From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id E81E61019 for ; Sun, 20 Dec 2015 07:39:08 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f176.google.com (mail-io0-f176.google.com [209.85.223.176]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6740EA0 for ; Sun, 20 Dec 2015 07:39:08 +0000 (UTC) Received: by mail-io0-f176.google.com with SMTP id 186so130235895iow.0 for ; Sat, 19 Dec 2015 23:39:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=qIZLw8g7+/TC7c7Pro8lg0j7gTrNdyXVhAo8pfFaN6A=; b=QaiOUu4Ke6fOMinZsMB2DrOjZJ11CjwMu8p5El8OvESmiP7IEjT519M2ciGS/q4cO+ o+uGdZmP4BoSduba0XMwPFymfIPZikNTgndW4RupTU5TVS/Cc4SykiJmzC42DezaoOD2 F3/HGrKKsF3j/lM1h9QkWvUWPq/xf0NNIOV4pZeZr0IicvLFPMhsy1wJnelMQxTx4/ph 93zmegJIFDNJ6gMoFa/YW0y37EE0NrPRe6hrVD50iPoRX2yLJ/0qOThPYiUDVGNeXWE7 PEfoH4gp7//dbTGV48VS2ihQLoYFyGkjbFzQPasmZOQN9kEuTzMXsh5GgXVujH13xm3x QxJg== MIME-Version: 1.0 X-Received: by 10.107.40.76 with SMTP id o73mr9394742ioo.157.1450597147890; Sat, 19 Dec 2015 23:39:07 -0800 (PST) Sender: nbvfour@gmail.com Received: by 10.36.20.142 with HTTP; Sat, 19 Dec 2015 23:39:07 -0800 (PST) In-Reply-To: References: <20151219184240.GB12893@muck> <219f125cee6ca68fd27016642e38fdf1@xbt.hk> Date: Sat, 19 Dec 2015 23:39:07 -0800 X-Google-Sender-Auth: TOiWLdjEGAv4K1I2qTa_TeIRPL4 Message-ID: From: Chris Priest To: =?UTF-8?Q?Emin_G=C3=BCn_Sirer?= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] We need to fix the block withholding attack X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Dec 2015 07:39:09 -0000 On 12/19/15, Emin G=C3=BCn Sirer wrote: > > Chris Priest is confusing these attacks with selfish mining, and further, > his characterization of selfish mining is incorrect. Selfish Mining is > guaranteed to yield profits for any pool over 33% (as a result, Nick > Szabo has dubbed this the "34% attack") and it may pay off even > below that point if the attacker is well-positioned in the network; > or it may not, depending on the makeup of the rest of the pools > as well as the network characteristics (the more centralized > and bigger the other pools are, the less likely it is to pay off). There > was a lot of noise in the community when the SM paper came out, > so there are tons of incorrect response narrative out there. By now, > everyone who seems to be Bitcoin competent sees SM as a > concern, and Ethereum has already adopted our fix. I'd have hoped > that a poster to this list would be better informed than to repeat the > claim that "majority will protect Bitcoin" to refute a paper whose title > is "majority is not enough." http://www.coindesk.com/bitcoin-mining-network-vulnerability/ just sayin'... But anyways, I agree with you on the rest of your email. This is only really an attack from the perspective of the mining pool. From the user's perspective, its not an attack at all. Imagine your aunt who has bitcoin on a SPV wallet on her iphone. Does she care that two mining pools are attacking each other? Its has nothing to do with her, and it has nothing to do with most users or bitcoin either. From the bitcoin user's perspective, the mining pool landscape *should* be constantly changing. Fixing this "attack" is promoting mining pool statism. Existing mining pools will have an advantage over up and coming mining pools. That is not an advantage that is best for bitcoin from the user's perspective. Now, on the other hand, if this technique is used so much, it results in too many pools getting shut down such that the difficulty starts to decrease, *then* maybe it might be time to start thinking about fixing this issue. The difficulty dropping means the security of the network is decreased, which *does* have an effect on every user.