コンセンサスアルゴリズム｜Delegated Proof of Stakeとは？

Blockchain has certainly come a long way since the idea's inception during the 1990s, and Satoshi Nakamoto's breakthrough on Bitcoin. However, if we take a look at the most popular blockchain networks, Bitcoin and Ethereum, we can see that it not only takes time to process a single transaction, but also use up so much energy.

What if there was a blockchain that could handle about 100, 000 transactions per second, secure the network without the need to spend so much electricity, and start your own currency? Apparently, it already exists and is called Delegated Proof of Stake (DPoS).

この記事でDelegated Proof of StakeとEOSについて話します。EOSはブロクチェーンネットにDPoSを使います。

# Delegated Proof of Stakeとは

![dpos.png](https://qiita-image-store.s3.amazonaws.com/0/300933/6b218f11-0231-4ae2-99a1-5c629c0e2f4a.png)

Delegated Proof of Stakeはコンセンサスアルゴリズムで、 where shares in the network or ownership of the network's currency is the measure of your voting power. Delegated Proof of Stakeはコンセンサスアルゴリズム。TRONとLiskとSteemやBitsharesやEOSのブロクチェーンはこのアルゴリズムを使っています。

## どのように機能するのか？

In Delegated Proof of Stake, members of the network get to stake a certain amount of the network's currency. Depending on the amount they staked, these members will vote for a certain number of people called "witnesses", who will then have the ability to validate and create the next block, then receive an incentive for doing so. However, in the case that a witness attempts to cheat the system, not only will the witness lose its witness status, but also that witness' stake will be burned.

## Proof of Work (PoW)との比較

Proof of Work (PoW)はサトシナカモトのビットコインのコンセンサスアルゴリズムです。PoWでは、マイナーは謎を解くことに競走します。一番早いマイナーはつぎのブロックを作って確認することができて、ブロクチェーンの暗号通貨を貰います。今まで、ビットコインにはチートすることができません。本当に素晴らしいですけど、そのアルゴリズムにはたくさん問題があります。でも、DPoSでその問題を解くことができます。

### 速度
マイナーは謎を解くことに競走しなければならないから、Proof of Workはとても遅いです。でも、Delegated Proof of Stakeでは、ぜんぶのメンバーはいくつかブロック作る人を選びましたから、謎を解くことに必要がありません。

### コスト
This not only concerns transaction fees that users have to pay when performing transactions through the network, but also electricity wise. In PoW, all miners have to utilize so much electricity to mine or try to solve the puzzle, but only one at a time gets to actually validate the next block and get rewarded. In DPoS, only the pre-elected block producers are required to provide the needed computing power. This does not only lowers or eliminates transaction fees, but also help save the planet, because of the lesser usage of electricity.

### バリデーター
In Proof of Work, transaction validators are called "miners" and compete through their computing power, attempting to solve a certain puzzle. In the case of Delegated Proof of Stake, transaction validators are called "delegates", and are elected instead of competing for a spot. 

# EOSとは
Ethereumのような、EOSはブロクチェーンネットです。EOSでDappsを作ることができます。このブロクチェーンはDPosを使いますから、短い時間でたくさんトランザクションすることができます。それから、代金はとても安いです。

__ウェブサイト__
https://eos.io/

## EOSのブロック作成者になるには
Since EOS utilizes DPoS, then there is a need to elect or select block producers. Anyone with the resources can be block producers, but have to follow a specific criteria that EOS provides.

> * __PUBLIC PRESENCE__ - The candidate should have a public website URL and at least one social media account.

> * __ID ON STEEMIT__ - The candidate should post information about themselves such as : location of headquarters, type of servers, expected location of servers. 

> * __TECH SPECS__ - The candidate should post an estimate of technical specifications and total expenditure for resources.

> * __SCALING PLAN__ - The candidate should have an estimated scaling plan for hardware, which will be reviewed.

> * __COMMUNITY BENEFIT__ - The candidate should post an outline regarding the benefit that the community will receive from the project.

> * __TELEGRAM + TESTNET__ - The candidate should have a list of Telegram and Test-net node names for community testnet participation.

__ウェブサイト__
https://steemit.com/eos/@eosgo/eos-block-producer-candidate-report-10-may-30-2018

# まとめ
At the moment, there is still no single and perfect consensus algorithm that could render all other algorithms as obsolete. However, despite being flawed and imperfect, Delegated Proof of Stake certainly shows promise and is probably the best solution as of now.

もっと読む：
* [A Hitchhiker's Guide to Concensus Algorithms](https://hackernoon.com/a-hitchhikers-guide-to-consensus-algorithms-d81aae3eb0e3)
* [Delegated Proof-of-Stake Consensus](https://bitshares.org/technology/delegated-proof-of-stake-consensus/)