Cross-chain technology for connecting different blockchain introduction __ Blockchain

If the consensus mechanism is the core of the soul of the blockchain, then for the blockchain, especially the alliance chain and private chain, cross-linking technology is the key to realize the value network, it is to save the alliance chain from the separate isolated islands to rescue the medicine, is the blockchain outward expansion and connection of the bridge.

Since Bitcoin was born seven years ago, hundreds of competing coins have been developed, with new strengths and features, but the dominance of bitcoin remains the same, and many of the copied competition coins have been obliterated in history. Although Bitcoin has many shortcomings and limitations, but Bitcoin is the most centralized, the most distributed nodes, the most equitable blockchain, from the status of digital currency, the number of nodes, to the authority of the center and other aspects of Bitcoin is still very advantageous. At the same time, the blockchain like Ethereum, bit shares in technology and applications from behind, a significant threat to the Bitcoin blockchain, and bitcoin-based applications because of the difficulty of development more limited, so the application of a few. In order to innovate at the same time, but also to retain the Bitcoin network to the central protection, the side-link technology is introduced. The side chain is a new blockchain based on anchor Bitcoin, which realizes new financial ecological targets and further expands the application scenarios of the Bitcoin network in a converged way.

On the other hand, while the blockchain public network of encrypted digital currencies is flourishing, the alliance chain and private chain technology are widely adopted by commercial organizations, especially financial institutions, based on the consideration of transaction performance, capacity scale, privacy protection and regulatory compliance. Compared to the public chain, now the development momentum of the alliance chain is much more dazzling, but we need to be vigilant, do not let the alliance chain into a purely centralized or multi-centric, compared to the traditional blockchain design technology, now most of the alliance chain obviously does not provide too much to achieve irreversible transactions or reduce the risk of central to the way, These centralized trusts will cause the chain of alliance chains to be at risk due to network censorship and simple failure points. In contrast, in the framework of a public network blockchain, such as Bitcoin, once a transaction has been confirmed that no one can change, no court enforcement orders or a small number of participants are entitled to freeze funds or impose fines. For the alliance chain, regardless of the subjective group evil or because of the non-anti-censorship or multi-node failure and other risks, so that their users can not completely trust and rest assured. Elwin that the alliance chain and the private chain of the way from a certain extent against the blockchain to the central value and trust system, but also the blockchain within the digital assets can not be transferred directly between the different blockchain, active or passive led to the value of the island, the various links to different blockchain cross-chain technology has also been people began to pay attention to and explore.

At present, the cross-chain technology in the blockchain is still in the research and trial, and is not used in the scale, Elwin try to introduce some current research cases of relevant technology.

one, side chain

The side chain is a new blockchain based on the anchoring of bitcoins, just as the dollar is anchored to gold bars. Side chaining is the goal of implementing crypto-monetary financial ecology in a converged way, rather than rejecting existing systems like other cryptocurrency. Using the side chain, we can easily establish a variety of intelligent financial contracts, stocks, futures, derivatives and so on. You can have thousands of anchor-to-Bitcoin side chains, with different characteristics and purposes, all of which depend on the elasticity and scarcity of Bitcoin's main blockchain support. On this basis, the side-link technology further expands the application scope and innovation space of blockchain technology, so that the traditional blockchain can support multiple asset types, small micro-payment, intelligent contract, security processing mechanism, real-world property registration and so on, and can enhance the privacy protection of blockchain.

The more famous Bitcoin side chain is the Consensys BTC Relay, rootstock and Blockstream element chains, non-bitcoin side chains such as Lisk and domestic Asch.

The BTC relay is a smart contract based on the Ethereum blockchain that connects the Ethereum network to the Bitcoin network in a secure, centralized way. BTC Relay allows users to verify Bitcoin transactions on the Ethereum blockchain by using the Ethereum Smart Contract feature. BTC Relay uses a chunk header to create a small version of the Bitcoin blockchain, and Ethereum Dapp developers can make API calls from the smart contract to the BTC relay to verify the Bitcoin network activity. BTC Relay makes a meaningful attempt to communicate across blockchain, opening the channels for different blockchain exchanges.

Rootstock is a distributed platform of intelligent contracts built on the bitcoin blockchain. Its goal is to implement complex smart contracts as a side-chain that adds value and functionality to the core Bitcoin network. Rootstock implements an improved version of the Ethereum virtual machine, which acts as a side-chain of bitcoin, using a convertible token that can be converted to Bitcoin as the "fuel" of a smart contract.

Element chain is an open-source side-chain project of Blockstream, using bitcoin bidirectional hook technology, the goal of the side-chain protocol is to achieve two-way anchoring (two-way Peg), so that Bitcoin can be in the main chain and the side of the cross-link. The element chain quickly brings many innovative technologies to Bitcoin, and in addition to the smart contracts, he has quickly brought many innovative technologies to Bitcoin, including private transactions, evidence separation, relative lockout time, new opcode, signature overlay amount, and more. These techniques can be applied to any side chain in any combination.

Lisk is a new generation of blockchain platforms that add each application to the Lisk's individual side chain. With Bitcoin and ethereum friends know that because Bitcoin and Ethereum have only one main chain, all the functions and data added to this main chain caused the rapid expansion of chunks, large chunk volume, ultra-long synchronization time, this is a very painful experience. The side-chain mode of Lisk provides a method for solving the problem of network congestion under high transaction volume, and the user only needs to download the corresponding side chain when the relevant application is used, which greatly reduces the invalid synchronization data, and maintains the efficient operation of the whole Lisk network, and The speed of the Lisk network will continue to accelerate over time, and the more it shows his particular advantage.

Second, M2

Notarial (Factom) uses blockchain technology to innovate the data management and  methods of the Business society and government departments, and the core is to establish the non-changing audit notarization business process on the blockchain. Factom was originally a data deposit through the Bitcoin network, and later through the M2 function, while integrating the Bitcoin and Ethereum blockchain to make sure that the data is always secure and trustworthy.

The M2 function presumably is that Factom integrates all the data in the network into items or chains. User data is stored in an entry, and the chain interacts with the entry to create an interactive collaboration. Each chain has an entry block, which in turn generates a new one every 10 minutes. At the end of 10 minutes all new entry blocks for all chains are integrated into a directory block, then embedded in the bitcoin and Ethereum blockchain. If there is no new entry for a chain within 10 minutes, the chain does not add new entry chunks.

Factom the significance of doing so can make their data storage not just dependent on the bitcoin ledger a single blockchain, is a meaningful exploration as a link to multiple public links.

Third, Polkadot

Polkadot Technology, a third generation of publicly unlicensed blockchain technology launched by the Ethereum Core development Ethcore (parity technology), is designed with the core concept of instant extensibility and extension to address the challenges of today's two major block chain technology transmission and acceptance.

Polkadot plans to incorporate the private chain/alliance chain into the public-chain consensus network while preserving the privacy and licensing protections of the private chain/alliance chain. It gives us a whole new layer of trading and has the opportunity to connect hundreds of blockchain links to each other.

The core idea of Polkadot is to differentiate the way in which a trader initiates and executes a transaction and the way in which the counterparty records it. POLKADOT provides the underlying relay chain (Relay-chain), which is based on a number of verifiable, globally dynamic synchronous data architectures that are parallel or side-chained. Blockchain applications can fork the Ethereum, adjust to their needs, connect to the Ethereum public chain via Polkadot, or set different functions for different chains to achieve better scalability and efficiency.

Polkadot is currently based on Ethereum to achieve its interconnection with the private chain, and other public chain network as an upgrade target, and finally let Ethereum directly communicate with any chain.

Iv. Other

Cross-chain identity authentication platform: Technology giant Microsoft has partnered with Startups Blockstack Labs and Consensys to build an open source identity certification platform to integrate bitcoin and Ethereum blockchain. They use Consensys's uport to ensure interconnection with the Ethereum blockchain, and then integrate the platform and Bitcoin blockchain with Blockstack Onename. This cross-chain solution can be extended to all future blockchain, or new decentralized distributed systems.

Ethereum Alliance Blockchain Network: Microsoft is about to formally release the Ethereum Alliance Blockchain Network based on Ethereum technology, and enterprise users will be able to quickly deploy private, semi-private, or community Blockchain (Consortium blockchain) networks, or through Azure to deploy a common ethereum node. Microsoft hopes the project will help the industry unite to create more complex alliances to better leverage the network effect of immutable shared books, and Microsoft's overall goal in this service is to help the global industry build blockchain alliances.

Multichain:multichain is backwards-compatible with Bitcoin, so users can import existing Bitcoin applications to Multichain. Instead of supporting a single chain like the Bitcoin kernel, Multichain can be configured to support different blockchain at the same time in the same network. Multichain can support many third-party assets, enabling private blockchain and Bitcoin blockchain to be converted to each other.

Dragon Chain: The Dragon chain is a blockchain platform that blends public/private blockchain with strong interoperability with other public and private blockchain chains. Dragon Chain Blockchain has a total of five levels of various types of nodes, in any one level of node validation processing, you can choose to connect with other blockchain and contact. For example, the first layer is a business node, used to process transactions and can determine whether a transaction is approved or rejected, if you want to provide a more centralized implementation, you can choose to use the Bitcoin network or other based on the POW consensus mechanism of the blockchain to achieve the consensus processing of transactions.

Conclusion:

Blockchain technology is decentralized database and distributed ledger technology, from the commercial level is the value network, in this value network, the more effective nodes and distribution of connections, the potential value of the superposition will be greater. Blockchain is the core infrastructure of value network space, blockchain application should not only be confined to and stop in the Alliance chain application, will value circle in a small scope, we need cross-chain technology, the different blockchain to connect and expand, build Value Network highway. Author: Gao Zhihao (Weibo.com/elwingao)