On Mon, Jan 15, 2018 at 11:15 PM, Luke Dashjr wrote: > On Tuesday 16 January 2018 1:06:14 AM Rusty Russell via bitcoin-dev wrote: > > The rule AFAICT is "standard transactions must still work". This was > > violated with low-S, but the transformation was arguably trivial. > > > > OTOH, use of altstack is completely standard, though in practice it's > > unused and so only a theoretical concern. > > I'm not aware of a single standard/BIP that uses the altstack at all. > By "standard transaction" here, Rusty means that (P2SH or Segwit) scripts that use the alt-stack pass the standardness checks and will be relayed by recent Bitcoin Core software. ---- Regarding lowS: I think the more severe standardness change was the added requirement that (some of the) pubkeys in a multisig must be parsable. I have talked with people who cannot retrieve their funds now, when before they could. However, like lowS, this was only a change to the standardness rules and not a consensus change, so these funds are not necessarily permanently lost. They can be retrieved with miner help. I don't see how BIP 117, which is a change in consensus rules that could cause permanent loss of otherwise well-secured funds (in addition to the other issues raised about BIP 117), is even comparable to the previous changes in only the standardness rules.