BTC hash pointer
hash algorithm is a cryptographic algorithm that can only encrypt, but not decrypt. It can convert any length of information into a fixed length string
this string has two characteristics:
1. Even if the input value changes only a little, the output hash value will be very different
2. Only exactly the same input value can get exactly the same output value
3. There is no rule between the input value and the output value, so the input value cannot be calculated by the output value. In order to find the specified output value, we can only use enumeration method: constantly change the input value to find the output value that meets the conditions
hash algorithm ensures that the results of bitcoin mining can not be deced reversely. Therefore, the miner's continuous operation is essentially brutally cracking the correct input value. Whoever finds the first one will get the bitcoin reward.
In today's era of high development of the Internet, we are using the Internet more and more frequently, which has become an indispensable and important tool in our life. In particular, the mobile phone used for Internet communication has been used as a medium. In today's era, we are using mobile payment more and more, There are more and more ways to move. So what is digital currency? What do you know about it{ But generally speaking, it is a form of money< p> Finally, for such a form of transaction, it's all for the convenience of our daily life, and it's also for serving our own broad masses of people, so we don't have to worry about the advantages and disadvantages of digital currency and mobile payment
1 - data layer: data block, chain structure and time stamp
2 - network layer: P2P network, propagation mechanism, verification mechanism
3 - consensus layer: pow, POS, dpos
4 - incentive layer: issuance mechanism, distribution mechanism
5 - contract layer: script code, algorithm mechanism, smart contract
6-application layer: encapsulates various application scenarios
in the future, jinwowo group will focus on promoting the legal circulation and commercial application of big data with blockchain technology.
Hash algorithm maps any length of binary value to a fixed length of smaller binary value, which is called hash value. Hash value is a unique and compact numerical representation of a piece of data. If you hash a piece of plaintext and change only one letter of the paragraph, subsequent hashes will proce different values. It is computationally impossible to find two different inputs with the same hash value
message authentication code (MAC) hash function is usually used with digital signature to sign data, while message detection code (MDC) hash function is used for data integrity
the basic information of bitcoin network is as follows:
all digital currencies that need to be mined have hash values, such as Laite coin, Ruitai coin, doggy coin, Weimeng coin, Diandian coin, Yuanbao coin, etc< br />
[comedy + compare h bar]<
grandson of the slippery ghost
[so this is introced by a friend = v = I haven't seen it]
black cat
[male master is a killer, and he was called the terminator of hell later because he was influenced by Shaye]
holy mark of the wind
[absolutely recommended!! The handsome male protagonist is the contractor, controlling the wind is the wind warlock, while the female owner is the famous fire warlock family. Then they quarrel when they meet, but they have very good feelings. They are both arrogant. But later, another person who lives in the male owner's memory appears. The male owner of the weak and weak shrimp suddenly knows that his family has the power to become a robber. Then turn around and turn into a robber. It's very handsome
goblin's tail
[keep pushing. Magic. The painting style is beautiful, the plot is better, it's just a little hot, but you're sure to like it!]
leaves... If it's not enough, then you go to QQ, I'm telling you, I've seen animation ~ give me 0.0
The concept difference between hash table and linked list:
linked list is a kind of non continuous and non sequential storage structure on physical storage unit, and the logical order of data elements is realized through the pointer link order in linked list. The linked list is composed of a series of nodes (each element in the linked list is called a node), which can be generated dynamically at runtime
hash table is a data structure directly accessed according to the key value. It can access records by mapping the key value to a position in the hash table to speed up the search. This mapping function is a hash function. The array of records is called a hash table
special attention:
each node includes two parts:
one is the data field where data elements are stored
The other is the pointer field to store the address of the next node. Compared with the linear table order structure, the operation is more complex. One drawback of the chain storage representation of linear list is that it is very troublesome to find a number from the beginningthe basic idea of hash storage: take the keyword K of each element in the data as the independent variable, calculate the function value through hash function H (k), take the function value as the cell address of a continuous storage space, and store the element in the cell corresponding to the function value
java common collection system: