Return-Path: <ethan.scruples@gmail.com> Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id AED97C0A for <bitcoin-dev@lists.linuxfoundation.org>; Fri, 14 Sep 2018 14:49:28 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ot1-f47.google.com (mail-ot1-f47.google.com [209.85.210.47]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id CFCE53CC for <bitcoin-dev@lists.linuxfoundation.org>; Fri, 14 Sep 2018 14:49:27 +0000 (UTC) Received: by mail-ot1-f47.google.com with SMTP id v10-v6so4819285otk.7 for <bitcoin-dev@lists.linuxfoundation.org>; Fri, 14 Sep 2018 07:49:27 -0700 (PDT) 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=razz3zvM3EyCvkh5u1yiz9c0Wfw24za+oBFi8qtX4JE=; b=jIVqw3pKOE8tZZ5WTfGU4+nOEzmmClVPZqOl0tjjcnUdtCVbIu4gK8WydKzGtn1Zko qirJiK01t6MtgFoL7ZgErQndrYZAAOibqUaj+PI1LVe6d09XUuouSHAVvpT4ErBrERro E5ROurufjaGAKKzpLkQft41jq5KPaHeARKok6O+hdo2lqcLs/EaQSySLu5l2EF9de5s6 8Qh7sU/S/j1/7IhOLoyK/iwLH6cckcJoFMdcAbj3wRG+gnKMkqXivew6aAyXiK0VMuA4 Uib5WIN2vC5DXurzlhbiWYwBrXbZMof+CwqXoQ7YKeuh6zwMLqotLjMtax+9jl0IPPhp 3Iig== 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=razz3zvM3EyCvkh5u1yiz9c0Wfw24za+oBFi8qtX4JE=; b=NpovvD3OJYpKAGWeAGLBdACFs96G5WMe3HhAzwNF20d4SDcDJFRN71izA5DU4jeU2P fMRBeQsUbAYBsWiLmF2C4nS60qcySwgpDhOSOsjcaxgUhZUuCAXwS8odx1h8UFnb3TqB Y0G+ru4+p8ItBADxkrpAhCRg3L4parj/pebp/BOE2qRsaua0mvol09euf8Ls9NET7zXK GCIJ90Iyqu8YNoNix87vuJ13OBeRIUcjxECleHlX+mqgNDKnmPXKUsdfJXeotk20lNA3 DYxMjZPGlQYyw4BimP9IQx/sd0RUSFUaFpFIL5UsamxzCu9eC/M0NsczOF6p2BwakiqM jzpQ== X-Gm-Message-State: APzg51BNCLL3iJu8ied4XxRlfSXdDo1L19KIa1pbDe+hS61wfrWD7MSv zfdgatw7You18c48a9Vys3CEMUjo2nXYGA7NkDY= X-Google-Smtp-Source: ANB0VdaiLl73NwKohvdPdBzocfsxSE0lHI+RV41e8tPN8PCcg9fIFKel2NZu3ECKceCzoyuOMsp5PXs4b7hJnOcLnLo= X-Received: by 2002:a9d:56a4:: with SMTP id o33-v6mr4860022oth.196.1536936567095; Fri, 14 Sep 2018 07:49:27 -0700 (PDT) MIME-Version: 1.0 References: <CAL8tG=k+kXHMbQdUXO3BXKv7fQwp5t2QuaQut7sPUtEYgwzn0A@mail.gmail.com> <CAL8tG=mui_izrob0V66QqNzSJs1Lpbm0xxUYMpzb65-JR9QhRw@mail.gmail.com> In-Reply-To: <CAL8tG=mui_izrob0V66QqNzSJs1Lpbm0xxUYMpzb65-JR9QhRw@mail.gmail.com> From: Moral Agent <ethan.scruples@gmail.com> Date: Fri, 14 Sep 2018 10:49:16 -0400 Message-ID: <CACiOHGzZ3VQVDsRdU6wsC+mqYJ6nTa4sm4snqDNTcR6x5XP2=Q@mail.gmail.com> To: onelineproof@gmail.com, Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org> Content-Type: multipart/alternative; boundary="0000000000001fc4970575d5ee74" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE 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: Fri, 14 Sep 2018 15:05:14 +0000 Subject: Re: [bitcoin-dev] Selfish Mining Prevention X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol 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: Fri, 14 Sep 2018 14:49:28 -0000 --0000000000001fc4970575d5ee74 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable You might be interested in an idea I wrote about that is in a similar spirit here: https://medium.com/coinmonks/taming-large-miners-with-helper-blocks-6ae67ac= 242f6 From the article: When a block is solved, it randomly selects one satoshi from the utxo set and gives whomever controls that satoshi the power to generate a =E2=80=9CH= elper Block=E2=80=9D. The Helper Block commits to a subset of transactions for in= clusion in the next block. A miner can accept the Helper Block by including the suggested transactions and giving the associated transaction fees to a payment address specified in the Helper Block. Miners who do not use a Helper Block must satisfy a 25% higher difficulty. On Fri, Sep 14, 2018 at 9:56 AM Andrew via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > I discussed this more at bitcointalk: > https://bitcointalk.org/index.php?topic=3D4998410.0 > > The attacks I'm interested in preventing are not only selfish mining > and collusion, but also more subtle attacks like block withholding, > and in general anything that aims to drive out the competition in > order to increase hashrate fraction. I also scrapped the idea of > changing the block subsidies, and I am only focuses on fees. > > You can read more about the motivation and details in the bitcointalk > thread, but my proposal in short would be to add the concept of > "reserve fees". When a user makes a transaction, for each txout > script, they can add parameters that specify the fraction of the total > fee that is held in "reserve" and the time it is held in "reserve" > (can set a limit of 2016 blocks). This "reserve" part of the fee will > be paid to miners if the hashrate rises. So if hashrate is