Shulou(Shulou.com)06/02 Report--

Introduction: in the previous article, I analyzed the origin of Substrate framework and its relationship with ETH and IPFS. This article will deeply reveal the technical architecture between Substrate framework and cross-chain network Polkadot, explore the reason why Polkadot is called "the king of cross-chain", and analyze the importance of cross-chain communication and distributed technology for future applications.

Blockchain technology has entered the next stage. The Substrate framework, led by the former ethernet CTO, allows developers to build their own blockchain. "one-click hair chain" is no longer a dream. The Polkadot block chain network based on this framework has become the most anticipated cross-chain solution, and Polkadot is also known as the King project. Under the background that a new round of reform of Internet science and technology begins quietly, what on earth are Substrate and Polkadot, and is their technical architecture really unnatural? Why did they appear and what problems did they solve? How will the integration with IPFS technology make the evolution of blockchain technology?

Run away from Ethernet Square and create another Miracle

Speaking of Etay Square, many people will think of Vitalik Buterin. In fact, one is the soul of Etay Fong-Gavin Wood (Gavenwood), a doctor of computer science and a hidden god in the real world. He co-founded the etheric Fong project with God V and served as the Technical Director of CTO. Gavin Wood invented the Solidity language to write smart contracts, which is the biggest difference between ethernet and bitcoin. The introduction of smart contracts made Taifang explode completely.

Photo: Gavin Wood has 13, 000 followers on Github

Leaving Ethernet Square, Gavin Wood co-founded Parity Tech with partners such as Dr. Jutta Steiner, who served as director of security and audit. They developed the Substrate project, a powerful blockchain cross-chain development framework to help developers build their own blockchain using next-generation technologies.

Key problems encountered in existing block chain technology

Including the existing three main blockchain systems: Bitcoin, Ethernet Square, EOS, etc., each blockchain project, user, miner, DApp, etc., form an independent ecological kingdom, which is separated from each other. In a sense, they violate the promise of the decentralization of blockchain and make the Internet more closed and isolated, which seriously restricts the development of blockchain technology.

There are five key problems in the current blockchain technology stack: the first is the lack of scalability, lack of interoperability and developability, and the development of DApp decentralized applications is limited, so it is difficult to apply on a large scale. Secondly, governance sacrifices the interests of most people, the monopoly of computing power and the rights and interests of super nodes, and the interests of most scattered users / miners are actually abandoned. Finally, there is the isolation between blockchain networks, which has existed for a long time from the beginning to the present.

Cross-chain to open the value exchange channel of block chain

The so-called cross-chain (Cross Chain) is the technology of value exchange in different block chain networks. Why is the interworking between blockchain networks so important? Because it can break the isolation of existing networks and establish the exchange of assets on the chain of multiple networks. Crossing the chain is like digging the Panama Canal to quickly connect and merge two unfamiliar waters.

In many ways, the challenge of interoperability and scalability of blockchain is interrelated, cross-chain let two blockchain networks successively play a role, each platform to achieve interoperability, and improve the overall throughput to enhance scalability.

It looks good, but cross-chain solutions also have technical difficulties:

First: how to ensure the atomicity of cross-chain transactions?

Second: how to confirm the transaction of another chain?

Third: cross-chain trading, how to maintain the invariance of total assets?

Fourth: how to ensure the network security of the two chains?

Fifth: how to realize the cross-chain interconnection between multiple chains?

In order to solve the above technical problems, many solutions have emerged in the blockchain industry.

1. Transaction atomicity

HTLC (Hash time Lock contract) is an implementation of atomic exchange protocol, which ensures the atomicity of transactions through hash locking and time locking mechanisms.

two。 Transaction confirmation

The blockchain is closed and independent, and there is no direct communication channel. Cross-chain transaction how to confirm that the transaction of the sending chain does take place and is confirmed? The answer is "middleman". Information is exchanged through the role of "middleman", which can be a node or a group, a centralized organization or a distributed group. The existing solutions mainly include the following: notarization mode, relay mode, side chain mode.

▶ notarization model: the "middleman" of the notarization model not only collects data, but also confirms and validates transactions. According to the way of verification transaction, it can also be divided into the following types: centralized notarization scheme, multi-signal notarization scheme and distributed signature notarization scheme.

▶ relay mode: the "man in the middle" of the relay mode only acts as a data collector and forwards the collected data to the target chain. The target chain validates the transaction based on the collected data. Verification methods vary according to the structure of the system, such as relying on SPV authentication, or relying on the number of signatures of verification nodes. Relay mode is a relatively decentralized and loosely coupled way, which has higher scalability. There are many cross-chain implementation schemes for relay mode, such as Cosmos Hub, Relay chain in Polkadot (described in more detail below), Relayer in BTC-Relayer, etc., all of which act as relays.

