? Blockchain, originally a blockchain, is a growing list of records, called blocks, which are linked and protected by encryption technology. Each block usually contains the encrypted hash, timestamp and transaction data of the previous block. According to the design, the blockchain is inherently resistant to data modification. It is "an open and distributed ledger, which can effectively, verifiably and permanently record the transactions between the two parties". In order to be used as a distributed platform R, the blockchain is usually managed by peer-to-peer networks that jointly abide by the protocol for verifying new blocks. Once recorded, the data in any given block cannot be changed retroactively without changing all subsequent blocks, which requires the collusion of the majority of the network.
In short, the blockchain system includes the following elements:
Data: The data stored in the blockchain can be information such as transaction records or smart contracts;
Block: used to save data; A block has a block header, which contains the hash value of the block, the hash value of the previous block header, time stamp, block ID and other information;
Chain: Blocks form a linked list. The first block is called the creation block, and the following blocks are added to the chain as described above, and can only be added but not deleted.
Distributed: It is a distributed system. Different from other distributed systems, each node in the system will save complete data (some practices may be different, but at least most nodes).
Security: the data will not be tampered with, and each block records the hash value of its previous block. If the content of a block changes, its hash value will also change, that is, all blocks after the block will be modified. In addition, all nodes store complete linked lists. If it is possible to change a single node, it is basically difficult to change all (most) nodes. It's easier to break one chopstick than to break a hundred chopsticks.
Transparency: the operation of any node will be perceived by other nodes, and the data in the existence chain will be verified, further providing security and mutual trust.
Decentralization: there is no central node or key node, which provides high reliability, but there is also the consistency problem of distributed system. Now different products use different consistency algorithms, such as POW in Bitcoin, POW+POS in Ethereum and so on.
From the technical characteristics of blockchain, it can be seen that it is suitable for some scenarios that need to cross organizations/individuals.
semi-finished product