From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Wjpub-0003TW-Uo for bitcoin-development@lists.sourceforge.net; Mon, 12 May 2014 13:04:57 +0000 X-ACL-Warn: Received: from mail-pa0-f41.google.com ([209.85.220.41]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Wjpua-00021Q-5V for bitcoin-development@lists.sourceforge.net; Mon, 12 May 2014 13:04:57 +0000 Received: by mail-pa0-f41.google.com with SMTP id lj1so8651774pab.0 for ; Mon, 12 May 2014 06:04:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=tE30xsD8kn0N5UvfTrlWsXaB63lvmT2f1DzSh+NfSLE=; b=g5Ru1pDC7AE7Wzf0gLNOVpGE1fqDma/6yaP950M5KgERSl+d/6Yhzc0Kx1kSbtOnuk s1JVqXmPNqjSlpAl+q36jqxblFhYPkdnHuysmvgDV0a75NsIq5mSx/biUZg2quEzSpit /L30n7/aJvx+XEq1G1LRVjmg+m4MIGeOLasaacVli2iZic6+C6ml6wMTHWNpDsPAahRk ubUzeGcNeV23gPsL18x5M0kX2YCJC77/z3R6Hdp/K1dQBYSOiElyaSPC+3PyD63TvmUe UNRldZjToBRyPqVV25BCS65HxzOIjeM/s1z3YOnxFuEuA5ycB2CXvHURt3evZcIZgMkb 24Ew== X-Gm-Message-State: ALoCoQmk6iB0LLXpt0E4zHZpXv5R7sNCmgpJGdRt9hB4aU69oBPFHnXmK46wbd7MBmjd1f7aCfaw X-Received: by 10.66.139.168 with SMTP id qz8mr18917692pab.3.1399899890396; Mon, 12 May 2014 06:04:50 -0700 (PDT) Received: from [192.168.1.89] (99-6-44-248.lightspeed.sntcca.sbcglobal.net. [99.6.44.248]) by mx.google.com with ESMTPSA id xk1sm48417789pac.21.2014.05.12.06.04.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 12 May 2014 06:04:49 -0700 (PDT) Message-ID: <5370C6EF.8020001@thinlink.com> Date: Mon, 12 May 2014 06:04:47 -0700 From: Tom Harding User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: bitcoin-development@lists.sourceforge.net References: <536589CC.8080005@thinlink.com> <537050E0.2040008@thinlink.com> In-Reply-To: <537050E0.2040008@thinlink.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: 0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. X-Headers-End: 1Wjpua-00021Q-5V Subject: Re: [Bitcoin-development] A statistical consensus rule for reducing 0-conf double-spend risk 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, 12 May 2014 13:04:58 -0000 Sorry to run on, a correction is needed. A much better approximation requires that the rule-following minority finds the next TWO blocks, so the cost is (total miner revenue of block)*(fraction of hashpower following the rule)^2 So the lower bound cost in this very pessimistic scenario is .0025 BTC, still quite high for one transaction. I guess miner could try to make a business out of mining double-spends, to defray that cost. On 5/11/2014 9:41 PM, Tom Harding wrote: > Back up to the miner who decided to include a "seasoned" double-spend > in his block. Let's say he saw it 21 seconds after he saw an earlier > spend, and included it, despite the rule. > > The expected cost of including the respend is any revenue loss from > doing so: (total miner revenue of block)*(fraction of hashpower > following the rule). So today, if only 1% of hashpower follows the > rule (ie a near total failure of consensus implementation), he still > loses at least .25 BTC. > > .25 BTC is about 1000x the typical "double-spend premium" I'm seeing > right now. Wouldn't the greedy-rational miner just decide to include > the earlier spend instead