From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WQhIJ-0008Uv-Ry for bitcoin-development@lists.sourceforge.net; Thu, 20 Mar 2014 18:02:19 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of bitpay.com designates 209.85.213.48 as permitted sender) client-ip=209.85.213.48; envelope-from=jgarzik@bitpay.com; helo=mail-yh0-f48.google.com; Received: from mail-yh0-f48.google.com ([209.85.213.48]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WQhIE-0001Ir-9d for bitcoin-development@lists.sourceforge.net; Thu, 20 Mar 2014 18:02:19 +0000 Received: by mail-yh0-f48.google.com with SMTP id z6so1219499yhz.21 for ; Thu, 20 Mar 2014 11:02:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=YhRJmxDWebO2/fErRyzTu2CPv9iVn/2wrRMTfWySSSA=; b=Xn+kM/5wF1zn7gbrT6syklw4ikTTIDeJ+U98R4jGkHLUl/qibF/ItLsLJYA7t4VcFp vKsTkLT2V2/YWiE1+xtznM4Nj07WSbUkrRKZFwd8b09kjAhYLolRPBMosZ+H5SZMaWav pG7mKmVwqPs5/aKKcikcCPIGRhH779Tc7qhz0VXAO6EvVVSt0kf8jDz7l9hiZVuJCvms UhunlkMTqFOUkGDTBROurP6Jweghh/SfdmGSUONgeMnCmYNua6f+NpoVaZHqk/Km8Zrh PT0fa1nt4knEGOL8PrYkS/HF3opg5kSyrrThyOjcLweqsHSGfulpzD/tGZYMiQyVL3cD /cFw== X-Gm-Message-State: ALoCoQk2nB7O6JY2PYsinxmHgZXNnQ7N+gBpW2zOKa5A/19f+IuHUzw7NAJ2RMqboFj0gsVAepS3 X-Received: by 10.236.125.12 with SMTP id y12mr36648468yhh.42.1395338528729; Thu, 20 Mar 2014 11:02:08 -0700 (PDT) MIME-Version: 1.0 Received: by 10.170.162.214 with HTTP; Thu, 20 Mar 2014 11:01:48 -0700 (PDT) In-Reply-To: References: <20140320121221.GA25052@netbook.cypherspace.org> From: Jeff Garzik Date: Thu, 20 Mar 2014 14:01:48 -0400 Message-ID: To: Alex Kotenko Content-Type: text/plain; charset=ISO-8859-1 X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1WQhIE-0001Ir-9d Cc: Bitcoin Dev , Andreas Schildbach Subject: Re: [Bitcoin-development] Payment Protocol for Face-to-face Payments X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Mar 2014 18:02:20 -0000 It really depends on the physical, real world size of the QR code. If you have a big screen, and security permits displaying a larger QR code, you can afford more bytes. If you are displaying a tiny postage stamp 1-2cm in size, the practical byte limit is very low. Ideally, you test your QR codes in real world conditions, before picking the best path. On Thu, Mar 20, 2014 at 1:42 PM, Alex Kotenko wrote: > 2014-03-20 17:31 GMT+00:00 Jeff Garzik : >> >> On Thu, Mar 20, 2014 at 8:12 AM, Adam Back wrote: >> > Whats a sensible limit on practical/convenient QR code size? >> >> Extremely limited. Preferably under 100 bytes. You will see >> increasingly poor operating in varying light conditions, such as >> paying via QR code on a printed receipt in a pub at night. That was >> one of the motivations for BIP 73. > > Hmm, in this case I think base43 discussion is irrelevant. Even with best > space utilization we can get we will not be able to fit in anything bigger > than a smallest unsigned payment certificate. And that is not so useful. So > probably we should stick with BIP73 approach and bluetooth URI scheme we're > inventing. > > >> >> >> >> On Thu, Mar 20, 2014 at 4:09 AM, Andreas Schildbach >> wrote: >> > Afaik, BIP73 needs an external server (the web server). >> >> Yes. Internet connectivity is not a rarity these days. Near-field >> web servers also work fine. >> >> -- >> Jeff Garzik >> Bitcoin core developer and open source evangelist >> BitPay, Inc. https://bitpay.com/ >> >> >> ------------------------------------------------------------------------------ >> Learn Graph Databases - Download FREE O'Reilly Book >> "Graph Databases" is the definitive new guide to graph databases and their >> applications. Written by three acclaimed leaders in the field, >> this first edition is now available. Download your free book today! >> http://p.sf.net/sfu/13534_NeoTech >> _______________________________________________ >> Bitcoin-development mailing list >> Bitcoin-development@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/bitcoin-development > > -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/