Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id A02151199 for ; Tue, 29 Dec 2015 19:25:19 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-oi0-f54.google.com (mail-oi0-f54.google.com [209.85.218.54]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B1FF2175 for ; Tue, 29 Dec 2015 19:25:18 +0000 (UTC) Received: by mail-oi0-f54.google.com with SMTP id o62so187165833oif.3 for ; Tue, 29 Dec 2015 11:25:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=sH3Q4LT97Z/uY4ayYEBJq6nqJuZSg3H9b6tsMlnMsz4=; b=Q11GBuu7en39iUAI2j0ZVMdKtL6fFDx3t5YXV0xphn4PnD5vDuFBzUKot0YO2lLZu5 SEv2qquJBsmyHi6684kNg0K96MZH8rlXArRHMyuKxyy0I3LxyIweCArOZmhakGj8sIg5 5VeuM/9O1I/bANN82wSWdc1QP6AQpGOZgG/ddUS/DOLcHk+rokJfOCV5tNOXKjuh1zq6 xWPXpSOG3IajDbRT8joVzmr3ZH5Dm4GcTmnFKq4KFUUkcobVpwBKreRiNvuo2Yv5L62G 6PjUrtkH9EPZi56seoGnqgr/c0LhRPvCm8yE9S7BPfGKsZYP/sDjFdqUXsL9sECJOmVW lYzQ== MIME-Version: 1.0 X-Received: by 10.202.84.12 with SMTP id i12mr35886521oib.133.1451417118038; Tue, 29 Dec 2015 11:25:18 -0800 (PST) Received: by 10.76.24.101 with HTTP; Tue, 29 Dec 2015 11:25:17 -0800 (PST) In-Reply-To: References: <20151219184240.GB12893@muck> <4882BD35-D890-4860-9222-5C23AEB6AE89@mattcorallo.com> <20151220044450.GA23942@muck> <20151228191228.GC12298@muck> Date: Tue, 29 Dec 2015 13:25:17 -0600 Message-ID: From: Allen Piscitello To: Dave Scotese Content-Type: multipart/alternative; boundary=001a113ad09ebde2df05280e6194 X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,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 X-Mailman-Approved-At: Wed, 30 Dec 2015 03:51:47 +0000 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: Tue, 29 Dec 2015 19:25:19 -0000 --001a113ad09ebde2df05280e6194 Content-Type: text/plain; charset=UTF-8 How could this possibly be enforced? On Tue, Dec 29, 2015 at 12:59 PM, Dave Scotese via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > There have been no decent objections to altering the block-selection > mechanism (when two block solutions appear at nearly the same time) as > described at > > http://bitcoin.stackexchange.com/questions/39226 > > Key components are: > > - Compute BitcoinDaysDestroyed using only transactions that have been > in your mempool for some time as oBTCDD ("old BTCDD"). > - Use "nearly the same time" to mean separated in time by your guess > of the average duration of block propagation times. > - When two block solutions come in at nearly the same time, build on > the one that has the most oBTCDD, rather than the one that came in first. > > The goal of this change is to reduce the profitability of withholding > block solutions by severely reducing the chances that a block solved a > while ago can orphan one solved recently. "Came in first" seems more > easily gamed than "most oBTCDD". As I wrote there, "*old coins* is > always a dwindling resource and *global nodes willing to help cheat* is > probably a growing one." > > I will write a BIP if anyone agrees it's a good idea. > > On Mon, Dec 28, 2015 at 12:26 PM, Ivan Brightly via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> On Mon, Dec 28, 2015 at 2:12 PM, Peter Todd via bitcoin-dev < >>> bitcoin-dev@lists.linuxfoundation.org> wrote: >>> Far more concerning is network propagation effects between large and >>> small miners. For that class of issues, if you are in an environemnt >>> where selfish mining is possible - a fairly flat, easily DoS/sybil >>> attacked network topology - the profitability difference between small >>> and large miners even *without* attacks going on is a hugely worrying >>> problem. OTOH, if you're blocksize is small enough that propagation time >>> is negligable to profitability, then selfish mining attacks with <30% >>> hashing power aren't much of a concern - they'll be naturally defeated >>> by anti-DoS/anti-sybil measures. >>> >> >> Let's agree that one factor in mining profitability is bandwidth/network >> reliability/stability. Why focus on that vs electricity contracts or >> vertically integrated chip manufacturers? Surely, sufficient network >> bandwidth is a more broadly available commodity than <$0.02/kwh >> electricity, for example. I'm not sure that your stranded hydroelectric >> miner is any more desirable than thousands of dorm room miners with access >> to 10gbit university connections and free electricity. >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> > > > -- > I like to provide some work at no charge to prove my value. Do you need a > techie? > I own Litmocracy and Meme Racing > (in alpha). > I'm the webmaster for The Voluntaryist > which now accepts Bitcoin. > I also code for The Dollar Vigilante . > "He ought to find it more profitable to play by the rules" - Satoshi > Nakamoto > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > --001a113ad09ebde2df05280e6194 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
How could this possibly be enforced?

