The difference between public key and private key of blockchain

2. I'll give you my address (address). You can find my zip code (public key). You can write to me with my zip code (public key) + address. The mail will be sent to my mail cabinet. I'll open the mail cabinet (private key) with the key I have
1. The mail cabinet is stolen (the database is stolen)
2. The key is stolen (the private key is stolen)
3. Knowing my home address (the public key is stolen), the mail cabinet lock is opened violently (the private key is cracked violently).

3. Today, I'd like to show you what you don't know about social workers...
in the embryonic stage
before 2006, social work in our province had not been included in the scope of work of Party committees and governments at all levels
with the increasingly frequent exchanges in the field of social services between Guangdong, Hong Kong and Macao, some social service institutions in Guangzhou began to explore social work practice since the 1990s. For example, Fengyuan street in Liwan District of Guangzhou cooperated with neighborhood counseling association to provide social work services to meet the needs of residents for community services; Guangzhou old people's home cooperated with Hong Kong Sheng Kung Hui to introce professional social workers to implement social work services for the elderly in homes; Some social organizations such as Guangzhou YMCA also try to introce social workers to accumulate practical experience< On the other hand, social work ecation started. Since 1999, South China Agricultural University, Guangdong Business University, Sun Yat sen University, Guangzhou University, Guangdong University of technology and other universities have set up social work programs
the social work service practice explored by social forces and the development of social work professional ecation have laid a certain foundation for the start of social work in our province< In 2006, after the Ministry of Civil Affairs held the national civil affairs system social work talent team construction promotion meeting in our province, our province quickly launched the pilot exploration, graally built social work demonstration areas in all parts of the province, strengthened the decision-making and coordination on major issues of social work, and steadily promoted the pilot work. Comprehensive promotion stage (2011 to present)
in 2011, the ninth meeting of the 10th CPC Guangdong Provincial Committee focused on strengthening social construction. The general office of the CPC Guangdong Provincial Committee and the general office of the provincial government issued the implementation opinions on strengthening the construction of social work talent team, and included "the number of social workers with certificates per 10000 people" into the evaluation index system of "happy Guangdong", The social work of our province has entered the stage of comprehensive promotion
the practice of social work has been graally deepened, and the service field has graally expanded from social welfare and social assistance to disability rehabilitation, drug control and ecation, community correction, employment assistance, employee assistance, dispute mediation, emergency response and other fields. The service area has expanded from urban areas to rural areas, and the service object has extended from children and adolescents, the elderly, the disabled to the floating population, the elderly and the disabled Disaster victims, women with special needs and other groups
social work professionals and social work service institutions are the main bodies that directly provide social work services. All parts of our province take the cultivation and expansion of social work talents and social work service institutions as the core of the development of social work, promote social work talents to take root in the front line to do service, and social work service institutions to build brand based on the long-term
judging from the government's emphasis on social work, Xiaobian thinks that social workers will graally appear as a profession, which is not only to distinguish them from the enthusiastic aunts of the neighborhood committee, but also to distinguish a mode of helping others and solve the existing problems in depth
social workers may be needed by more people in the future. If you have a social worker card at this time, it will be even better.

4. Of course it's true. But bitcoin is the representative of digital currency, cryptocurrency. According to the current 24-hour market of China currency, the highest price of bitcoin is 73900.00 QC (equivalent to RMB)
When did you buy 500? Now you make a lot of money

5. 1、 Similarity

distributed
git ensures that each code warehouse maintains a complete project library locally, not just the branch in which it works and its own submission history. At the same time, it also keeps all the snapshot and index information after the latest pull

on the blockchain, each node keeps a complete database locally, not just its own transaction information

traceability
in Git commit chain, each commit object contains a parent object (the object of the last commit, except the first commit), which can trace all the previous records

on the blockchain, each block contains the index of the previous block (except the genesis block), which can trace all valid transactions before<

tamper proof
in Git's commit chain, each object itself calculates a checksum before storing, and then references it with a checksum. Once modified, the checksums will not be correct, which means that it is impossible to change the contents of any file or directory without git's knowledge< The mechanism used by git to calculate the checksums is called SHA-1 hash. This is a string composed of 40 hexadecimal characters (0-9 and A-F), which is calculated based on the content or directory structure of the file in GIT. SHA-1 hash looks like this:



in the blockchain, each block contains the last block ID, and this block ID has two SHA-256 hashes, which are calculated based on the block content. Once the content is modified, the hash will change, which is inconsistent with the chain of other nodes and cannot be added to the longest chain, so the content cannot be tampered with< 2. Difference

collective consensus and central node will: 1 - blockchain merges based on collective consensus (POW / POS) to form the longest chain, which is the main chain

