王小云密码技术与区块链,区块链王小彬

① Is the dash chain an alliance chain?

DASHING protocol.

The Central Bank’s Digital Research Institute teamed up with Tsinghua University to launch the DASHING protocol to solve the four-party problem of blockchain consensus algorithm
For a long time, traditional consensus algorithms have been unable to solve the high security and high-security problems in financial technology scenarios. The innovation of consensus algorithms with four major problems: scalability, high throughput, and low latency has become the key to promoting the application of consortium chains in the field of financial technology

In response to this technical difficulty, the Institute of Mathematics and the team of Academician Wang Xiaoyun of Tsinghua University Jointly innovate and tackle key problems, innovate the blockchain f+1 voting theory under provably secure conditions, and develop the internationally leading DASHING protocol. This protocol is a brand new variable threshold chain consensus protocol in the alliance chain, taking into account both security and Efficiency fills the gap in consensus protocols that meet the three high and one low financial scenarios. In different scenarios of actual testing, its performance is up to 15 times higher than the existing international mainstream blockchain consensus algorithms. In practical applications, the DASHING protocol can not only be used as An independent module Lego replaces the consensus algorithm in the existing alliance chain, and also helps to build a multi-party collaboration, safe and efficient new financial infrastructure

Academician Wang Xiaoyun said that blockchain technology flexibly uses passwords The core theoretical system of science, the core of the innovative blockchain that relies heavily on cryptography is consensus, and the core of consensus is the simplification of information and provable security

Lu Wei, Secretary of the Party Committee of the National Internet Emergency Center, suggested , give full play to the pilot demonstration effect of innovative applications, lead technological innovation and industrial development, implement risk prevention and control and regulatory regulations, guide the healthy and orderly development of the industry, and explore new application models for continuous blockchain to serve the digital economy and the real economy.

Di Gang, deputy director of the institute, said that the institute will continue to carry out three innovations in the blockchain: First, based on the efficiency-lossless solution, it will improve the fairness of transactions and enhance the blockchain The second is to support post-quantum cryptographic algorithms and build a post-quantum security alliance chain. The third is to adopt the idea of ​​parallel computing to continuously improve the scalability and high concurrent processing capabilities of the system.

Wei Liang, deputy director of the China Academy of Information and Communications Technology, said that digital trust infrastructure based on new generation information technologies such as blockchain and privacy computing should continue to become the trust foundation of the digital economy and provide a high-level platform for the digital economy. Quality development lays a solid foundation for safety.

Yu Rui, deputy director of the First Research Institute of the Ministry of Public Security, said that security has always been the core proposition of blockchain, and the dash protocol has effectively solved the long-standing blockchain security problem through provable security. Insufficient problem.

For the industrial application of blockchain, Ren Changrui, deputy director of Microchip Blockchain Research Institute, put forward three suggestions: first, the combination of underlying innovation needs and application scenarios; second, solving the problem of things to digital The third is to solve the identity problem.

National Internet Emergency CenterDirector Wu Zhen said that at present, the scalability of the alliance chain is insufficient and security issues are becoming increasingly prominent. The DASHING protocol solves problems that have long plagued the industry and provides innovative solutions for industry applications

Academic Shandong University Network Representative Wang Meiqin, executive vice president of the Security Institute, said that the DASHING protocol effectively solved the four-party problem, and its security proof has been strictly demonstrated. It is a new generation of blockchain consensus protocol optimized on the basis of the traditional alliance chain consensus protocol


Li Maocai, general manager of the digital currency department of Tencent Financial Technology, said that the dash protocol is a bottom-level innovation that plays a very important role. The future development direction is that it can be used in high-concurrency scenarios such as health codes; It can be used in complex network scenarios of small and medium-sized enterprises. Third, the triple certificate security theory proposed by the DASHING protocol is worthy of reference by financial technology companies

Bao Ta, vice president of Meituan, pointed out that the has protocol has constructed a new consensus paradigm and is a demonstration The nature, advancement and practicality. He looks forward to strengthening communication with the Digital Research Institute and Tsinghua University in the next step to jointly promote the industrial application of the DASHING protocol

As the host of the conference, Deputy Director of the Beijing Local Financial Supervision and Administration Bureau Wang Ying said that Beijing attaches great importance to the development of blockchain as the basic capability of the underlying blockchain. DASHING protocol will effectively solve the problems faced by financial technology innovation and bring new path options for the development of blockchain in Beijing
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② Wang Xiaoyun, a strong woman in the cryptography industry, once cracked the code considered the most secure in the United States. What happened next?

Not only "bringing peace to all generations", but also " To carry on the unique learning to the saints." While Wang Xiaoyun has important responsibilities, he is also a professor and a teacher. In order to persist in front-line work, she came to Beijing and worked at Tsinghua University. Her work focus gradually shifted to talent cultivation. She tells students that they should either do nothing or do their best. She often cares and greets students every day.

In front of her students, she is not only a strict teacher but also a loving mother. It not only masters the unique skills of developing the Holy Spirit, but also passes them on to the next generation of young people, cultivating talents in cryptography for the country. Hard-working gardeners always cultivate the most brilliant flowers of the motherland.

