From mboxrd@z Thu Jan 1 00:00:00 1970 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 1WoMSe-0004FO-DF for bitcoin-development@lists.sourceforge.net; Sun, 25 May 2014 00:38:48 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.179 as permitted sender) client-ip=209.85.216.179; envelope-from=etotheipi@gmail.com; helo=mail-qc0-f179.google.com; Received: from mail-qc0-f179.google.com ([209.85.216.179]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WoMSd-0004Lo-Ik for bitcoin-development@lists.sourceforge.net; Sun, 25 May 2014 00:38:48 +0000 Received: by mail-qc0-f179.google.com with SMTP id r5so1837804qcx.38 for ; Sat, 24 May 2014 17:38:42 -0700 (PDT) X-Received: by 10.224.54.68 with SMTP id p4mr19494242qag.47.1400978322067; Sat, 24 May 2014 17:38:42 -0700 (PDT) Received: from [192.168.1.85] (c-76-111-96-126.hsd1.md.comcast.net. [76.111.96.126]) by mx.google.com with ESMTPSA id a42sm4986902qge.35.2014.05.24.17.38.41 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 24 May 2014 17:38:41 -0700 (PDT) Message-ID: <53813B91.2070309@gmail.com> Date: Sat, 24 May 2014 20:38:41 -0400 From: Alan Reiner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Gregory Maxwell References: <53813391.7040503@gmail.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 (etotheipi[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: 1WoMSd-0004Lo-Ik Cc: Bitcoin Development Subject: Re: [Bitcoin-development] Cut-through propagation of blocks 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, 25 May 2014 00:38:48 -0000 On 05/24/2014 08:14 PM, Gregory Maxwell wrote: > On Sat, May 24, 2014 at 5:04 PM, Alan Reiner wrote: >> I think the most important change is modifying the way Bitcoin Core >> prioritizes blocks. Right now it uses the first full block verified. >> Instead, it should consider the first valid header received as highest >> priority, but only mine on it once it has done full verification of the > This directly opens an attack where as soon as you find a block you > announce the header to the world and then you delay announcing the > block content. You can continue to mine on the block but no one else > can (or alternatively they break their rule and risk extending an > invalid block— bad news for SPV wallets)— then when you find a > successor block or someone else finds a competing block you > immediately announce the content. > > It basically means that you can always delay announcing a block and be > sure that doing so doesn't deprive you of your winning position. > > Would this not be solved by putting a expiration on application of this logic? For instance, if you haven't received the full new block within 5-10 seconds (perhaps adjusted based on local bandwidth), then the header-received time is ignored. Or is this too hacky? I suppose this is exactly what Ashley is trying to solve, she's just already made a few more leaps forward in the design process than I have. I'll stop derailing it.