[bitcoin-dev] OP_DIFFICULTY to enable difficulty hedges (bets) without an oracle and 3rd party.

Nathan Cook nathan.cook at gmail.com
Thu May 23 20:07:30 UTC 2019


You're right, I didn't remember the whole procedure. You provide the
80-byte header in the spend script, duplicate it on the stack, hash it, and
compare to what OP_CHECKBLOCKATHEIGHT gives you. Then you do bit masking on
the header with OP_AND to extract the difficulty. You can compare two
compressed difficulties directly by using more bit masking to separate the
exponent and mantissa.

On Thu, 23 May 2019 at 22:54, Tamas Blummer <tamas.blummer at gmail.com> wrote:

> Block hash can suggest much higher difficulty than what is in effect, so
> OP_CHECKBLOCKATHEIGHT would not work to decide if difficulty is above the
> level of the bet.
>
> > On May 23, 2019, at 21:45, Tamas Blummer <tamas.blummer at gmail.com>
> wrote:
> >
> > I see. The uncompressing needs to be done either to compare. How are
> chances for that BIP?
> >
> > This BIP would be explicitly offering risk managment of miners biggest
> risk.
> > Doing so without relying on external markets or oracle, self cointained
> would be an impressive and adequate feature.
> >
> > Tamas Blummer
> >
> >> On May 23, 2019, at 21:21, Nathan Cook <nathan.cook at gmail.com> wrote:
> >>
> >> It's true that it fetches the block hash; the idea is to compare the
> block hash's numeric value to the desired (uncompressed) difficulty
> directly, using a 256-bit version of OP_LESSTHAN.
> >>
> >> Nathan Cook
> >>
> >>
> >> On Thu, 23 May 2019 at 22:18, Tamas Blummer <tamas.blummer at gmail.com>
> wrote:
> >> That opcode would not help as it fetches block hash and not the content
> of the header.
> >>
> >>> On May 23, 2019, at 21:05, Nathan Cook <nathan.cook at gmail.com> wrote:
> >>>
> >>> You can get the same effect with OP_CHECKBLOCKATHEIGHT as proposed by
> Luke Dashjr (
> https://github.com/luke-jr/bips/blob/bip-cbah/bip-cbah.mediawiki) if you
> also re-enable/extend certain opcodes like OP_AND and OP_LESSTHAN. See
> https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-September/013149.html
> and the ensuing thread.
> >>>
> >>> Nathan Cook
> >>>
> >>>
> >>> On Thu, 23 May 2019 at 21:33, Tamas Blummer via bitcoin-dev <
> bitcoin-dev at 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.
> >>>
> >>> Once signed by both the transaction would not carry any counterparty
> risk and would not need an oracle to settle according to the bet.
> >>>
> >>> I plan to draft a BIP for this as I think this opcode would serve
> significant economic interest of Bitcoin economy, and is compatible with
> Bitcoin’s aim not to introduce 3rd party to do so.
> >>>
> >>> Do you see a fault in this proposal or want to contribute?
> >>>
> >>> Tamas Blummer
> >>>
> >>> _______________________________________________
> >>> bitcoin-dev mailing list
> >>> bitcoin-dev at lists.linuxfoundation.org
> >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >>
> >
>
>
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