From: Anthony Towns <aj@erisian•com.au>
To: Antoine Riard <antoine.riard@gmail•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] TAPLEAF_UPDATE_VERIFY covenant opcode
Date: Tue, 21 Sep 2021 00:52:46 +1000 [thread overview]
Message-ID: <20210920145246.GB21263@erisian.com.au> (raw)
In-Reply-To: <CALZpt+Hczvy1Fxu40cCKKC8bR9fouQ+sAiqV65-Z4VuLp+Bi7w@mail.gmail.com>
On Sat, Sep 18, 2021 at 10:11:10AM -0400, Antoine Riard wrote:
> I think one design advantage of combining scope-minimal opcodes like MERKLESUB
> with sighash malleability is the ability to update a subset of the off-chain
> contract transactions fields after the funding phase.
Note that it's not "update" so much as "add to"; and I mostly think
graftroot (and friends), or just updating the utxo onchain, are a better
general purpose way of doing that. It's definitely a tradeoff though.
> Yes this is a different contract policy that I would like to set up.
> Let's say you would like to express the following set of capabilities.
> C0="Split the 4 BTC funds between Alice/Bob and Caroll/Dave"
> C1="Alice can withdraw 1 BTC after 2 weeks"
> C2="Bob can withdraw 1 BTC after 2 weeks"
> C3="Caroll can withdraw 1 BTC after 2 weeks"
> C4="Dave can withdraw 1 BTC after 2 weeks"
> C5="If USDT price=X, Alice can withdraw 2 BTC or Caroll can withdraw 2 BTC"
Hmm, I'm reading C5 as "If an oracle says X, and Alice and Carol agree,
they can distribute all the remaining funds as they see fit".
> If C4 is exercised, to avoid trust in the remaining counterparty, both Alice or
> Caroll should be able to conserve the C5 option, without relying on the updated
> key path.
> As you're saying, as we know the group in advance, one way to setup the tree
> could be:
> (A, (((((B, C), BC), D), BCD), ((((E, F), EF), G), EFG)))
Make it:
(((AB, (A,B)), (CD, (C,D))), ACO)
AB = DROP <alice+bob> DUP 0 6 TLUV CHECKSIGVERIFY IN_OUT_AMOUNT SUB 2BTC LESSTHAN
CD = same but for carol+dave
A = <alice> DUP <B'> 10 TLUV CHECKSIGVERIFY IN_OUT_AMOUNT SUB 1BTC LESSTHAN
B' = <bob> DUP 0 2 TLUV CHECKSIGVERIFY IN_OUT_AMOUNT SUB 1BTC LESSTHAN
B,C,D = same as A but for bob, etc
A',C',D' = same as B' but for alice, etc
ACO = <alice+carol> CHECKSIGVERIFY <oracle> CHECKSIG
Probably AB, CD, A..D, A'..D' all want a CLTV delay in there as well.
(Relative timelocks would probably be annoying for everyone who wasn't
the first to exit the pool)
> Note, this solution isn't really satisfying as the G path isn't neutralized on
> the Caroll/Dave fork and could be replayed by Alice or Bob...
I think the above fixes that -- when AB is spent it deletes itself and
the (A,B) pair; when A is spent, it deletes (A, B and AB) and replaces
them with B'; when B' is spent it just deletes itself.
Cheers,
aj
next prev parent reply other threads:[~2021-09-20 14:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 6:41 Anthony Towns
2021-09-09 6:53 ` Anthony Towns
2021-09-09 12:56 ` darosior
2021-09-09 15:54 ` Jeremy
2021-09-09 19:26 ` Jeremy
2021-09-10 7:42 ` Anthony Towns
2022-07-08 19:52 ` Tim Ruffing
2021-09-09 9:16 ` Matt Corallo
2021-09-10 4:12 ` Antoine Riard
2021-09-11 3:26 ` Anthony Towns
2021-09-12 23:37 ` Antoine Riard
2021-09-15 6:50 ` Anthony Towns
2021-09-18 14:11 ` Antoine Riard
2021-09-20 14:52 ` Anthony Towns [this message]
2021-09-22 1:40 ` Antoine Riard
2021-09-23 0:29 ` Olaoluwa Osuntokun
2021-10-29 15:47 ` Billy Tetrud
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