On Tue, Dec 29, 2015 at 12:59 PM,= Dave Scotese via bitcoin-dev <bitcoin-dev@lists.linux= foundation.org> wrote:
There have been no decent objections to altering the bloc= k-selection mechanism (when two block solutions appear at nearly the same t= ime) as described at

http://bitcoin.stackexchange.com/questions= /39226

Key components are:
  • Compute BitcoinDaysD= estroyed using only transactions that have been in your mempool for some ti= me as oBTCDD ("old BTCDD").
  • Use "nearly the same tim= e" to mean separated in time by your guess of the average duration of = block propagation times.
  • When two block solutions come in at ne= arly the same time, build on the one that has the most oBTCDD, rather than = the one that came in first.

The goal of this change is to reduc= e the profitability of withholding block solutions by severely reducing the= chances that a block solved a while ago can orphan one solved recently.=C2= =A0 "Came in first" seems more easily gamed than "most oBTCD= D".=C2=A0 As I wrote there, "old coins is always a dwind= ling resource and global nodes willing to help cheat is probably a= growing one."

I will write a BIP if anyone agrees it's = a good idea.


On Mon, Dec 28, 2015 at 12:26 PM, Ivan Brig= htly via bitcoin-dev <bitcoin-dev@lists.linuxfoundatio= n.org> wrote:
<= div>
On Mon, Dec 28, 2015 at 2:12 PM, P= eter Todd via bitcoin-dev=C2=A0<bitcoin-dev@lists.linu= xfoundation.org>=C2=A0wrote:
Far more concerning is network propagation effects between large and
small miners. For that class of issues, if you are in an environemnt
where selfish mining is possible - a fairly flat, easily DoS/sybil
attacked network topology - the profitability difference between small
and large miners even *without* attacks going on is a hugely worrying
problem. OTOH, if you're blocksize is small enough that propagation tim= e
is negligable to profitability, then selfish mining attacks with <30% hashing power aren't much of a concern - they'll be naturally defea= ted
by anti-DoS/anti-sybil measures.

Let's agree that one factor in mining profitability is bandwidth/netwo= rk reliability/stability. Why focus on that vs electricity contracts or ver= tically integrated chip manufacturers? Surely, sufficient network bandwidth= is a more broadly available commodity than <$0.02/kwh electricity, for = example. I'm not sure that your stranded hydroelectric miner is any mor= e desirable than thousands of dorm room miners with access to 10gbit univer= sity connections and free electricity.

__________________________________________= _____
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev




--
I like to provide = some work at no charge to prove my value. Do you need a techie?=C2=A0
I= own Litmocracy= and Meme Racing (in alpha).
I'm the webmaster for The Voluntaryist which now accepts Bitcoin.<= br>I also code for The Dollar Vigilante.
"He ought to find it more profitable to= play by the rules" - Satoshi Nakamoto
_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.= linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev


--001a113ad09ebde2df05280e6194--