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| author | Jeff Garzik <jgarzik@gmail.com> | 2015-07-11 11:34:54 -0400 |
|---|---|---|
| committer | bitcoindev <bitcoindev@gnusha.org> | 2015-07-11 15:34:57 +0000 |
| commit | 3049a62271c8670fa0c999d4ae42cef140187a4f (patch) | |
| tree | 4c062bd3fb29f9c44d85bae16f8442a45d173134 | |
| parent | 00055294c3bed7ee65de92cd91ed23a89d3e3a67 (diff) | |
| download | pi-bitcoindev-3049a62271c8670fa0c999d4ae42cef140187a4f.tar.gz pi-bitcoindev-3049a62271c8670fa0c999d4ae42cef140187a4f.zip | |
Re: [bitcoin-dev] SPV Mining reveals a problematic incentive issue.
| -rw-r--r-- | 98/bae895d596afef9e3be872c4392800430d50f0 | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/98/bae895d596afef9e3be872c4392800430d50f0 b/98/bae895d596afef9e3be872c4392800430d50f0 new file mode 100644 index 000000000..afa2c3085 --- /dev/null +++ b/98/bae895d596afef9e3be872c4392800430d50f0 @@ -0,0 +1,183 @@ +Return-Path: <jgarzik@gmail.com> +Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org + [172.17.192.35]) + by mail.linuxfoundation.org (Postfix) with ESMTPS id 5B6FDAAC + for <bitcoin-dev@lists.linuxfoundation.org>; + Sat, 11 Jul 2015 15:34:57 +0000 (UTC) +X-Greylist: whitelisted by SQLgrey-1.7.6 +Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com + [209.85.212.181]) + by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 473CE195 + for <bitcoin-dev@lists.linuxfoundation.org>; + Sat, 11 Jul 2015 15:34:56 +0000 (UTC) +Received: by wiga1 with SMTP id a1so36529299wig.0 + for <bitcoin-dev@lists.linuxfoundation.org>; + Sat, 11 Jul 2015 08:34:55 -0700 (PDT) +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=D8+5A3FQUGQ8I9GG+h/7AhOpCpVMWdMfq6u7Mi+Q+S0=; + b=I46cDByWueviBOFubR8yNXYKcz29ktVdfvJRy+i87FNjnj4qo8vhx/uSCVD/od4HRS + EmYik61sif78wWYuaF6HLXV/zsMlzgfWVy+MgdkJfoIRwJTmCRvXRk4gpL2mh8duweRp + 1M8nDflpj4iwEXZdzqoOBzxM2QF/YUpu6ek9VqOXAplJtgg9LAnBo7KBq3Fva2aN2T/O + yXjQw9U3iYoJ3yZIiKYNdUi8waet8zqmMNktKMwmmXKrNAD9CWN8cpEKIlpgFzQgkQ9a + Vb/+BF5DJXLG7BnhZAtF68UAs/CbmVSOmRLttZFW3KPQGOtWtOID1Y31pU7OPBh91ozy + lYTw== +MIME-Version: 1.0 +X-Received: by 10.180.101.138 with SMTP id fg10mr7672259wib.46.1436628894901; + Sat, 11 Jul 2015 08:34:54 -0700 (PDT) +Received: by 10.28.140.196 with HTTP; Sat, 11 Jul 2015 08:34:54 -0700 (PDT) +In-Reply-To: <CAFdHNGg2dezj4V-i-E6dRLp99nZMQ_ErKdBo0OgQJ=9WPm90jQ@mail.gmail.com> +References: <CAFdHNGg2dezj4V-i-E6dRLp99nZMQ_ErKdBo0OgQJ=9WPm90jQ@mail.gmail.com> +Date: Sat, 11 Jul 2015 11:34:54 -0400 +Message-ID: <CADm_WcbQcCtenoinvVCeeKz8Pdqju=tTNkm+NB91PLBTeA0nXQ@mail.gmail.com> +From: Jeff Garzik <jgarzik@gmail.com> +To: Nathan Wilcox <nathan@leastauthority.com> +Content-Type: multipart/alternative; boundary=f46d0444e9a5f46d6f051a9b3a15 +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 +Cc: bitcoin-dev@lists.linuxfoundation.org +Subject: Re: [bitcoin-dev] SPV Mining reveals a problematic incentive issue. +X-BeenThere: bitcoin-dev@lists.linuxfoundation.org +X-Mailman-Version: 2.1.12 +Precedence: list +List-Id: Bitcoin Development Discussion <bitcoin-dev.lists.linuxfoundation.org> +List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe> +List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/> +List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org> +List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help> +List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe> +X-List-Received-Date: Sat, 11 Jul 2015 15:34:57 -0000 + +--f46d0444e9a5f46d6f051a9b3a15 +Content-Type: text/plain; charset=UTF-8 + +The miners with invalid blocks were punished with a loss of bitcoin +income... + + +On Sat, Jul 11, 2015 at 4:05 AM, Nathan Wilcox <nathan@leastauthority.com> +wrote: + +> Thesis: The disincentive miners have for verifying transactions is +> problematic and weakens the network's robustness against forks. +> +> According to the 2015-07-04 bitcoin.org alert [1]_ so-called "SPV Mining" +> has become popular across a large portion of miners, and this enabled the +> consensus-violating forks to persist. Peter Todd provides an explanation +> of the incentive for SPV Mining over in another thread [2]_. +> +> .. [1] https://bitcoin.org/en/alert/2015-07-04-spv-mining#cause +> +> .. [2] +> https://www.mail-archive.com/bitcoin-dev@lists.linuxfoundation.org/msg00404.html +> +> If there is a cost to verifying transactions in a received block, then +> there is an incentive to *not verify transactions*. However, this is +> balanced by the a risk of mining atop an invalid block. +> +> If we imagine all miners verify all transactions, except Charlie the +> Cheapskate, then it's in Charlie's interest to forego transaction +> verification. If all miners make a similar wager, then in the extreme, +> no miners verify any transactions, and the expected cost of skipping +> transaction verification becomes very high. +> +> Unfortunately, it's difficult to measure how many miners are not +> validating transactions, since there's no evidence of this until they +> mine