How to let hundreds of billions of ecology quickly enter Polkadot, and see the magical power of the transfer bridge


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Since the cover report of the world-renowned magazine “The Economist” The Economist in 2015, “Blockchain: a machine of trust”, the blockchain can be said to have been plugged in with flying wings and advancing all the way, but the road seems to be uneven. , The middle is bumpy, even now, there are still many technical or commercial problems that plague the development of blockchain.

In 2017, the blockchain was based on the premise of breaking through the TPS setting, which has troubled the industry for one or two years. Everyone went on to claim how good their TPS is. Each company also relied on the data to compete for its position in the industry. But by 2019, it seems that No one emphasized TPS anymore, just like “the emperor’s new clothes”, everyone fell silent.

But what thoughts did TPS really leave behind?

Everyone suddenly understood that although it is not a good choice to deliberately compete with TPS, the performance problem before everyone is a real gap, so everyone started looking for a new way out, whether it is Bitcoin or Ethereum. People hope to expand some of their originally set parameters through some innovative ways, especially Ethereum 2.0 is the most prominent.

In contrast, there are some smart developers who have discovered another way to expand the performance of the blockchain, that is, the heterogeneous cross-chain we see in Polkadot now, which is different from the way of widening a road. Polkadot is clever The method of increasing lanes is used to solve the performance problem, thus opening the door to a new world of cross-chain.

At the same time, the cross-chain happened to solve another problem that plagued everyone-“information islands”. After all, in the past few years, each blockchain has worked hard in its own ecology, but with half the effort, Polkadot is solving performance problems. Under the premise of, it seems that various “closed and closed countries” blockchain ecology can be opened up, and this is a new world…

What is a transit bridge?

1 Revisit the Polkadot architecture

We know that the important role of Polkadot’s heterogeneous cross-chain function includes the relay chain, as well as the matching parachain and transfer bridge. Of course, we have introduced the concepts and functions of the three in more detail in the previous article. Under the narration, it is easy for you to understand.

Among them, the relay chain is the main chain responsible for handling the overall consensus and security of the network, and the parachain is based on the Substrate framework and has the same consensus as the relay chain, so Polkadot’s cross-chain The essence also belongs to the category of “sharding”, but the direction is different.

At the same time, most of the calculation work in the Polkadot network will be entrusted to each parachain for processing, and the parachain will be responsible for the realization of specific business scenarios, but the security still comes from the provision of the relay chain. Parachains can communicate with each other through XCMP (Cross-chain Message Passing). Therefore, parachains and relay chains are very important roles in the Polkadot network.

So what exactly does the third role, that is, Bridge?

2 What is a transit bridge?

First of all, we need to make it clear that Polkadot is ultimately to achieve the function of heterogeneous cross-chain, what is heterogeneous cross-chain, as the name implies, enables interaction between blockchains with different architectures.

At present, the basic framework of Polkadot’s parachain code has been basically completed, and the cross-chain between parachain and parachain, because everyone is formed by the same framework, the cross-chain between them is actually an isomorphic cross-chain, and Heterogeneous cross-chains are like mature blockchains. For example, Bitcoin and Ethereum have crossed to Polkadot. Because they are different from Polkadot’s underlying consensus, they cannot be directly connected to the relay chain.

Therefore, the transit bridge acts as an intermediate role. It is a parachain between the Polkadot relay chain and the external chain. On the one hand, it makes the relay chain feel that the external chain is a parachain. Smart contracts are deployed on the parachain and external blockchains to allow the relay chain to interact with other blockchains that are not compatible with Polkadot in order to achieve cross-chain functions.

According to the literal meaning, the bridge itself is a large structure used to cross obstacles. To be precise, it is used to cross traffic routes or other facilities over natural obstacles (such as rivers, straits, canyons, etc.) or artificial obstacles (highways, The structure of the railway line), so it is quite appropriate to use it in Polkadot ecology.


In a more popular analogy, the bridge is the converter, like Polkadot is the Apple system, and its cable is also the interface of the Apple system, and other chains are like the Android device, the USB3.0 interface, if you want to connect to On Polkadot, you need an Apple-Android adapter to connect, and this adapter is the adapter bridge.

Comprehensive analysis, the transfer bridge can be understood as a special kind of parallel chain, mainly to allow those mature blockchain projects with their own ecology to access the Polkadot ecology, and this is not only for Polkadot, but also for those that originally have it. For their own ecological projects, it provides an excellent way to expand.

The meaning of transit bridge

1 Expand the performance and functions of the original blockchain

As we mentioned earlier, due to the relatively early development of some blockchain networks and the limitations of technology and industry development, the logic envisaged in the initial development is somewhat inconsistent with the current market. Because of this, there will be something like Bit Solutions such as the Bitcoin Lightning Network, Bitcoin’s side chain RSK, and Layer2 were produced.

However, as we have seen, in fact, many solutions do not seem to completely solve some blockchain development problems. Therefore, the ceiling of their ecological development has also become criticized, and the setting of the bridge in the Polkadot network can allow the already well-developed blockchain network to connect to a larger ecosystem, especially for developments like Bitcoin and Ethereum. For a blockchain network that is long enough and has a sufficiently rich ecology, it is even more significant.

In the middle of this year, DeFi was not affected by the epidemic, and Compound emerged as a new force. Then many DeFi projects emerged in an endless stream, causing a sudden outbreak of DeFi. And such an outbreak has brought DeFi’s entire asset scale to more than 10 billion US dollars. Although this is already a milestone achievement, there is also one of the most important roles missing in such a lively DeFi, that is Bitcoin, which has a market value of more than 300 billion US dollars. If Bitcoin funds can enter the DeFi ecosystem at will, it will be a win-win situation for Bitcoin and DeFi.

Some projects in the Ethereum ecosystem have also seen this opportunity, such as wBTC that issued BTC on Ethereum in a centralized manner, and renBTC issued in a decentralized manner. But in this way, BTC is still trapped in the ecology of Ethereum (just as 90% of DeFi is on Ethereum this time), and it will also be affected by the performance and development of Ethereum itself. Therefore, Bitcoin needs a more There is a scalable ecology to integrate it with DeFi.

And through Polkadot’s transfer bridge, we can connect Bitcoin and Polkadot ecology. On the one hand, we can give Bitcoin the function of smart contract through the smart contract module of the parachain, and on the other hand, we can enjoy the Polkadot sharding mechanism. Performance improvement.

So Bitcoin is like this, and other blockchains will also get the same advantages, all of which are based on the role of “bridge”.

The “network effect” brought by 20,000 chain interconnection

Recall that when we first started using WeChat, there were not many people. Everyone’s main friends were still on QQ. Later, more and more people used WeChat, and everyone gradually couldn’t do without WeChat. In the process, we actually felt what network effects are.

When we look back on the development of the Internet, we have to mention the word “traffic”. As the backbone of the Internet’s development in the past 10 years, traffic has used a data to win many Internet giants, and the deep meaning behind it is: when a network (or More and more users are used in products), the more valuable it is, which brings about network effects, which is also the valuation logic behind Internet traffic companies.

And this kind of network effect is not only applicable to the Internet, but also to the blockchain. As we all know, the blockchain does not have very mature products, and the number of users is poor. Even the lively DeFi products have just broken through 100. Ten thousand, and it is a collection of all DeFi products, not a single product.

Therefore, the blockchain world urgently needs to produce the “network” that produces network effects first. The so-called “collection of the strengths of hundreds of families” and the significance of building a large ecosystem is that the bridges in the Polkadot network can connect countless (in theory) The Polkadot consensus blockchain network brings the foundation for the formation of network effects.

If it was not a relatively unified Internet protocol that was produced and recognized, perhaps the Internet is still like a local area network, which can only be used to fight landlords and play chess, and the blockchain is also at this stage. The current development of various blockchains is always in a relationship of independent development or competition, just like EOS is challenging ETH. Even if ETH is big, there will be projects competing with it.

But Polkadot is doing a different direction. Polkadot is a more open and inclusive project. What it wants to do is the underlying infrastructure of each blockchain to link each blockchain into a larger network. From this point of view, ETH and Polkadot are not in a competitive relationship at all, and Polkadot can inclusively link ETH to its own ecosystem through a transfer bridge. Even Cosmos, one of the so-called cross-chain duo, currently has projects for Cosmos. Development of the transfer bridge to Polkadot.

Once Polkadot connects all high-quality projects in a cross-chain way, a huge network effect will be formed. In the future, new blockchain projects will definitely want to join the Polkadot ecosystem, which is like a new online game. I want to borrow Tencent’s traffic. And this network effect is the moat of Polkadot, and it will also be the most fundamental reason for Polkadot’s endurance.

Overview of Polkadot Transition Bridge Ecological Project

Note: Some of the projects introduced in this section are self-positioned as transit bridges, and some have some functions including transit bridges, which does not mean that all projects are transit bridges. Secondly, the projects introduced here are not all projects in the transition bridge niche. The selected projects are more representative and do not represent any investment advice. Our purpose is to let everyone know what kind of layout each project party has in the niche of the transition bridge, so as to better understand the development of the entire Polkadot ecology.

1 Bitcoin on Polkadot: PolkaBTC

Bitcoin is the largest cryptocurrency by market value and consensus. Naturally, there are many projects that hope to integrate Bitcoin into the Polkadot ecosystem. Interlay is such a team. Interlay, which has received a grant from the Web3 Foundation, plans to launch Polkadot’s first trustless packaged Bitcoin PolkaBTC in early 2021. This is a key step for Polkadot to move towards a true cross-chain (interoperable) ecosystem.

Users can mint the Bitcoin-anchored asset-PolkaBTC on Polkadot 1:1. Once this step is completed, as we said before, Bitcoin can be introduced into the DeFi ecosystem. This is indeed the case. The Interlay team has received olive branches from a number of Polkadot ecological projects, hoping to add PolkaBTC to their ecosystems, including Acala, Larminar, Equilibrium, Polkaswap in the DeFi sector, and Plasm Network in many other sectors. , Edgeware, Moonbeam, Chorus One, etc.

Therefore, this project can be said to be highly anticipated. After all, the significance of Bitcoin access to Polkadot is so extraordinary that it is evident that the official personally wrote an article to introduce PolkaBTC.

At present, according to the roadmap provided by Interlay, the first Alpha testnet is planned to be launched in November 2020, and a fully functional Beta testnet (including oracles and XCMP inter-chain information transmission) will be launched in January 2021. Once the code base audit is completed in February 2021 and parachains are enabled on Polkadot and Kusama, BTC Parachain will go live: first on Kusama, then on the Polkadot mainnet.


2 Kusama wants to become regular?

We mentioned in the previous article that the Polkadot team’s expectation for Kusama is that in the future it will become a parallel relay chain network and formally link into the Polkadot ecosystem, not just a test network.

The way to become positive is to connect Kusama to the Polkadot ecosystem through a transfer bridge. At present, this work is indeed being done by the Bridge Team in Parity Tech, one of Polkadot’s main R&D teams.

This was clearly mentioned in the Polkadot Decoded, the first Polkadot community meeting on December 3rd, which paved the way for the potential value of Kusama. For details on the progress of Kusama’s transit bridge, we need to wait for the official follow-up to be more detailed Disclosure.

3 ETH is also the highlight

Ethereum is currently the largest blockchain application platform. Naturally, many project parties are considering adding Ethereum to the Polkadot ecosystem. In August this year, the software development company Snowfork announced that they are establishing Polkadot and Ethereum ( The transfer bridge between ETH) finally transmits direct smart contract instructions. The initial implementation is very simple. It will allow the transfer of Ethereum and ERC20 tokens to Polkadot. Snowfork has currently received Grant support from the Web3 Foundation.

In addition, Polkadot and Cosmos, EOS, ZCash and other blockchain projects are also planning or under development.

4 List of projects with bridge function

A. The pioneer of asset cross-chain: ChainX

As for ChainX, which first started to study Polkadot, and used Substrate to launch a blockchain earlier than the official chain (ChainX was launched on the mainnet in May 2019, the official Kusama was in August 2019), asset cross-chain has been It is their positioning, just like their name, which means that they can link any asset.

In 2019, ChainX realized the cross-chain of BTC to ChainX, which means that as long as ChainX can obtain the Parachain slot of Polkadot, it also has the function of a Bitcoin transfer bridge. And in the same year, ChainX added the smart contract function, which means that the Bitcoin crossed to ChainX can already use smart contracts. This is the first project to implement this function.


ChainX, which is positioned as a cross-chain asset, has made great efforts in cross-chain mode. ChainX has been iterating on Bitcoin custody, which is mainly divided into 5 stages:

1) Trust node management multi-signature address

2) An independent trustee manages the BTC custody address, everyone can do trust (similar to the effect achieved by Interlay)

3) Trustless custody scheme based on MPC (multi-party secure computing, a privacy computing technology), the multi-signature mechanism does not rely on smart contracts, and theoretically can be connected to any chain

4) Based on the third escrow plan, the upgraded user holds the master encrypted private key fragment, which strengthens the security of the escrow system

5) Homomorphic encryption to achieve decentralized custody

The continuous upgrade of the Bitcoin custody method is used as the basis for further cross-chain. While upgrading the Bitcoin custody method, ChainX will use Bitcoin as a mortgage to generate all other currencies, including Ethereum. ChainX is called mirror cross-chain, just like the vision In the future, its goal is to realize that all types of blockchain assets can be crossed to ChainX.

