From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1VnoZ0-0004pE-03 for bitcoin-development@lists.sourceforge.net; Tue, 03 Dec 2013 11:54:50 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 74.125.82.48 as permitted sender) client-ip=74.125.82.48; envelope-from=gavinandresen@gmail.com; helo=mail-wg0-f48.google.com; Received: from mail-wg0-f48.google.com ([74.125.82.48]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1VnoYy-00075M-4l for bitcoin-development@lists.sourceforge.net; Tue, 03 Dec 2013 11:54:49 +0000 Received: by mail-wg0-f48.google.com with SMTP id z12so13373021wgg.15 for ; Tue, 03 Dec 2013 03:54:41 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.194.85.233 with SMTP id k9mr474223wjz.91.1386071681747; Tue, 03 Dec 2013 03:54:41 -0800 (PST) Received: by 10.195.13.68 with HTTP; Tue, 3 Dec 2013 03:54:41 -0800 (PST) In-Reply-To: References: <5E4597E4-C1C7-4536-8CF0-82EDD7715DAB@plan99.net> <39921E12-B411-4430-9D56-04F53906B109@plan99.net> Date: Tue, 3 Dec 2013 21:54:41 +1000 Message-ID: From: Gavin Andresen To: Mike Hearn , Bitcoin Dev Content-Type: multipart/alternative; boundary=089e0102e3e039535504ec9ff658 X-Spam-Score: -0.6 (/) 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 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (gavinandresen[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.0 HTML_MESSAGE BODY: HTML included in message -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: 1VnoYy-00075M-4l Subject: Re: [Bitcoin-development] Floating fees and SPV clients 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: Tue, 03 Dec 2013 11:54:50 -0000 --089e0102e3e039535504ec9ff658 Content-Type: text/plain; charset=ISO-8859-1 > > A merchant can always refuse the payment and refund it if that's a > practical problem. > No, they can't, at least not in bitcoin-qt: when the user pokes the SEND button, the transaction is broadcast on the network, and then the merchant is also told with the Payment/PaymentACK round-trip. Allowing merchants to cancel (e.g. having a PaymentNACK) makes implementation harder, and brings up nasty issues if we want to allow CoinJoin or CoinJoin-like transactions as payments to merchants. Bitcoin-Qt ALREADY allows you to pay several PaymentRequests with one transaction; handling the case where one merchant gives you a PaymentACK and another gives you (or wants to give you) a PaymentNACK is a nightmare. -- Gavin Andresen --089e0102e3e039535504ec9ff658 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
A merchant can always refuse the payment and refund it if that's a= practical problem.

No, they can't, at least not in bitcoin-qt: =A0when the user pokes the= SEND button, the transaction is broadcast on the network, and then the mer= chant is also told with the Payment/PaymentACK round-trip.

Allowing merchants to cancel (e.g. having a PaymentNACK= ) makes implementation harder, and brings up nasty issues if we want to all= ow CoinJoin or CoinJoin-like transactions as payments to merchants. =A0Bitc= oin-Qt ALREADY allows you to pay several PaymentRequests with one transacti= on; handling the case where one merchant gives you a PaymentACK and another= gives you (or wants to give you) a PaymentNACK is a nightmare.

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Gavin Andresen
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