In January 2009, Bitcoin network based on blockchain structure came out quietly, which combined modern cryptography and distributed network technology and other important achievements. In the years after the emergence of Bitcoin, the Bitcoin network stably supported massive transfer transactions in a purely distributed scenario, which proved that the blockchain data structure solved the basic needs of distributed accounting, and distributed accounting technology based on blockchain structure began to appear in large numbers. With the latest information technology achievements being continuously integrated into the financial industry, Distributed Ledger Technology (DLT) based on Blockchain has emerged, and it has been explored and landed in some scenarios, such as cross-border payment. The core value of distributed ledger technology lies in providing a credible foundation for future multi-party collaborative networks. The evolution of bookkeeping technology triggered by blockchain will promote the change of business cooperation and organizational form.
2. Blockchain terminology
There are three important concepts in the realization of blockchain: a. Transaction is an operation on the account book, which leads to a change in the account book status, such as adding a transfer record. B. Block block is used to record all transactions and status results that occurred in a period of time, and it is a consensus on the current account book status. C. Chain chain is composed of blocks connected in series according to the order of occurrence, and it is a log record of the state change of the whole account book.
3. Implementation principle of blockchain
The goal of blockchain is to realize a distributed data record book, which can only be added and not deleted. The basic structure of the distributed ledger is a linear linked list, which consists of blocks connected in series, and the Hash value of the leading block is recorded in the subsequent block. Whether a block (and the transactions in the block) are legal or not can be quickly checked by calculating the hash value. Nodes in the network can propose to add a new block, but the block must be confirmed by consensus mechanism.
4. The blockchain working process of Bitcoin
The blockchain of Bitcoin works as follows: (1) The user initiates a transaction through the Bitcoin client, and the message is broadcast to the Bitcoin network for confirmation. Nodes in the network will package the received transaction requests waiting for confirmation together, and add the hash value of the previous block header and other information to form a block structure. Then, try to find a nonce string (random string) and put it in the block, so that its hash result meets certain conditions (such as less than a certain value). The process of calculating nonce string is commonly known as "mining". It takes a certain amount of computing power to find nonce strings. (2) Once a node finds a nonce string that meets the conditions, the block becomes legal in format and becomes a candidate block. The node broadcasts it in the network. After receiving the candidate block, other nodes verify it and find that it is indeed legal, so they recognize the block as a new legal block and add it to the local blockchain structure they maintain. When most nodes accept the block, it means that the block is accepted by the network and the transactions included in the block are confirmed. The blockchain work process of Bitcoin can be simplified into two key processes. One is to complete the consensus on a batch of transactions (creating a legal blockchain structure), and the other is to add new blocks to the blockchain structure and be recognized by the network to ensure that it cannot be tampered with in the future. Bitcoin’s consensus mechanism based on computing power (finding nonce strings) is called Proof of Work (PoW).Because there is no known fast heuristic algorithm to make the hash result meet certain conditions, we can only calculate the brute force of nonce values one by one. The more times you try (the greater the workload), the greater the probability of calculation. By adjusting the restrictions on hash results, Bitcoin network control generates a legal block in an average of about 10 minutes. The node that calculates the block will receive the management fee of all transactions in the block and the incentive fee fixed by the agreement (halved every four years). Anyone can join the Bitcoin network. If there are malicious nodes in the network, can malicious operations be carried out to tamper with the records in the blockchain, thus destroying the entire Bitcoin network system? For example, deliberately not recognizing the legitimate candidate blocks generated by others or simply rejecting the transaction requests from other nodes. In fact, because there are a large number of maintenance nodes (estimated to be thousands) in the Bitcoin network, and most of them are working normally, only the longest chain structure is recognized by default. As long as more than half of the nodes in the network do not collude in advance to take malicious actions, the longest chain will become the final legal chain with great probability. And with the increase of time, the probability will get bigger and bigger. For example, after six blocks are generated, even if half of the nodes unite to subvert the confirmed results, the probability is only (1/2) 6 ≈ 1.6%, that is, the probability is less than 1/60. After 10 blocks, the probability will drop to less than one thousandth. If most nodes in the whole network unite to do evil, the whole system can’t work normally.It often means paying a high price, which is often not worth the loss compared with the gains obtained by doing evil.
1. Technical characteristics of blockchain
The technical characteristics of blockchain are as follows: a. Distributed fault-tolerant distributed ledger network is extremely robust and can tolerate the abnormal state of some nodes. B. The data submitted by the consensus on non-tampering will always exist and cannot be destroyed or modified. C. Privacy-protecting cryptography ensures data privacy, and even if the data is leaked, it cannot be analyzed.
2. Business characteristics of blockchain
The business characteristics of blockchain are as follows: a. Trusted and willful blockchain technology can provide a natural and credible distributed ledger platform without the participation of additional third-party intermediaries. B, reduce costs Compared with traditional technologies, blockchain technology may bring faster transactions by automating contract execution, while reducing maintenance costs. C. Enhancing the security blockchain technology will be conducive to safe and reliable audit management and account settlement, and reduce the risk of crime.
3. Characteristics of distributed ledger technology
The characteristics of distributed ledger based on blockchain are as follows: a. Maintaining a growing chain, only records can be added, and once the records are confirmed, they cannot be tampered with. B, decentralized or multi-centralized consensus, without centralized control, as far as possible distributed in implementation. C, through the mechanism of cryptography to ensure that the transaction can not be denied and destroyed, and try to protect the privacy of user information and records.
1. Brief introduction of blockchain application scenarios
Blockchain technology has moved from simple technical discussion to the stage of application landing. A large number of companies and teams related to blockchain have emerged at home and abroad. A few companies have explored distinctive application scenarios in combination with their own businesses, but more companies are still in the stage of continuous exploration and verification. The suitable application scenario of blockchain must be analyzed from the characteristics of blockchain technology itself. Blockchain can provide decentralized, tamper-proof, safe and reliable characteristics without introducing third-party intermediaries. Therefore, all activities that directly or indirectly rely on third-party guarantee institutions can benefit from blockchain technology. At present, the blockchain application fields that have attracted much attention from investment mainly include financial services, credit reporting and ownership management, resource sharing, trade management and other fields.
2. Financial services
The potential advantages brought by blockchain include reducing transaction costs and reducing cross-organizational transaction risks. The blockchain application in the field of financial services is currently the most concerned, and many banks and financial trading institutions around the world are the main promoters. Some investment institutions are also applying blockchain technology to reduce management costs and control risks. However, when introducing blockchain technology, we should also pay attention to possible problems and risks.
3. Credit investigation and ownership management
Digital management of credit information and ownership is the dream of large social platforms and insurance companies. At present, the main technical problems in the field of credit information and ownership include lack of sufficient data and analysis ability, lack of reliable platform support and effective data integration management. Blockchain is considered to promote data transaction and flow and provide safe and reliable support. The threshold of the credit information industry is relatively high, and it needs the joint efforts of various resources.
4. Resource sharing
Sharing economy companies represented by Airbnb will welcome decentralized applications, which can reduce management costs. The theme of resource sharing field is relatively concentrated, and the design space is large, which has attracted a lot of investment attention.
5. Trade management
Blockchain technology can help automate cumbersome procedures and processes in the field of international trade and logistics supply chain. The trade management scheme based on blockchain design will bring great convenience to the participating multi-party enterprises. In addition, the digitalization of sales and legal contracts in trade, goods monitoring and testing, real-time payment and other directions may all become the breakthrough points of startup companies.