Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 5CE4A305 for ; Wed, 1 Jul 2015 02:57:22 +0000 (UTC) X-Greylist: delayed 00:05:01 by SQLgrey-1.7.6 Received: from dmz-mailsec-scanner-3.mit.edu (dmz-mailsec-scanner-3.mit.edu [18.9.25.14]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2702BE7 for ; Wed, 1 Jul 2015 02:57:20 +0000 (UTC) X-AuditID: 1209190e-f79c76d000002631-90-559355e27afd Received: from mailhub-auth-1.mit.edu ( [18.9.21.35]) (using TLS with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by dmz-mailsec-scanner-3.mit.edu (Symantec Messaging Gateway) with SMTP id 0F.99.09777.2E553955; Tue, 30 Jun 2015 22:52:18 -0400 (EDT) Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by mailhub-auth-1.mit.edu (8.13.8/8.9.2) with ESMTP id t612qHb7026218 for ; Tue, 30 Jun 2015 22:52:18 -0400 Received: from mail-yk0-f182.google.com (mail-yk0-f182.google.com [209.85.160.182]) (authenticated bits=0) (User authenticated as jlrubin@ATHENA.MIT.EDU) by outgoing.mit.edu (8.13.8/8.12.4) with ESMTP id t612qGjp020334 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Tue, 30 Jun 2015 22:52:17 -0400 Received: by ykfy125 with SMTP id y125so27318525ykf.1 for ; Tue, 30 Jun 2015 19:52:16 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.129.76.70 with SMTP id z67mr30352498ywa.17.1435719136607; Tue, 30 Jun 2015 19:52:16 -0700 (PDT) Received: by 10.13.222.2 with HTTP; Tue, 30 Jun 2015 19:52:16 -0700 (PDT) In-Reply-To: References: Date: Wed, 1 Jul 2015 10:52:16 +0800 Message-ID: From: Jeremy To: Pieter Wuille Content-Type: multipart/alternative; boundary=001a113f1ce62286b20519c76948 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrMKsWRmVeSWpSXmKPExsUixCmqrPsodHKowc4zYhZNr20dGD1+/5jM GMAYxWWTkpqTWZZapG+XwJVxqeEYU8El14pDa/pYGxivWncxcnJICJhITNl9kxXCFpO4cG89 WxcjF4eQwGImidMdqxghnLuMEk8frILKfGSS+L1vDyNIi5DAREaJX5vqQGxeAUGJkzOfsECM KpZo+HGNFaLGU2LL0blMIDanQKDEi/nHWSEGTWeUOPtwI3MXIwcHi4CKxN8tOhBzAiR6Z3wC 2yws0Mwo8WbFKUaQGjYBOYkPv0xBakQEtCVmPt4CtotZoEZi9prXrBC2l8SUfzMYJzAKzUJy 0iwkqVlAk5gF1CXWzxOCCKtJ3N52lR3C1pZYtvA18wJG1lWMsim5Vbq5iZk5xanJusXJiXl5 qUW6xnq5mSV6qSmlmxjBIS/Jt4Px60GlQ4wCHIxKPLwCYpNDhVgTy4orcw8xSnIwKYny/g8A CvEl5adUZiQWZ8QXleakFh9ilOBgVhLhzdAGyvGmJFZWpRblw6SkOViUxHk3/eALERJITyxJ zU5NLUgtgsnKcHAoSfDGhQA1ChalpqdWpGXmlCCkmTg4QYbzAA3XCgUZXlyQmFucmQ6RP8Vo zLHl97W1TBzbpt5byyTEkpeflyolztsLMk4ApDSjNA9uGixtvWIUB3pOmHcfSBUPMOXBzXsF tIoJaNVL+0kgq0oSEVJSDYwhp27k7C+wOWq+2P3jlO0XY1qvGt800dJvfZb/MMRW0vz9rJfG 2db9rds3Tzg+f8ZD/Uu7VvCvyfZmEf3/K1yAozDx86KvQlnJTzbEiu09PK32weWMn6eSs3pe Lnwt6yNlX1ax6vVSf+Obwrll669lb7lbl+8Ut2DZgsJqiebfLu/7+BLWqv5SYinOSDTUYi4q TgQATBDIGDYDAAA= X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00,HTML_MESSAGE, RCVD_IN_DNSWL_MED,RP_MATCHES_RCVD 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] A possible solution for the block size limit: Detection and rejection of bloated blocks by full nodes. 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: Wed, 01 Jul 2015 02:57:22 -0000 --001a113f1ce62286b20519c76948 Content-Type: text/plain; charset=UTF-8 A simple hack to achieve this would be phase shifting the transaction fees by one block. There may be other problems, but also potential benefits, with that though. This hack works because then a miner would orphan a block which didn't properly reward them, which makes it very costly for even a miner to put in a bunch of transactions for free. This phase can be adjusted to different amounts, spread over multiple blocks, or even randomly selected at the time of mining from a pool of un-fee claimed blocks (although this would require some seeding to create a pool of any size greater than 1). Again, this is probably a bad idea and I haven't thought it through completely, but just tossing it out there. Ps sorry if you're seeing this many times I think it bounced due to the not-subscribed rule (sent from my other account) On Wednesday, July 1, 2015, Pieter Wuille wrote: > The problem with this approach is that you need 100% exact behaviour for > every node on the network in their decision to reject a particular block. > So we need a 100% mempool synchronization across all nodes - otherwise just > an attempted double spend could result in a fork in the network because > some nodes saw it and some didn't. And actually, if we had 100% mempool > synchronization, we wouldn't need a blockchain in the first place, because > we could just use "first to enter mempool" as validity criterion. > > On Wed, Jul 1, 2015 at 1:41 AM, Peter Grigor > wrote: > >> The block size debate centers around one concern it seems. To wit: if >> block size is increased malicious miners may publish unreasonably large >> "bloated" blocks. The way a miner would do this is to generate a plethora >> of private, non-propagated transactions and include these in the block they >> solve. >> >> It seems to me that these bloated blocks could easily be detected by >> other miners and full nodes: they will contain a very high percentage of >> transactions that aren't found in the nodes' own memory pools. This >> signature can be exploited to allow nodes to reject these bloated blocks. >> The key here is that any malicious miner that publishes a block that is >> bloated with his own transactions would contain a ridiculous number of >> transactions that *absolutely no other full node has in its mempool*. >> >> Simply put, a threshold would be set by nodes on the allowable number of >> non-mempool transactions allowed in a solved block (say, maybe, 50% -- I >> really don't know what it should be). If a block is published which >> contains more that this threshold of non-mempool transactions then it is >> rejected. >> >> If this idea works the block size limitation could be completely removed. >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> > -- -- @JeremyRubin --001a113f1ce62286b20519c76948 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
A si= mple hack to achieve this would be phase shifting the transaction fees by o= ne block. There may be other problems, but also potential benefits,=C2=A0wi= th that though.
This hack works because then a miner would orphan a block = which didn't properly reward them, which makes it very costly for even = a miner to put in a bunch of transactions for free. This phase can be adjus= ted to different amounts, spread over multiple blocks, or even randomly sel= ected at the time of mining from a pool of un-fee claimed blocks (although = this would require some seeding to create a pool of any size greater than 1= ).

