Subject: Re: [Bitcoin-development] [RFC] Canonical input and output ordering in transactions

From: Peter Todd <[email-masked]>
Date: Mon, 8 Jun 2015 17:36:11 -0400

On Mon, Jun 08, 2015 at 02:25:40PM -0700, Danny Thorpe wrote:
> FWIW, The Open Assets colored coin protocol (CoinPrism) places special
> significance on the zeroth input and the position of the OP_RETURN colored
> coin marker output to distinguish colored coin issuance outputs from
> transfer outputs. Reordering the inputs or the outputs breaks the colored
> coin representation.
> 
> Recommending sorting of the inputs and outputs as a best practice is fine
> (and better than random, IMO), but not as part of IsStandard() or consensus
> rules.  There are cases where the order of the inputs and outputs is
> significant.

Timestamping is another case where order matters: if you put the digest
in the last vout you can use SHA256 midstate's to reduce the size of the
timestamp proof.

Anyway, there's no reason to rush re: changes to IsStandard()

-- 
'peter'[:-1]@petertodd.org
0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778