DOM Chain - The "New Player" in Cross-Chain Project

• The significance of cross-chain lies not only in the increase in the scalability of the blockchain, but also in the means of communication between different blockchains.

• Cross-chain solutions are mainly divided into three types: Notary mechanism, Sidechain/Relay, and Hashlock. The most mainstream cross-chain solution at present is undoubtedly the Relay Chain by Polkadot.

• Before the breakthrough in cross-chain technology, Polkadot will still be one of the most high-quality public chains in the cross-chain market.

1. Overview

Ethereum was officially launched in 2014, and its use of smart contracts marked a new milestone in the development of the public chain, and various types of decentralized applications (DApp) could be built on the underlying public chain. At the same time, the industry was stuck in the "Impossible Triangle", which has inspired various attempts to solve the problem. Among them, cross-chain is currently the most popular and widely used solution.

Note: The "Impossible Triangle" refers to the fact that the blockchain can only satisfy two of the three in terms of decentralization, scalability, and security. The improvement of one aspect means the sacrifice of other aspects.

Since 2016, the industry has begun an attempt to cross-chain, which is not only a solution to the "Impossible Triangle", but also a way to realize asset exchange and value transfer in different blockchains. The early form of cross-chain was the notary mechanism that Atomic Swap and Ripple (a payment project) proposed in order to increase transaction speed and realize the interconnection of different ledgers. The building of Layer-2 and sidechain expansion represented by BTC Relay are also the way to achieve cross-chain.

From the early stage of cross-chain, the main focus was to expand the capacity of the blockchain and improve transaction efficiency. Later, Cosmos, Polkadot and other projects dedicated to connecting different blockchains and realizing cross-chain ecology have emerged. Whether in technological or scenario applications, they have experienced a diversified development. From the perspective of industry development, cross-chain has transformative significance.

Generally speaking, the current cross-chain solutions introduced by the industry can be divided into four types: Hashlock, Notary mechanism, Sidechain and Relay mechanisms. The details of each solution are shown in the table below:

Current mainstream cross-chain solutions, source: tokeninsight.com

In the above cross-chain solutions, the Hashlock mechanism is relatively simple and has limited functions, so it cannot support cross-chain asset transfer and cross-chain smart contracts. The Notary mechanism has centralization risks due to its reliance on notary nodes. As an upgraded version of the Sidechain Pegged solution, the Relay mechanism is more advantageous in actual use. While Cosmos and Polkadot are sought after by the market, they have gradually built a comprehensive and good ecological network.

2. Mature Relay Cross-Chain Solution: Cosmos and Polkadot

Cosmos

Cosmos officially launched its mainnet in March 2019. Its goal is to create a network between blockchains. Under the premise of maintaining the sovereignty of each chain, it breaks barriers, builds bridges, and realizes cross-chain transactions and interactiveness between blockchains.

Cosmos has three important parts technically: Tendermint, Cosmos SDK and IBC. Tendermint is the consensus engine and BFT consensus algorithm. Simply put, Tendermint can ensure that transactions are recorded on different machines in the same order, and support any computer language to process transactions, saving time spent on development. Cosmos SDK is developed for the purpose of simplifying the process of building blockchain applications for developers. IBC is a communication protocol between blockchains that realizes the connection among the Zones in Cosmos.

Cosmos Hub is the first Zone in the Cosmos network. It is essentially a multi-asset distributed ledger designed for connecting Zones. The native token Atom is the only staking token on the Cosmos Hub, which gives holders the right to vote, verify, and delegate verification, but the transaction fee can be paid by any token. Atom adopts an inflation mechanism, and 1/3 of the total amount of Atom will be issued every year. At the same time, in order to maintain the transaction speed, the initial number of validators will be set to only about 100.

In the Cosmos ecosystem, applications such as Hard, Kava, and Iris have appeared. At present, the market value and user volume of DApps developed based on the Cosmos public chain are far smaller than those of Ethereum and Polkadot, indicating that the development of Cosmos is stagnant to a certain extent. However, the public chains that substrates on Cosmos SDK include Binance Chain, Terra and Lino, indicating that Cosmos SDK is currently one of the most popular blockchain development frameworks.

Polkadot

The three important roles in the Polkadot mechanism are Relay Chain, Parachain, and Bridge. They correspond respectively to those of Cosmos Hub, Zone and IBC in Cosmos. As the core of the Polkadot network, Relay Chain is responsible for the security of the network. Parachain can be connected to the Polkadot network for a long time or temporarily in the form of the Parathread. Bridge connects Parachain with the external blockchain networks such as Bitcoin and Ethereum.

The role design in the Polkadot consensus mechanism is more complicated, consisting of a Validator, Nominator, Collator, and Fisherman. The Collator provides proof for the Validator and the Fisherman is responsible for supervising the malicious behavior of the Validator in the network.

