From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1UZQ6o-0006Al-GR for bitcoin-development@lists.sourceforge.net; Mon, 06 May 2013 18:25:58 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.41 as permitted sender) client-ip=209.85.215.41; envelope-from=gmaxwell@gmail.com; helo=mail-la0-f41.google.com; Received: from mail-la0-f41.google.com ([209.85.215.41]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1UZQ6n-00068j-MB for bitcoin-development@lists.sourceforge.net; Mon, 06 May 2013 18:25:58 +0000 Received: by mail-la0-f41.google.com with SMTP id fn20so3598275lab.14 for ; Mon, 06 May 2013 11:25:51 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.152.37.196 with SMTP id a4mr8471007lak.55.1367864750929; Mon, 06 May 2013 11:25:50 -0700 (PDT) Received: by 10.112.35.43 with HTTP; Mon, 6 May 2013 11:25:50 -0700 (PDT) In-Reply-To: <20130506180418.GA3797@netbook.cypherspace.org> References: <20130506161216.GA5193@petertodd.org> <20130506163732.GB5193@petertodd.org> <20130506180418.GA3797@netbook.cypherspace.org> Date: Mon, 6 May 2013 11:25:50 -0700 Message-ID: From: Gregory Maxwell To: Adam Back Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (gmaxwell[at]gmail.com) -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 0.0 LOTS_OF_MONEY Huge... sums of money X-Headers-End: 1UZQ6n-00068j-MB Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Discovery/addr packets (was: Service bits for pruned nodes) 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: Mon, 06 May 2013 18:25:59 -0000 On Mon, May 6, 2013 at 11:04 AM, Adam Back wrote: > bitcoins primary > vulnerability IMO (so far) is network attacks to induce network splits, > local lower difficulty to a point that a local and artificially isolated > area of the network can be fooled into accepting an orphan branch as the > one-true block chain, Uh. It currently costs about 2016*25*$120 =3D six million dollars to reduce the difficulty in your isolated fork by a factor of 4. To reduce it by a factor of 1000 (what would be required to make a parallel fork that you could maintain in realtime with a single avalon device) the cost is sum(2016*25/4^n*120,n,0,ceil(log4(1000))) or about eight million dollars. Surely you can think of attacks on Bitcoin which are less expensive than eight million dollars. :P > maybe even from node first install time. Protecting against that=E2=80=94 making sure any such attack has to start f= rom a high difficulty=E2=80=94 is, in my opinion, the biggest continued justification for checkpoints. > (btw I notice most of the binaries and tar balls are not signed, nor serv= ed > from SSL - at least for linux). They are signed. > With ToR, it has a similar bootstrap problem to bitcoin. So while that m= ay > help it is also passing the buck, not necessarily solving the problem. A= nd No, it doesn't. It has centrally controlled directories that publish an official Truth of the Network. Someone can isolate you and thus DOS you, but they can't put you on a fantasy tor network. But ... centeralized. > as I said I think its possible bitcoin has a higher assurance need in tha= t > the attackers motivated my $$ might put more effort in than the odd It does, and we also consider decentralization a core value. But even the tor project would like to decentralize more.