DPOS: Delegated Proof of Stake とは何か?



  • BitsharesやLiskで利用されているコンセンサス・アルゴリズム
  • Proof of Stakeの発展系


  • 自分のシェア分の投票権を代理人に託すことが可能
  • 全投票トップ100の代理人で新ブロックを生成


  • 普通のネットワーク状態だと、10-30秒でブロック生成ができる
  • チェーンのフォークもほとんど発生しないか、数分で修正されうる


Delegated Proof of Stake | BitShares


Proof of Work

  • Bitcoin の場合、10分で新ブロックを生成
  • 6ブロック(約1時間)で、ブロック戻せなくなるとされている

Proof of Stake

  • いくつか実装があるが、Peercoin と Nxt が有名
  • Peercoinの場合、ハイブリッドモデルで、保持比率がマイニングの難易度を変える
  • Nxtの場合、ランダムなシェアホルダーを選び、次のブロックを作る

TaPOS (Transaction as Proof of Stake)

  • どのトランザクションも前のブロックのハッシュを含む
  • 最終的に、全シェアホルダーによって全ブロックが投票される

Ripple Consensus

  • ユニークなノードリストに基いてコンセンサスに同意する
  • 初期のユニークなノードリストは、51%のクラブ会員が、新しいメンバーを向かい入れるのに投票しなくてはいけないクラブのようなもの
  • Bitcoin, Peercoin等に比べ centralized

Delegated Proof of Stake

  • 投票権利を代理人に渡しても良い
  • 全投票のトップ100の代理人が、決められたスケジュールで、新しいブロックを生成
  • 各代理人が、ブロック生成のための時間スロットを割り与えられる
  • 全ての代理人は、平均的なブロックに含まれるトランザクション・フィーの10%を受け取る
  • 平均的なブロックは、100シェアのフィーを含んでいる
  • このモデルだと
    • 普通のネットワーク状態だと、10-30秒でブロック生成ができる
    • チェーンのフォークもほとんど発生しないか、数分で修正されうる




CT: Explain the 101 delegates system.

KC: BitShares delegates take the place of Bitcoin miners in certifying the validity of changes to the global public ledger. Anyone with a BitShares account can seek election as a delegate.

BitShares holders get one vote per each BTS token they own and can use their wallet interfaces to tell the blockchain which delegates they trust. The top 101 delegates with the most owner approval are authorized to take turns adding a block of transactions to the ledger. So this is a mechanism for explicitly determining who the owners trust most to sign the blocks.

Bitcoin miners appoint themselves to wield this authority and bitcoin holders have no say at all in how long they can serve.

Delegates can only include valid transactions or the rest of the network will reject their block. So it is hard to earn enough trust to get elected and very easy to lose it under the certainty of being caught misbehaving.

CT: Why does there need to be a central group of delegates? Could BitShares function without it?

KC: Delegates are distributed around the world and are far more decentralized than Bitcoin. BitShares has a way to hold block producers accountable while owners of bitcoin and its clones do not.

With Bitcoin, over half the blocks are signed by two or three individuals (owner/operators of large mining arrays or pools). These two or three people control what version of the software is official and publicly collude to implement hard forks.

With BitShares, no delegate is permitted to sign even 1% of the blocks and each must have a reputation that is among the most approved by BTS owners.

With Bitcoin, mining entities appoint themselves and there is nothing that actual bitcoin holders can do to get rid of a bad actor that controls a lot of hash power. BitShares owners can fire delegates who lose their confidence in ten seconds.

“[Distilled trust] enables products and services that are beyond the reach of first generation systems, no matter how ‘trustless’ they may claim to be.”

To regain such trust, a disgraced delegate must start over building a new reputation capable of being elected.

Finally, the BitShares delegate architecture produces a useful by-product that we call “distilled trust”. Such trust is a useful commodity in its own right. For example, selecting software versions, publishing information feeds and choosing system parameters are functions that benefit from having trusted humans in the loop.

This enables products and services that are beyond the reach of first generation systems, no matter how “trustless” they may claim to be. Bitcoin inherently trusts the several large pool operators to faithfully run the software specified by its core developers who are themselves in positions of trust. Bitshares just makes this trust explicit, accountable and quickly revocable by BTS owners.



  • Bitcoin, ビットコイン
  • Blockchain, ブロックチェーン, ブロックチェイン
  • Bitshares, ビットシェアーズ
  • PoW, Proof of Work, プルーフ・オブ・ワーク
  • PoS, Proof of Stake, プルーフ・オブ・ステーク