Is the cross-chain of Cosmos and Polkadot the same thing? It is enough to understand the cross-chain article

Editor's Note: This article comes fromPolkadot Ecological Research Institute, reprinted by Odaily with authorization.

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Editor's Note: This article comes from

Polkadot Ecological Research Institute

, reprinted by Odaily with authorization.

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Of course, Cross Chain did not appear in the last two years. Cross Chain can be traced back to 2012, when Ripple Labs proposed a protocol called Interledger, which was designed to connect different blockchain ledgers. And realize the synergy between them, and its goal is to create a global unified payment standard and create a unified network financial transmission protocol.

To put it simply, the cross-chain brought by Ripple is more like a payment agreement. It sets up an automatically executed "middleman" to bring together the information of both parties to the transaction. Once the two parties reach an agreement, the transaction will be automatically completed. In fact, this This kind of cross-chain is more like a special smart contract later, rather than the cross-chain we are familiar with now.

Then, 8 years after the cross-chain was proposed, what kind of great changes have taken place in the cross-chain field, and where will it go? We try to analyze the development of cross-chain in depth through two cross-chain projects, Polkadot and Cosmos, for readers.

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What is a real cross-chain?

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1 Misunderstanding of cross-chain

Of course, when we talk about cross-chain, everyone may have heard this term, and it is not an exaggeration to regard it as a blockchain buzzword in 2020. After all, the blockchain world also needs some fresh stories to fill in the history As for smart contracts and public chains, it was a story 2 years ago, and cross-chains seem to be more in line with the grand goal of blockchain development, although this is indeed the case.

However, many people in the market seem to have some misunderstandings about cross-chain, and these misunderstandings have created a threshold for understanding what is real cross-chain. Therefore, let’s start with a few common misunderstandings.

A. Cross-chain means to exchange assets on the chain like exchanging positions?

When it comes to cross-chain, some friends may really think that cross-chain can transfer assets similar to Bitcoin chain to Ethereum through "cross-chain", just like swapping apples and pears on the table. This sounds amazing, but is cross-chain really so?

In the blockchain world, the cross-chain we often talk about is actually more like a relationship between RMB and US dollars. What does it mean? Cross-chain is like exchanging RMB into US dollars, euros or other currencies, and the intermediate exchange process is called For cross-chain, this is also the retained form of earlier cross-chain, but it is not a real transfer like barter exchange, but a peer-to-peer exchange of value.

B. The implementation path of cross-chain is very simple?

Perhaps many people will think that this is an extremely simple science and engineering project when they hear about cross-chain technology. After all, the literal meaning seems to be very simple, just like transmitting information from A to B, as long as the mobile phone or logistics It can be done, but in fact, for cross-chain, it is not so simple.

Even for the easy-sounding method of asset cross-chain, people have been groping for many years, trying to break through some problems and bottlenecks in different ways, but still haven't found a best or more universal way to accomplish this. a goal.

For example, we have seen the Bitcoin side chain mentioned a few years ago, in which two-way anchoring is a very important concept in the Bitcoin side chain technology, the purpose is to realize the cross-chain between Bitcoin main chain coins and side chain coins . Two-way anchoring allows the side chain to "know" whether a specific coin on the main chain is in a locked state, and unlock or destroy the corresponding number of side chains based on the locked state, which is like BTC "crossing" to the side chain, or vice versa , The side chain currency "crossed" back to the main chain, but the senior technicians still think that this method is too simple and there are even many security risks.

Therefore, cross-chain is not as simple as everyone thinks. In fact, it is much more complicated than we expected. This is why it has become a problem that the blockchain industry needs to tackle.

C. There is only one way to realize cross-chain?

This may be a common mistake made by most blockchain practitioners who do not know much about technology. They will think that there is actually only one cross-chain method of blockchain, and everyone is working towards a correct way, but believe that Through the explanation of the above two points, everyone will no longer think so. There are actually too many ways to realize cross-chain, but we collectively refer to them as cross-chain.

In the next section, we will explain in more detail the current common implementation methods of cross-chain, which I believe will make everyone feel enlightened.

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2 Ways to realize cross-chain

A. Centralized gateway cross-chain

As the name implies, this is a cross-chain method input by an authoritative organization’s external oracle (Oracle) mode. By introducing external forces to access the cross-chain, it is equivalent to using a third-party organization to complete the cross-chain action, just like transferring money through a bank. Like the system, although this method is more efficient, it also has some security risks.