atop on invalid block. Because of this, I worry that over time, +> more and more miners cut this particular corner, to save on costs. +> +> If true, then the network continues to grow more brittle towards the kind +> of forking-persistence behavior we saw from the July 4th (and 5th) forks. +> +> This gets weird. For example, a malicious miner which suspects a large +> fraction of miners are neglecting transaction verification may choose to +> forego a block reward by throwing an erroneous transaction into their +> winning block, then, as all the "SPV Miners" run off along a worthless +> chain, they can reap a higher reward rate due to controlling a larger +> network capacity fraction on the valid chain. +> +> Can we fix this? +> +> -- +> Nathan Wilcox +> Least Authoritarian +> +> email: nathan@leastauthority.com +> twitter: @least_nathan +> +> Standard Disclaimer: I'm behind on dev archives, irc logs, bitcointalk, +> the wiki... if this has been discussed before I appreciate mentions of +> that fact. +> +> +> _______________________________________________ +> bitcoin-dev mailing list +> bitcoin-dev@lists.linuxfoundation.org +> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev +> +> + +--f46d0444e9a5f46d6f051a9b3a15 +Content-Type: text/html; charset=UTF-8 +Content-Transfer-Encoding: quoted-printable + +<div dir=3D"ltr">The miners with invalid blocks were punished with a loss o= +f bitcoin income...<div><br></div></div><div class=3D"gmail_extra"><br><div= + class=3D"gmail_quote">On Sat, Jul 11, 2015 at 4:05 AM, Nathan Wilcox <span= + dir=3D"ltr"><<a href=3D"mailto:nathan@leastauthority.com" target=3D"_bl= +ank">nathan@leastauthority.com</a>></span> wrote:<br><blockquote class= +=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd= +ing-left:1ex"><div dir=3D"ltr">Thesis: The disincentive miners have for ver= +ifying transactions is<br>problematic and weakens the network's robustn= +ess against forks.<br><br>According to the 2015-07-04 <a href=3D"http://bit= +coin.org" target=3D"_blank">bitcoin.org</a> alert [1]_ so-called "SPV = +Mining"<br>has become popular across a large portion of miners, and th= +is enabled the<br>consensus-violating forks to persist. Peter Todd provides= + an explanation<br>of the incentive for SPV Mining over in another thread [= +2]_.<br><br>.. [1] <a href=3D"https://bitcoin.org/en/alert/2015-07-04-spv-m= +ining#cause" target=3D"_blank">https://bitcoin.org/en/alert/2015-07-04-spv-= +mining#cause</a><br><br>.. [2] <a href=3D"https://www.mail-archive.com/bitc= +oin-dev@lists.linuxfoundation.org/msg00404.html" target=3D"_blank">https://= +www.mail-archive.com/bitcoin-dev@lists.linuxfoundation.org/msg00404.html</a= +><br><br>If there is a cost to verifying transactions in a received block, = +then<br>there is an incentive to *not verify transactions*.=C2=A0 However, = +this is<br>balanced by the a risk of mining atop an invalid block.<br><br>I= +f we imagine all miners verify all transactions, except Charlie the<br>Chea= +pskate, then it's in Charlie's interest to forego transaction<br>ve= +rification.=C2=A0 If all miners make a similar wager, then in the extreme,<= +br>no miners verify any transactions, and the expected cost of skipping<br>= +transaction verification becomes very high.<br><br>Unfortunately, it's = +difficult to measure how many miners are not<br>validating transactions, si= +nce there's no evidence of this until they<br>mine atop on invalid bloc= +k. Because of this, I worry that over time,<br>more and more miners cut thi= +s particular corner, to save on costs.<br><br>If true, then the network con= +tinues to grow more brittle towards the kind<br>of forking-persistence beha= +vior we saw from the July 4th (and 5th) forks.<br><br>This gets weird.=C2= +=A0 For example, a malicious miner which suspects a large<br>fraction of mi= +ners are neglecting transaction verification may choose to<br>forego a bloc= +k reward by throwing an erroneous transaction into their<br>winning block, = +then, as all the "SPV Miners" run off along a worthless<br>chain,= + they can reap a higher reward rate due to controlling a larger<br>network = +capacity fraction on the valid chain.<br><br>Can we fix this?<br><br>--<br>= +Nathan Wilcox<br>Least Authoritarian<br><br>email: <a href=3D"mailto:nathan= +@leastauthority.com" target=3D"_blank">nathan@leastauthority.com</a><br>twi= +tter: @least_nathan<br><br>Standard Disclaimer: I'm behind on dev archi= +ves, irc logs, bitcointalk,<br>the wiki...=C2=A0 if this has been discussed= + before I appreciate mentions of<br>that fact.<br><br></div> +<br>_______________________________________________<br> +bitcoin-dev mailing list<br> +<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.= +linuxfoundation.org</a><br> +<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" = +rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail= +man/listinfo/bitcoin-dev</a><br> +<br></blockquote></div><br></div> + +--f46d0444e9a5f46d6f051a9b3a15-- + |