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 ) id 1R3WAN-0000Gm-M9 for bitcoin-development@lists.sourceforge.net; Tue, 13 Sep 2011 16:48:59 +0000 X-ACL-Warn: Received: from zinan.dashjr.org ([173.242.112.54]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1R3WAL-0000OD-Hk for bitcoin-development@lists.sourceforge.net; Tue, 13 Sep 2011 16:48:59 +0000 Received: from ishibashi.localnet (fl-184-4-160-40.dhcp.embarqhsd.net [184.4.160.40]) (Authenticated sender: luke-jr) by zinan.dashjr.org (Postfix) with ESMTPSA id DB8C2204002; Tue, 13 Sep 2011 16:48:38 +0000 (UTC) From: "Luke-Jr" To: bitcoin-development@lists.sourceforge.net Date: Tue, 13 Sep 2011 12:48:29 -0400 User-Agent: KMail/1.13.7 (Linux/2.6.39-gentoo; KDE/4.6.5; x86_64; ; ) References: In-Reply-To: X-PGP-Key-Fingerprint: CE5A D56A 36CC 69FA E7D2 3558 665F C11D D53E 9583 X-PGP-Key-ID: 665FC11DD53E9583 X-PGP-Keyserver: x-hkp://subkeys.pgp.net MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201109131248.32502.luke@dashjr.org> X-Spam-Score: -0.5 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -0.5 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain X-Headers-End: 1R3WAL-0000OD-Hk Subject: Re: [Bitcoin-development] Difficulty adjustment / time issues 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: Tue, 13 Sep 2011 16:48:59 -0000 On Tuesday, September 13, 2011 11:06:37 AM Gavin Andresen wrote: > Fixing (2) is easier; incorporating a ntp library and/or simply > removing the bitcoin mining code from the client but requiring pools > and miners to have accurate-to-within-a-minute system clocks (or their > blocks will be "discouraged") seems reasonable to me. If you want to > produce blocks that the rest of the network will accept, run ntp on > your system. This is not currently reasonable. Rolling extranonce is not efficient, and using it to generate work for 400+ GH/s worth of miners every new block (longpoll) can easily take seconds. Noncerange helps a little, but has poor support presently, and still requires an otherwise-unique work per 4 GH/s. That only leaves pools with the time header to play with. Furthermore, within- a-minute accuracy basically forces all miners to rollntime-- I'm not against this result, but it does mean many miners and pools will be left out in the cold. > I THINK that fixing (2) will make (1) a non-issue-- if miners can't > mess around with block times very much then it will be very difficult > for them to manipulate the difficulty for their benefit. Miners already have very limited area to mess around with block times. My understanding of these attacks is that they somehow bypass the limitations in place.