Agai= n, this is probably a bad idea and I haven't thought it through complet= ely,=C2=A0but just tossing it out there.

Ps sorry if you're seeing this many times I think it b= ounced due to the not-subscribed rule (sent from my other account)
On We= dnesday, July 1, 2015, Pieter Wuille <pieter.wuille@gmail.com> wrote:
The problem with this approach is that you need 100= % exact behaviour for every node on the network in their decision to reject= a particular block. So we need a 100% mempool synchronization across all n= odes - otherwise just an attempted double spend could result in a fork in t= he network because some nodes saw it and some didn't. And actually, if = we had 100% mempool synchronization, we wouldn't need a blockchain in t= he first place, because we could just use "first to enter mempool"= ; as validity criterion.

On Wed, Jul 1, 2015 at 1:41 AM, Peter Grigor <peter@grigor.ws> wrote:
The block size debate centers around one concern it seems. To wi= t: if block size is increased malicious miners may publish unreasonably lar= ge "bloated" blocks. The way a miner would do this is to generate= a plethora of private, non-propagated transactions and include these in th= e block they solve.

It seems to me that these b= loated blocks could easily be detected by other miners and full nodes: they= will contain a very high percentage of transactions that aren't found = in the nodes' own memory pools. This signature can be exploited to allo= w nodes to reject these bloated blocks. The key here is that any malicious = miner that publishes a block that is bloated with his own transactions woul= d contain a ridiculous number of transactions that *absolutely no other ful= l node has in its mempool*.

Simply put, a thres= hold would be set by nodes on the allowable number of non-mempool transacti= ons allowed in a solved block (say, maybe, 50% -- I really don't know w= hat it should be). If a block is published which contains more that this th= reshold of non-mempool transactions then it is rejected.

If this idea works the block size limitation could be completely = removed.

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bitcoin-dev@lists.linuxfoundation.= org
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