The role design of the Polkadot consensus mechanism can better ensure network security. Since the roles of the Parachain and Relay Chain in the Polkadot network are similar to the subchain and the fundamental chain, the security of the Parachain comes from the Relay Chain, and the Relay Chain theoretically has the final decision on the state change of the Parachain. Therefore, it is particularly important to ensure the security of the Relay Chain.

There are currently three networks in the Polkadot ecosystem, Polkadot, Kusama and Recoco. Among them, Recoco is a Relay Chain testnet, which can test the consensus mechanism on Parachains and the interaction between Parachains. Only tested Parachains can participate in the slot auction. Kusama is the first beta version of the Polkadot network. The two codes are similar but independent of each other. Compared with Polkadot, Kusama has a faster governance speed and a lower access card. Parachains need to go through Kusama's test before they are deployed on the Polkadot network. In this way, it can not only help the project to test the shortcomings of its own project or try and innovate the project, but also ensure the security and stability of the Polkadot network.

According to data from Polkaproject's official website, there are currently 459 projects running on Polkadot and 149 projects built on the Substrate platform. The ten most active projects in the ecosystem are: Polkadot, Phala Networ, Toystream, ChainX, Reef Finance, PolkaBTC, Ocean Protocol, Crust Network, Darwinia, Centrifuge.

There are 34 projects on Kusama, the most popular ones are Kusama and MathWallet. According to Polkadot's official disclosure, the first slot auction of Kusama will officially open at 12:00 GMT on June 15, 2021. Each auction lasts for a week, divided into a two-day auction period and a 5-day end period. There are a total of five auctions in this round, which takes 5 weeks, and then enters a period of rest, and then the next round of auctions.

Polkadot Relay cross-chain solution, source: Polkadot, tokeninsight.com

"New Player": DOM Chain

The success of Cosmos and Polkadot has attracted more developers to start participating in the development of cross-chain solutions, many of whom are imitators of the two and try to make certain improvements. DOM Chain is one of the imitators.

DOM Chain imitates BTY (BitYuan public chain) in the design of the system architecture. BitYuan was released in early 2014. It was originally a PoW version and converted to PoS in the second half of 2014. BitYuan is the first public chain network to implement parallel public chain technology. The DOM main chain corresponds to the BitYuan main chain, the Relay Chain corresponds to the BitYuan Relay Chain, and the Cloud Chain corresponds to the Parachain in the BitYuan network. The cross-chain of public chains such as Ethereum adopts the form of transfer bridge, and the cross-chain of Bitcoin adopts Hashlock. Based on the DOM main chain, developers can simultaneously expand multiple parallel cloud public chains, and each cloud public chain can develop independent Dapps. As the current project ecology is still in the development stage, DOM-based DApps are also still under development.

Unlike Cosmos and Polkadot, the Dom Chain mainnet adopts the SPoS (Safe PoS) consensus algorithm. In this consensus algorithm, every main node that is normally online may become a bookkeeping node. SafePoS has a higher degree of decentralization. At the same time, the accounting and block generation are performed among 9 nodes. Therefore, the efficiency is higher than that of PoW and PoS algorithms. Unlike other public chains that use asymmetric encryption systems, DOM uses proxy re-encryption to encrypt information. In short, it makes the private keys of others accessible to unlock the ciphertext encrypted by our public key that can only be unlocked by our own private key originally. This process is called proxy re-encryption.

In terms of data structure, traditional public chains such as Ethereum use Merkle Tree or Merkle Patrcia Tree to store transaction data in the block, while Dom uses MVCCKVDB (Multi-Version Concurrency Control KV Data Base), which speeds up data read and write and improves the capacity of blockchain for carrying transactions.

DOM system architecture, source: DOM, tokeninsight.com

At present, from the perspective of the market value of circulation, compared to other mature cross-chain projects, DOM is still in the early stage of operation of the testnet, and there are no projects or demos deployed on the public chain. Due to the lack of ecology, the market value on its testnet is currently only about 5% of that of Cosmos, which is still some distance from the actual application, and its user community is still under construction.

Comparison between DOM and current mainstream cross-chain solutions, source: tokeninsight.com

Summary

In general, since there is no breakthrough in cross-chain technology in the market today, the Polkadot solution is still the mainstream for cross-chain public chain development. Other cross-chain solutions are more based on the compatibility and imitation of Polkadot and Cosmos solutions. More developers tend to develop DApps on cross-chain public chains, that is, the development of parachains, which has resulted in the popular Polkadot slot auction market. However, due to the diversity of the Ethereum ecosystem and strong liquidity, many users have not yet become accustomed to cross-chain asset interaction, and the demand for cross-chain is not too great.

However, with the increasing number of Defi users, coupled with the auction of parallel slots, more cross-chain applications will be connected to the Polkadot mainnet. Before the breakthrough in cross-chain technology, Polkadot will still be one of the most high-quality public chains in the cross-chain market.