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From: Adam Back <adam@cypherspace.org>
To: Andreas Schildbach <andreas@schildbach.de>
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Payment Protocol for Face-to-face Payments
Date: Fri, 21 Mar 2014 11:59:06 +0100	[thread overview]
Message-ID: <20140321105906.GA1725@netbook.cypherspace.org> (raw)
In-Reply-To: <lgh438$tnn$1@ger.gmane.org>

Maybe its time to explore raw ECDSA signed message based certs.

btw I dont think its quite 4kB.  eg bitpay's looks to be about 1.5kB in der
format.  And they contain a 2048-bit RSA server key, and 2048-bit RSA
signatures (256byte each right there = 512bytes).  And even 2048 is weaker
than 256-bit ECDSA.

Adam

On Fri, Mar 21, 2014 at 11:25:59AM +0100, Andreas Schildbach wrote:
>On 03/20/2014 01:12 PM, Adam Back wrote:
>
>> Whats a sensible limit on practical/convenient QR code size?
>
>Technically 3 KB. In my experience codes above 1.5 KB become impossible
>to scan (ZXing scanner, 3 years ago). You will want to stay below 500
>bytes for convenient scanning. That said, I'm convinced there is a lot
>of room for scanning improvements.
>
>> How much of the payment protocol message size comes from use of x509?
>
>As said in the OP, a minimal PR uses 50 bytes. X.509 seems to put about
>4000 bytes on top of that.
>
>As you can see, we have quite some room for improvements to PR payload
>(PaymentDetails). X.509 certification will probably not be possible via
>QR, at least not until specialized CA's will issue space-efficient certs
>(using ECDSA?).



  reply	other threads:[~2014-03-21 10:59 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 [this message]
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
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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