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-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Y7obP-0007Cg-DF for bitcoin-development@lists.sourceforge.net; Sun, 04 Jan 2015 17:04:31 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.213.171 as permitted sender) client-ip=209.85.213.171; envelope-from=gmaxwell@gmail.com; helo=mail-ig0-f171.google.com; Received: from mail-ig0-f171.google.com ([209.85.213.171]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Y7obN-00078l-MP for bitcoin-development@lists.sourceforge.net; Sun, 04 Jan 2015 17:04:31 +0000 Received: by mail-ig0-f171.google.com with SMTP id z20so1477304igj.4 for ; Sun, 04 Jan 2015 09:04:24 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.42.107.83 with SMTP id c19mr63294843icp.48.1420391064335; Sun, 04 Jan 2015 09:04:24 -0800 (PST) Received: by 10.107.16.30 with HTTP; Sun, 4 Jan 2015 09:04:24 -0800 (PST) In-Reply-To: <54A95179.2070200@jrn.me.uk> References: <54A95179.2070200@jrn.me.uk> Date: Sun, 4 Jan 2015 17:04:24 +0000 Message-ID: From: Gregory Maxwell To: Ross Nicoll Content-Type: text/plain; charset=UTF-8 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 (gmaxwell[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: 1Y7obN-00078l-MP Cc: bitcoin-development Subject: Re: [Bitcoin-development] Re-enabling simple tx replacement 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: Sun, 04 Jan 2015 17:04:31 -0000 On Sun, Jan 4, 2015 at 2:43 PM, Ross Nicoll wrote: > Dear all, > > I've been looking at atomic cross-chain trading ( > https://en.bitcoin.it/wiki/Atomic_cross-chain_trading ) between the > Bitcoin and Dogecoin blockchains, and have a mostly functional > prototype. However as it stands if the refund transaction is relayed > before the actual spend transaction, it "blocks" the legitimate spend > transaction from being accepted into the memory pool. Unless there is a serious bug that I am not aware of this is not the case. The unlocked transaction is not relayable and will not be mempooled (well, until right before it locks). > I've drafted a patch for this > https://github.com/rnicoll/bitcoin/commit/e668d36607f008990ccaac7275e463a6efdd9b5a > but have not yet raised a PR, as historically this has lead to a lot of > discussion in Github which is better suited to this mailing list. > > I'm therefore looking for feedback while I continue testing that patch, > and any comments would be welcomed. This appears to have absolutely no protection against denial of service, it seems to me that a single user can rapidly update their transaction and exhaust the relay bandwidth of the entire network.