Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CCB9EB79 for ; Fri, 4 Oct 2019 19:51:29 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C310F8A7 for ; Fri, 4 Oct 2019 19:51:28 +0000 (UTC) Received: by mail-pf1-f178.google.com with SMTP id q12so4509818pff.9 for ; Fri, 04 Oct 2019 12:51:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=purse.io; s=google; h=to:references:from:openpgp:autocrypt:subject:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=XWRHM+p+eNoTWIJm10pdo6wfw27kMOEh68Ha5jCYvtw=; b=OHIISZp4a9Y9K+1mb8FdJxcBeS4w5aVdU0uYd5iq03ctmCQxlZouoiVvsdvVV1SWHn LsqUk69EfYOMdJuPSkQwNAk4fCtE50oawN0c2ERbge9qDYJe9G9CcURmYC66mdBuYIK8 8fkZ4fMVh7ag8uVCoHb3OwrQJ6KwUvi4PslI8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:references:from:openpgp:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-transfer-encoding:content-language; bh=XWRHM+p+eNoTWIJm10pdo6wfw27kMOEh68Ha5jCYvtw=; b=QnkTOXIKZyijkF7s7W1byAd6wZRSv3Nn1vxAQLEJtJJfTtydkA49XWDN14Elw4usZh jTCO/N8udvrc84xFoeOfIXNtXxoiesGi2/IfHvVKrbOVmAKBDR1shNjwrhO/c7w+5N2e WfR5XV7AlUpAykepV9qDrM+1tswqjh6ZYAK/HbkhH/rFbfeaavWvWZqZGhCHhqyVfUrA 05MZ3poj9LL5xM07SiXAoGwJmPfd/pI431eNpKZcsc0IokMwHNyMnZtQvUcuHfSIa0YO 6i440YIDTSn2F3vMSZyM/O8dMlHd+2+/eJeDZfBx3Mezc2DjX369Ni+Mr9sZRtm36AR3 BjMQ== X-Gm-Message-State: APjAAAUdPzG79DGIkGjWjvJjFkzafN24+uEj3E5gXV5mW0BpHyg5w0G1 JGnd5LMOLOpQXf+ny4E+racXYsawR/0= X-Google-Smtp-Source: APXvYqwxbJIgCHdAuuIsXLBgLAPQ2U1FrgfmZpFjKLiYA9SGuyp9NEZJWYF/eeYI7iQg8c7UtaV51w== X-Received: by 2002:a62:14cb:: with SMTP id 194mr19849470pfu.192.1570218687904; Fri, 04 Oct 2019 12:51:27 -0700 (PDT) Received: from [10.0.0.199] ([198.244.101.193]) by smtp.gmail.com with ESMTPSA id o9sm7194945pfp.67.2019.10.04.12.51.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Oct 2019 12:51:27 -0700 (PDT) To: "David A. Harding" , Bitcoin Protocol Discussion References: <42cd5ffd-63e8-b738-c4ea-13d0699b1268@purse.io> <20191004082031.ns3pgzwh2zz2mxyc@ganymede> From: Braydon Fuller Openpgp: preference=signencrypt Autocrypt: addr=braydon@purse.io; keydata= xsFNBFsEkasBEAC4oPJQsFWAM0OjNJlYUxJbTV8bo1TgXwZdNZWewG6fvQQ+iGGImy/a5h10 /9V+/Ctio8ayAfpk6V3z/vxq8IdPVcsWccHLnguaAEEhYnKdGZfsohcQMO4LR63R6vPrUYUJ ehVzt2YZ5F495iRDKwbQLXbmXF9vLtaKuf/6hbVmlG7bM59eVKcvpE8EKm95Lpw+CBE3uKc3 RxTcKHgo6QrkClm19GNDDkmHxM/k+hGT3M+sXGhgpL2940AGKsXuTPghgLQ+5seBWtzuWV31 Uf0ltHx6Ks1w0mlgZZ+u4wlljMHIBKLr4cYDOF8AYxyVcPzuQLdRjIIKEgpMDQW7ftbgGM/q hgGg2mN036KTUfT1HkmT82Z3D3z4ACJ/bY/J+mJw0baqcJpezndd1M6dnDNF9Slst2Mr+Loe JdN1tY5kk6/OWwAI5L15hmdiRWUBryJqun7sy23cmVPSOrtaIfl7/SEFJ+MuXbK53+mFGT2P