B. Multi-signature custody cross-chain

Compared with the previous method, a group of authoritative institutions are added on the basis of a single centralization, and they vote to undertake the interaction of cross-chain data. This is similar to the parliamentary system, because the existence of multiple institutions further improves security. Sex, but relatively, efficiency is greatly reduced.

C. Mirror cross-chain

D. Light node cross-chain

Recently, a senior person in blockchain technology talked about a more interesting description of cross-chain. First, he gave a definition of consensus penetration. Consensus penetration refers to two blockchains with different consensus. Open up, let the two chains interconnect with each other, and finally realize the consensus cross-chain.

To sum up, we believe that the basic function of cross-chain is to realize the interaction of inter-chain assets, followed by information interaction. In terms of zooming in, what needs to be solved in cross-chain is actually the information transmission and interaction between the chain and the chain under the same consensus, but more In essence, cross-chain solves transactions between chains under different consensuses, and the way or technology that can solve this problem is called cross-chain.

Of course, this is only what we think is a relatively accurate definition of cross-chain, but with the development of blockchain, it is not ruled out that there will be more interesting descriptions.

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Why does the blockchain need cross-chain?

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USDT is currently the stablecoin with the highest market value and the most widely used range. It is the encrypted currency Tether USD (USDT for short) based on the stable value currency US dollar (USD) launched by Tether Company. 1USDT = 1 US dollar. Tether strictly abides by the 1:1 reserve guarantee, that is, for every USDT issued, its bank account will have a USD 1 fund guarantee.

And USDT is also issued on multiple blockchains after several twists and turns, from the initial issuance based on the Omni protocol, and then began to issue the ERC20 version of USDT on Ethereum, and then issued the TRC20 version of USDT on Tron, so It developed step by step and eventually became the third largest cryptocurrency by market value.

Since USDT is backed by corresponding U.S. dollars, USDT can be issued additionally with the increase in the number of guaranteed U.S. dollars. However, such situations often occur. For example, this year’s DeFi is hot, and many ERC20 USDTs on Ethereum have been issued. In all DeFi projects, the USDT of ERC20 is not enough. At this time, it is difficult to quickly raise a large amount of USD if additional USDT is issued urgently. Tether has no choice but to transfer the USDT on TRC20 to Ethereum to meet Market needs. The method adopted by Tether is to destroy part of the TRC20 USDT, and then issue the same amount of ERC20 USDT on Ethereum.

Later, some DeFi projects on TRON were gradually born, and it appeared that the TRC20 version of USDT on TRON was not enough. Therefore, Tether had to frequently transfer USDT on several blockchains back and forth.

This is a big pain point of the current blockchain. Data (that is, information and assets) cannot be transferred between blockchains at will. No matter how good the ecology of each blockchain is, it is only equivalent to a Cities that are well developed but cannot communicate with other cities, and this is an island of information.

And a good blockchain application is definitely not satisfied with only one blockchain, just like the USDT we just exemplified. Another way is to issue the encrypted asset LRN under another name similar to the Loopring protocol (LRC) on the NEO chain to expand the usage scenarios of the Loopring protocol on NEO.

Therefore, if there is a cross-chain technology that can interact with data from different blockchains, the teams of Tether and Loopring will not have to bother to toss back and forth on different chains. The original intention of Polkadot's design is to link all blockchains together, interconnect and interoperate, and finally form an interconnected network composed of multiple blockchains. It perfectly fits this demand. The blockchain application project applied on the Internet only needs to be issued on Polkadot, and the application can be extended to all blockchains.

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DeFi is hot this year, and Ethereum once again proved that it is the largest blockchain application platform in the blockchain field. During this DeFi feast, some old problems of blockchain have come to the fore again, making it difficult for us to ignore it.

At present, more than 90% of DeFi projects are on Ethereum. One of the results is that the transfer speed of Ethereum and ERC20 Token has slowed down, and the transfer fee has soared. The transfer Gas fee of Ethereum has remained high at an average of more than 500Gwei for a long time, and the highest has reached 1000Gwei, and this has seriously affected projects and organizations outside the DeFi ecosystem.

On the other hand, exchanges are also another victim. The high transfer fees make many exchanges lose a few dollars or more every time users transfer Ethereum and ERC20. Coinbase Pro, the largest cryptocurrency exchange in the United States, was overwhelmed, and finally issued an announcement to let users bear the network fees for transfers.

