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author | Runchao Han <runchao.han@monash.edu> | 2019-12-09 11:45:27 +1100 |
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committer | bitcoindev <bitcoindev@gnusha.org> | 2019-12-09 02:30:15 +0000 |
commit | d58e1f5ab49c5d52758d5eb66e228bd51589a032 (patch) | |
tree | 17192a5266d15fe854ccf53efc7da3067d241640 | |
parent | 3c4c917d2f740817b7abeeba26e4d3408eac2687 (diff) | |
download | pi-bitcoindev-d58e1f5ab49c5d52758d5eb66e228bd51589a032.tar.gz pi-bitcoindev-d58e1f5ab49c5d52758d5eb66e228bd51589a032.zip |
Re: [bitcoin-dev] Reducing energy consumption and increasing security at the same time
-rw-r--r-- | 01/c5e18415064a343a544417888f45d394fecb57 | 276 |
1 files changed, 276 insertions, 0 deletions
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[49.127.13.214]) + by smtp.gmail.com with ESMTPSA id a2sm26091835pfg.90.2019.12.08.16.45.30 + (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); + Sun, 08 Dec 2019 16:45:31 -0800 (PST) +From: Runchao Han <runchao.han@monash.edu> +Message-Id: <29C07E1A-DC6B-49F0-893B-A59E7BD8DB1C@monash.edu> +Content-Type: multipart/alternative; + boundary="Apple-Mail=_83A96B04-E5BD-42EE-8DF6-3D3076A186B7" +Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3601.0.4\)) +Date: Mon, 9 Dec 2019 11:45:27 +1100 +In-Reply-To: <mailman.3482.1575825776.25512.bitcoin-dev@lists.linuxfoundation.org> +To: Cheng Wang <cheng@alephium.org> +References: <mailman.3482.1575825776.25512.bitcoin-dev@lists.linuxfoundation.org> +X-Mailer: Apple Mail (2.3601.0.4) +X-Mailman-Approved-At: Mon, 09 Dec 2019 05:36:26 +0000 +Cc: bitcoin-dev@lists.linuxfoundation.org +Subject: Re: [bitcoin-dev] Reducing energy consumption and increasing + security at the same time +X-BeenThere: bitcoin-dev@lists.linuxfoundation.org +X-Mailman-Version: 2.1.15 +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: Mon, 09 Dec 2019 02:30:15 -0000 + + +--Apple-Mail=_83A96B04-E5BD-42EE-8DF6-3D3076A186B7 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=us-ascii + +Hi Cheng, + +This is an interesting proposal! +While the incentive analysis is sound, I have two concerns: + +## What if a guy keeps mining easy blocks to launch 51% attacks? + +With PoLW, a miner can sacrifice the coinbase reward as much as possible = +to mine blocks faster. +If the blockchain follows the longest chain rule, PoLW may make 51% = +attacks much easier. +An easy way of fixing this is to choose the chain with most work rather = +than most blocks. + +## What if the coinbase tx is no longer the majority of mining reward, = +but the fx fee? + +This might happen in the future. +A possible solution is to limit the number of txs for easy blocks. +For example, if a miner chooses to mine blocks N times easier, he can = +only include txs of which the total size is <=3D (block_size - = +metadata_size) / N. + +Best regards, +Runchao + +> Date: Sun, 8 Dec 2019 11:43:49 +0100 +> From: Cheng Wang <cheng@alephium.org> +> To: bitcoin-dev@lists.linuxfoundation.org +> Subject: [bitcoin-dev] Reducing energy consumption and increasing +> security at the same time +> Message-ID: +> = +<CAJgZxF4G_BjJ=3DOhuzhjfZtkePnEc2hz8DMZzFzWKBNh17XhBeQ@mail.gmail.com> +> Content-Type: text/plain; charset=3D"utf-8" +>=20 +> Hi Everyone, +>=20 +> I would like to share my serious work on reducing the energy = +consumption of +> PoW without sacrificing security. My new type of algorithm is called = +PoLW. +> For a practical system where mining is profitable, PoLW could actually +> improve the security of the system. +>=20 +> The idea is to shift part of the external cost of mining in the = +physical +> world (mainly energy consumption) to the internal cost of the network. = +In +> PoLW, the miners are able to give up part of the