Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WoKum-0001DL-EQ for bitcoin-development@lists.sourceforge.net; Sat, 24 May 2014 22:59:44 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.217.176 as permitted sender) client-ip=209.85.217.176; envelope-from=bernd.jendrissek@gmail.com; helo=mail-lb0-f176.google.com; Received: from mail-lb0-f176.google.com ([209.85.217.176]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WoKul-00043K-5E for bitcoin-development@lists.sourceforge.net; Sat, 24 May 2014 22:59:44 +0000 Received: by mail-lb0-f176.google.com with SMTP id p9so3527803lbv.35 for ; Sat, 24 May 2014 15:59:36 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.152.21.130 with SMTP id v2mr9936645lae.1.1400972376403; Sat, 24 May 2014 15:59:36 -0700 (PDT) Sender: bernd.jendrissek@gmail.com Received: by 10.112.94.228 with HTTP; Sat, 24 May 2014 15:59:36 -0700 (PDT) In-Reply-To: References: Date: Sun, 25 May 2014 00:59:36 +0200 X-Google-Sender-Auth: pTTOZdPxUIH9UCaRKAZ-C9hN0ho Message-ID: From: Bernd Jendrissek To: Ashley Holman Content-Type: text/plain; charset=UTF-8 X-Spam-Score: -1.5 (-) 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 (bernd.jendrissek[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 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: 1WoKul-00043K-5E Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Cut-through propagation of blocks 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: Sat, 24 May 2014 22:59:44 -0000 On Sat, May 24, 2014 at 5:57 AM, Ashley Holman wrote: > * As far as I can tell, this shouldn't change any game theory or incentives > because nodes still receive blocks exactly as they do now, just sooner. The > difference is, invalid blocks that meet the PoW will be broadcast to > everyone, but this is nothing new since someone can peer with you and send > you an invalid block already. Network DoS should not be a possibility since > it is very expensive to make invalid blocks that meet network PoW. The difference is that with cut-through forwarding of blocks, a sufficiently motivated attacker (being willing to blow 25BTC's worth of electricity on the effort) can subjugate the entire Bitcoin network to its DoS attack, rather than having to connect to every node individually and then still have those individual nodes reject that invalid block without relaying any knowledge of its existence. An attack could also take the form of a block body that never arrives - a sort of teergrube attack, where the goal is to get the network mining empty block upon empty block on top of that valid-PoW header whose body never arrives. It doesn't have to be with an explicitly invalid block. Could one mitigate such attacks by allowing nodes to send a message to the effect of, "Oops, I know that header i just sent is valid PoW, but I'd like you to forget about it - I think its body is invalid"?