Improving performance, reducing transfer fees, and expanding the capacity of the blockchain are urgent needs.

The second category is off-chain expansion, such as what we often call Layer2 expansion, which is the expansion method of the two-layer network. As the name suggests, the second-tier network is to hand over the data on one blockchain to another network for processing, and then send it back after processing. It is also divided into centralized solutions, such as Bitcoin’s off-chain expansion solution - Lightning Network, and decentralized solutions, such as ChainX, which can cross Bitcoin over. The difference lies in whether the second network is Blockchain, whether the intermediate process is completed through smart contracts.

As a well-known cross-chain project, Polkadot's own architecture belongs to sharding, so there is no need to worry about the performance of Polkadot. On the other hand, Polkadot can link other parachains, and these parachains can spontaneously serve as the second-layer extension of certain chains. A chain to improve the performance of this chain.

3 Increase blockchain scalability

In the previous point, we mentioned that Polkadot’s parachain can be used as a second-layer network of some chains, so if this chain has attributes that the original blockchain does not have, more functions can be added to the original chain . If we make a two-layer network with smart contract function for Bitcoin on Polkadot, then Bitcoin can also have the function of smart contract.

4 Enrich the blockchain ecology

5 Protect the privacy of each chain

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6 Further refinement of business logic

In the future, each chain will have an independent business. When multiple chains are combined, the understanding and analysis will be relatively clear. For example, there are chains that focus on DeFi, chains that focus on games, smart contract chains that include Bitcoin, and Ethereum. Layer2 chains and so on, so cross-chains can make chains of different businesses also generate links.

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How is Polkadot's cross-chain achieved?

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We have introduced in previous articles that Ethereum 2.0 is a homogeneous shard, and Polkadot is a heterogeneous shard structure. As shown in the figure below, the main structure of Polkadot is composed of the main chain - the relay chain, and then connected to other Fragmentation - composed of parachains.

To clearly understand the structure of Polkadot, we need to understand the three important chains (relay chain, parachain and bridge parachain) and four important roles of the Polkadot structure.

Among them, the relay chain is the main chain responsible for handling the overall consensus and security in the network. The parachain is a shard that has the same consensus as the relay chain based on the Substrate framework. The transfer bridge parachain is due to some mature The underlying blockchains (such as Bitcoin and Ethereum) are different from Polkadot's underlying consensus, and cannot be directly connected to the relay chain. Therefore, the bridge is achieved by deploying smart contracts on Polkadot's parachains and external blockchains. effect to achieve cross-chain functionality.

The Polkadot network maintains four basic roles: Collectors (help validators collect, verify and submit alternative parachain blocks), Nominators (similar to Bitcoin miners), Validators (similar to Bitcoin miners) Pool, packing network blocks), phisher (to prevent network evil, responsible for reporting other roles).

Through these roles, and Polkadot's cross-chain messaging scheme (XCMP), data can be interacted between different blockchains.

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If there is such a scenario, I want to use 1 asset of parachain A to exchange 10 assets of parachain B with you, then if I compare parachain A to the United States and parachain B to Japan, it is equivalent to using If 10,000 USD is exchanged with you for 100,000 yen, then the entire cross-chain process is as follows:

I initiate a transfer in a bank in the United States to transfer $10,000 to your account in the United States, and the collector in the United States will indicate that I will transfer $10,000 to your account in the United States, and I beg your bank in Japan Transfer me 100,000 yen.

The collectors in the United States are going to pass this information along with the destination and time to Japan. The information will first be placed in the output queue in the United States. Following the chain this organization places the message from the outgoing queue in the United States to the incoming queue in Japan.

After the validator in Japan receives the information, the collector in Japan will implement the requirements in the information, and then transfer the 100,000 yen in your account to my account in Japan, thus completing the whole process .

The same path is mapped to the blockchain network. The United States and Japan are like different blockchains. In this way, the link between the two information isolated island networks is completed. The specific cross-chain implementation of Polkadot, the entire The process is all executed by blockchain and smart contracts, and inter-chain communication is achieved in a decentralized manner.

How is the cross-chain of Cosmos realized?

Although Polkadot is the current king in the cross-chain field, people often compare Cosmos as a powerful opponent of Polkadot. Therefore, we need to talk about the cross-chain composition of Cosmos from the same perspective.

