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 1Vdk6a-00060R-5h for bitcoin-development@lists.sourceforge.net; Tue, 05 Nov 2013 17:07:52 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.149.56 as permitted sender) client-ip=62.13.149.56; envelope-from=pete@petertodd.org; helo=outmail149056.authsmtp.com; Received: from outmail149056.authsmtp.com ([62.13.149.56]) by sog-mx-2.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Vdk6Y-00016X-4b for bitcoin-development@lists.sourceforge.net; Tue, 05 Nov 2013 17:07:52 +0000 Received: from mail-c235.authsmtp.com (mail-c235.authsmtp.com [62.13.128.235]) by punt10.authsmtp.com (8.14.2/8.14.2) with ESMTP id rA5H5rKO027201; Tue, 5 Nov 2013 17:05:53 GMT Received: from petertodd.org (petertodd.org [174.129.28.249]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id rA5H5fMV033599 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 5 Nov 2013 17:05:44 GMT Date: Tue, 5 Nov 2013 12:05:41 -0500 From: Peter Todd To: Ittay Message-ID: <20131105170541.GA13660@petertodd.org> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="XsQoSWH+UP9D9v3l" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Server-Quench: 82a9971a-463c-11e3-b802-002590a15da7 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR bgdMdgcUFloCAgsB AmUbWlNeUFh7XWY7 ag1VcwRfa1RMVxto VEFWR1pVCwQmQ20E fhtIL39ydAZDcXc+ ZEJqWXUVVEYrfE96 Qx9JEWsFNnphaTUc TRJQdwFJcANIexZF O1F6ACIKLwdSbGoL NQ4vNDcwO3BTJTpY RgYVKF8UXXNDNB8E DwgYGi0oBkQBD2B7 NxU6IV5UAEFZKEwz KlZpQl8cPR4JCm8W GkBLASlWb0UBXScw DQReUQh2 X-Authentic-SMTP: 61633532353630.1023:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 174.129.28.249/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Score: -1.5 (-) 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 SPF_PASS SPF: sender matches SPF record 0.0 URIBL_BLOCKED ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [URIs: petertodd.org] X-Headers-End: 1Vdk6Y-00016X-4b Cc: Bitcoin Dev , Gavin Andresen , Emin =?iso-8859-1?B?R/xu?= Sirer Subject: Re: [Bitcoin-development] BIP proposal - patch to raise selfish mining threshold. 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, 05 Nov 2013 17:07:52 -0000 --XsQoSWH+UP9D9v3l Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Nov 05, 2013 at 11:56:53AM -0500, Ittay wrote: > Hello, >=20 > Please see below our BIP for raising the selfish mining threshold. > Looking forward to your comments. > 2. No new vulnerabilities introduced: > Currently the choice among equal-length chains is done arbitrarily, > depending on network topology. This arbitrariness is a source of > vulnerability. We replace it with explicit randomness, which is at the > control of the protocol. The change does not introduce executions that we= re > not possible with the old protocol. Credit goes to Gregory Maxwell for pointing this out, but the random choice solution does in fact introduce a vulnerability in that it creates incentives for pools over a certain size to withhold blocks rather than immediately broadcasting all blocks found. The problem is that when the pool eventually choses to reveal the block they mined, 50% of the hashing power switches, thus splitting the network. Like the original attack this can be to their benefit. For pools over a certain size this strategy is profitable even without investing in a low-latency network; Maxwell or someone else can chime in with the details for deriving that threshold. I won't get a chance to for a few hours, but someone should do the analysis on a deterministic switching scheme. --=20 'peter'[:-1]@petertodd.org 0000000000000005e25ca9b9fe62bdd6e8a2b4527ad61753dd2113c268bec707 --XsQoSWH+UP9D9v3l Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQEcBAEBCAAGBQJSeSVlAAoJEBmcgzuo5/CFp18H/2TV/QDwqsHtYLJXN/wCJ5Tf JU+0b8ZHmkZzfh65a45DgkgwkltzyRUtoOc+/35kjk95726feVdtF5TjvaAs8uu/ v413flPPJYeqcaPXjp2gmynKNmyxD6XZEdYYpvT0KyiT9Zk/HH2zDKja1payYqU4 us2lhI/E1S1vkPB4ZyvCgn6W7ac9TG6lYyBsqyhv8BJiyddgHCqbGnk+et7ZcR41 3LAT6+gQm3Tw6XF27HzTloetSVU5MzaOv+89VQnctxk6GLtx/AASNm4CepoguNp7 dWaojDhTb8fzU0MmHOQlLiuAEJqoOjFRyVo2B/FQtCngAmRoTH9Dxz228MduDt8= =ygPG -----END PGP SIGNATURE----- --XsQoSWH+UP9D9v3l--