Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WQgp9-00072q-4D for bitcoin-development@lists.sourceforge.net; Thu, 20 Mar 2014 17:32:11 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of bitpay.com designates 209.85.213.49 as permitted sender) client-ip=209.85.213.49; envelope-from=jgarzik@bitpay.com; helo=mail-yh0-f49.google.com; Received: from mail-yh0-f49.google.com ([209.85.213.49]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WQgp7-0004IY-W8 for bitcoin-development@lists.sourceforge.net; Thu, 20 Mar 2014 17:32:11 +0000 Received: by mail-yh0-f49.google.com with SMTP id z6so1188543yhz.22 for ; Thu, 20 Mar 2014 10:32:04 -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=tZVH+qraEyudURin9fERsZ0f3XZfdF1BNq2WhlPXNes=; b=e43aKafm3nS/mtB30IdnumkD708Te3WUO9KUWTMx41klN20MyQFd+e3TDiMnvjGoF1 iQjlBAptxGuiykrRVx1uCjKqYnFNmXlz0z9i8mvC2DQlVQtIBQM30rUZGL199QXUIvVl yM1PDQWNsLC6y5AmTjLOzfpWzAXBhY9MebXxf9sgXMb7Rmvtp2EaFV/2GocwFlm9aWF/ c//WOzw3GOO5tVaGjOQBQARlAlcdQkwHRI8Mz7v1I+nV9Wln92RZWVtWggYsQJeBSKzK xt6hyREeQxOIuHKh1/rCG3XErkJPGFjCSJPNXkLUjNTONxIjCKHvZc3xgfK08QhmPFlc cIzg== X-Gm-Message-State: ALoCoQnjlU8jbMvE4Cj8SW7amtDjKLHKO3rPt88mjd1INhnhBlAcVKpoJ/4v69kDjFrejXvleaid X-Received: by 10.236.180.232 with SMTP id j68mr11865697yhm.122.1395336724356; Thu, 20 Mar 2014 10:32:04 -0700 (PDT) MIME-Version: 1.0 Received: by 10.170.162.214 with HTTP; Thu, 20 Mar 2014 10:31:44 -0700 (PDT) In-Reply-To: <20140320121221.GA25052@netbook.cypherspace.org> References: <20140320121221.GA25052@netbook.cypherspace.org> From: Jeff Garzik Date: Thu, 20 Mar 2014 13:31:44 -0400 Message-ID: To: Adam Back , Andreas Schildbach 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: 1WQgp7-0004IY-W8 Cc: Bitcoin Dev 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 17:32:11 -0000 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. 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/