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Wed, 16 Oct 2019 12:25:32 -0700 (PDT) To: =?UTF-8?Q?Joachim_Str=c3=b6mbergson?= References: <42cd5ffd-63e8-b738-c4ea-13d0699b1268@purse.io> <93649df9-27ab-abaf-00f3-da6c528344cc@purse.io> <7b0d0bff-d898-10ff-5fdb-c982b82054a1@purse.io> 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: <9e42533b-aac6-1438-068b-d02a13db53f5@purse.io> Date: Wed, 16 Oct 2019 12:25:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: 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: Wed, 16 Oct 2019 19:45:31 +0000 Cc: Bitcoin Protocol Discussion 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: Wed, 16 Oct 2019 19:25:35 -0000 On 10/15/19 8:50 AM, Joachim Str=C3=B6mbergson wrote: >>>>> [...] to generate much longer chain with superslow timestamp increa= se (~5 blocks in 1 second) without increasing difficulty (i.e. staying at= min. diff.). [...] >>>>> In that case, it would take about 7 minutes of block time seconds f= or >>>>> the next retarget period, every 2016 blocks, and the difficulty wou= ld >>>>> adjust. The difficulty would adjust in that case as if 2 weeks of b= locks >>>>> had been mined in 7 minutes. For the difficulty to remain the same = the >>>>> time between blocks needs to be 10 minutes. >>>>> This calculation does not apply under time warp attack. You can fak= e timestamps of all blocks except for those relevant to the retarget calc= ulation. Those are only the first and the last block in the 2016 block wi= ndow. >> This must be in reference to the non-overlapping difficulty calculatio= n >> and off-by-one bug? > Indeed. > Yeah, limiting the width of the chain would not be effective unless the timewarp off-by-one bug is resolved =E2=80=94 the height can be extended = instead. Rate limiting based on chainwork would slow down a timewarped low work header chain. There would be a maximum rate at which the headers could be sent. It would be around 32KB/s. It would take about a month to send 100GB.