Replying to Avatar waxwing

Bitcoin shower thought:

It's a failure of bitcoin's model that sighashing serializes inputs and outputs in a particular order.

The ordering of inputs and outputs has no meaning (which is why we have, in the past, had rather tedious discussions about BIP69 or random ordering, for coinjoins) to the actual effect of A pays B.

So the sighashing (the process by which we define what exact chunk of data must be signed to validate the tx) shouldn't need to know about the ordering.

Left as an exercise to the reader: how can we encode the full set of information about the tx into a string of bytes (i.e. sighashing) in such a way that it's the same, no matter the order of inputs and outputs.
Avatar
Peter Todd 2y ago

Make the consensus algorithm consistently sort them first.

Reply to this note

Please Login to reply.

Discussion

Avatar
waxwing 2y ago

Right, @mark said the same thing, it definitely seems the simplest correct way (with the caveat that I mentioned, we lose SIGHASH_SINGLE which no one seems to end up using anyway).

Avatar
Peter Todd 2y ago

You could add SIGHASH_SINGLE back by just committing to which output it applies to in the signature (we're talking about a new sig system after all, so we can do what we want).