currently h > and peak hashrate (from past year) is p, then for each period (1 day), > a new hashrate is calculated h1, and if h1 > h, then the fraction > (h1-h)/p from the reserve fees created in the past 2016 blocks will be > released to miners for that period (spread out over the 144 blocks in > that period). And this will keep happening as long as hashrate keeps > rising, until the "contract" expires, and the leftover part can be > used by the owner of the unspent output, but it can only be used for > paying fees, not as inputs for future transactions (to save on block > space). > > This should incentivize miners to not drive out the competition, since > if they do, there will be less of these reserve fees given to miners. > Yes in the end the miners will get all the fees, but with rising > hashrate they get an unconditional subsidy that does not require > transactions, thus more space for transactions with fees. > > I can make a formal BIP and pull request, but I need to know if there > is interest in this. Now fees don't play such a large part of the > block reward, but they will get more important, and this change > wouldn't force anything (would be voluntary by each user), just miners > have to agree to it with a soft fork (so they don't spend from the > anyone-can-spend outputs used for reserve fees). Resource requirements > for validation are quite small I believe. > > On Sat, Sep 1, 2018 at 12:11 AM, Andrew <onelineproof@gmail.com> wrote: > > As I understand, selfish mining is an attack where miners collude to > > mine at a lower hashrate then with all miners working independently. > > What are the current strategies used to prevent this and what are the > > future plans? > > > > One idea I have is to let the block reward get "modulated" according > > to peak hashrate. Say p is the peak hashrate for 365 periods (1 year) > > consisting of 144 blocks, h is the hashrate of the last 144 block (1 > > day) period, and r is the base subsidy (12.5 BTC currently). You can > > then make the max block reward 0.5 r (1 + h/p). So if hashrate is at > > peak you get the full reward. Otherwise you get less, down to a min of > > 0.5 r. > > > > If miners were to collude to mine at a lower than peak hashrate, then > > they may be able to do it profitably for 144 blocks, but after that, > > the reward would get modulated and it wouldn't be so much in their > > interest to continue mining at the lower hashrate. > > > > What flaws are there with this? I know it could be controversial due > > to easier mining present for early miners, so maybe it would have to > > be done in combination with a new more dynamic difficulty adjustment > > algorithm. But I don't see how hashrate can continue rising > > indefinitely, so a solution should be made for selfish mining. > > > > Also when subsidies stop and a fee market is needed, I guess a portion > > of the fees can be withheld for later if hashrate is not at peak. > > > > > > -- > > PGP: B6AC 822C 451D 6304 6A28 49E9 7DB7 011C D53B 5647 > > > > -- > PGP: B6AC 822C 451D 6304 6A28 49E9 7DB7 011C D53B 5647 > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --0000000000001fc4970575d5ee74 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div dir=3D"ltr"><div>You might be interested in an idea I= wrote about that is in a similar spirit here:</div><div><br></div><div><a = href=3D"https://medium.com/coinmonks/taming-large-miners-with-helper-blocks= -6ae67ac242f6">https://medium.com/coinmonks/taming-large-miners-with-helper= -blocks-6ae67ac242f6</a></div><div><br></div><div>From the article:</div><d= iv><br></div><div>When a block is solved, it randomly selects one satoshi f= rom the utxo set and gives whomever controls that satoshi the power to gene= rate a =E2=80=9CHelper Block=E2=80=9D. The Helper Block commits to a subset= of transactions for inclusion in the next block. A miner can accept the He= lper Block by including the suggested transactions and giving the associate= d transaction fees to a payment address specified in the Helper Block. Mine= rs who do not use a Helper Block must satisfy a 25% higher difficulty.