coinbase reward so as = +to +> get weight (> 1) for the block hash they produce. The total cost of +> generating a new block would still be equal to maximal coinbase reward = +in +> equilibrium. +>=20 +> I analyzed two algorithms in the paper: linear PoLW and exponential = +PoLW. +> Linear PoLW could reduce energy consumption by a factor close to 1/2 = +in +> equilibrium, while exponential PoLW could reduce energy consumption by = +an +> arbitrary factor in equilibrium. +>=20 +> In a practical system, mining is usually (if not always) profitable. = +If we +> transition from PoW to PoLW, the external costs of mining would = +decrease +> and the internal costs will increase. However, the decrease in = +external +> costs would be less than the increase in internal costs since mining = +is +> profitable. The total cost of block generation would get higher, = +therefore, +> the security will increase. +>=20 +> Of course, we could not decrease the external costs of any existing = +system +> by a factor close to zero immediately. There is a section in my paper +> discussing this particularly. The principle of applying PoLW is that +> keeping the absolute external cost increasing all the time, but the +> percentage of external cost in the total cost gets lower eventually. +>=20 +> This work is based on solid math calculation, and I am looking forward = +to +> feedback and discussions. My paper is available at: +> https://github.com/alephium/research/raw/master/polw.pdf +>=20 +> It's inspired by the recent great paper of Itay, Alexander, and Ittay: +> https://arxiv.org/abs/1911.04124 +>=20 +> Best, +> Cheng Wang + + +--Apple-Mail=_83A96B04-E5BD-42EE-8DF6-3D3076A186B7 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=us-ascii + +<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; = +charset=3Dus-ascii"></head><body style=3D"word-wrap: break-word; = +-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><div = +class=3D"">Hi Cheng,</div><div class=3D""><br class=3D""></div>This is = +an interesting proposal!<div class=3D"">While the incentive analysis is = +sound, I have two concerns:</div><div class=3D""><br class=3D""></div><div= + class=3D"">## <span style=3D"font-family: "Helvetica = +Neue"; font-size: 13px;" class=3D"">What if a guy keeps mining easy = +blocks to launch 51% attacks?</span></div><div class=3D""><span = +style=3D"font-family: "Helvetica Neue"; font-size: 13px;" = +class=3D""><br class=3D""></span></div><div class=3D""><font = +face=3D"Helvetica Neue" size=3D"2" class=3D"">With PoLW, a miner can = +sacrifice the coinbase reward as much as possible to mine blocks = +faster.</font></div><div class=3D""><font face=3D"Helvetica Neue" = +size=3D"2" class=3D"">If the blockchain follows the longest chain = +rule, PoLW may make 51% attacks much easier.</font></div><div = +class=3D""><font face=3D"Helvetica Neue" size=3D"2" class=3D"">An easy = +way of fixing this is to choose the chain with most work rather than = +most blocks.</font></div><div class=3D""><br class=3D""></div><div = +class=3D"">## What if the coinbase tx is no longer the majority of = +mining reward, but the fx fee?</div><div class=3D""><br = +class=3D""></div><div class=3D"">This might happen in the = +future.</div><div class=3D"">A possible solution is to limit the number = +of txs for easy blocks.</div><div class=3D"">For example, if a miner = +chooses to mine blocks N times easier, he can only include txs of which = +the total size is <=3D (block_size - metadata_size) / N.