019-05-23 17:42 ` [bitcoin-dev] OP_DIFFICULTY to enable difficulty hedges (bets) without an oracle and 3rd party Tamas Blummer
2019-05-23 19:03 ` Jorge Timón
2019-05-23 19:10 ` Tamas Blummer
2019-05-23 19:05 ` Nathan Cook
2019-05-23 19:18 ` Tamas Blummer
2019-05-23 19:21 ` Nathan Cook
2019-05-23 19:45 ` Tamas Blummer
2019-05-23 19:54 ` Tamas Blummer
2019-05-23 20:07 ` Nathan Cook
2019-05-23 19:45 ` Pieter Wuille
2019-05-23 20:26 ` Tamas Blummer [this message]
2019-05-24 8:36 ` Natanael
2019-05-24 16:23 ` Tamas Blummer
2019-05-24 8:15 ` Johnson Lau
2019-05-24 19:12 ` [bitcoin-dev] Congestion Control via OP_CHECKOUTPUTSHASHVERIFY proposal Johnson Lau
2019-05-24 20:36 ` Jeremy
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