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Similarly, Cosmos also adopts the relay chain method for cross-chain interaction, but Cosmos intends to provide a standard protocol (IBC) to allow other blockchains to enter the protocol to complete information interaction.

The information transfer between them is a protocol called "IBC" (communication protocol between blockchains) to transmit information. Readers can understand it as a unique coding mode in Cosmos, as long as you pass this coding. Confirmation is part of the Cosmos ecosystem, and secure information exchange is also possible.

Based on these underlying components and communication protocols, Cosmos has also developed a general framework called Cosmos SDK, which aims to create a module ecosystem that allows developers to easily create application-specific blockchains without having to start from scratch Write every function of the application, thereby greatly reducing the time spent by programmers on the underlying development of the blockchain.

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When it comes to how Cosmos specifically completes cross-chain actions, we still have to go back to its structural composition. Cosmos splits the blockchain into a consensus layer (Tendermint core), a network layer, and an application layer (Cosmos SDK). Developers have greater flexibility when developing various types of applications.

Therefore, the cross-chain method of Cosmos is actually to build a set of blockchain development framework by itself, so that other blockchains can develop on this framework, and satisfy their own applications such as BFT consensus algorithm or Cosmos SDK. The ideal state sounds interesting, but there is still a lot of distance from the real cross-chain, so it is still working hard on the "light node cross-chain" approach.

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The difference between Polkadot and Cosmos

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1 Core comparison between the two

In order to make it easier for users to understand the difference between Polkadot and Cosmos, we have made the following diagram:

2 The development status of the two

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Since the Cosmos project was established in 2015, it has not received varying degrees of attention from the industry. After all, as a leader in the cross-chain field, both the capital and the community have given great expectations, and its main network ushered in the launch in the first half of 2019.

But just half a year after the mainnet was launched, Zaki Manian, director of Tendermint Labs (the core development team behind Cosmos), publicly stated on Twitter that Jae Kwon (the founder of Cosmos) has been focusing on the Virgo project for the past 6 months. However, Cosmos' IBC development was ignored, and IBC was not provided with resources, resulting in a situation where many talented engineers left the company, which seriously under-resourced the core software team, and said that they would resign from the CEO position, which caused huge turmoil in the Cosmos community .

It is precisely because of the decline in the number of developers in the Cosmos community that the development of its IBC cross-chain communication protocol has been in a slow climbing stage, so the cross-chain goal has become out of reach, and now only a Cosmos SDK framework has come out.

Of course, in a sense, Polkadot’s cross-chain is to use XCMP to complete the message interaction between parallel chains, and it is also a cross-chain under the same consensus, which is still far from our ideal ultimate cross-chain (interaction of different consensus chains). , but according to the development path, it is in line with expectations.

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In terms of the functionality and development of cross-chain, we think that Polkadot is more like a real cross-chain at present, while Cosmos is still a pseudo-cross-chain, and its design is only at the level of transferring assets. The most important thing is that the Cosmos team is realizing the most The underlying asset transfer comes to a screeching halt. Although the original ideal was beautiful, the reality is very skinny, and the important task of cross-chain should be handed over to Polkadot to realize it.

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Although we have learned that there are many cross-chain methods, we prefer the cross-chain form designed by Polkadot, because many cross-chain technologies often only consider solving certain problems in a targeted manner so that a certain chain can be expanded, but This does not make the blockchain truly a so-called internet of value and internet of trust.

To carry the name of the Internet of Value, it must be a very large network, not just limited to a certain blockchain. The current public chain or consortium chain is just like a local area network. Only the one designed by Polkadot will All blockchains are interconnected and eventually form an interconnected network composed of many blockchains, which is more in line with this standard.

Of course, cross-chain solutions are by no means what we see now, and it is not ruled out that there will be more innovative ways in the future, but from the perspective of project evolution and blockchain development, cross-chain projects like Polkadot and Cosmos are all It is worth understanding, and as for who can become the "king of cross-chain" in the future, in addition to technical factors, the market and commercial implementation may also be considered, and this is the issue that the blockchain should be more concerned about at the moment. In subsequent articles, we will further explore such high-quality projects as Polkadot or the Polkadot ecosystem.

Special thanks: Thanks to PolkaWorld, the first Chinese community of Polkadot, for its content support.

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