▶ side chain mode: side chain mode is a strong coupling design. The two chains collect each other's data through "middlemen" and embed the data directly into their own blocks or storage space in some way. In cross-chain transactions, transaction verification can be done directly through the original chain data stored in its system.

3. Total assets remain unchanged

In order to ensure that the total amount of assets remains unchanged, it is necessary to ensure that the asset transfer process is accurately calculated on two chains. In other words, it is necessary to ensure that: 1) the atomicity of cross-chain transactions, whether it occurs or not. 2) the cross-chain transaction is real and effective on both chains, the transaction is confirmed by the whole network, and the possibility of fork is very small. Therefore, under normal circumstances, difficulty 3 is solved as long as difficulty 1 and difficulty 2 are solved.

4. Independent security

There are basic security and independence considerations in different cross-chain implementations, and each scheme is generally associated with it.

5. Cross-chain interconnection

This problem contains two potential problems: first, how the existing blockchain systems achieve interconnection and interoperability. Second, how to prepare and pave the way for the interconnection of block chains developed in the future.

Block chain frame Substrate of one-button hair chain

Substrate is the next generation block chain technology framework. Gavin Wood once said, "In the future, trusting an institution with our interests will be as archaic a concept as reckoning on an abacus is today." Its meaning is "in the future, trusting an institution that is in our interests will become an ancient concept, just like using an abacus today." If you want to break down the barrier, get rid of the old and the new, and establish cross-chain communication, a strong technical framework design is essential.

The main technical features of Substrate are as follows:

● creates a perfect custom block chain for enterprises

○ creates a blockchain with a strict privacy level

○ light client (Light Client) preferred design for mobile applications and the Internet of things

○ network is almost unbifurcated and upgradeable

Among them, Light Client (light client) allows decentralized access to the blockchain and interacts with the network without synchronizing the complete blockchain. The aim is to simplify transaction verification, that is, instead of downloading every transaction and block, you only need to download the first-class data of the block, such as the hash value of the previous block head, timestamp, proof random number, root hash value, and so on.

Based on the next generation technology of ●

○ is based on the industry standard WebAssembly architecture

○ highly Scalable Libp2p Network

○ is fast and reliable based on Rust integration.

○ supports the secondary development of Javascript

○ 's Wasm WebAssembly interpreter written in Rust

Here is an extremely important technology: WebAssembly (abbreviated as Wasm), a joint project developed by Mozilla, Google, Microsoft and Apple, can be written in non-JavaScript programming languages and run on browsers. It can be seen as an enhancement to JavaScript (not yet a replacement) to make up for the shortcomings of JavaScript in execution efficiency. It executes low-level binary syntax through Web, compiling high-level languages (Cregorian + and Rust) to WebAssembly so that it can be run in a browser. It is characterized by geometric performance improvement, fast flexibility and portability. In 2015, the big four browser vendors (Chrome, Firefox, Edge, Safari) all supported WebAssembly by default, and this technology later made a splendor in the field of front-end high-performance development.

Breakthrough in ● Security and Extensibility

○ WebAssembly intelligent combination

○ multi-level permissions

○ transaction and status double encryption

○ restricts asynchronous invocation options

○ account-level locking

○ governance tools and methods (such as voting systems)

Overview of ● technical components

Network Libp2p

Consensus algorithm hybrid PBFT / Aurand

Random beacon Collective coin flipping

Verification algorithm Edwards-Curve Ed25519

Hash algorithm Blake2b

Address format Versioned Base-58 + Blake2b check

Among them, Substrate has an extremely powerful algorithm-Blake2b hash algorithm. What are its advantages? In the past, encrypted digital currencies such as bitcoin mostly used SHA-1 hash function as the running algorithm, but this algorithm was found to have security problems by cryptographic experts, so cryptocurrency gradually began to use blake2b algorithm instead of SHA-1 algorithm.

Speed comparison of BLAKE2 Hash algorithm

Blake2b is considered as the hash function with the highest safety factor at present. The algorithm was released in 2012, and the BLAKE2 hash algorithm has been used by package managers for OpenSSL, WhatsApp, and FreeBSD since then.

Polkadot: the King of Cross-chains

Open source Substrate itself is a framework and platform that is available to everyone. In order to better support the connectivity between blockchain networks, it is necessary to build a new blockchain network. Polkadot is a cross-chain solution designed to solve the above problems. It uses the typical cross-chain technology mentioned above, that is, relay technology. Polkadot was developed by a team led by Gavin Wood based on the Substrate framework.

In the architecture of Polkadot, the construction technology is mainly divided into parallel chain, relay chain and transfer bridge.

Parallel chain: application-based customization chain

Parallel chain (Parachains) is a block chain parallel to Boca network. Each parallel chain can independently design its own architecture according to different business requirements. Flat necklaces can also be used for concurrent transactions to improve scalability, which ensures its security by connecting relay chains.

Trunk chains: connecting and verifying parallel chains

The trunk chain (Relay chain) can connect the Boca network and the parallel chain, and ensure the security of the communication between the two, which can be a transaction or any form of data.

