From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WcGbo-0007fk-Be for bitcoin-development@lists.sourceforge.net; Mon, 21 Apr 2014 15:58:16 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.48 as permitted sender) client-ip=209.85.216.48; envelope-from=etotheipi@gmail.com; helo=mail-qa0-f48.google.com; Received: from mail-qa0-f48.google.com ([209.85.216.48]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WcGbl-0004w6-5X for bitcoin-development@lists.sourceforge.net; Mon, 21 Apr 2014 15:58:16 +0000 Received: by mail-qa0-f48.google.com with SMTP id s7so3901838qap.21 for ; Mon, 21 Apr 2014 08:58:07 -0700 (PDT) X-Received: by 10.140.108.200 with SMTP id j66mr45180767qgf.7.1398095887730; Mon, 21 Apr 2014 08:58:07 -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 f3sm74250211qag.7.2014.04.21.08.58.06 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 21 Apr 2014 08:58:07 -0700 (PDT) Message-ID: <5355400E.1060108@gmail.com> Date: Mon, 21 Apr 2014 11:58:06 -0400 From: Alan Reiner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: bitcoin-development@lists.sourceforge.net References: <52CDA01B-13BF-4BB8-AC9A-5FBBB324FD15@sant.ox.ac.uk> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: multipart/alternative; boundary="------------020600030704050406030703" 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 (etotheipi[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: 1WcGbl-0004w6-5X Subject: Re: [Bitcoin-development] Economics of information propagation 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: Mon, 21 Apr 2014 15:58:16 -0000 This is a multi-part message in MIME format. --------------020600030704050406030703 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On 04/21/2014 11:40 AM, Ashley Holman wrote: > On Mon, Apr 21, 2014 at 1:36 PM, Peter Todd > wrote: > > That is mistaken: you can't mine on top of just a block header, > leaving small miners disadvantaged as they are earning no profit > while they wait for the information to validate the block and > update their UTXO sets. This results in the same problem as > before, as the large pools who mine most blocks can validate > either instantly - the self-mine case - or more quickly than the > smaller miners. > > > Under the headers first scenario, wouldn't the full block still reach > everyone in the same time as it would under the current rules? So the > small miner loses nothing in terms of updating their UTXO set, but > gains an early "heads up" alert that a new block is coming. This > allows them spend the propagation time working more productively on an > empty block in the new chain rather than wasting time on an orphan. > It's true that it doesn't solve the problem of larger pools vs > smaller pools, but if it doesn't make it any worse then headers-first > propagation would be a net benefit to the network since it removes the > incentive to make small blocks. > I think the most important part is that nodes can reliably decide on "first received", regardless of how they subsequently act on it. I believe it would be fine for a node to receive a header and continue mining the old block, or a subsequently-verified competing block, until it has the necessary pieces to fully verify the first header received. If that block data doesn't come, then it will be naturally ignored. But if multiple blocks come at once, even if a competing block "verifies" first, the node would still switch to considering the first header received as the best block when it later receives proof it is valid (which may only be a couple seconds). In other words, the node will always consider the header-received time as the primary ordering criteria, but will not mine on anything until it has full proof of validity, even if /that/ is out of order. This means that new blocks "effectively" propagate at the speed of 80 bytes, which limits certain kinds of block-injection/racing attacks. --------------020600030704050406030703 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On 04/21/2014 11:40 AM, Ashley Holman wrote:
On Mon, Apr 21, 2014 at 1:36 PM, Peter Todd <pete@petertodd.org> wrote:
That is mistaken: you can't mine on top of just a block header, leaving small miners disadvantaged as they are earning no profit while they wait for the information to validate the block and update their UTXO sets. This results in the same problem as before, as the large pools who mine most blocks can validate either instantly - the self-mine case - or more quickly than the smaller miners.

 
Under the headers first scenario, wouldn't the full block still reach everyone in the same time as it would under the current rules?  So the small miner loses nothing in terms of updating their UTXO set, but gains an early "heads up" alert that a new block is coming.  This allows them spend the propagation time working more productively on an empty block in the new chain rather than wasting time on an orphan.  It's true that it doesn't solve the problem of larger pools vs smaller pools, but if it doesn't make it any worse then headers-first propagation would be a net benefit to the network since it removes the incentive to make small blocks.


I think the most important part is that nodes can reliably decide on "first received", regardless of how they subsequently act on it.  I believe it would be fine for a node to receive a header and continue mining the old block, or a subsequently-verified competing block, until it has the necessary pieces to fully verify the first header received.  If that block data doesn't come, then it will be naturally ignored.  But if multiple blocks come at once, even if a competing block "verifies" first, the node would still switch to considering the first header received as the best block when it later receives proof it is valid (which may only be a couple seconds).

In other words, the node will always consider the header-received time as the primary ordering criteria, but will not mine on anything until it has full proof of validity, even if that is out of order.  This means that new blocks "effectively" propagate at the speed of 80 bytes, which limits certain kinds of block-injection/racing attacks. 


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