Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 0D3F2279 for ; Sun, 11 Dec 2016 03:17:48 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-oi0-f47.google.com (mail-oi0-f47.google.com [209.85.218.47]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7C984125 for ; Sun, 11 Dec 2016 03:17:47 +0000 (UTC) Received: by mail-oi0-f47.google.com with SMTP id v84so57284956oie.3 for ; Sat, 10 Dec 2016 19:17:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=yO03YzMhYNyMgzVyDj5+BApGsiKSDyFyKhAibw34vS0=; b=FW/LPJOP3JgE4JpJZc3tREmox80YKUv2VkP/Be3R4mzjOkgrKiZ69+rCmhVrvy6L5J 3ddMmNUvPJO6TzAA8wa73r2bDW1QwG4NGWCOhq1UnxAUMGEzdSNJbJfO8TERikuJ1PtC 9dn6FZoVmj9zvtvu9Ho7kFhYafTFKoaleS/IrGnvGI82CAFiN75jEgs68RxQfx94MT/Z S2o103pJr2VF6ouDC9WjPKcKUJOKbssrLXYr5bc0ZoeOS0Cj0rm8WPKIP4aRMR43efFH t00oK8/TPAlynmduIKn1+BsQL9TcC4eH9pEI/uDaChnAnSjswUgRf5ojrikpoUBCQ6ak Ybbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=yO03YzMhYNyMgzVyDj5+BApGsiKSDyFyKhAibw34vS0=; b=H4lfasUrdspqb+WkQnovEaG3juI+xW2d6luErWCSKrniYAd4I7kZAuydHl+SvOGMhI 16KNx5OS/mxu9xNxsHufAHA/xx2QnD5zMAa5n1BuxSkz+HQBdng2fl2thVXlpzNupZTX VSEdMzCsREopP6OvWPuqb5pqFJQRjtjXHol0UDBdXYetfxhF4JDUoKtOq0sW1V8Uq8xm RVxLaec8tsbatVlrLO2JV6hxDnPNjIPspHORHBUBuV/NE2OdIwchqE3lrVTdbcJhoLdf VAeVuz4MtivnaBONO/+rC9kZmWIp7NX18xz6RAYxKiZn/agu2hyYNRlTt7sWCCqa3sKn 8R0Q== X-Gm-Message-State: AKaTC029mAL1DYdt5kHaL5jYrLNiMPzRSPIcD74GVzJuLvEDHAnp/NMda3M30yFXQiZCDdtCeacBzhuJEQJJHQ== X-Received: by 10.157.37.102 with SMTP id j35mr47010156otd.44.1481426266692; Sat, 10 Dec 2016 19:17:46 -0800 (PST) MIME-Version: 1.0 Received: by 10.157.31.29 with HTTP; Sat, 10 Dec 2016 19:17:45 -0800 (PST) Received: by 10.157.31.29 with HTTP; Sat, 10 Dec 2016 19:17:45 -0800 (PST) In-Reply-To: References: From: Daniele Pinna Date: Sun, 11 Dec 2016 04:17:45 +0100 Message-ID: To: Pieter Wuille Content-Type: multipart/alternative; boundary=001a114134526322a70543596e50 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Sun, 11 Dec 2016 03:21:59 +0000 Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty (aka Block75) 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: Sun, 11 Dec 2016 03:17:48 -0000 --001a114134526322a70543596e50 Content-Type: text/plain; charset=UTF-8 How is the adverse scenario you describe different from a plain old 51% attack? Each proposed protocol change where 51% or more of the network can potentially game the rules and break the system should be considered just as acceptable/unacceptable as another. There comes a point where some form of basic honesty must be assumed on behalf of participants benefiting from the system working properly and reliably. Afterall, what magic line of code prohibits all miners from simultaneously turning all their equipment off... just because? Maybe this 'one': "As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure." Is there such a thing as an unrecognizable 51% attack? One where the remaining 49% get dragged in against their will? Daniele On Dec 10, 2016 6:39 PM, "Pieter Wuille" wrote: > On Sat, Dec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> We have models for estimating the probability that a block is orphaned >> given average network bandwidth and block size. >> >> The question is, do we have objective measures of these two quantities? >> Couldn't we target an orphan_rate < max_rate? >> > > Models can predict orphan rate given block size and network/hashrate > topology, but you can't control the topology (and things like FIBRE hide > the effect of block size on this as well). The result is that if you're > purely optimizing for minimal orphan rate, you can end up with a single > (conglomerate of) pools producing all the blocks. Such a setup has no > propagation delay at all, and as a result can always achieve 0 orphans. > > Cheers, > > -- > Pieter > > --001a114134526322a70543596e50 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
How is the adverse scenario you describe different from a= plain old 51% attack? Each proposed protocol change =C2=A0where 51% or mor= e =C2=A0of the network can potentially game the rules and break the system = should be considered just as acceptable/unacceptable as another.=C2=A0

There comes a point where some for= m of basic honesty must be assumed on behalf of participants benefiting fro= m the system working properly and reliably.=C2=A0
Afterall, what magic line of code prohibits all m= iners from simultaneously turning all their equipment off... =C2=A0just bec= ause?=C2=A0

Maybe this &= #39;one':

"As l= ong as a majority of CPU power is controlled by nodes that are not cooperat= ing to attack the network, they'll generate the longest chain and outpa= ce attackers. The network itself requires minimal structure."

Is there such a thing as an unre= cognizable 51% attack?=C2=A0 One where the remaining 49% get dragged in aga= inst their will?=C2=A0

D= aniele=C2=A0

On Dec 10, 2016 6:39 PM, "Pieter Wuille" <pieter.wuille@gmail.com> wrote:
On Sat, D= ec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin-dev <= ;bitcoin-dev@lists.linuxfoundation.org> wrote:
We have models for estimating the probability that a= block is orphaned given average network bandwidth and block size.=C2=A0

The question is, do we have objective meas= ures of these two quantities? Couldn't we target an orphan_rate < ma= x_rate?=C2=A0

Models can predi= ct orphan rate given block size and network/hashrate topology, but you can&= #39;t control the topology (and things like FIBRE hide the effect of block = size on this as well). The result is that if you're purely optimizing f= or minimal orphan rate, you can end up with a single (conglomerate of) pool= s producing all the blocks. Such a setup has no propagation delay at all, a= nd as a result can always achieve 0 orphans.

Cheers,
<= br>--
Pieter

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