Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id AED97C0A for ; 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 ; Fri, 14 Sep 2018 14:49:27 +0000 (UTC) Received: by mail-ot1-f47.google.com with SMTP id v10-v6so4819285otk.7 for ; 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: In-Reply-To: From: Moral Agent Date: Fri, 14 Sep 2018 10:49:16 -0400 Message-ID: To: onelineproof@gmail.com, Bitcoin Protocol Discussion 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 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-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 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
You might be interested in an idea I= wrote about that is in a similar spirit here:


From the article:

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.

On Fri, Sep 14= , 2018 at 9:56 AM Andrew via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wr= ote:
I discussed this more at bitco= intalk:
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 "re= serve"
(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 b= e
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<= br> 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<= br> > future plans?
>
> One idea I have is to let the block reward get "modulated" a= ccording
> 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 > 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<= br> > 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=C2=A0 49E9 7DB7 011C D53B 5647



--
PGP: B6AC 822C 451D 6304 6A28=C2=A0 49E9 7DB7 011C D53B 5647
_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev
--0000000000001fc4970575d5ee74--