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 3259DE9C for ; Sun, 20 Dec 2015 03:44:01 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ig0-f178.google.com (mail-ig0-f178.google.com [209.85.213.178]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 9ACA2EC for ; Sun, 20 Dec 2015 03:44:00 +0000 (UTC) Received: by mail-ig0-f178.google.com with SMTP id ph11so17287481igc.1 for ; Sat, 19 Dec 2015 19:44:00 -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; bh=zuKDuEACzociBQtEfXp0IE7skDGTlCBupNppWNDOMTE=; b=ieJlT0GLhRZRMGK5RyILrptd4PIPLWW+Hcu5cU6l6ZvbmsAHxv0AvGhPF1/ZHl8Mvr PYWTFFTexNNzLFuyaV0rA6jOjQXTZtxmm1VE/1v0fYEuHoAXVt4psy17lfObzISPqv8x h9V0h//RbDX0Sb7//tyhQHponEiQof+ANdwYbGCzOI8+VHqvfxpdu3LYVn5pevKMKyFL TzYGPwp9fq19ZO8ktFN3otypWS1tY0UcAZyAWqDew/KX/q1lvxr/JxgvyCBmIjimb2mm Utmt8iaLBOLayG+dMdrlkFPH3yw9IMKbf+Wg1w6NoGqi5HZ0BO9smisn/H/sJShleeBN ZtLg== MIME-Version: 1.0 X-Received: by 10.50.3.71 with SMTP id a7mr10901488iga.80.1450583040041; Sat, 19 Dec 2015 19:44:00 -0800 (PST) Sender: nbvfour@gmail.com Received: by 10.36.20.142 with HTTP; Sat, 19 Dec 2015 19:43:59 -0800 (PST) In-Reply-To: <4882BD35-D890-4860-9222-5C23AEB6AE89@mattcorallo.com> References: <20151219184240.GB12893@muck> <4882BD35-D890-4860-9222-5C23AEB6AE89@mattcorallo.com> Date: Sat, 19 Dec 2015 19:43:59 -0800 X-Google-Sender-Auth: lccQMrUO_f4dkhJvjn0UbYgC92c Message-ID: From: Chris Priest To: Matt Corallo Content-Type: text/plain; charset=UTF-8 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@lists.linuxfoundation.org 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 03:44:01 -0000 Then shouldn't this be something the pool deals with, not the bitcoin protocol? On 12/19/15, Matt Corallo wrote: > Peter was referring to pool-block-withholding, not selfish mining. > > On December 19, 2015 7:34:26 PM PST, Chris Priest via bitcoin-dev > wrote: >>Block witholding attacks are only possible if you have a majority of >>hashpower. If you only have 20% hashpower, you can't do this attack. >>Currently, this attack is only a theoretical attack, as the ones with >>all the hashpower today are not engaging in this behavior. Even if >>someone who had a lot of hashpower decided to pull off this attack, >>they wouldn't be able to disrupt much. Once that time comes, then I >>think this problem should be solved, until then it should be a low >>priority. There are more important things to work on in the meantime. >> >>On 12/19/15, Peter Todd via bitcoin-dev >> wrote: >>> At the recent Scaling Bitcoin conference in Hong Kong we had a >>chatham >>> house rules workshop session attending by representitives of a super >>> majority of the Bitcoin hashing power. >>> >>> One of the issues raised by the pools present was block withholding >>> attacks, which they said are a real issue for them. In particular, >>pools >>> are receiving legitimate threats by bad actors threatening to use >>block >>> withholding attacks against them. Pools offering their services to >>the >>> general public without anti-privacy Know-Your-Customer have little >>> defense against such attacks, which in turn is a threat to the >>> decentralization of hashing power: without pools only fairly large >>> hashing power installations are profitable as variance is a very real >>> business expense. P2Pool is often brought up as a replacement for >>pools, >>> but it itself is still relatively vulnerable to block withholding, >>and >>> in any case has many other vulnerabilities and technical issues that >>has >>> prevented widespread adoption of P2Pool. >>> >>> Fixing block withholding is relatively simple, but (so far) requires >>a >>> SPV-visible hardfork. (Luke-Jr's two-stage target mechanism) We >>should >>> do this hard-fork in conjunction with any blocksize increase, which >>will >>> have the desirable side effect of clearly show consent by the entire >>> ecosystem, SPV clients included. >>> >>> >>> Note that Ittay Eyal and Emin Gun Sirer have argued(1) that block >>> witholding attacks are a good thing, as in their model they can be >>used >>> by small pools against larger pools, disincentivising large pools. >>> However this argument is academic and not applicable to the real >>world, >>> as a much simpler defense against block withholding attacks is to use >>> anti-privacy KYC and the legal system combined with the variety of >>> withholding detection mechanisms only practical for large pools. >>> Equally, large hashing power installations - a dangerous thing for >>> decentralization - have no block withholding attack vulnerabilities. >>> >>> 1) http://hackingdistributed.com/2014/12/03/the-miners-dilemma/ >>> >>> -- >>> 'peter'[:-1]@petertodd.org >>> 00000000000000000188b6321da7feae60d74c7b0becbdab3b1a0bd57f10947d >>> >>_______________________________________________ >>bitcoin-dev mailing list >>bitcoin-dev@lists.linuxfoundation.org >>https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > >