OurChain上的跨鏈流量設計與實作

跨鏈是指區塊鏈之間能夠互通，以達成價值的交換和轉移。單一區塊鏈都是獨立運作的，無法直接取得其他鏈的資訊。主要是因為區塊鏈只能讓鏈內的各節點資料維持一致以取得信任，並不能提供鏈與鏈之間的信任。因此，跨鏈技術要提供一種機制讓區塊鏈之間在跨鏈時資料同步，使鏈內的資訊與價值可以轉移到另一條鏈上，並且要達成最終性確保跨鏈交易不可逆。這種機制是一種第三方機制，要如何利用去中心化的第三方維持信任，同時在不干涉各鏈鏈內運作，來達成跨鏈的共識與最終性尤其重要。OurChain是少數能提供全局事件順序與決定性最終性來達到分散式同步的公共鏈。本論文利用OurChain的特性製作GrandChain，所有參與GrandChain協定的區塊鏈都能夠透過GrandChain達成決定式最終性並驗證其他鏈上的資料，達成跨鏈的資料同步。參與GrandChain協定不會減少各區塊鏈運作的自主性，所以不論任何區塊鏈都能夠參與GrandChain協定。並且，根據GrandChain協定，我們可以大幅改善跨鏈技術的效率及安全性，如流量控制、簡易支付驗證證明、原子交換智能合約等，達到所有跨鏈的需求。

關鍵字

跨鏈；區塊鏈；最終性；分散式同步； OurChain ；流量控制

並列摘要

Cross chain addresses the communication among blockchains to achieve value exchange and transfer. One blockchain runs independently and cannot directly access information from other chains. The main reason is that blockchain technology can only keep the data of each node consistent and provide trust within the blockchain, but it cannot provide trust among blockchains. Therefore, cross-chain technology should provide a mechanism for data synchronization among blockchains, so that the information and value in one chain can be transferred to another chain, and finality could be reached to ensure that cross-chain transactions are also irreversible. The mechanism is a third-party mechanism. How to use a decentralized third party to maintain trust and to reach consensus and finality among blockchains without interfering in the operation of each chain is particularly important. OurChain is one of few public chains providing global event ordering and deterministic finality to achieve decentralized synchronization. Thus, GrandChain is designed in this thesis based on OurChain. All blockchains participating in a GrandChain protocol can reach deterministic finality through GrandChain and verify the data on other chains to achieve data synchronization among blockchains. Participation in the GrandChain protocol also will not reduce the autonomy of blockchain, so any blockchain would like to participate in the GrandChain protocol. Moreover, with the advantages of the GrandChain protocol, we can greatly improve the efficiency and security of cross-chain technologies, such as flow control, simple payment verification proof, atomic swap contract, etc., to meet all cross-chain demands.