Transfer bridge: connecting heterogeneous external chains

Bridges is a special parallel chain, which allows Boca network to communicate with external independent block chains, such as BTC and ETH, without passing the security verification of the trunk chain.

Parallel chain can be regarded as a highly scalable solution in Polkadot network. Parallel chain does not have the ability to identify blocks, so it needs to be verified by trunk chain. As a trust agent, relay chain participates in the communication between polkadot network and parallel chains, which ensures the security of communication and can also achieve risk isolation. The transfer bridge serves other external block chain networks with independent security verification mechanisms. These chains have their own consensus and blocking mechanisms, such as BTC or ETH networks, which communicate directly with the polkadot network through the transfer bridge.

In addition, Polkadot defines several roles that are necessary for the protocol to operate:

1. Validator: validates and finalizes parallel chain candidate blocks, adds them to the trunk chain blocks, and receives token rewards

two。 Collector (Collators): collect parallel chain transactions, put them into candidate blocks for proof of validity, and charge transaction fees

3. Fishermen (angler): acts as an inspector, fishing for all kinds of improper behavior on the Internet, and receives part of the deposit of various malicious operators as a reward

4. Nominee (nominator): have the right to vote, nominate who to become the verifier, to ensure the security of the verifier.

Polkadot is a network protocol that can pass any data (not just tokens) to all blockchains. This means that it is a true multi-chain application environment, making similar operations such as cross-chain registration and cross-chain computing possible. Polkadot can pass data to public, open, public blockchains and private or federation chains. Makes it possible to build applications that obtain license data from the private chain and use it on the public chain.

In Polkadot, Parachain (parallel chain) is the key construction technology, which refers to the use of chain relay to achieve the interaction between block chains. Polkadot has shared security to avoid other cross-chain double-flower transactions. Parallel chains are also universal, and there are no unnecessary restrictions and constraints. Here, due to the role of parallel chains, between block chains is like having an Internet.

The emergence of parallel chain Parachain is regarded as the evolution direction of the next generation block chain technology.

Polkadot + IPFS = unlimited possibilities

Markov, a famous Russian mathematician, has a famous saying: "any progressive system is also open." There are no isolated technologies and there are no isolated engineers in the world. Otherwise, the possibility of its development will be lost.

The reason why Polkadot has become the king of cross-chain among many solutions is largely due to its openness. Its basic Substrate framework is open source, and at the bottom, it is also applied to the protocol of the next generation Internet-IPFS. The interstellar file system is a decentralized, peer-to-peer, distributed hypermedia transmission protocol. The Polkadot network (and the Substrate framework) uses the IPFS underlying core Libp2p protocol.

Libp2p is a modular P2P protocol stack positioned as a standard for future decentralized applications, a flexible cross-platform network framework for peer-to-peer applications. Can handle the discovery and communication of peers in the Polkadot ecosystem. Now many networks have adopted Libp2p technology. Such as EOS, Ethernet Square 2.0 (in progress), Substrate (Polkadot), Agoric, Filecoin (IPFS incentive layer).

For the development of science and technology, we can not talk about technology in isolation from the specific application scenarios. In the IPFS application retrieval layer, IPSE network can integrate the Parachain parallel chain technology of Polkadot. The IPSE main chain is responsible for value settlement based on DPos, while the parallel chain is mainly responsible for value transactions. All transactions between parallel chains can be executed immediately without fear of conflict.

For example, there are now 10 parallel chains that can achieve the same security and perform 10 times as many tasks. IPSE is a search engine based on IPFS, and Filecoin is both a storage layer and an official incentive layer. IPSE is mainly responsible for search, while Filecoin is responsible for storage. The underlying storage of both depends on the IPFS interstellar file system. The introduction of parallel chain allows IPSE to obtain the most efficient solution for data storage and transaction operations with Filecoin.

The vision of Polkadot development is to provide the most powerful platform for interoperability, security, scalability and innovation. According to the official roadmap, the network will increase to about 100 parallel chains. IPFS is a point-to-point distributed hypermedia transmission protocol. The decentralized distributed storage network constructed by IPFS is expected to be composed of global distributed nodes, and its main network will also be online in Q2/Q3. Both represent the pinnacle of cross-chain technology and peer-to-peer distributed technology, and may change the existing blockchain technology and applications.

Reference:

[1] Github: Substrate

[2] Polkadot:A scalable, interoperable & secure network protocol for the next web

[3] Medium:Cross-chain Technology and Polkadot,by LongHash-Dot

[4] Polkadot Lightpaper:A scalable, interoperable & secure network protocol for the next web

[5] IPSE:A Distributed Search Engine Based on IPFS

[6] Filecoin:A Decentralized Storage Network

[7] what are trunk chains, parallel chains and bridges in Polkaworld:Polkadot?

[8] WebAssembly technology

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