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 1WYNXV-0007Zc-Li for bitcoin-development@lists.sourceforge.net; Thu, 10 Apr 2014 22:33:45 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.42 as permitted sender) client-ip=209.85.215.42; envelope-from=gmaxwell@gmail.com; helo=mail-la0-f42.google.com; Received: from mail-la0-f42.google.com ([209.85.215.42]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WYNXT-000868-KJ for bitcoin-development@lists.sourceforge.net; Thu, 10 Apr 2014 22:33:45 +0000 Received: by mail-la0-f42.google.com with SMTP id ec20so2842973lab.15 for ; Thu, 10 Apr 2014 15:33:37 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.112.27.133 with SMTP id t5mr13240328lbg.21.1397169216945; Thu, 10 Apr 2014 15:33:36 -0700 (PDT) Received: by 10.112.89.68 with HTTP; Thu, 10 Apr 2014 15:33:36 -0700 (PDT) In-Reply-To: <53471A35.3040805@jcea.es> References: <53470E65.5080402@jcea.es> <534717F3.6@monetize.io> <53471A35.3040805@jcea.es> Date: Thu, 10 Apr 2014 15:33:36 -0700 Message-ID: From: Gregory Maxwell To: Jesus Cea 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 X-Headers-End: 1WYNXT-000868-KJ Cc: Bitcoin Development Subject: Re: [Bitcoin-development] Chain pruning 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: Thu, 10 Apr 2014 22:33:45 -0000 On Thu, Apr 10, 2014 at 3:24 PM, Jesus Cea wrote: > On 11/04/14 00:15, Mark Friedenbach wrote: >> Checkpoints will go away, eventually. > Why?. The points in the forum thread seem pretty sensible. Because with headers first synchronization the major problems that they solve=E2=80=94 e.g. block flooding DOS attacks, weak chain isolation, = and checking shortcutting can be addressed in other more efficient ways that don't result in putting trust in third parties. They also cause really severe confusion about the security model. Instead you can embed in software knoweldge that the longest chain is "at least this long" to prevent isolation attacks, which is a lot simpler and less trusting. You can also do randomized validation of the deeply burried old history for performance, instead of constantly depending on 'trusted parties' to update software or it gets slower over time, and locally save your own validation fingerprints so if you need to reinitilize data you can remember what you've check so far by hash.