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 10C76BE0 for ; Thu, 6 Apr 2017 17:51:40 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vk0-f51.google.com (mail-vk0-f51.google.com [209.85.213.51]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 837D61F2 for ; Thu, 6 Apr 2017 17:51:39 +0000 (UTC) Received: by mail-vk0-f51.google.com with SMTP id z204so49675115vkd.1 for ; Thu, 06 Apr 2017 10:51:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jtimon-cc.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=lkRgJmdly/lgOto7EIVazTUKp5k1g/yJxpTWzW2JmHA=; b=nkevQpyfe8q26uNRd89Kj++HsQl81aL8UqT4Rb06OcTt7nfHLU/5oxjzXNcNzjHxBq t7sgpPIRlj5KteY5Q37IozPrD/MOtVnHdu7c6tS0gZX4Yth7MUpF5Uq4JUucYLzqLRbb xWBjbaCgx/woQqtf66yVkSm34JUtm3iFaryE8h+bodX2xefJ+ORX2S3UD4khGUvE2SSv BE01RGWRxiwxiiKVHn7ySI8iPJ6WQYBrMG6rRLTGPy4i9Vs6nndd2WJh92TVDX/HyyP4 Zu6HSPLk9Vfg2I0RIpom8gYVRReDbh61MLUUCHByUFiRF48X9FQ5gvvadAJv4HY5pDNV IBRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=lkRgJmdly/lgOto7EIVazTUKp5k1g/yJxpTWzW2JmHA=; b=TDatYjF6rHLEphpIDoQsiIj+zQsSqMJbgj29f8fyCJlNN9U5S8d6QtaXx5blZqmXZB u+obuRNqAMwWxO/oejfnwIMQifzu5OgO52ncaurmeNpNK2wBfgHBDqaRNNI+d4gPnIDD xx17JldSCFUpT8nLmdN48weTRxJkAmPzxwIaGUTkg3p8SD0RGZAkUh8zWA1UZ8h6KXQ7 SqmsjVE+t9EsWROHFy6ICLSa94erCcL5CTh655W2gtmPW41olsG7cuCbfPvsN/xEbJUq 5Zl00MlEoYLiCrKRaXeOYrF9nELrswVDpiGzrmzfEKEtUjE5NwvrHMT0SczZ+Zl5oe4J WfPA== X-Gm-Message-State: AFeK/H07HBgYErbGYr4HGp0vIpH7Pj6SUO0AB1ArQtgmBUFb3+edvTIpbER0g2rOIsp96++v4dJ+9LDLvPpNiQ== X-Received: by 10.31.68.130 with SMTP id r124mr16746982vka.72.1491501098556; Thu, 06 Apr 2017 10:51:38 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.151.136 with HTTP; Thu, 6 Apr 2017 10:51:37 -0700 (PDT) In-Reply-To: References: <20170406023123.GA1071@savin.petertodd.org> From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= Date: Thu, 6 Apr 2017 19:51:37 +0200 Message-ID: To: Bram Cohen , Bitcoin Protocol Discussion Content-Type: text/plain; charset=UTF-8 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: =?UTF-8?Q?Ricardo_P=C3=A9rez_Marco?= Subject: Re: [bitcoin-dev] BIP proposal: Inhibiting a covert attack on the Bitcoin POW function X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Apr 2017 17:51:40 -0000 On Thu, Apr 6, 2017 at 4:39 AM, Bram Cohen via bitcoin-dev wrote: > > Asicboost also has the problem that it isn't treating the hashing as a black > box, and thus has impacts on what gets mined. In particular it creates an > incentive to make blocks smaller. That's a very unwanted effect, and > anything like it should be engineered out on principle. This is an interesting point. If you have a precise description why it makes an incentive to make blocks smaller I would love to read it. Somebody asked and I didn't have an answer. I imagine you try several reorderings sometimes excluding certain branches of the merkle tree, permuting the branches you exclude or something similar, but I really don't know the algorithm in detail and I didn't want to say something inaccurate.