Can blockchain blocks be deleted
on the other hand, all nodes (computers in short) participating in the network will store one account book, which is updated in real time. Even if one node fails, the blockchain will not be affected.
however, it's easy for people with an eye to see why there is no security layer? In fact, several key features of blockchain have already solved the security problem. First, the blockchain uses asymmetric encryption technology. In fact, encryption and decryption are different keys, namely public key and private key. In short, the public key is open to the public, while the private key is absolutely confidential
secondly, distributed bookkeeping is a way for blockchain to store data. It can also be understood as distributed storage, which is consistent with the concept of decentralization. In the form of ledger, there is no central ledger in the network, and the ledger is stored in each node. Each node is not only independent, but also can act as the central node. Therefore, the central node will not be attacked, leading to the loss of core books or data, and the whole network will not be paralyzed
moreover, tamper proof is the basic feature of blockchain. As long as the chain can not be modified, and can not be deleted. If it needs to be changed, based on the principle of transparency and openness, the whole network and all nodes need to be informed. Therefore, under the democratic mechanism, the possibility of tampering with data at will is very low. Therefore, blockchain technology is applied in various instries, such as finance, payment, traceability, games, etc., such as the network "universe", Tencent's "come together to catch the demon", and Zhongan Huanyu blockchain "Dr dragon hunt" are the safe and high-quality procts under the blockchain technology.
Art Instry
ascribe allows artists to declare ownership, issue numbered and limited edition works, and aim at any type of artwork in digital form. It even includes a trading market where artists can buy and sell through their websites without any intermediary services
legal instry
bitproof is the most advanced of many document time stamp applications emerging in recent years, which will make the traditional notarization method a thing of the past. Bitproof offers more services than versions including blocksgin and originstaemp, including one for intellectual property. Interestingly, bitproof recently cooperated with an it school in San Francisco to put their students' academic certificates on the blockchain, completely redefining how to handle and use diplomas and student certificates
development instry
colu is the first enterprise to allow other enterprises to issue digital assets. They can "token" all kinds of assets and make a profound impact on many people. Although the bitcoin wallet couperparty also allows the issuance of simple tokens and transactions among other wallet holders, the tokens of colu can be set with various states and types, and can be detached from or returned to the system. When the data stored on the blockchain is too large, the data can be stored on the BitTorrent network
network mutual aid instry
concentric mutual aid is the first blockchain network mutual aid platform to be implemented and applied. Technically, through blockchain and big data technology, the defects of traditional network mutual aid mode can be eliminated, and a new open and transparent network mutual aid platform can be established.
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
Let's suppose villagers Lao Wang and Xiao Li. Lao Wang borrowed some money from Xiao Li, who wrote it in an IOU signed by both parties. A few days later, Lao Wang denied the existence of borrowing money and claimed that Xiao Li forged the paper. Xiao Li can't argue because he finds it difficult to prove that Lao Wang actually owes him money
in this example, Lao Wang and Xiao Li are two nodes
now assuming the same scenario, there are many pairs of people trading with each other in the village. The only evidence for each pair is the IOU. If one party fails, it will be difficult to do so. Seeing this scene, the village head came up with a solution. He suggested using a common notebook for the whole village to record all the transactions. Due to the high prestige of the village head, the villagers unanimously decided to let the village head keep this important transaction book. Each transaction, the villagers go to the village head's home, let the village head witness and record, each transaction is written into a notebook, and then safely saved. That notebook can be called a database
because this notebook is very important, the village head locked it in the safe. However, there are always some problems. Sometimes, the village head will accidentally sprinkle ink on the paper, making some transaction records illegible. This is called a single point of failure. The thief knows that there is an important notebook in the safe of the village head's house. He tries his best to steal it. This is called hacking
until one day, the village head's son owed others a lot of money, so the village head secretly deleted his son's debt entry. In this way, the village head's son "does not owe money."
when the villagers knew this, they began to question the fairness and authority of the village head. So some people put forward a new idea:
abolish the power of the village head, which is called decentralization. Let all villagers keep a notebook, and the transaction records are copied and distributed, which is called distributed database. Therefore, if there are n people in the village, there are n notebooks, that is, n nodes. Every time there is a trade between any two people, all the people in the village get together and record it in their notebooks. And no one can cover the sky. This is called decentralization
they also decided that they would never delete the mentioned transactions from their notebooks, which is irreversible. For example, Lao Wang borrowed a sum of money from Xiao Li before, but in the twinkling of an eye, he wants to return the money. Then the transaction book will not delete the previous borrowing record, but write a new repayment record, so there are two records
next, let's try to break this rule. What if we bribe Lao Wang to change his notebook? It's not feasible, because the next time the villagers meet, they find that Lao Wang's notebook is different from everyone else's, so the villagers notice that Lao Wang may be engaged in an indescribable transaction, and decide to abolish Lao Wang's transaction record and kick Lao Wang out of the organization
What if you try to bribe all the villagers? It's too expensive
the characteristic of this model is that greedy people need to pay a lot to attack the rules. He will find it more profitable to follow the rules
a smart child in the village suggested that each transaction data be called "block" and linked into a "chain" in chronological order, which is called blockchain
