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 _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
