How to exit blockchain
This situation must be timely feedback to customer service, to retrieve
if bitcoin is stored in the account of the exchange, all the coins are in the big account of the exchange. If the exchange stops trading or goes bankrupt, all the coins belong to the actual controller of the exchange (the person who has the key of the big account)
therefore, if there are official problems in the exchange, we must contact the official customer service in time to retrieve them. In addition, digital assets, blockchain and other technologies will have unpredictable effects, and problems in the development process need to be standardized
extended information:
people who really own bitcoin do not store them on the Internet, but store them on the hard disk. Bitcoin's code is open source, which means that technicians can modify the code to proce a continuous stream of virtual currency
which breaks through the "limited amount" attribute of bitcoin. These virtual currencies can be exchanged with fiat currencies. For example, bitcoin can be exchanged into yen, and yen can be exchanged with almost all fiat currencies in the world
in this case, if the number of virtual currencies increases arbitrarily, there will be problems in the whole international monetary system. Therefore, on September 4, 2017, the central bank stopped the exchange function of the token trading platform, especially the exchange function with legal tender
(1) distributed ledger, that is, transaction bookkeeping is completed by multiple nodes distributed in different places, and each node records complete accounts, so they can participate in monitoring the legitimacy of transactions, At the same time, they can testify together
different from traditional distributed storage, the uniqueness of distributed storage of blockchain is mainly reflected in two aspects: one is that each node of blockchain stores complete data according to block chain structure, while traditional distributed storage generally stores data in multiple copies according to certain rules. Second, the storage of each node in the blockchain is independent and has the same status, which relies on the consensus mechanism to ensure the consistency of storage, while the traditional distributed storage generally synchronizes data from the central node to other backup nodes[ 8]
no single node can record the account data separately, so as to avoid the possibility that a single bookkeeper is controlled or bribed to record false accounts. In theory, unless all the nodes are destroyed, the accounts will not be lost, so as to ensure the security of the account data
(2) asymmetric encryption and authorization technology, the transaction information stored on the blockchain is public, but the account identity information is highly encrypted, which can only be accessed under the authorization of the data owner, thus ensuring the data security and personal privacy
(3) consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and achieve a balance between efficiency and security
the consensus mechanism of blockchain has the characteristics of "the minority is subordinate to the majority" and "everyone is equal", in which "the minority is subordinate to the majority" does not completely refer to the number of nodes, but also can be the computing power, the number of shares or other characteristics that can be compared by computers“ "Everyone is equal" means that when the nodes meet the conditions, all nodes have the right to put forward the consensus results first, and then directly recognized by other nodes, and finally may become the final consensus results. Taking bitcoin as an example, the workload proof is adopted. Only when more than 51% of the accounting nodes in the whole network are controlled can a nonexistent record be forged. When there are enough nodes in the blockchain, this is basically impossible, thus eliminating the possibility of fraud.
(4) smart contract, which is based on these trusted and tamperable data, can automatically execute some pre-defined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and reliable, it is easy to carry out automatic claim settlement in some standardized insurance procts
coinbase transaction is a special transaction that generates bitcoin "out of thin air". Only miners can write this kind of transaction, and the number of generated bitcoin is limited by rules (new currency reced by half for every 210000 blocks + transaction fee for this block)
however, the rules do not stipulate that the miner must take away all the rewards that can be taken, and can choose not to take them
therefore, a mine pool connected with the RSK side chain has made a bug before, forgetting to take away the reward and occupying a pit in a block for nothing, which is equivalent to destroying the corresponding amount of bitcoin, making the total amount of bitcoin decrease a little bit permanently
in addition, to spend a bitcoin, you only need to specify the transaction ID and output serial number
as like as two peas in multiple blocks repeatedly write identical coinbase transactions, the transaction ID is also repeated.