</div= ></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr">On Fri, Sep 14= , 2018 at 9:56 AM Andrew via bitcoin-dev <<a href=3D"mailto:bitcoin-dev@= lists.linuxfoundation.org">bitcoin-dev@lists.linuxfoundation.org</a>> wr= ote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;= border-left:1px #ccc solid;padding-left:1ex">I discussed this more at bitco= intalk:<br> <a href=3D"https://bitcointalk.org/index.php?topic=3D4998410.0" rel=3D"nore= ferrer" target=3D"_blank">https://bitcointalk.org/index.php?topic=3D4998410= .0</a><br> <br> The attacks I'm interested in preventing are not only selfish mining<br= > and collusion, but also more subtle attacks like block withholding,<br> and in general anything that aims to drive out the competition in<br> order to increase hashrate fraction. I also scrapped the idea of<br> changing the block subsidies, and I am only focuses on fees.<br> <br> You can read more about the motivation and details in the bitcointalk<br> thread, but my proposal in short would be to add the concept of<br> "reserve fees". When a user makes a transaction, for each txout<b= r> script, they can add parameters that specify the fraction of the total<br> fee that is held in "reserve" and the time it is held in "re= serve"<br> (can set a limit of 2016 blocks). This "reserve" part of the fee = will<br> be paid to miners if the hashrate rises. So if hashrate is currently h<br> and peak hashrate (from past year) is p, then for each period (1 day),<br> a new hashrate is calculated h1, and if h1 > h, then the fraction<br> (h1-h)/p from the reserve fees created in the past 2016 blocks will be<br> released to miners for that period (spread out over the 144 blocks in<br> that period). And this will keep happening as long as hashrate keeps<br> rising, until the "contract" expires, and the leftover part can b= e<br> used by the owner of the unspent output, but it can only be used for<br> paying fees, not as inputs for future transactions (to save on block<br> space).<br> <br> This should incentivize miners to not drive out the competition, since<br> if they do, there will be less of these reserve fees given to miners.<br> Yes in the end the miners will get all the fees, but with rising<br> hashrate they get an unconditional subsidy that does not require<br> transactions, thus more space for transactions with fees.<br> <br> I can make a formal BIP and pull request, but I need to know if there<br> is interest in this. Now fees don't play such a large part of the<br> block reward, but they will get more important, and this change<br> wouldn't force anything (would be voluntary by each user), just miners<= br> have to agree to it with a soft fork (so they don't spend from the<br> anyone-can-spend outputs used for reserve fees). Resource requirements<br> for validation are quite small I believe.<br> <br> On Sat, Sep 1, 2018 at 12:11 AM, Andrew <<a href=3D"mailto:onelineproof@= gmail.com" target=3D"_blank">onelineproof@gmail.com</a>> wrote:<br> > As I understand, selfish mining is an attack where miners collude to<b= r> > mine at a lower hashrate then with all miners working independently.<b= r> > What are the current strategies used to prevent this and what are the<= br> > future plans?<br> ><br> > One idea I have is to let the block reward get "modulated" a= ccording<br> > to peak hashrate. Say p is the peak hashrate for 365 periods (1 year)<= br> > consisting of 144 blocks, h is the hashrate of the last 144 block (1<b= r> > day) period, and r is the base subsidy (12.5 BTC currently). You can<b= r> > then make the max block reward 0.5 r (1 + h/p). So if hashrate is at<b= r> > peak you get the full reward. Otherwise you get less, down to a min of= <br> > 0.5 r.<br> ><br> > If miners were to collude to mine at a lower than peak hashrate, then<= br> > they may be able to do it profitably for 144 blocks, but after that,<b= r> > the reward would get modulated and it wouldn't be so much in their= <br> > interest to continue mining at the lower hashrate.<br> ><br> > What flaws are there with this? I know it could be controversial due<b= r> > to easier mining present for early miners, so maybe it would have to<b= r> > be done in combination with a new more dynamic difficulty adjustment<b= r> > algorithm. But I don't see how hashrate can continue rising<br> > indefinitely, so a solution should be made for selfish mining.<br> ><br> > Also when subsidies stop and a fee market is needed, I guess a portion= <br> > of the fees can be withheld for later if hashrate is not at peak.<br> ><br> ><br> > --<br> > PGP: B6AC 822C 451D 6304 6A28=C2=A0 49E9 7DB7 011C D53B 5647<br> <br> <br> <br> -- <br> PGP: B6AC 822C 451D 6304 6A28=C2=A0 49E9 7DB7 011C D53B 5647<br> _______________________________________________<br> bitcoin-dev mailing list<br> <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">= 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> </blockquote></div> --0000000000001fc4970575d5ee74--