On Sunday, February 22, 2015, Peter Todd wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > > > On 22 February 2015 08:41:56 GMT-05:00, Eric Lombrozo > wrote: > >In case it wasn't clear in my earlier post, there's of course a third > >possibility - namely, some outputs are kept but not all. Here, it is > >generally impossible to tell whether the motivation was fee > >replacement, > >output replacement, or both. My proposal is to always treat these > >instances > >as output replacement and punish the sender. The sender needs to make > >it > >unambiguously clear it's only a fee replacement by creating a new > >transaction that produces an output with the desired extra fee and then > >adding an input that spends it to the original transaction. > > That's a really old idea - I proposed it about two years ago. The optimal > way is to allow any txout to be replaced with one with an equal or greater > nValue and same scriptPubKey, as well as additional txouts added. > (obviously so long as none are removed) > > That won't work because in general it is impossible to know which transaction is the original. Did we add outputs to transaction A? Or remove outputs from transaction B? > Alas, there's lots of situations where this restricts you from doing > useful things, for instance collapsing multiple payments into one by > repeated updating to reduce tx size. Equally the benefit is marginal at > best given how insecure unconfirmed transactions are - breaking what is > already broken isn't a negative. > > I think you're unnecessarily complicating use cases. As for 0-conf security, there are instances where 0-conf transactions make a lot of sense - i.e. paying for utilities, ISP, web hosting, or other such services which could be immediately shut off upon detection of a double-spend. > -----BEGIN PGP SIGNATURE----- > > iQE9BAEBCAAnIBxQZXRlciBUb2RkIDxwZXRlQHBldGVydG9kZC5vcmc+BQJU6d9O > AAoJEMCF8hzn9LncUOUH/3yY4wDyFSkL9o6GsntphAmJSN35wVAlxPxBmNTk0KR3 > YfVhY1cTBIXKqsfqz/n1Sqn264aMzW48xUTtDF2xLzJc1FY5qTBw7zbVrZgYIvvr > GEakZW1SxLXsfSs2Onutl0WQWi8EMfxEXEPQIiiWy9mq4EtwxMOcDviETycu6Wmn > pmHY00Lo8jhLUyuIkzIZrZetEtWz1VtovbJO5l7WfmLgPWzW+zERPY/pGGioqdiJ > NOEaocQ+2+OZjyx3MJ4YAch5ZtfB45g+NBm8WyeGpBgxzK3ZIpmyZIQ6HqZr0gpl > NMUQh6Sbi8WaTEp6hoYTiEfZcEy4IDPg6f0DEW71BPs= > =1vbN > -----END PGP SIGNATURE----- > >