CpdRzV4MrKr9qbBaXkkhvEfoL2z6VwIFBprqZjthPHcHR8r6QSTpZdsD+7+qoq2o4MDUqP54 5a3kGI3l6VW767VE/NUIocyO7Z9D/EZOCk22ElTLTCzWm0JvxxGJoalebLQcGey/A9WWGOv/ ydwvTry3PWAzrrXNt43McHHwZXU4vSLnAtAxQy06Nt9wsWo+2QARAQABzSFCcmF5ZG9uIEZ1 bGxlciA8YnJheWRvbkBwdXJzZS5pbz7CwZcEEwEIAEECGwMFCwkIBwIGFQgJCgsCBBYCAwEC HgECF4ACGQEWIQRbfcWNkP7B6ZCjELryTyMtEIs61AUCXL9UPwUJA5v2FAAKCRDyTyMtEIs6 1HOwEACedBLpkYrFeLANxD25USZunMt4KA58ZkY7Ap2m7KFcxjZD07YIjtxJyMLhHhMz6pR7 fF5BFHbl8CtAhpTuz5Sj9X3K0eilNsXvdx18+3RMUpFVAwlEEev707q6zNqKsRd1CG7e0k4o 28YAgwbt42UIPUoKTcEpT4C51sDa5d4NZsGnFcXeEdpBSQVi56vap0eJrQTSFpV0sG497HNN p96ErrGpqlOkTofcBeytpQbhH9kbP58PMABwU3tmoMFhT0kklPPZatv7RDLmC8cra5muXEwd wv7ggauHbMbV3U1xZ/BNPwHm7jO1ygqR6Q4Y98miRUP4yH9SJsnr+q7bpD4yOUy/qP0Ve0Y0 jFgX4e4DrnckO/2rG4lB2SbKiAWAOW5aGTnUAZt6agegXY62kHpuUHGcgYkeQqDWKLZWjFAA vj8Gm5f+1thWk+4I0rFQBtaAoitd+qKPWFYSojjvKH4PLqoOV413qxZbrRlGxZb2TkJnxYpO imOq/H6bHCnJUA8NI1v5rXmGQXfwhofMX9dHpGK864G+i59AX9L0EEQngDXZPlSEkyISaBY7 JFBhuIPcY8MrhUkNWl1G2RcssjHeexmo2qNrKH4bWFF7xCCTmdGUSoHzaHDe/cIqmI0aRkqf HQ4MpadD8flLLMqV/ODYfpSD3AuwM/m8Uj9nvfnMRs7BTQRbBJGrARAA3+SVdBJUThjPx/J5 G4A1dd2vKVRRprW+pyJ0XDbNrRVOEnxr3okz2F4Htg72oULwsNcuCmgFxDlxIFMitzZAWbuL fq9FR7snaW3PMlkj44eezq3emYXVv3C3lc6MudAOqkQKNzakyaA/6cNVlQnVmrpctpFHtUNi oeivM9IeCP52scTH84qeRZofmnedc3FAxKMJ9OZi4Miigsd/DhzhUqbAePrCMlQQsM/HXSNs 2qoMK3Bo6lcHzV7qyI9w19tmFouX06ULnAAM1dJZcCUL31FLtaIrGbcXA+99a8dlOUb68rj9 9H3V3zDjJscDBgJ2mziuuS/naG/NK+RVhVh3KqtViC62nGgA1tS1aLKZ7KDeyzu4FiE2bCPh 6b4IlIQijzqwTyPJt+0Muf2FYxir9GwgMnVqJ/fYaT671RCcUrkq2krVzdHq/HX7A8Hyfftc BMEt4yZJt/bZ7ryyWJ8PlQJP3HGqz+hpHmwrwmJgj5RbmktVMw3RAEipJrEHD1Q7wIhPNYpy 6FIwFlDxwpUQOUYGEZYww9LRZiapN0FeDcFp6CUMRgJH24ZQzFk8J5N4PAzZrIZfQba71bDA z3902PDt66qiIiG2muTbd8eIeCzx9RxWhDmQclzXn5WxfPU6l0E9NgLNFoNCppLaTz2S/Gxw ZzrSduMLfVlhKPDjv2EAEQEAAcLBZQQYAQIADwUCWwSRqwIbDAUJAeEzgAAKCRDyTyMtEIs6 1MLqD/9vMXLRhe5w6oBKuL0tj+ChLhkQEM66Q7O4urWmvl8yf/ThNi0/LydGAYawCUWud2ph aOg4vH0IUvUhlLDRcYc2MdfwJi8aj8G7YC/OUKwwFDfYyY9zIk1C5yXn6LigkjOL0PyYI0MM 2gk64t/PK+Rny8jz6QjwZ4AMsoTpo698LSYS7LcvOETp+3yz0LYtkPP36FqoG2hudjh015Gk DSIHWckot4TJXK8OOHOuKwUz2fteGsFeM4bmTiArCRXsAkRWo0VbA6hPinK0Zr/xLNSYIx94 IXe5q9ISZc6ceuWyisVsUZxUgJJGyNSvXXwx4zoSS7BXyTo7syjpKd09nhCL3QGfuHugJ/1/ DCaNtKUu2C+rUe1Ux6/qteCVUsAM+bDfDBQ/vS1tnyn9OVBTOZqXvChL4f+MAN2Wws/+Llxw DqGMX6YC/ZBWM56XGApL1zj93nygxbN8s8yXqqMQNghTjwj9IqyaNQcKO/AslSmFlW6RXz1Y RDT4mSKdAogbdDqmguGc05kUaOSkqSb0bL34iQ/dm4PyVxjSGSDRr8TQOjQGz0rSEh6Q+LZ9 zRltkmEMkdkyWQZ4tYsBbQv2TU+tCfKMIUCZ7xEHuvjAKZIms9Ers3zVS+PcRr9i6mvMtbNM