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
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@JeremyRubin


On Fri, Sep 3, 2021 at 8:32 PM Jeremy <jlrubin@mit.edu> 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