Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from <laanwj@gmail.com>) id 1XSj5R-0000yk-1v for bitcoin-development@lists.sourceforge.net; Sat, 13 Sep 2014 08:53:41 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.213.176 as permitted sender) client-ip=209.85.213.176; envelope-from=laanwj@gmail.com; helo=mail-ig0-f176.google.com; Received: from mail-ig0-f176.google.com ([209.85.213.176]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XSj5P-00050C-Qz for bitcoin-development@lists.sourceforge.net; Sat, 13 Sep 2014 08:53:40 +0000 Received: by mail-ig0-f176.google.com with SMTP id hn15so1732945igb.9 for <bitcoin-development@lists.sourceforge.net>; Sat, 13 Sep 2014 01:53:34 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.50.22.101 with SMTP id c5mr8236382igf.29.1410598414152; Sat, 13 Sep 2014 01:53:34 -0700 (PDT) Received: by 10.64.1.209 with HTTP; Sat, 13 Sep 2014 01:53:34 -0700 (PDT) In-Reply-To: <06D9FBBD-30DB-4591-A932-B5A19F1D6543@coinqy.com> References: <mailman.342174.1410547421.2163.bitcoin-development@lists.sourceforge.net> <06D9FBBD-30DB-4591-A932-B5A19F1D6543@coinqy.com> Date: Sat, 13 Sep 2014 10:53:34 +0200 Message-ID: <CA+s+GJBWTji2JfTF+8+zb+9LWV2mK7inqVakdMhoXQYi4_a-Jw@mail.gmail.com> From: Wladimir <laanwj@gmail.com> To: Mark van Cuijk <mark@coinqy.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (laanwj[at]gmail.com) -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: 1XSj5P-00050C-Qz Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net> Subject: Re: [Bitcoin-development] BIP72 amendment proposal X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: <bitcoin-development.lists.sourceforge.net> List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>, <mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe> List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development> List-Post: <mailto:bitcoin-development@lists.sourceforge.net> List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help> List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>, <mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe> X-List-Received-Date: Sat, 13 Sep 2014 08:53:41 -0000 On Fri, Sep 12, 2014 at 10:59 PM, Mark van Cuijk <mark@coinqy.com> wrote: > If you do so, please make sure the length of the hash is included in the = PaymentDetails/PaymentRequest. If someone parses the URI and doesn=E2=80=99= t have an authenticated way of knowing the expected length of the hash, a M= ITM attacker can just truncate the hash to lower security. But if they can truncate they can just as well pass a completely different hash that matches their payment request. If an attacker can change the bitcoin: URI, this scheme is broken. The point of the proposal is to make sure that the payment request matches the URI. So *if* you communicate the URI by secure means, this authenticates the associated payment request as well, even if fetched by insecure means (such as http:...) itself. Wladimir