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 18029B8E for ; Thu, 18 May 2017 14:59:52 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-oi0-f50.google.com (mail-oi0-f50.google.com [209.85.218.50]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id BF85A10A for ; Thu, 18 May 2017 14:59:51 +0000 (UTC) Received: by mail-oi0-f50.google.com with SMTP id w10so57483708oif.0 for ; Thu, 18 May 2017 07:59:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:cc; bh=1fibNfsf3j9DSoOlmtyI0eOY3lgaHGj6MGQ2GeDIZIg=; b=mGLXu+DP5mw320JUz1ycEsPKlNedNTTqswoGgEN4j3r86HG2+oPd0CABL2w5D6B6D4 fLP37xTMXLL4mwcJeUU2rdY9FDWv3bXRuRUVc66nqM1+yoRxa0JVgqMg7lDMaGKPawma EjY+IqOwcoF6Mo8aTJlBYJh2A6HMjNGKIcSZhyiFxfzUvGIbU56KOkUt0sfom/HZd5oH yMkDSnYdxzuUSTFgxa4xOT6cuD2gOQhJEFNd32jgp1EzITm1rjLYSYBJ2KJevLvpjRG/ LG9rNtnMz4BVBhIEe+5NDsml7FpumywOQmVcpelcCsVsbybs2Totf3KSKqerW1On16L8 0d5g== 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:cc; bh=1fibNfsf3j9DSoOlmtyI0eOY3lgaHGj6MGQ2GeDIZIg=; b=S5N8lFRHv652h0Rtgv0yqKc1v+dj0yAwCmjYu06w+a2xyf1f2bUIF211b+/jvPJB+v ByNr1+kSauXMdYRXu3XjR7hhPSAYqgnaqTjkKTDjpvWFejRQXxrFXwbH3bxNUn6tiIPP 8UNcQCBGJEKB2Th0we3A+ywKrMHL2z010drel4bj8KcGJJmFFkC9J8rMDTrj2fCc5XgP Y8ZfXOyMZzooahmk2HCUeRm4fZSml9peT8qtpo6WvCSX9gvMjMtUUB2HgHqQj4gpUxAR CZQJSFwXj6acbyG4hNZ9WZOQn8Ehz5R8wN72fenVs5K60MsGIEUt5/K7EIY0bPZfPSYv kJfw== X-Gm-Message-State: AODbwcBzfxfzO81+lFuyb4gHspiy2KsSyBbwZmNt/3sfq542uplanuRn vJybkEjTnHGOH0JsGIeSEM5Un9FoRQ== X-Received: by 10.202.80.142 with SMTP id e136mr2859200oib.40.1495119591050; Thu, 18 May 2017 07:59:51 -0700 (PDT) MIME-Version: 1.0 Received: by 10.74.100.89 with HTTP; Thu, 18 May 2017 07:59:50 -0700 (PDT) In-Reply-To: <4BA0FA5D-7B29-4A7F-BC5B-361ED00D5CB2@gmail.com> References: <4BA0FA5D-7B29-4A7F-BC5B-361ED00D5CB2@gmail.com> From: Tier Nolan Date: Thu, 18 May 2017 15:59:50 +0100 Message-ID: Cc: Bitcoin Dev Content-Type: multipart/alternative; boundary="001a113d692e1f12d2054fcda88b" X-Spam-Status: No, score=-0.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,MISSING_HEADERS, 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 Subject: Re: [bitcoin-dev] =?utf-8?b?VHJlYXRpbmcg4oCYQVNJQ0JPT1NU4oCZIGFzIGEg?= =?utf-8?q?Security_Vulnerability?= 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, 18 May 2017 14:59:52 -0000 --001a113d692e1f12d2054fcda88b Content-Type: text/plain; charset="UTF-8" On Thu, May 18, 2017 at 2:44 PM, Cameron Garnham via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > 1. Significant deviations from the Bitcoin Security Model have been > acknowledged as security vulnerabilities. > > The Bitcoin Security Model assumes that every input into the Proof-of-Work > function should have the same difficulty of producing a desired output. > This isn't really that clear. Arguably as long as the effort to find a block is proportional to the block difficulty parameter, then it isn't an exploit. It is just an optimisation. A quantum computer, for example, could find a block with effort proportional to the square root of the difficulty parameter, so that would count as an attack. Though in that case, the fix would likely be to tweak the difficulty parameter update calculation. A better definition would be something like "when performing work, each hash should be independent". ASICBOOST does multiple checks in parallel, so would violate that. --001a113d692e1f12d2054fcda88b Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On T= hu, May 18, 2017 at 2:44 PM, Cameron Garnham via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
1.=C2=A0 =C2=A0 =C2=A0Significant deviations from the Bitcoin Security Mode= l have been acknowledged as security vulnerabilities.

The Bitcoin Security Model assumes that every input into the Proof-of-Work = function should have the same difficulty of producing a desired output.
=

This isn't really that clear.

=
Arguably as long as the effort to find a block i= s proportional to the block difficulty parameter, then it isn't an expl= oit.=C2=A0 It is just an optimisation.

A quantum computer, for example, could find a block with effort proport= ional to the square root of the difficulty parameter, so that would count a= s an attack.=C2=A0 Though in that case, the fix would likely be to tweak th= e difficulty parameter update calculation.

A better definition would be something like "when performing w= ork, each hash should be independent".=C2=A0

ASICBOOST does multiple checks in parallel, so would viola= te that.
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