In recent years, as a superstar of Internet finance, blockchain has drawn immeasurable attention. Bitcoin is also a popular chicken in blockchain technology. In the technology industry, no one knows the super virtual currency - bitcoin.
Bitcoin how fire?
It was born in 2009 and in 2010 it was enough to buy only two pizzas out of ten thousand bitcoin. In 2018, the bitcoin price exceeded 10,000 USD, and the original 10,000 bitcoin that bought two pizzas is now around 7.8 Billion yuan. From the initial price of less than 1 cent in 2010, up to now more than 10,000 US dollars, bitcoin was born eight years to achieve a 100 million-fold increase.
Why a reality does not exist bitcoin will fire to this extent? The core is that it is safe and reliable.Exquisite design of bitcoin bring it so few features:
1, it can achieve individual to individual transactions, do not need any middleman;
2, bitcoin can never be stolen without trading;
3, bitcoin is automatically quantitative issue, access to bitcoin way only to dig and buy from others, no matter who you are, the difficulty of obtaining bitcoin by mining are the same.
The reason for Bitcoin fire stems from the freedom, security and fairness given by blockchain technology. However, in the near future such a romantic virtual monetary mechanism may have to be completely disintegrated and many people believe The safe, secure, rock-solid foundation may be destroyed by a rapidly emerging and emerging technology.
This emerging technology is quantum computing.
Just last week, a breakthrough was made in quantum computer research at the Chinese Academy of Sciences. The Institute of Quantum Information and Quantum Technology Innovation, CAS released 11 quantum bits of cloud access superconducting quantum computing services in the field of superconducting quantum computing. Worldwide, 10 A quantum computing service above the bit, which is the second after the IBM, the progress of quantum computing once again become the focus.
The rapid development of quantum computation exceeds all expectations and predicts that in 10 years, quantum computing will have a devastating blow to the blockchain (including bitcoin), then how can quantum computing threaten the blockchain? What will cause the threat? Block chain there is no strategy to resist it?
This starts with the principles of quantum computers and blockchain.
Quantum Computer and Blockchain
1, quantum computer
A few years ago, Wisdom had published an article on Quantum Computers (how scary the quantum computer deciphers all the world's passwords in a second!). In simple terms, the quantum computer's unit of operation is a qubit rather than a classic computer's bit bit). In a classical computer, the value of a bit is deterministic, either 1, or 0, but in a quantum computer, the value of one qubit is not known until it is observed. This value is likely to be 1 , It is also possible that 0, but also can be a superposition of 1 and 0, that is, equal to 0 and 1 at the same time.
How big is the difference?
Take Naruto for example. That is, Sasuke is a classic computer. Naruto is a quantum computer. Looking for one thing, Sasuke can only go there one by one, perhaps for a year.
But the Naruto can be divided into five shadow body, and then five shadow points and then split five shadow avatar, avatar sub-avatars, all avatars go to different places at the same time, instantly find something, and then sub-recover, leaving only one Naruto, get things done.
Professor Robert Schoelkopf of Yale University said: 'When a quantum computer has 50 or 100 qubits, and these qubits work well and can be completely error-corrected, then you can use this Quantum computers do computations that no classical computer in the world can ever do.
The quantum computing power of the changes brought about by the earth-shaking changes that may even affect the national security.
Therefore, academician Pan Jianwei from the Chinese Academy of Sciences once said: 'I believe the importance of quantum technology in the 21st century can be compared with the Manhattan plan of the last century.'
2, blockchain and bitcoin mining
In 2008, the concept of blockchain was first proposed by Satoshi Nakamoto. Blockchain is a rule and a technology. Its core is safety and reliability.
At present, bitcoin is the most famous application of blockchain technology in the world. Nakamoto was the founder of bitcoin. Next, we took a peek at the realities of blockchain from the concept of bitcoin.
Now we can think of a blockchain as a ledger, with a portion of this ledger in each block, with the complete information on the books held at all nodes in the block, which is the decentralization of blockchain technology , Each block has only a part of the book, but this part will record the information of a block, a block with a block, forming a blockchain.
The advantage of a blockchain is that it forms a trust mechanism. For example, if you save 100 yuan in a bank, if the hacker is bank black and you have taken away your money and cleared the data, There is no information on hand to prove that you have a bank in the $ 100 assets, but if replaced by a blockchain, then it means that the bank where the block has a complete account of each node records, which means you Home neighbors and the ladies next door, and even every inhabitant of the district, have books to prove that you have $ 100 in bank deposits.
