From: Kalle Rosenbaum <kalle@rosenbaum•se>
To: Martin Lie <martin@datamagi•no>,
Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Proof of Payment
Date: Thu, 23 Apr 2015 16:39:15 +0200 [thread overview]
Message-ID: <CAPswA9x7LGFjWce35+4=m1t-DCOA==R+6=1tdimgV7TsAkZ1MQ@mail.gmail.com> (raw)
In-Reply-To: <55384AC9.80501@datamagi.no>
[-- Attachment #1: Type: text/plain, Size: 3787 bytes --]
Hi Martin,
Thank you very much for your comments. See my answers inline:
Den 23 apr 2015 03:28 skrev "Martin Lie" <martin@datamagi•no>:
>
> Hej, Kalle.
>
> I love the idea of standardised PoPs, including a protocol for
requesting/sending them as an extension of BIP-70.
>
Me too!
>
> A couple of comments:
>
> 1. You admit that the txid is just a convenience and not strictly
necessary. Perhaps this should be reflected in the sequence of bits/bytes
in the record you're proposing, e.g. "OP_RETURN POP_LITERAL <nonce> <txid>"?
>
I was thinking that txid should be mandatory just as the nonce so the order
was arbitrarily chosen. I think you may be right that it's more intuitive
to put txid last if it's not mandatory in a future version. It makes sense
to swap order. I'll put that on my todo list.
> 2. Building on #1, perhaps there could be other identifying information
than a txid? Perhaps a txid field shouldn't be "hardcoded" into the
standard at all?
>
> How about taking the same approach as BIP-43 (and others) and use a
prefix that determines how the rest of the records should be interpreted,
i.e. a "type" (or "purpose" or "version" or whatever you'd like to call it)
field. This would allow for different purposes/versions of a PoP, including
as of now unforeseen ones.
>
> The new structure would then be:
> OP_RETURN POP_PREFIX POP_TYPE POP_NONCE POP_PAYLOAD
>
> POP_PREFIX (? bytes): I'll leave it up to you to specify the exact bits
(and length) of the POP_PREFIX, but if your literal is used, it'd be 3
bytes: 0x506f50.
>
> Literals in Bitcoin protocols generally seem to be of the "binary" sort
as opposed to human-readable text, so perhaps the devs wouldn't ACK
something as "wasteful" as using 3 bytes just to identify it as a PoP
record? Obviously, this is a small detail that can be changed at short
notice, but as with all standards - once people start using it, you're
mostly stuck with what you have. ;)
>
Yes, maybe we could drop POP_PREFIX altogether. The server is expecting a
pop and can therefore just assume it's a pop. No need to explicitly write
that inside the pop. Can you think of a scenario where it is actually
needed. Keeping the POP_PREFIX makes sense only if other transaction-like
data structures with OP_RETURN appears in the same contexts as pops. What
do you think?
> POP_TYPE: (1 byte): 0x01 for your "standard" version, which would mean
that the payload contains a txid.
>
This is a good idea. Todo!
> POP_NONCE: (4 bytes): "2^32 re-uses should be enough for everyone", no? ;)
>
Euhm, well, I don't know... The bigger the better. If we drop POP_PREFIX we
could allow for 2 bytes version and 6 bytes nonce. Or 1 byte version and 7
bytes nonce.
> POP_PAYLOAD (32+ bytes): The contents of which is determined by POP_TYPE,
e.g. a txid or possibly extra nonce data. Or perhaps some text that makes
the purpose or context of this PoP human-readable? (This could then be
stored by wallets in order to show a list of what kind of proofs you've
sent.)
>
For now I think I'll stick to "txid is mandatory".
>
> 3. I noticed that your post-OP_RETURN structure included exactly 40
bytes. Is that due to the 40-byte limitation on OP_RETURN's "data"? Are you
aware that it will be increased to 80 bytes? Cf. https://
<https://github.com/bitcoin/bitcoin/pull/5286>github.com
<https://github.com/bitcoin/bitcoin/pull/5286>/
<https://github.com/bitcoin/bitcoin/pull/5286>bitcoin
<https://github.com/bitcoin/bitcoin/pull/5286>/
<https://github.com/bitcoin/bitcoin/pull/5286>bitcoin
<https://github.com/bitcoin/bitcoin/pull/5286>/pull/5286
<https://github.com/bitcoin/bitcoin/pull/5286>
>
Yes, I deliberately limited the data to 40 bytes for that reason. With
versioning, this may change in the future.
> :)
>
>
> Vennlig hilsen
> Martin Lie
[-- Attachment #2: Type: text/html, Size: 4656 bytes --]
next prev parent reply other threads:[~2015-04-23 14:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-13 19:29 Kalle Rosenbaum
2015-03-13 20:30 ` Natanael
2015-03-13 21:31 ` Mike Hearn
2015-03-13 21:47 ` Kalle Rosenbaum
2015-03-13 22:03 ` Mike Hearn
[not found] ` <CAPswA9y5bDs1urRCmh8Oxeho4As8pBt2rRVP6fjhjJA0cZrvfA@mail.gmail.com>
[not found] ` <CANEZrP35_h_-2c=A-1+M8umSpAC70DJ7sYhPPo_62dm2QKHCEg@mail.gmail.com>
2015-03-14 9:28 ` Kalle Rosenbaum
[not found] ` <A2849710-1069-45A1-89C0-9D8E40C4A8D6@newcastle.ac.uk>
2015-03-14 18:16 ` Kalle Rosenbaum
2015-04-22 20:03 ` Kalle Rosenbaum
[not found] ` <55384AC9.80501@datamagi.no>
2015-04-23 14:39 ` Kalle Rosenbaum [this message]
2015-04-27 0:50 ` Tom Harding
2015-04-27 12:35 ` Kalle Rosenbaum
2015-04-27 12:41 ` Kalle Rosenbaum
2015-04-28 7:23 ` Jorge Timón
2015-04-28 12:41 ` Kalle Rosenbaum
2015-04-28 12:53 ` Jorge Timón
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAPswA9x7LGFjWce35+4=m1t-DCOA==R+6=1tdimgV7TsAkZ1MQ@mail.gmail.com' \
--to=kalle@rosenbaum$(echo .)se \
--cc=bitcoin-development@lists$(echo .)sourceforge.net \
--cc=martin@datamagi$(echo .)no \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox