Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1YbZBc-0002ad-Hs for bitcoin-development@lists.sourceforge.net; Fri, 27 Mar 2015 18:40:52 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of taplink.co designates 50.117.27.232 as permitted sender) client-ip=50.117.27.232; envelope-from=jeremy@taplink.co; helo=mail.taplink.co; Received: from mail.taplink.co ([50.117.27.232]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES128-SHA:128) (Exim 4.76) id 1YbZBb-0001zT-JN for bitcoin-development@lists.sourceforge.net; Fri, 27 Mar 2015 18:40:52 +0000 Received: from [192.168.1.113] (c-76-21-80-35.hsd1.ca.comcast.net [76.21.80.35]) by mail.taplink.co with ESMTPSA (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256) ; Fri, 27 Mar 2015 11:42:59 -0700 References: <55034205.4030607@localhost.local> <7854077.3GbzoT9yL1@crushinator> <2210650.iUsfZECcCc@crushinator> Mime-Version: 1.0 (1.0) In-Reply-To: <2210650.iUsfZECcCc@crushinator> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Message-Id: <2B8DBE05-E38E-433F-A4D2-A6D93D2FD4AA@taplink.co> X-Mailer: iPhone Mail (12B466) From: Jeremy Spilman Date: Fri, 27 Mar 2015 11:40:43 -0700 To: Matt Whitlock X-Spam-Score: -1.6 (-) 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 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -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 X-Headers-End: 1YbZBb-0001zT-JN Cc: "bitcoin-development@lists.sourceforge.net" Subject: Re: [Bitcoin-development] "network disruption as a service" and proof of local storage 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: Fri, 27 Mar 2015 18:40:52 -0000 > On Mar 27, 2015, at 8:16 AM, Matt Whitlock wrote: >=20 > Isn't the goal of this exercise to ensure more full nodes on the network? Basically we're talking about a form of Sybil defense and better quantifying= true blockchain resiliency by proof of storage. In this case the goal is to see if we can prove the number of distinct digit= al copies of the blockchain. This is actually a tricky problem because it wi= ll (always?) devolve to inferences from response timing, and we are running o= ver a heterogenous network with heterogeneous machines. It would be extremely impressive to achieve a reliable mechanism for discern= ing a local copy exists under these constraints, particularly without false p= ositives and false negatives, and without imposing very substantial one-time= encoding costs, e.g. on par with doubling the verification cost.=20 I think while its a difficult cost-benefit analysis, even code complexity as= ide, it's interesting to discuss all the same! Simply having many unique IP addresses possibly accessing the same unique co= py provides a different (if any) benefit. E.g. Tor uses IPs as a cost factor= , but (until recently?) didn't even factor in things like them all being the= same Class C.=20=