Compared with the centralized mechanism in the traditional financial field, the decentralization of the blockchain makes it more reliable and robust. The system can continue to operate normally even if some nodes are lost, so the blockchain is considered to be a very safe and reliable technology.
So what is bitcoin mining?
Based on the blockchain, Nakamoto put forward the concept of bitcoin in 2009, which stipulates that every ten minutes in a bitcoin network will generate 50 bitcoin. When the total amount reaches 10.5 million (21 million Half), producing 25 bitcoins every 10 minutes, producing 12.5 every 10 minutes when the total reaches 15.75 million, and ceasing to grow when the total reaches 21 million The total amount has been set at 21 million since the very beginning.
And bitcoin 'mining' is a way to generate new bitcoins. 'Mining' people are called 'miners,' and miners use computers to solve math problems in bitcoin networks. The first miners to solve the problem , Credited to the books, simultaneously credited to all nodes, which is called mining success, access to bitcoin.
The mechanism of the blockchain is safe and reliable before the notion of quantum computing has evolved. At least for so many years, bitcoin has not been overshadowed by hackers, but in recent years quantum computing has grown rapidly beyond what was previously envisioned, Industry insiders predict that within a decade, the security of the blockchain will be a tremendous threat from quantum computers.
How does quantum computing threaten the blockchain?
To understand the threat of quantum computing to the blockchain, first of all, starting with the security protocols in bitcoin systems, the bitcoin protocol involves two types of cryptography, the hash function (hash function) used in the mining process, And asymmetric cryptography for providing digital signatures on the blockchain.
Miners use their computational power to compute a random number for each block using the SHA-256 hash function, the result of which is very easy to verify but hard to find, while asymmetric cryptography is used to authorize Bitcoin blockchain transactions, each user throughout the chain will be assigned a public key and a private key, which is the public key public key system, the public key cryptography uses a pair of keys to encrypt information : Public key that can be widely shared and private key only known to the key owner Anyone can encrypt a message using the intended recipient public key, but only the recipient can use his private key to decrypt the message.
Such an asymmetric cryptographic algorithm generates a key using an ECDSA called the Elliptic Curve Digital Signature Algorithm (ECDSA). Given a private key, it is easy to derive the corresponding public key, but in turn calculate the difficulty.That is now bitcoin security s reason.
The quantum computer may pose a huge threat to these two lines of defense. In the future, quantum computers will soon be able to crack the hash function to monopolize the entire blockchain. In the near future, in 2027, Shure of Quantum Computer The Shor's algorithm is predicted to crack the key in ten minutes (600 seconds).
In the bitcoin world, the success rate of mining with a classic computer is somewhat related to the amount of calculation, but large amounts of calculation do not necessarily mean that you will be able to dig into the mine (no more than 50% ), Mining and luck have a certain degree of relationship to take the maze, for example, a person go fast, if one by one, then he will certainly be able to reach the end of the maze as soon as possible, but if a person walked slowly , But with only one attempt to find the way to the end of the maze? Therefore, people who go faster may not be stable and slow people, in the same token, the big miner is not necessarily calculated Small miners first dug into the mine.
As said above, mining is actually solving math problems and finding out random numbers that hash functions encrypt, but it is possible that two different miners will find two random numbers at the same time, announcing different blocks, which In that case, the bitcoin rule is that the block that is more processed is added to the blockchain and the other block is invalidated, which is analogous to having 51 people in a cell that you have deposited in your bank 100 dollars, while 49 individuals say that you have saved 50 dollars. In this case, the minority obeys the majority. The bank thinks you have saved 100 yuan is true, and you have saved 50 dollars.
Further elaborating on the concept of a '51% attack 'from this provision, in a blockchain, if a miner's group has 51% of the entire network, he can monopolize the entire blockchain because he will always be better than the other 49 The% Miner's team processes the block faster, meaning that he will get all the bitcoin generated thereafter.
Researchers at Divesh Aggarwal and the National University of Singapore (NUS) conducted an in-depth study of the issue of quantum computers threatening mining and published a paper there in October 2017, First of all, ASIC mining will be faster than quantum computers at least for the next ten years, but the mining of quantum computers will grow rapidly ten years later. Second, in the face of quantum computers, asymmetric cryptographic algorithms used in blockchain , That is, public key cryptography will be more threatened.
