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Date: Mon, 17 Nov 2014 11:35:24 +0100
Message-ID: <CAPg+sBgM4ja0Y96KekJUN7Qg=o0xa1B0VUiiPuFQTYfrupoERg@mail.gmail.com>
From: Pieter Wuille <pieter.wuille@gmail.com>
To: Alan Reiner <etotheipi@gmail.com>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Increasing the OP_RETURN maximum payload
	size
Precedence: list

On Mon, Nov 17, 2014 at 4:19 AM, Alan Reiner <etotheipi@gmail.com> wrote:
>
> On 11/16/2014 02:04 PM, Jorge Tim=F3n wrote:
>> I remember people asking in #bitcoin-dev "Does anyone know any use
>> case for greater sizes OP_RETURNs?" and me answering "I do not know of
>> any use cases that require bigger sizes".
>
> For reference, there was a brief time where I was irritated that the
> size had been reduced to 40 bytes, because I had an application where I
> wanted to put ECDSA in signatures in the OP_RETURN, and you're going to
> need at least 64 bytes for that.   Unfortunately I can't remember now
> what that application was, so it's difficult for me to argue for it.
> But I don't think that's an unreasonable use case:  sending a payment
> with a signature, essentially all timestamped in the blockchain.

You can still send the signature out of band (for example using the
payment protocol), and just have the transaction commit to a hash of
that signature (or message in general), either using an OP_RETURN
output to store the hash, or using the pay-to-contract scheme that
Jorge mentioned above. That has exactly the same timestamping
properties.

My main concern with OP_RETURN is that it seems to encourage people to
use the blockchain as a convenient transport channel, rather than just
for data that the world needs to see to validate it. I'd rather
encourage solutions that don't require additional data there, which in
many cases (but not all) is perfectly possible.

--=20
Pieter