Blockchain private key signature

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. Indeed, there are blockchain wallets using this technology, such as IDC
wallet. In fact, mnemonics are another form of expression of the private key, which has the same function as the private key, mainly to protect your blockchain money

5. People who play digital currency know that everyone's wallet account has a private key. If you lose the private key, all the property in the wallet will no longer exist, so losing the private key is a terrible thing for friends who play currency. In addition, the person in charge of an encrypted digital currency exchange in a foreign country said: "it is the iron law of the blockchain world to recognize only the private key but not the person. With the current computing power and technology, it is absolutely impossible to dece the private key from the address. If it is feasible, all the addresses on the whole blockchain will lose security, and the assets on the blockchain will lose their meaning. "

6. 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

7. Although

has completed payment in the early days of mobile payment, it has been through the input of payment password or fingerprint. But now Ma Yun's Alipay has opened a quicker and more convenient way, that is, brush face payment. P>

Alipay has already done the payment method of face recognition through camera. We have to wonder that the progress of high technology brings people convenience and quick, which is really very attractive, so that people do not need to take out the mobile phone operation.

there is no need to worry about this. In fact, it's just like using a mobile phone to brush your face and open your mobile phone. You can't and can't unlock your mobile phone just by using people's photos. Of course, people who are curious about this will take photos to do experiments, but this photo is not their own

someone took out a picture of Ma Yun's face and scanned it. They thought that he would brush his face successfully or that some of Ma Yun's eggs would happen. However, no matter how many times he did it, it didn't work. It just showed that he failed to brush his face. In fact, the payment wire has been very stable, and the payment security we are worried about has been taken into consideration by the technical personnel and is now in use, so we can use it safely

8.

As an emerging technology, blockchain has attracted more and more attention. It is a new application of traditional technology in the Internet era, including distributed data storage technology, consensus mechanism and cryptography. With the establishment of various blockchain research alliances, more and more funds and personnel support related research. Hash algorithm, zero knowledge proof, ring signature and other cryptographic algorithms used in blockchain:

hash algorithm

as the basic technology of blockchain, the essence of hash function is to map a set of data of any length (limited) to a set of defined length data stream. If this function satisfies the following conditions:

(1) the calculation of hash value for any group of data is very simple

(2) it is difficult to find two different data with the same hash value

hash functions satisfying the above two properties are also called encrypted hash functions. In case of no contradiction, hash functions usually refer to encrypted hash functions. For the hash function, finding such that is called a collision. The current popular hash functions are MD5, SHA1, Sha2, Sha3

bitcoin uses sha256, and most blockchain systems use sha256 algorithm. So here's sha256< Step 1: additional filling bits. The length of the message is congruent with that of 448 mod512 (length = 448 mod512). The number of bits to be filled ranges from 1 to 512. The highest bit of the filled bit string is 1, and the rest bits are 0

Step2: additional length value. The bit length of the initial message (before filling) represented by 64 bit is appended to the result of step 1 (the low byte takes precedence)

Step3: initialize cache. A 256 bit cache is used to store the intermediate and final results of the hash function

Step 4: process 512 bit (16 word) packet sequence. The algorithm uses six basic logic functions and consists of 64 steps of iterative operation. Each step takes the 256 bit cache value as the input, and then updates the cache content. Each step uses a 32-bit constant KT and a 32-bit wt. Where WT is the packet after the packet, t = 1,2,..., 16

step5: after all 512 bit packets are processed, the output of the last packet of sha256 algorithm is 256 bit packet< In 2001, Rivest, Shamir and TauMan proposed ring signature for the first time. It is a simplified group signature, only ring members have no manager, and it does not need the cooperation between ring members. In the ring signature scheme, the signer first selects a temporary signer set, which includes signers. Then the signer can generate the signature independently by using his private key and the public key of others in the signature set without the help of others. Members of the signer collection may not know that they are included in it

ring signature scheme consists of the following parts:

(1) key generation. A key pair (public key PKI, private key ski) is generated for each member of the ring

(2) signature. The signer uses his private key and the public keys of any n ring members (including himself) to generate the signature a for the message M

(3) signature verification. According to the ring signature and message M, the verifier verifies whether the signature is signed by the member in the ring. If it is valid, it will be received, otherwise it will be discarded

ring signature satisfies the following properties:

(1) unconditional anonymity: the attacker can not determine which member of the ring generated the signature, even if the private key of the ring member is obtained, the probability is not more than 1 / n

(2) Correctness: the signature must be verifiable by all others

(3) unforgeability: other members of the ring can't forge the real signer's signature, and even if an external attacker obtains a valid ring signature, he can't forge a signature for message M

(1) anonymity. The verifier can verify that the signature is signed by a member of the group, but can't know which member it is, so that the signer can be anonymous< (2) traceability. In group signature, the existence of group administrator ensures the traceability of signature. The group administrator can revoke the signature and expose the real signer. The ring signature itself cannot reveal the signer unless the signer wants to expose or add additional information to the signature. A verifiable ring signature scheme is proposed. In this scheme, the real signer wants the verifier to know his identity. At this time, the real signer can confirm his identity by disclosing his secret information< (3) management system. Group signature is managed by group administrator, ring signature does not need to be managed, signer can only select a set of possible signers, obtain its public key, and then publish the set, all members are equal

the Xueshuo innovation blockchain Technology Workstation of Lianqiao ecation online is the only approved "blockchain Technology Specialty" pilot workstation of "smart learning workshop 2020 Xueshuo innovation workstation" launched by the school planning, construction and development center of the Ministry of ecation of China. Based on providing diversified growth paths for students, the professional station promotes the reform of the training mode of the combination of professional degree research, proction, learning and research, and constructs the applied and compound talent training system< br />