Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 22EB1113F for ; Tue, 8 Sep 2015 15:10:58 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ig0-f177.google.com (mail-ig0-f177.google.com [209.85.213.177]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A0FDD1F8 for ; Tue, 8 Sep 2015 15:10:57 +0000 (UTC) Received: by igcrk20 with SMTP id rk20so76619527igc.1 for ; Tue, 08 Sep 2015 08:10:57 -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=wEM7T3/JQ7Pd9iBNmbOKTdgU0gYH6al0VEkMP3bPKbA=; b=QbeKRNvG424xjnMXGiyoyQB/EgK6PFVt89G2EoQeuekeWGquxmcF4SCfB2FujIhvZH WmBYMxCFA/nJ2dRt0Q81IUbyAC2Trp3HPMXBh6IkAx+r4yXyEznozc5FQOMN6kkdQn7o IOeMOtoyZdjReXKZwuKscps/kuZvA8MFC0fGXaK57FYBK7JkvwsF1T7dt0deE+zLrh2S 7pnd4Rt5LxrFYEUFD29sMUpeyO6EqDkh7GIEhMNXHuzTQRhToPSExrL4JsKN/8NpJddL 6cJoXCZ8UKn24ZiO+y8LQyGf0aE6pYSn7mj72deQGngSlclujfzUDbwFzr6edshgpuy9 YqUw== MIME-Version: 1.0 X-Received: by 10.50.39.80 with SMTP id n16mr22323117igk.44.1441725054983; Tue, 08 Sep 2015 08:10:54 -0700 (PDT) Received: by 10.107.178.12 with HTTP; Tue, 8 Sep 2015 08:10:54 -0700 (PDT) In-Reply-To: References: Date: Wed, 9 Sep 2015 01:10:54 +1000 Message-ID: From: Washington Sanchez To: Adam Back Content-Type: multipart/alternative; boundary=e89a8f83a259c42c01051f3dc53a 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 Subject: Re: [bitcoin-dev] Dynamic limit to the block size - BIP draft discussion 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, 08 Sep 2015 15:10:58 -0000 --e89a8f83a259c42c01051f3dc53a Content-Type: text/plain; charset=UTF-8 1) It's not really clear to me how that would work, but assuming it does then it will go into a basket of attacks that are possible but unlikely due to the economic disincentives to do so. 2) That said, is the Achilles heal of this proposal the lack of a mechanism to lower the block size? 3) Let me put it another way, I've read that both Gavin and yourself are favorable to a dynamic limit on the block size. In your view, what is missing from this proposal, or what variables should be adjusted, to get the rules to a place where you and other Core developers would seriously consider it? On Wed, Sep 9, 2015 at 12:18 AM, Adam Back wrote: > > A selfish mining attack would have to be performed for at least 2000 > blocks over a period of 4 weeks in order to achieve a meager 10% increase > in the block size. > > You seem to be analysing a different attack - I mean that if someone > has enough hashrate to do a selfish mining attack, then setting up a > system that has no means to reduce block-size risks that at a point > where there is excess block-size they can use that free transaction > space to amplify selfish mining instead of collecting transaction > fees. > > Adam > -- ------------------------------------------- *Dr Washington Y. Sanchez * Co-founder, OB1 Core developer of OpenBazaar @drwasho --e89a8f83a259c42c01051f3dc53a Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

1) It's not really clear to me how that= would work, but assuming it does then it will go into a basket of attacks = that are possible but unlikely due to the economic disincentives to do so.<= div>
2) That said, is the Achilles heal of this proposal the = lack of a mechanism to lower the block size?=C2=A0

3) Let me put it another way, I've read that both Gavin and yourself a= re favorable to a dynamic limit on the block size. In your view, what is mi= ssing from this proposal, or what variables should be adjusted, to get the = rules to a place where you and other Core developers would seriously consid= er it?

On Wed, Sep 9, 2015 at 12:18 AM, Adam Back <adam@cypherspace.org= > wrote:
> = A selfish mining attack would have to be performed for at least 2000 blocks= over a period of 4 weeks in order to achieve a meager 10% increase in the = block size.

You seem to be analysing a different attack - I mean that if someone=
has enough hashrate to do a selfish mining attack, then setting up a
system that has no means to reduce block-size risks that at a point
where there is excess block-size they can use that free transaction
space to amplify selfish mining instead of collecting transaction
fees.

Adam



--
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Co-founder, OB1

<= /div>
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