</div><div = +class=3D""><br class=3D""></div><div class=3D"">Best regards,</div><div = +class=3D"">Runchao</div><div class=3D""><br class=3D""></div><div = +class=3D""><div><blockquote type=3D"cite" class=3D""><div class=3D""><div = +class=3D"">Date: Sun, 8 Dec 2019 11:43:49 +0100<br class=3D"">From: = +Cheng Wang <<a href=3D"mailto:cheng@alephium.org" = +class=3D"">cheng@alephium.org</a>><br class=3D"">To: <a = +href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" = +class=3D"">bitcoin-dev@lists.linuxfoundation.org</a><br = +class=3D"">Subject: [bitcoin-dev] Reducing energy consumption and = +increasing<br class=3D""><span class=3D"Apple-tab-span" = +style=3D"white-space:pre"> </span>security<span = +class=3D"Apple-tab-span" style=3D"white-space:pre"> </span>at the = +same time<br class=3D"">Message-ID:<br class=3D""><span = +class=3D"Apple-tab-span" style=3D"white-space:pre"> </span><<a = +href=3D"mailto:CAJgZxF4G_BjJ=3DOhuzhjfZtkePnEc2hz8DMZzFzWKBNh17XhBeQ@mail.= +gmail.com" = +class=3D"">CAJgZxF4G_BjJ=3DOhuzhjfZtkePnEc2hz8DMZzFzWKBNh17XhBeQ@mail.gmai= +l.com</a>><br class=3D"">Content-Type: text/plain; charset=3D"utf-8"<br= + class=3D""><br class=3D"">Hi Everyone,<br class=3D""><br class=3D"">I = +would like to share my serious work on reducing the energy consumption = +of<br class=3D"">PoW without sacrificing security. My new type of = +algorithm is called PoLW.<br class=3D"">For a practical system where = +mining is profitable, PoLW could actually<br class=3D"">improve the = +security of the system.<br class=3D""><br class=3D"">The idea is to = +shift part of the external cost of mining in the physical<br = +class=3D"">world (mainly energy consumption) to the internal cost of the = +network. In<br class=3D"">PoLW, the miners are able to give up part of = +the coinbase reward so as to<br class=3D"">get weight (> 1) for the = +block hash they produce. The total cost of<br class=3D"">generating a = +new block would still be equal to maximal coinbase reward in<br = +class=3D"">equilibrium.<br class=3D""><br class=3D"">I analyzed two = +algorithms in the paper: linear PoLW and exponential PoLW.<br = +class=3D"">Linear PoLW could reduce energy consumption by a factor close = +to 1/2 in<br class=3D"">equilibrium, while exponential PoLW could reduce = +energy consumption by an<br class=3D"">arbitrary factor in = +equilibrium.<br class=3D""><br class=3D"">In a practical system, mining = +is usually (if not always) profitable. If we<br class=3D"">transition = +from PoW to PoLW, the external costs of mining would decrease<br = +class=3D"">and the internal costs will increase. However, the decrease = +in external<br class=3D"">costs would be less than the increase in = +internal costs since mining is<br class=3D"">profitable. The total cost = +of block generation would get higher, therefore,<br class=3D"">the = +security will increase.<br class=3D""><br class=3D"">Of course, we could = +not decrease the external costs of any existing system<br class=3D"">by = +a factor close to zero immediately. There is a section in my paper<br = +class=3D"">discussing this particularly. The principle of applying PoLW = +is that<br class=3D"">keeping the absolute external cost increasing all = +the time, but the<br class=3D"">percentage of external cost in the total = +cost gets lower eventually.<br class=3D""><br class=3D"">This work is = +based on solid math calculation, and I am looking forward to<br = +class=3D"">feedback and discussions. My paper is available at:<br = +class=3D""><a = +href=3D"https://github.com/alephium/research/raw/master/polw.pdf" = +class=3D"">https://github.com/alephium/research/raw/master/polw.pdf</a><br= + class=3D""><br class=3D"">It's inspired by the recent great paper of = +Itay, Alexander, and Ittay:<br = +class=3D"">https://arxiv.org/abs/1911.04124<br class=3D""><br = +class=3D"">Best,<br class=3D"">Cheng Wang<br = +class=3D""></div></div></blockquote></div><br = +class=3D""></div></body></html>= + +--Apple-Mail=_83A96B04-E5BD-42EE-8DF6-3D3076A186B7-- + |