2 - in Git system, when multi node cooperation is carried out through the warehouse hosting platform, it is the manager of the platform project who controls the power of merge, which reflects the will of the central node<

cryptography
1 - in bitcoin blockchain, cryptography mainly uses the following methods

in the whole system of bitcoin blockchain, a large number of public encryption algorithms are used, such as Merkle tree hash number algorithm, elliptic curve algorithm, hash algorithm, symmetric encryption algorithm and some coding algorithms. The functions of various algorithms in bitcoin blockchain are as follows:

A) hash algorithm

the two hash functions used in bitcoin system are: 1. SHA-256, which is mainly used to complete pow (proof of workload) calculation; 2. Ripemd160, mainly used to generate bitcoin address

b) Merkle hash tree

binary tree or multi tree based on hash value. In the computer field, Merkle tree is mostly used for integrity verification. In the distributed environment, integrity verification can greatly rece the complexity of data transmission and calculation<

C) elliptic curve algorithm

in bitcoin, the public key cryptography algorithm based on secp256k1 elliptic curve mathematics is used for signature and verification. On the one hand, it can ensure that the user's account is not replaced by an impostor, on the other hand, it can ensure that the user can not deny the signed transaction. The private key is used to sign the transaction information, and the user's public key is used to verify the signature. If the verification is passed, the transaction information will be recorded and the transaction will be completed

d) symmetric encryption algorithm

the official bitcoin client uses AES (symmetric block cipher algorithm) to encrypt the wallet file. After the user sets the password, the private key of the wallet is encrypted by the user set password through AES to ensure the security of the private key of the client

e) base58 encoding

base58 is a unique encoding method used in bitcoin. It is mainly used to generate the wallet address of bitcoin, which is similar to the permutation algorithm mechanism in classical cryptography. Its purpose is to increase the readability of bitcoin and change the binary hash value into the address we see

2 - git: SSH key is mainly used for remote login verification, SHA-1 is used for code content checking sum<

SSH is the abbreviation of secure shell, developed by IETF's network working group. It is a protocol designed to provide security for remote login sessions and other network services. SSH protocol can effectively prevent information leakage in the process of remote management< The process of SSH transmission is as follows: (1) the remote host receives the user's login request and sends its public key to the user 2) The user uses the public key to encrypt the login password and send it back 3) The remote host uses its own private key to decrypt the login password. If the password is correct, the user is allowed to log in.

6.

Many small white just admission, was the private key, public key, address, and other relations confused. Some of them even lost their private key. They had money on the address, but they just couldn't get it out. Today, Xiao will try to figure out the relationship between the private key, the public key and the address

The relationship among

private key, public key and address is as follows:

the private key is converted into (generated) public key, and then converted into address. If there is bitcoin or integrity coin on an address, you can use the private key converted into this address to spend the above integrity coin. The generation of public key and address depends on private key, so private key is the most important

The same is true for mobile phone wallet, but the file management method of mobile phone is not as convenient as that of computer. Therefore, the general mobile wallet will provide a function called or similar to "export private key". Through this function, the private key can be exported in various forms

for example, bitcoin mobile wallet can be exported as a two-dimensional code, which can be printed or scanned on paper. When replacing a mobile phone, install a bitcoin wallet and scan the QR code to migrate bitcoin. Bitcoin mobile wallet and trustcoin mobile wallet can be exported as a clear text string and printed on paper - this is paper wallet

paper wallet allows users to spend your bitcoin or trustcoin at any terminal with bitcoin or trustcoin wallet

the loss or damage of the wallet will lead to the loss of the private key, thus completely losing the transfer right of the digital currency. To prevent such tragedies, you should always back up the data in your wallet. In addition to the address, all the private keys are saved ring the backup

summary

1, the private key should be well protected to prevent loss and forgetting. When the mobile phone clears the information, it is best to it by hand, but do not disclose it

2, you should prevent your wallet from being lost or damaged, resulting in the loss of your private key and the right to transfer in digital currency. Otherwise, you can't take out more than one currency, which is not useless