Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1UXAOa-00071g-RQ for bitcoin-development@lists.sourceforge.net; Tue, 30 Apr 2013 13:15:00 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 74.125.82.45 as permitted sender) client-ip=74.125.82.45; envelope-from=gavinandresen@gmail.com; helo=mail-wg0-f45.google.com; Received: from mail-wg0-f45.google.com ([74.125.82.45]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1UXAOa-0008H8-0a for bitcoin-development@lists.sourceforge.net; Tue, 30 Apr 2013 13:15:00 +0000 Received: by mail-wg0-f45.google.com with SMTP id l18so439417wgh.0 for ; Tue, 30 Apr 2013 06:14:53 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.180.212.3 with SMTP id ng3mr3872528wic.22.1367327693833; Tue, 30 Apr 2013 06:14:53 -0700 (PDT) Received: by 10.194.143.36 with HTTP; Tue, 30 Apr 2013 06:14:53 -0700 (PDT) In-Reply-To: <517FABE6.8020205@bitonic.nl> References: <20130428180304.GA30115@crunch> <517FABE6.8020205@bitonic.nl> Date: Tue, 30 Apr 2013 09:14:53 -0400 Message-ID: From: Gavin Andresen To: Jouke Hofman Content-Type: multipart/alternative; boundary=001a11c356f47b90f904db93c91e 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: 1UXAOa-0008H8-0a Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Cold Signing Payment Requests 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, 30 Apr 2013 13:15:01 -0000 --001a11c356f47b90f904db93c91e Content-Type: text/plain; charset=ISO-8859-1 RE: Timo's proposal for protecting the refund address: Seems to me there are two risks: 1) The risk that the merchant's web server will be compromised and the attacker will redirect refunds 2) The risk that the merchant will miss payments because they miss a POST to the payment_url (maybe the customer's machine crashes during the HTTPS handshake) If payments are a lot more common than refunds, then (2) will outweigh (1). I also think an attacker who compromises the front-end web server would probably just have it start generating plain-old pay-to-bitcoin-address payment requests, and hope that lots of customers pay them directly before the attack is discovered. -- -- Gavin Andresen --001a11c356f47b90f904db93c91e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
RE: Timo's proposal for protecting the refund address:
<= br>
Seems to me there are two risks:

1) = The risk that the merchant's web server will be compromised and the att= acker will redirect refunds
2) The risk that the merchant will miss payments because they miss a P= OST to the payment_url (maybe the customer's machine crashes during the= HTTPS handshake)

If payments are a lot more commo= n than refunds, then (2) will outweigh (1).

I also think an attacker who compromises the front-end = web server would probably just have it start generating plain-old pay-to-bi= tcoin-address payment requests, and hope that lots of customers pay them di= rectly before the attack is discovered.

--
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Gavin Andresen
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