From: Runchao Han <runchao.han@monash•edu>
To: Cheng Wang <cheng@alephium•org>
Cc: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] Reducing energy consumption and increasing security at the same time
Date: Mon, 9 Dec 2019 11:45:27 +1100 [thread overview]
Message-ID: <29C07E1A-DC6B-49F0-893B-A59E7BD8DB1C@monash.edu> (raw)
In-Reply-To: <mailman.3482.1575825776.25512.bitcoin-dev@lists.linuxfoundation.org>
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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 <= (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=OhuzhjfZtkePnEc2hz8DMZzFzWKBNh17XhBeQ@mail•gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Everyone,
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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
>
> It's inspired by the recent great paper of Itay, Alexander, and Ittay:
> https://arxiv.org/abs/1911.04124
>
> Best,
> Cheng Wang
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next parent reply other threads:[~2019-12-09 2:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.3482.1575825776.25512.bitcoin-dev@lists.linuxfoundation.org>
2019-12-09 0:45 ` Runchao Han [this message]
2019-12-09 9:47 ` Cheng Wang
2019-12-08 10:43 Cheng Wang
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