Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XbaFA-0000SW-4N for bitcoin-development@lists.sourceforge.net; Tue, 07 Oct 2014 19:16:20 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.213.173 as permitted sender) client-ip=209.85.213.173; envelope-from=gmaxwell@gmail.com; helo=mail-ig0-f173.google.com; Received: from mail-ig0-f173.google.com ([209.85.213.173]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XbaF9-0003Fr-3h for bitcoin-development@lists.sourceforge.net; Tue, 07 Oct 2014 19:16:20 +0000 Received: by mail-ig0-f173.google.com with SMTP id h18so4754705igc.12 for ; Tue, 07 Oct 2014 12:16:13 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.51.17.66 with SMTP id gc2mr8971713igd.40.1412709373176; Tue, 07 Oct 2014 12:16:13 -0700 (PDT) Received: by 10.107.168.5 with HTTP; Tue, 7 Oct 2014 12:16:13 -0700 (PDT) In-Reply-To: <54343948.1030400@certimix.com> References: <543438E4.8080501@certimix.com> <54343948.1030400@certimix.com> Date: Tue, 7 Oct 2014 19:16:13 +0000 Message-ID: From: Gregory Maxwell To: Sergio Lerner Content-Type: text/plain; charset=UTF-8 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: 1XbaF9-0003Fr-3h Cc: bitcoin-development Subject: Re: [Bitcoin-development] The Bitcoin Freeze on Transaction Attack (FRONT) 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: Tue, 07 Oct 2014 19:16:20 -0000 On Tue, Oct 7, 2014 at 7:04 PM, Sergio Lerner wrote: > Using the my previous terminology, automatic fee-sharing ("ORBS") is a > solution to the freeze problem ("FRONT") but opens the windows to > "CHAKIDO" double-spending. and CHAKIDO double-spending is a much worse > problem than FRONT. I'm not following this. Perhaps I'm getting lost in terminology here. It's already to provide double spending bounties to greedy-rational miners, via a simple approach that has been known since at least early in 2011. I pay someone then create a later fraudulent doublespend which is nlocked at the height the original payment occurred, paying large fees. Then I spend the output of the fraudulent spend nlocked one block higher, and spend the output of that one again, nlocked one block higher, and so on... each step paying fees. A hypothetical purely greedy miner which considers all sequences of acceptable forks and transactions would see that they have higher expected returns assisting the theft (assuming the honest party doesn't fight back by also adopting a similar strategy), at least if the population of greedy miners is large relative to altruistic ones. I don't see how miners being able to roll forward fees makes anything worse, since the transactions themselves can also roll forward fees.