From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1RTEuE-0001XK-NW for bitcoin-development@lists.sourceforge.net; Wed, 23 Nov 2011 15:38:38 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.214.47 as permitted sender) client-ip=209.85.214.47; envelope-from=timon.elviejo@gmail.com; helo=mail-bw0-f47.google.com; Received: from mail-bw0-f47.google.com ([209.85.214.47]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1RTEuD-0007ct-RX for bitcoin-development@lists.sourceforge.net; Wed, 23 Nov 2011 15:38:38 +0000 Received: by bkbzs2 with SMTP id zs2so1832112bkb.34 for ; Wed, 23 Nov 2011 07:38:31 -0800 (PST) MIME-Version: 1.0 Received: by 10.204.152.87 with SMTP id f23mr24892814bkw.18.1322062711467; Wed, 23 Nov 2011 07:38:31 -0800 (PST) Received: by 10.223.132.194 with HTTP; Wed, 23 Nov 2011 07:38:30 -0800 (PST) In-Reply-To: <201111231529.46154.andyparkins@gmail.com> References: <201111231035.48690.andyparkins@gmail.com> <201111231254.41426.andyparkins@gmail.com> <201111231529.46154.andyparkins@gmail.com> Date: Wed, 23 Nov 2011 16:38:30 +0100 Message-ID: From: =?ISO-8859-1?Q?Jorge_Tim=F3n?= To: Andy Parkins Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Spam-Score: 0.1 (/) 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 (timon.elviejo[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 2.5 FREEMAIL_REPLY From and body contain different freemails -0.8 AWL AWL: From: address is in the auto white-list X-Headers-End: 1RTEuD-0007ct-RX Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Addressing rapid changes in mining power 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: Wed, 23 Nov 2011 15:38:38 -0000 But the protocol must have a deterministic way to determine if a block must be accepted or rejected. I don't know what NTP is, but if you can have a perfect distributed clock your proposal may work. 2011/11/23, Andy Parkins : > On 2011 November 23 Wednesday, Jorge Tim=F3n wrote: > >> Well, I meant "the probability of your block being the hardest". >> What a miner can do is hash the block (cheating the timestamp) for 2 >> more minutes than the rest of the people and then send it to the other >> nodes. Nodes cannot possibly know when did you hashed the block only >> by looking at their clock when they receive it, because there's also >> network latency. > > True enough; but then the same is true for everyone else. If the window = is > 2 > minutes after the stated time, then everyone _can_ wait until the end of > that > window. However, they risk their block being rejected by their peers, an= d > their efforts are wasted. In fact, it can be guaranteed by making the > accept > window zero. There is then no reason to carry on computing after the rew= ard > window closes, since you know your peers will reject it. > >> > (2) For the network clock; see util.cpp:GetAdjustedTime(). >> >> 1) This is part of the satoshi client but not the protocol. A miner >> can rewrite this part of the code and there won't be anything in the >> chain that contradicts the protocol. > > Well yes. What does that matter? It's only a way of calculating an aver= age > time. The node can use any clock it wants, as long as the block time is > verified by the peers. > >> 2) I haven't read the code but I'm pretty sure that's not a perfect >> decentralized clock. > > It definitely isn't. NTP is mentioned in the source as an alternative. > >> I will be more specific. Where's the network clock in the chain (in >> the protocol)? > > It's nothing to do with the protocol; it's an individual miner choosing > whether to accept or reject a block based on the timestamp it claims, and > the > current time as the miner sees it. For the sake of compatibility, the > clients > currently choose to use a community clock as "current", as established fr= om > the time they receive from peers in the "version" message (it actually ho= lds > offsets between them, which is pretty bad, as a long-connected client wil= l > drift). They don't have to, but if miners aren't using time that > approximates > what their peers are using, under my system, their blocks would be reject= ed: > so an incentive to use that "community clock" exists. > > > > Andy > > -- > Dr Andy Parkins > andyparkins@gmail.com > --=20 Jorge Tim=F3n