From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 1E982BA3 for ; Wed, 8 Nov 2017 05:04:19 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ot0-f180.google.com (mail-ot0-f180.google.com [74.125.82.180]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A52BB4F5 for ; Wed, 8 Nov 2017 05:04:18 +0000 (UTC) Received: by mail-ot0-f180.google.com with SMTP id s88so1332697ota.4 for ; Tue, 07 Nov 2017 21:04:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=5EbobjILUwpqQgUIeimnuToTgoXviWLSyXLcSdPOdB4=; b=XCcwGZR4oTM8e6f6Pfd9KYdt/qSim66K1SZW2ixf5V8B8sAksp/7dL/YVqlhG/qP9y wZTYJG1EXw3L/0qxRQLfIigKWFFdfGExSNaMP3ynzqWiUC9cqm/LwPG6HyBBiQz6fIG3 I9DsiRyl/DhZLm+th8SP80OPsVbteYNOByWuzS1Wx5d/OyxubU4UmlKzfLHnLpY2RH3F 33RVubWh/LJbPoutLun5LtdN6BbmXEahNn7tS3w5GfFUNKQ8IbUBUV1hi81x6H1eip2B jQdWR4cA3ZR2Z8CWw8f2PGk5dE7UvqwLGJHT9BdNcobQbDzWps3vJhZ1Rmeto/lbfBi9 t7Tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=5EbobjILUwpqQgUIeimnuToTgoXviWLSyXLcSdPOdB4=; b=F+7GxH7S4+OKsBqIIYKXQNYt4S/5pF5aOqbkiOf1I/HxAOvN2Tj70TCLOKRDUl0Tjf Yv5KO1bo+FWf3RxFsoFXtlt3Ot1kS0yBSKGBbXz4kJGi2id+Edl1qIr0nSb4mVCvj3ab bML5u4Oj2w4SlcSP2xyu3O9yfbvIu7ZdAM5ZkshUUCM4tTigT0AmA1izN3ZdqMNvMc3v gWIJz14DLRqb6mK7zttnvAIOmrV+b5tG1r3ekjJdhkzopmWylks5dsC576j6dKqMPdcI dyvN/RkQ/fYpdhY+F6wWodTo16Pn/ZgttEYTPj6/xs7OuafwzmQP0mBL7tQHCqKIpBVT oNcg== X-Gm-Message-State: AJaThX4vMozMsTlec+tKqJZJ3OK7HlOA5QahJyV14UPMLmGOiWk92PQx UDD83UT3o7Cwnac1oI1rziAF0385wbnG+u9GHGc= X-Google-Smtp-Source: AGs4zMaDISmnEYripXQd27M6WXeFKPT5bjQao+y+qMd5pyqCePy09HbP+Kr4B1KJcUxZxs7N2n8zcKRsJ4CDKKf5eDE= X-Received: by 10.157.23.12 with SMTP id i12mr574174ota.424.1510117457790; Tue, 07 Nov 2017 21:04:17 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Marc Bevand Date: Wed, 08 Nov 2017 05:04:07 +0000 Message-ID: To: Robert Taylor , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="94eb2c1fd3f8a40daa055d719e86" X-Spam-Status: No, score=0.4 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=disabled 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, 08 Nov 2017 13:45:46 +0000 Subject: Re: [bitcoin-dev] Centralizing mining by force 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: Wed, 08 Nov 2017 05:04:19 -0000 --94eb2c1fd3f8a40daa055d719e86 Content-Type: text/plain; charset="UTF-8" What you describe is an example of a majority attack ("51% attack"). No technical mechanism in Bitcoin prevents this. However in practice, miners are not incentivized to perform this attack as it would destroy confidence in Bitcoin, and would ultimately impact their revenues. -Marc On Mon, Nov 6, 2017, 22:32 Robert Taylor via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Forgive me if this has been asked elsewhere before, but I am trying to > understand a potential failure mode of Bitcoin mining. > > A majority of miners can decide which valid blocks extend the chain. But > what would happen if a majority of miners, in the form of a cartel decided > to validly orphan any blocks made by miners outside of their group? For > example, they could soft fork a new rule where the block number is signed > by set of keys known only to the cartel, and that signature placed in the > coinbase. Miners outside of the cartel would not be able to extend the > chain. > > It would be immediately obvious but still valid under the consensus rules. > What are the disincentives for such behavior and what countermeasures could > be done to stop it and ensure mining remained permissionless? I think this > is a valid concern because while it may not be feasible for one actor to > gain a majority of hash alone, it is certainly possible with collusion. > > Robert > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --94eb2c1fd3f8a40daa055d719e86 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

What you describe is an example of a majority attack ("= 51% attack"). No technical mechanism in Bitcoin prevents this. However= in practice, miners are not incentivized to perform this attack as it woul= d destroy confidence in Bitcoin, and would ultimately impact their revenues= .

-Marc


On Mon, Nov 6, 2017, 22:32 = Robert Taylor via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
Forgive me if this has b= een asked elsewhere before, but I am trying to understand a potential failu= re mode of Bitcoin mining.

A majority of miners can decide which va= lid blocks extend the chain. But what would happen if a majority of miners,= in the form of a cartel decided to validly orphan any blocks made by miner= s outside of their group? For example, they could soft fork a new rule wher= e the block number is signed by set of keys known only to the cartel, and t= hat signature placed in the coinbase. Miners outside of the cartel would no= t be able to extend the chain.

It would be immediately obvious but s= till valid under the consensus rules. What are the disincentives for such b= ehavior and what countermeasures could be done to stop it and ensure mining= remained permissionless? I think this is a valid concern because while it = may not be feasible for one actor to gain a majority of hash alone, it is c= ertainly possible with collusion.

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