It was another dark and windy night, and silver was sprinkled beside the window. It was a time when everything was completely silent, and the frivolity of the breeze and the sky made people long for the darkest and brightest sky. There is a desire deep down, a desire for knowledge and a desire to explore. For the consistent Academician Wang Xiaoyun, it is a lifelong mission to break secrets.

③ Summarize the key points of the paper "Bitcoin: A Peer-to-Peer Electronic Cash System"

Summarize Bitcoin as a peer-to-peer electronic cash systemWhat are the tips for system papers? If you want to mention this paper, you can go to the official website and search to get the answer.

④ What is the blockchain cryptographic algorithm?

As an emerging technology, blockchain has received more and more widespread attention. It is a new application of traditional technology in the Internet era. , which includes distributed data storage technology, consensus mechanism and cryptography, etc. With the creation of various blockchain research alliances, related research has received more and more funding and personnel support. Hash algorithm, zero-knowledge proof, ring signature and other cryptographic algorithms used in the blockchain:

Hash algorithm

Hash algorithm is the basic technology of the blockchain. The essence of the Hash function is to A set of data of arbitrary length (finite) is mapped into a set of data streams of defined length. If this function satisfies both:

(1) The calculation of the Hash value of any input set of data is very simple;

(2) Think It is computationally difficult to find 2 different data with the same hash value.

Hash functions that satisfy the above two properties are also called cryptographic Hash functions. Unless there is any contradiction, the Hash function usually refers to the cryptographic Hash function. For the Hash function, finding such a value is called a collision. Currently popular Hash functions include MD5, SHA1, SHA2, and SHA3.

Bitcoin uses SHA256, and most blockchain systems use the SHA256 algorithm. So here we will introduce SHA256 first.

1. SHA256 algorithm steps

STEP1: Add padding bits. The message is padded so that the message length is congruent with 448 mod 512 (length = 448 mod 512). The number of padding bits ranges from 1 to 512. The highest bit of the padding bit string is 1 and the remaining bits are 0.

STEP2: Additional length value. Append the bit length of the initial message (before padding) expressed in 64-bit to the result of step 1 (low-order byte first).

STEP3: Initialize the cache. Use a 256-bit cache to store the intermediate and final results of the hash function.

STEP4: Process 512-bit (16 words) message packet sequence. The algorithm uses six basic logic functions and consists of 64 steps of iterative operations. Each step takes a 256-bit cache value as input and then updates the cache content. Each step uses a 32-bit constant value Kt and a 32-bit Wt. Where Wt is the message after grouping, t=1,2,...,16.

STEP5: After all 512-bit packets are processed, the output generated by the last packet of the SHA256 algorithmIt is a 256-bit message.

2. Ring signature

In 2001, three cryptographers, Rivest, Shamir and Tauman, proposed the ring signature for the first time. It is a simplified group signature, with only ring members and no managers, and does not require cooperation among ring members. In the ring signature scheme, the signer first selects a temporary set of signers, which includes the signer. The signer can then use his own private key and the public keys of others in the signature set to generate signatures independently without the help of others. Members of a set of signers may not be aware that they are included.

The ring signature scheme consists of the following parts:

(1) Key generation. Generate a key pair (public key PKi, private key SKi) for each member in the ring.

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

(3) Signature verification. The verifier verifies whether the signature is signed by a member of the ring based on the ring signature and message m. If it is valid, it will be accepted, otherwise it will be discarded.

The properties that ring signatures satisfy:

(1) Unconditional anonymity: The attacker cannot determine which member of the ring generated the signature, even after obtaining the ring member’s private In the case of key, the probability does not exceed 1/n.

(2) Correctness: The signature must be verified by all others.

(3) Unforgeability: Other members in the ring cannot forge the signature of the real signer. Even if an external attacker obtains a valid ring signature, he cannot forge a signature for message m.

3. Comparison between ring signature and group signature

(1) Anonymity. It is a system in which individuals sign on behalf of a group. The verifier can verify that the signature is signed by a member of the group, but cannot know which member, so as to achieve the anonymity of the signer.

(2) Traceability. In group signatures, the existence of the group administrator ensures the traceability of the signature. Group administrators can revoke signatures to reveal the true signer. The ring signature itself cannot reveal the signer unless the signer himself wants to reveal or add additional information to the signature. A verifiable ring signature scheme is proposed. In the scheme, the real signer hopes that the verifier knows his identity. At this time, the real signer can confirm his identity by revealing the secret information he holds.

(3) Management system. Group signatures are managed by the group administrator, while ring signatures do not need to be managed. The signer only has to select a possible set of signers, obtain its public key, and then publish the set. All members are equal.

The Xueshuo Innovation Blockchain Technology Workstation under Lianqiao Education Online is a "smart learning" project carried out by the School Planning, Construction and Development Center of the Ministry of Education of China."Workshop 2020 - Academic Master Innovation Workstation" is the only approved pilot workstation for "Blockchain Technology Major". The professional position provides students with diversified growth paths, promotes the reform of professional degree research, production, learning and research integration training model, and builds applied and compound talents Culture system.