Want to steal bitcoin? All you have to do is find the victim's 16-character public key and calculate their private key by solving the elliptic curve discrete logarithm problem. No problem, if you use a normal computer, it will cost you about 650 million years.
But with the right quantum computer, can information be processed exponentially? Suddenly, seemingly indestructible things become a breeze and can be cracked in less than 10 minutes.
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For cryptocurrencies, the quantum computing problem is not new. Many experts believe that we must at least ten years or more to propose anti-quantum cryptography. However, some observers say that recent rapid progress may significantly shorten this time. The most radical estimate is that bitcoin will be broken by 2027.
Stewart Allen, chief operating officer of IonQ, a company that researches quantum computers, said recently:
“In the past two years, the development of this technology has surpassed the growth rate of the past 15 or 20 years.”
On Thursday, leading cryptographers will participate in the National Standards Technical Service (NIST) Quantum Cryptography Semifinals at the University of California, Santa Barbara. According to cryptographers, this represents the greatest hope for blockchains to withstand the rapid erosion of quantum computers.
Rob Campbell, president of security company Med Cybersecurity, said:
"If someone cracks your key, they can do anything."
Anyone who retains sensitive information such as cash, personal data, medical records, etc. on the blockchain is at risk. With this type of information, quantum hackers can “forge your name and take away your assets,” Campbell said. If medical data is found, they will maliciously “make your dose increase twice… it’s like opening There is a big door."
Take the Bitcoin blockchain as an example: every bitcoin transaction sends an unencrypted public key that remains unencrypted during the network's confirmation of the block (approximately 10 minutes). In theory, a hacker with quantum technology has enough time to calculate the private key through the public key and replace the recipient's address with its own address.
Quantum technology is coming
Transistors in conventional computers capture data in the form of 1's and 0's. Is the sky today blue? 1 means yes. 0 means no. Computer computing is essentially a combination of these calculations: With enough transistors, you can calculate almost anything.
Using a quantum computer, the same input, the qubit, is likely to represent both 0 and 1, which is a non-binary state called "quantum superposition" – a cat like Schrödinger. This makes quantum computers even more powerful; a single, superimposed qubit can handle the load of at least two full-size transistors in a typical computer.
With the improved Shor's algorithm, hackers can make cracking private keys extremely simple. The Show algorithm is a quantum algorithm that quickly converts large numbers of numbers into prime factors.
At this stage, the best quantum computer is probably Google's Bristlecone, which has 72 qubits. Miruna Rosca, a Ph.D. student in post-quantum cryptography, said that cracking the current cryptographic algorithm may require about 4,000 qubits.
How much time do we have?
Allen speculates that it takes about 10 years for the post-quantum cryptography to become a big problem. He estimated that by then, someone might create an anti-quantum blockchain. Ethereum core researcher Danny Ryan has the same idea:
“In the next 10 years, this is not a really meaningful issue. It is unlikely in 20 to 30 years. However, we are often not good at forecasting, so we should be prepared for the transition as soon as possible.”
However, some people say that this issue needs to be paid attention to at this stage. Moreover, in addition to Bitcoin, quantum computing may pose a major threat to network security. Med Cybersecurity's Rob Campbell said that a government with quantum decryption software can read all the secrets of the world.
Campbell is a trained US Navy communications officer. His experience in confidential research and development tells him that the government's secret technology often exceeds commercially available technology.
“We are leading the business world for decades,” he said. "We don't want any potential opponents to know our capabilities."
He pointed out that if the enemy's security agencies collect all of your encrypted data — and they certainly do — they will be able to decrypt all the data, provided they build a powerful quantum computer. This is enough to make the development of anti-quantum cryptography a problem of national security.
In any case, the arms race for quantum hegemony is in full swing: China has just spent $10 billion to build a quantum computer research center, and the United States has invested hundreds of millions of dollars in the field.
Anti-quantum technology is the future trend?
Quantum computing is as effective for cryptographers as hackers. Unobserved superimposed particles exist in multiple states, and once detected, they "fold" into a certain point in space and time. Quantum cryptography has the same characteristics; since the protons that make up the encoded transaction are displaced during observation, the attacker must break the laws of physics to intercept it.
This allows information encoded at the quantum level to withstand the so-called "man in the middle" attack, ie the attacker can intercept the transmission itself without decrypting the secret key.
Some blockchains claim to use anti-quantum technology to ensure that signatures and hashes remain encrypted, such as QRL, IOTA, HyperCash, and Starkware. But because quantum computing is still in the molding stage, it is difficult to determine whether these technologies are effective.
Until the anti-quantum algorithms have been extensively tested and accepted by the academic community, there is no guarantee that these blockchains will be sufficient for quantum computers.
But for large blockchain networks like Ethereum or Bitcoin, developing such an algorithm may not be difficult. Although the owner of the centralization agreement is free to update the system, the blockchain is essentially democratic and requires thousands of miners to reach a broad consensus before the upgrade can be performed.
After the upgrade, all wallets that do not have anti-quantum technology are vulnerable. This includes 1 million bitcoins dug by Ben Bitong, the Bitcoin creator. If these bitcoins were not transferred to a new, anti-quantum wallet, they would be a treasure for the first person with a powerful quantum computer.
"If high-performance quantum computers appear tomorrow," said Ethanfang researcher Ryan, "we will face more problems than just the security of the blockchain."