Researchers at the National University of Singapore have pointed out that by using quantum computers, it is easy to reverse the process of using private keys to infer private keys, each of which is easily inferred by the quantum computer.
▲ Quantum computer to crack the encryption signature of the estimated time | unit: second, only 20 minutes is expected in 2027/600 seconds ▲ quantum computer crack encryption signature required time estimate | unit: second, is expected in 2027 only 10 minutes / 600 seconds Similarly, we can compare this decryption process to a labyrinth, and the classic computer can do is stupid to go in one direction until it reaches a dead end and then go back and re-select another way. However, the quantum computer It gives you a perspective of God overlooking the entire labyrinth. Which way is clear at a glance.
However, quantum computers need to reach a certain amount of qubits to achieve this level. According to Foreign Media Motherboard, a 4,000-qubit quantum computer can disintegrate the blockchain. That is, which person or team first make and apply such a quantum computer You can solve and verify every transaction, all cryptocurrencies generated in the future that are not yet in circulation will be monopolized by them, and the trust system of cryptocurrencies will be dismantled.
Quantum computer development is still in its infancy
Quantum computers are fast developing and may pose a huge threat to the blockchain in the future. However, quantum computers are still in the early stage of 'toy computers'. At present, only about 10 giants around the world can make Of the quantum computer that reaches the high-fidelity qubit, last week issued by the Chinese Academy of Sciences 11 qubits superconducting quantum computing service is the world's second 10 qubits above cloud computing services, the first is IBM, the end of last year, IBM has opened up 20 qubits of cloud computing services, and quantum computing services like this have not been able to solve any practical computational problems, but developers are already using such cloud services to learn about quantum computer-related programming knowledge.
It looks like the 4000 qubits are really far away from us, but probably not so far from our imagination, because in recent years Microsoft, Google and IBM (all three companies have built their own focus on quantum Computing research laboratory) made a series of breakthroughs in the field of quantum computing, "Fortune" magazine predicts the first practical quantum computer will be built within a decade.
In the long run, this is a long time that many companies have predicted. For example, Microsoft predicted that a practical quantum computer would be built in 2025, and Google will put it in 2017 within five years (that is, around 2022) Make a commercial practical quantum computer.
Conclusion: There are effects but also countermeasures
Quantum computer development is inevitable, one day it will threaten the blockchain, but it seems that many experts in the blockchain have not yet wary of it.
According to Fortune magazine, there's "no one" global concern about quantum computing risks at the Crypto 2017 conference (the top blockchain cryptographer conference) in November 2017. One expert said it would be a "very Expensive operation, "may require 'government-level' spending, while another expert laughed completely at the idea. He waved his hand and said that when the quantum computer came out, the public-key cryptography system had evolved to the point of not having to worry about quantum computers The extent, so this question does not matter at all.
But these same experts all share the same view that the advent of quantum computing will endanger the security of all existing encryption and encryption methods, including RSA tokens, and quantum computers will affect the security of the entire financial and banking industry, not just mere Is a blockchain.
At the same time, there are other organizations that attach great importance to this, for example, the National Security Agency announced in 2015 that it is studying quantum cryptography, a cryptographic system that can withstand quantum computing. In academia, there are also passwords Researchers are studying quantum cryptography and have already implemented blockchain projects that use quantum cryptography. For example, the team at Quantum Resistant Ledger and the Evgeny Kiktenko at the Russian Quantum Center are working on building a quantum blockchain that can withstand quantum computer attacks , And there is already a standard quantum cryptography system for commercial use.
At the moment, no one can accurately predict the exact moment when a practical quantum computer is born, but in a more positive light, commercial quantum computers may be born faster than we expected because today's technology is accelerating, not constant Perhaps in 2018, the quantum computer is still at a very early stage, the progress of practical quantum computers was only 5%, but it may be 10% by 2019. In 2020, the progress will reach 30% All this is possible.
Technology is constantly evolving, and emerging technologies such as blockchain and cryptocurrency are probably still in early childhood, and there is a long way to go before technology matures, and developers need to be careful about a series of obstacles that may arise in the process, which This also includes quantum computation.