therefore, this kind of situation also occupies the pit of a block in vain, and permanently destroys the corresponding amount of bitcoin
it seems to me that this is still a security vulnerability, so the new version of bitcoin software later banned the writing of repeated coinbase transactions. But until now, there has been no ban on miners not getting their e rewards
generally speaking, a coin is controlled by a private key. If a coin is transferred to an address where no one knows the private key, it will be destroyed
if the owner does a good job in security, and the private key is not disclosed and cannot be guessed, but he accidentally loses the private key, it is equivalent to destroying all the coins he owns
there are only some special circumstances that require intentional destruction of coins
one is irreversibly converted into another kind of currency, such as the contract currency XCP attached to bitcoin and wormhole cash WHC attached to BCH
the second is to save certificates and data on the chain, such as the time stamp: panbiao.com/2013/08 /
and the crowd funding of the original Ethereum founding team: zhuanlan.hu.com/p/29
the private key is essentially a big number. Whoever knows this number can control the currency on the corresponding address. So the private key must be generated with reliable random number, otherwise it may be guessed and stolen
compared with the token, the address is the hash of the public key. There is no way to judge whether an address has a corresponding public key and private key (even if the public key is known, the corresponding private key cannot be known). Therefore, even if it is explicitly the address of "burned" token, the system does not prohibit the transfer in
strictly speaking, what locks the currency is a small program (script). This program takes the input as the public key and digital signature. First, check whether the public key hash is consistent, and then check whether the digital signature is valid. If it is valid, it will be verified and transfer is allowed; Otherwise, it will be judged that the transaction is illegal and refuse to package into the chain
it is the whole node software that explains and executes this program. It can be said that the software code of the whole node specifically defines a coin
however, the current situation is very embarrassing. Most miners do not run the whole node, only a few mines are running. The vast majority of users do not run the whole node, even if they run the whole node, they can only perform verification, no computing power, no block
Pure blockchain technology can also be applied in non-financial fields. Here are some examples of blockchain technology application:
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cross center sharing of provident fund blacklist
ant financial blockchain and Huaxin Yong build "cloud platform of joint dishonesty punishment and deposit proof", Hainan province takes the lead in sharing the black list and deposit certificate of provident fund across centers and regions through the platform -
business service blockchain platform
the platform uses blockchain technology to open the service mode of "all-weather, zero meeting, one click" and applicants can apply for business license through the "blockchain + AI" platform, which takes only one and a half hours -
Jingdong Logistics creates a blockchain traceability platform with one click traceability of beef and mutton
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there are many areas where blockchain technology can be applied, and it does not have to be related to digital currency. Cryptography focuses on blockchain information< br />
The way in which people keep accounts together is also known as "distributed" or "decentralized", because everyone keeps accounts, and the accuracy of the account book is determined by the program algorithm, not by an authoritative organization
this is the blockchain, the core is finished, blockchain is so simple, a common account book
six core algorithms of blockchain Technology:
blockchain core algorithm 1: Byzantine agreement
the story of Byzantine is like this: the Byzantine Empire has great wealth, and the surrounding 10 neighbors have been around for a long time, but the Byzantine walls stand tall and firm, No single neighbor has been able to successfully invade. Any single neighbor's invasion will fail, and at the same time, it may be invaded by other nine neighbors. Byzantine Empire's defense ability is so strong that at least more than half of its ten neighbors attack at the same time before it can be broken. However, if one or several of the neighbors agree to attack together, but betray in the actual process, then the invaders may be annihilated. So each side was careful and could not easily trust its neighbors. This is the question of Byzantine Generals
blockchain core algorithm 2: asymmetric encryption technology
in the above Byzantine agreement, if several of the 10 generals send messages at the same time, it is bound to cause confusion in the system, resulting in different attack time schemes and inconsistent actions. Anyone can send the message of attack, but who will send it? In fact, it only needs to add a cost, that is, only one node can spread information in a period of time. When a node sends a unified attack message, each node must sign and seal to confirm its identity when receiving the message from the initiator
blockchain core algorithm 3: fault tolerance problem
we assume that in this network, messages may be lost, damaged, delayed and sent repeatedly, and the order of receiving is inconsistent with the order of sending. In addition, the behavior of nodes can be arbitrary: they can join or exit the network at any time, they can discard messages, forge messages, stop working and so on, and they may also have all kinds of human or non-human failures. Our algorithm provides fault tolerance for consensus system composed of consensus nodes, which includes both security and availability, and is suitable for any network environment
blockchain core algorithm 4: Paxos algorithm (consistency algorithm)
the problem solved by Paxos algorithm is how a distributed system can reach an agreement on a certain value (decision). A typical scenario is that in a distributed database system, if the initial state of each node is consistent, and each node performs the same operation sequence, then they can finally get a consistent state. In order to ensure that each node executes the same command sequence, it is necessary to execute a "consistency algorithm" on each instruction to ensure that the instructions seen by each node are consistent. A general consistency algorithm can be applied in many scenarios, which is an important problem in distributed computing. There are two models of node communication: shared memory and message passing. Paxos algorithm is a consistency algorithm based on message passing model
blockchain core algorithm 5: consensus mechanism
blockchain consensus algorithm is mainly workload proof and equity proof. Take bitcoin as an example. In fact, from a technical point of view, POW can be regarded as a reusable hashcash, and the generation workload proves to be a random process in probability. When mining a new secret currency and generating a block, the consent of all participants must be obtained, and the miner must obtain the pow work proof of all data in the block. At the same time, miners have to constantly observe and adjust the difficulty of this work, because the requirement for the network is to generate a block every 10 minutes on average
blockchain core algorithm 6: distributed storage is a kind of data storage technology, which uses the disk space of each machine through the network, and forms a virtual storage device with these scattered storage resources, and the data is stored in every corner of the network. Therefore, distributed storage technology does not store complete data in each computer, but stores the data in different computers after cutting. It's like storing 100 eggs, not in the same basket, but separately in different places. The total number is 100. Want to learn more, you can make more use of network search, network search results - small knowledge