B. Non-multi-signature cross-chain practice: Darwinia (Darwin)

Darwinia is a blockchain game to enter Polkadot, and now it has expanded many applications including Polkadot block explorer, DeFi, NFT and cross-chain functions based on Substrate-developed decentralized transfer bridge. In the field of transfer bridges, it proposes an innovative universal cross-chain transfer bridge solution Darwinia Relay. This solution is different from the general multi-signature solution. It does not rely on the participation of third parties. Instead, it solves the cost and performance problems of ordinary Light Client by implementing a Super Light Client on the chain that uses a special MMR data structure. And realized cross-chain verification.

In November this year, the one-way transfer bridge from Ethereum to Darwinia was successfully released. In the future, Darwinia will use its cross-chain advantages to promote the DeFi, GameFi applications and NFT cross-chains in its ecology to more mainstream blockchains.

C. Use the transfer bridge to give Libra a privacy function: pLibra

In June 2019, Facebook proposed the U.S. dollar stable currency Libra based on a basket of currencies (Libra was recently renamed Diem and positioned as a stable currency backed by a single U.S. dollar), which shocked countries and started to accelerate their central bank digital currencies. the study. If Facebook’s Libra can land smoothly, its more than 2 billion users around the world will directly enjoy the convenience of cryptocurrency. Such a huge impact is why countries attach great importance to this matter.

And Phala Network, a privacy project in the Polkadot ecosystem, is eyeing it. Because if Libra is implemented, many people will use Libra for payment, but we do not want our various data, including fund usage, to be controlled by Facebook, so protecting privacy is an important requirement.

The Phala Network is a project that uses the trusted execution environment (TEE) in the CPU and the blockchain, and thus realizes the function of a confidential smart contract. Phala Network customized a Libra to Polkadot transfer bridge for Libra, and in the process, added privacy protection functions, which can protect Libra user data privacy through decentralized means. This example is using the transfer bridge A case of adding specific functions to the original chain.

Regarding the introduction of the above projects, some readers may say after reading that there are several BTC cross-chain and ETH cross-chain companies. Is it enough to just recognize one?

In fact, this is not the case. The blockchain itself is a decentralized and open environment. There is no unique bridge for the cross-chain of the Polkadot ecology. For us (Polkadot Ecological Research Institute), we pay more attention to the later operation of the project. Whoever can finally run out, no matter the black cat or white cat, as long as it catches the mouse, it is a good cat. Of course, it is also possible that these projects have all come out. Then there are several cross-BTC or cross-ETH chains on Polkadot, and they are not conflicting. Instead, they may usher in a state of blooming flowers.


On December 8, the founder of Polkadot (Polkadot) Gavin Wood mentioned in the Element chat room about the online order of parachain related matters, specifically:

1. Launch Rococo v1 and wait for its stable operation;

2. Online Kusama’s system (public interest nature) parachain;

3. Open the auction on Kusama;

4. Go online Kusama to successfully bid on the parachain;

5. After the audit is completed, the public interest parachain of Polkadot will be launched;

6. Open the auction on Polkadot;

7. Launch the Parachain that successfully bids on Polkadot.

As in many of the projects we have introduced today, it is necessary to wait for the parachain to be launched and the slot bidding to let their function as a bridge truly land. Therefore, they are all staring at the development progress.

Therefore, in addition to the realization of an important function for Polkadot, the bidding of parachains means that Polkadot has officially opened the cross-chain function. This is a great news for Polkadot itself, and for many cross-chain functions that are needed For the Polkadot ecological project, it is a major benefit for the implementation of the project. Under this dual role, it is believed that early next year, the Polkadot ecology will set off a new upsurge. After all, there are now more than 300 teams around the world doing things related to Polkadot.

Special thanks: Thank you to PolkaWorld, the first community of Polka Chinese, for your content support.

Reference materials:

1. To understand Polkadot, first figure out these 3 concepts

2. Bitcoin will soon be connected to Polkadot!

3. How does the interoperability of parachains, transit bridges and oracles change the future? | Polkadot Decoded

4. The Darwin mainnet staking, which was missed in the last round, can be boarded again!