ufP9MwSx7PqsHuv/PWdoI3uwanxYzk1GTLALMsy2icLBfAQYAQIAJgIbDBYhBFt9xY2Q/sHp kKMQuvJPIy0QizrUBQJcv1RFBQkDm/YaAAoJEPJPIy0QizrUjvoP/R6Wi8Ol1QiOWrxLZyL9 NYtU1Q+P46R8Q0d6gFRkrC9MKJlzaTRzPxdaWyJURnh1pXHbykB3/b6Bg/WN7o7Wips8KIhL PzrNUiCZIsrBxUR29no7NzU6o7rSuu/9j5OfiyW/jViRJ3oi1jdYdFx7qx/56j1I54q6NHAk i2AoG07RbXsRsh0x5vv4VIEFNwRRHmn/d185NTDeoVj9IanVhF6zna9M2iX3AgUOLovF7PiM d/oF5XDwuzEDiBIorGi4WTqiCDjl7menb657af1DsPV68gKCiVFQNwfbawtUzUBasfaCFkR5 NuXWFqYN/305vlK/IN2GDPrwwOFsQK9pG4fYDDC5Pi9fy9wLrwtlebRuraLCHsiho8mYtEhM QTU7oQwWga9Ax6BXbnStmX1kEev41CEEvnaVtqzuT0VKJjnre/7z8+bRC1tbqvN5CKTQ1k3d 5uwFqCBOxtoY6NLmYT37zFq34etKgpqCri6lEMtM57icMd4SPaADSXly/EyUTPbb/iGvQVOS NFPpY30rTBA8rJJ5Iawe1OjG2dcYwKkFfGjGU7bbHp9ClG1d3YM7kDxVkgdIVAWhEY905HB4 KXQZd0eW19JjNwLVMNzgBh07BiaXl16tWY+P7pQdPrbLctiIVqsYx+IU74M7riDEMTGjsosr lL56VCOJffiN9F1L Message-ID: Date: Fri, 4 Oct 2019 12:51:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191004082031.ns3pgzwh2zz2mxyc@ganymede> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Fri, 04 Oct 2019 20:22:28 +0000 Subject: Re: [bitcoin-dev] Chain width expansion X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Oct 2019 19:51:29 -0000 On 10/4/19 1:20 AM, David A. Harding wrote: > On Thu, Oct 03, 2019 at 05:38:36PM -0700, Braydon Fuller via bitcoin-de= v wrote: >> This paper describes a solution [to DoS attacks] that does not >> require enabling or maintaining checkpoints and provides improved secu= rity. >> [...]=20 >> The paper is available at: >> https://bcoin.io/papers/bitcoin-chain-expansion.pdf > [..] But I worry that the mechanisms could also be used to keep a node = that > synced to a long-but-lower-PoW chain on that false chain (or other fals= e > chain) indefinitely even if it had connections to honest peers that > tried to tell it about the most-PoW chain. Here is an example: An attacker eclipses a target node during the initial block download; all of the target's outgoing peers are the attacker. The attacker has a low work chain that is sent to the target. The total chainwork for the low work chain is 0x09104210421039 at a height of 593,975. The target is now in the state of a fully validated low work dishonest chain. The target node then connects to an honest peer and learns about the honest chain. The chainwork of the honest chain is 0x085b67d9e07a751e53679d68 at a height of 593,975. The first 69,500 headers of the honest chain would have a delay, however the remaining 52,4475 would not be delayed. Given a maximum of 5 seconds, this would be a total delay of only 157 seconds.