In working on resolving this issue, one issue that has come up is what sequence values get used by wallet implementations? E.g., in Bitcoin Core a script test says BIP125_SEQUENCE_NUMBER = 0xfffffffd # Sequence number that is rbf-opt-in (BIP 125) and csv-opt-out (BIP 68) Are any other numbers currently expected by any wallet software to be broadcastable with the DISABLE flag set? Does anyone use *this* number? Is there any advantage of this number v.s. just 0? Do people commonly use 0xfffffffd? 0xfffffffe is special, but it seems the former has the alternative of either 0 valued sequence lock (1<<22 or 0). Are there any other sequence numbers that are not defined in a BIP that might be used somewhere? Cheers, Jeremy -- @JeremyRubin On Fri, Sep 3, 2021 at 8:32 PM Jeremy wrote: > Hi Bitcoin Devs, > > I recently noticed a flaw in the Sequence lock implementation with respect > to upgradability. It might be the case that this is protected against by > some transaction level policy (didn't see any in policy.cpp, but if not, > I've put up a blogpost explaining the defect and patching it > https://rubin.io/bitcoin/2021/09/03/upgradable-nops-flaw/ > > I've proposed patching it here > https://github.com/bitcoin/bitcoin/pull/22871, it is proper to widely > survey the community before patching to ensure no one is depending on the > current semantics in any live application lest this tightening of > standardness rules engender a confiscatory effect. > > Best, > > Jeremy > > -- > @JeremyRubin > >