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From: Alex Kotenko <alexykot@gmail.com>
To: Andreas Schildbach <andreas@schildbach.de>
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Payment Protocol for Face-to-face Payments
Date: Fri, 21 Mar 2014 13:54:25 +0000	[thread overview]
Message-ID: <CALDj+Bb=CR1pL0Ze1M6k22wfQM1bL6-w+EyipJQWc1OHhAY0rg@mail.gmail.com> (raw)
In-Reply-To: <lgh1q8$1dc$1@ger.gmane.org>

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2014-03-21 9:47 GMT+00:00 Andreas Schildbach <andreas@schildbach.de>:

> On 03/20/2014 05:14 PM, Alex Kotenko wrote:
>
> > Hmm, if we're inventing an URI for bluetooth, I'd rather follow existing
> > URI's patterns. BT is strictly point-to-point connection, so BT MAC
> > should be considered as server address, and payment request ID can be
> > considered as request path. Probably "bt:<bt-mac>/​
> > <random_id_of_payment_request>" would be more usual and easily
> > understandable.
>
> Agreed. I used the dash because I feared a slash would need to be
> escaped if used in an URL parameter.
>
​It will need to be ​escaped, but HTTP URLs used in BIP72 have it already,
so don't see why we should bother.



> > I wonder how complex it would be to implement HTTP-over-Bluetooth. Not
> > like I'm willing to do that now, but HTTP is well known and proven to be
> > quite good for tasks like this, so in theory it would be handy to have
> > such capacities in here.
>
> Thought of that as well. On the other hand, HTTP might be overkill and
> we inherit its potential downsides as well.
>
​It definitely is an overkill. Don't think we should do it now unless we
will see later during implementation that we really have to.



> >     Well, do we need to be compatible? If the dev community decides
> Base43
> >     PR QR's (or whatever other self-contained format) is the way to go,
> we
> >     just implement, roll it out and use it.
> >
> > My PoS needs to be compatible with BIP21, as when I'm presenting QR code
> > or sending NFC message - I have no way to tell what wallet/phone is ​​on
> > the accepting side, so I have to be compatible to existing widely
> > supported technologies.
>
> Agreed. All I wanted to say support for QR is still small enough that we
> might be able to switch to an incompatible standard. If we're determined
> that is.

Ok. Btw, I've tested ​QR possibilities on my PoS screen, in binary mode
it's limited to about 600 chars, so really I can include only unsigned and
rather short payment request. Signed requests longer than few hundred bytes
will not work.



> > ​Well, yes, it would be less efficient than base43. But did you
> > calculate how much less? ​It's a compatible and already widely used way
> > and loosing compatibility needs to have serious reasons, so would be
> > great to know exact figures here.
>
> Base 64 via binary QR:   64 chars / 256 chars
>                          ==> 6 bit / 8 bit = 0.75
>
> Base 43 via alphanum QR: 43 chars / 45 chars
>                          ==> 5.43 bit / 5.49 bit = 0.99
>
> That would be efficiency in terms of PR data size vs. amount space used
> in a QR code. Of course, the visual QR encoding also plays a role, for
> example its size is increased in discrete steps.
>
Ok, so base43-aphanum is winning about a quarter of capacity against
base64-binary. I probably will skip this anyway and go with bluetooth URI
scheme we've just agreed + old style payments over p2p network as fallback.
So no payment requests in QR codes at all from my side.




>
>
>
>
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  reply	other threads:[~2014-03-21 13:55 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-27 11:59 [Bitcoin-development] Payment Protocol for Face-to-face Payments Andreas Schildbach
2014-01-27 13:11 ` Mike Hearn
2014-01-27 18:18   ` Andreas Schildbach
2014-01-27 18:34     ` Mike Hearn
2014-01-27 20:53     ` [Bitcoin-development] Experiment with linking payment requests via href Andreas Schildbach
2014-01-27 21:47       ` Mike Hearn
2014-01-27 17:11 ` [Bitcoin-development] Payment Protocol for Face-to-face Payments Jeremy Spilman
2014-01-27 17:39   ` Andreas Schildbach
2014-01-27 18:18     ` Jeremy Spilman
2014-01-27 20:34   ` Roy Badami
2014-01-29 14:57     ` Christophe Biocca
2014-01-30 10:46 ` Andreas Schildbach
2014-01-30 10:50   ` Mike Hearn
2014-02-07 23:15   ` Andreas Schildbach
2014-03-02  9:47 ` Andreas Schildbach
2014-03-02 11:50   ` Mike Hearn
2014-03-20  2:22     ` Alex Kotenko
2014-03-20  3:31       ` Jeff Garzik
2014-03-20  8:09         ` Andreas Schildbach
2014-03-20 10:36           ` Mike Hearn
2014-03-20 12:12             ` Adam Back
2014-03-20 12:20               ` Mike Hearn
2014-03-20 17:31               ` Jeff Garzik
2014-03-20 17:42                 ` Alex Kotenko
2014-03-20 18:01                   ` Jeff Garzik
2014-03-21 10:28                 ` Andreas Schildbach
2014-03-21 13:59                   ` Alex Kotenko
2014-03-22 16:35                     ` Jeff Garzik
2014-03-22 16:45                       ` Mike Hearn
2014-03-22 16:55                       ` Mark Friedenbach
2014-03-22 17:24                         ` Jeff Garzik
2014-03-22 17:30                           ` Mike Hearn
2014-03-23  3:47                             ` Alex Kotenko
2014-03-21 10:25               ` Andreas Schildbach
2014-03-21 10:59                 ` Adam Back
2014-03-21 11:08                   ` Mike Hearn
2014-03-21 11:33                     ` Mike Hearn
2014-03-21 12:25                       ` Adam Back
2014-03-21 13:07                         ` Mike Hearn
2014-03-20 18:20             ` Alex Kotenko
2014-03-20 18:31               ` Mike Hearn
2014-03-20 18:50                 ` Alex Kotenko
2014-03-20 21:52                 ` Roy Badami
2014-03-20 23:02                   ` Mike Hearn
2014-03-26 22:48                     ` Roy Badami
2014-03-26 22:56                       ` Mike Hearn
2014-03-26 23:20                         ` Andreas Schildbach
2014-03-27 10:08                           ` Mike Hearn
2014-03-27 13:31                             ` vv01f
2014-06-30 19:26                               ` Alex Kotenko
2014-07-01  8:18                                 ` Mike Hearn
2014-07-01  9:48                                   ` Andreas Schildbach
2014-07-01 10:42                                     ` Michael Wozniak
2014-07-01 13:03                                       ` Alex Kotenko
2014-07-01 14:59                                         ` Andreas Schildbach
2014-07-01 15:07                                           ` Michael Wozniak
2014-07-01 15:39                                             ` Andreas Schildbach
2014-07-01 17:18                                               ` Alex Kotenko
2014-07-01 17:59                                                 ` Mike Hearn
2014-07-02  8:49                                                   ` Alex Kotenko
2014-03-21 10:43                   ` Andreas Schildbach
2014-03-20  8:08       ` Andreas Schildbach
2014-03-20 16:14         ` Alex Kotenko
2014-03-21  9:47           ` Andreas Schildbach
2014-03-21 13:54             ` Alex Kotenko [this message]
2014-03-21 14:51               ` Andreas Schildbach
2014-03-21 15:38                 ` Alex Kotenko
2014-03-21 15:20               ` Andreas Schildbach
2014-03-21 15:24                 ` Mike Hearn

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