Lightning Labsの定義するLightning Network

Lightning Networkと言っても、その定義は曖昧だ。標準仕様書としてboltは存在するけど、例えばMITのLitは準拠していないし、言葉が一人歩きしてるんじゃないか。
とりあえず、最もgithubでもstar数が多く、スタンダードっぽい立ち位置になっているLNDを提供しているLightning Labsの定義を見てみる。

The Lighting Network protocol dramatically improves the scalabilty of blockchain currencies like Bitcoin by streamlining the number of nodes involved in each transaction. A typical on-chain Bitcoin transaction is transmitted, verified and stored by many thousands of nodes. This can mean significant fees and delays for users.

Lightning Network transactions involve a small group of nodes that link sender and receiver. These nodes are connected via "payment channels" established on the underlying blockchain. Payment channels leverage blockchain smart contracts to enable virtually unlimited cheap, fast transactions.



という記述。これはいわゆるpayment channelによって関係するノードを制限することを指すんだと思うんだけど、確かにって感じ。

how it works

A "channel" is essentially a virtual money tube that connects peers within the network

To create a channel, two participants assign funds on the blockchain into an entry which requires both parties to sign off in order to move funds to/from the entry. This requires a single on-chain blockchain transaction

これは特に特徴はないけど、もっとも単純な双方向payment channelの図で、multi hop paymentはここでは想定していないね。



An open platform developed by Lightning Labs that enables users with mobile devices to conduct blockchain and Lightning Network transactions quickly and easily. Neutrino provides “light clients” with security and privacy that weren’t available with previous light client concepts (such as Bitcoin’s BIP 37 bloom filters). The coming availability of Neutrino promises to dramatically improve both safety and usability for typical blockchain users on laptops, tablets and smartphones.


以前のコンセプト(BitcoinのBIP 37ブルームフィルタなど)では利用できなかったセキュリティとプライバシーを提供します

とある。ここで言う“light clients”はSPVのことを指す気がするけれど、だとすると確かにセキュリティとプライバシーには課題がある。

  1. Transaction monitoring(資金量の推測・購買動向把握等)
  2. Node間通信の盗聴
  3. Spv nodeへのdos攻撃
  4. 偽のblockの連携




Metered payments

With a practical, low-cost metered payment system for continuously delivered services (such as bandwidth, storage or streaming content), Lightning can enable more efficient service delivery and foster new business models.

これはstreaming serviceだね。現行のサブスクリプションを超える料金体型が構築できればイノベーションになる。

Currency Exchanges

By making it fast and cheap for traders to deposit and withdraw currencies from exchanges on an order-by-order basis, Lightning can minimize the funds held by exchanges, decreasing custodial risk for both users and exchanges.

これはliquidityのことを言っているとおもうんだけど、すっきりしない。個人walletと取引板でpayment channelを結ぶような形のこと?

High Volume Transfers

Can support high-volume transactions without significant infrastructure and networking costs.