Getting started with blockchain | Can Google's latest quantum computer crack bitcoin? Is the wallet safe?

Recently, “ Google’s claim that it has achieved quantum hegemony ” has been screened in various media.

"Quantum hegemony" is also called "quantum advantage", which means that quantum computers have the advantage of compaction compared to current computers. That is, at a certain moment in the future, a very powerful quantum computer can complete the current computer. Possible tasks.

In the paper, Google researchers said that Google's processor can complete the calculation that the current world's number one supercomputer Summit needs 10,000 years to complete in 3 minutes and 20 seconds.

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Quantum Computer, Source: MIT Technology Review

This has caused a lot of concerns about the holders of encryption assets. Is it worried that the encryption assets such as Bitcoin are still safe and will they be easily cracked by quantum computers?

Let's start with the conclusion: At least at this stage, you don't need to worry, even if the general-purpose quantum computer appears on a large scale, bitcoin will not necessarily be "killed."

Next, let's talk about the related reasons.

There are two main encryption algorithms used by Bitcoin: Elliptic Curve Digital Signature Algorithm (ECDSA) and SHA256 Hash Algorithm. Among them, ECDSA is mainly used for the generation of private keys and public keys; SHA256 is mainly used for public key generation wallet address, and proof of work (PoW) when mining .

Quantum computers can threaten the security of ECDSA. In 1994, a Shor algorithm dedicated to the decomposition factor was designed. The quantum computer (hardware) and the Shor algorithm (software) were strong enough to crack the private key through the public key.

Of course, the cracking process of quantum computers also takes a long time, and the development of quantum computers is not smooth, and the performance at the beginning is not so strong.

Even if the quantum computer is powerful enough, there are ways to protect your bitcoin security: use only one-time bitcoin address at a time.

I would like to thank Nakamoto for not designing the bitcoin directly as the receiving address of the bitcoin. SHA256 encryption is performed between the public key of Bitcoin and the corresponding address, but there is currently no algorithm that can effectively crack SHA256.

For example, if Dabai needs to transfer 1BTC to Xiaohe, and there is 3BTC in Dabai's wallet address, as long as the transfer is made, set the bitcoin's change address to a brand new bitcoin address with its own private key. . In this way, when the transfer is made, 1BTC enters the address of Xiaohei, and the 2BTC that has changed to enter the new address of Dabai. Regarding Bitcoin's change mechanism and UTXO model, you can read the tweet before the vernacular blockchain " No UXTO, Bitcoin or can't run so stable for 10 years ."

When querying this transaction on the blockchain browser, you can see the address and the corresponding public key, the address of the black address, and the new address of the change. Since the transfer address is discarded when it is used up, there is no BTC in it, so even if you see the public key, it is okay to use a quantum computer to crack the private key.

As for the exposed black collection address and the new address for change, the quantum computer is safe because it lacks an algorithm to effectively crack SHA256 and cannot crack the public key through the address.

Mining machine, source: www.hellobtc.com

Will the quantum computer have an impact on bitcoin mining?

Today's computers comply with Moore's Law, in which the transistor density of computer chips doubles every 18 months and the computing power doubles. However, in recent years, the size of transistors has gradually approached the physical limit, the exponential growth of computer computing power has slowed down, and Moore's Law has gradually failed. What makes quantum computers so powerful is that they grow at a rate of double exponentials, that is, the growth index of computing power is also exponential. This allows traditional computers to take tens of thousands of years of computation, and quantum computers can be completed in a short time.

However, quantum computers only do a significant reduction in computing time, and it takes time to calculate.

As mentioned earlier, there is currently no algorithm that can effectively crack SHA256. Therefore, when using quantum computers to dig bitcoin, you can only try to find random numbers one by one, just like quantum computers. It’s fast. Bitcoin has a difficulty adjustment mechanism that can adjust the difficulty against the growth of computing power from quantum computers, and can also increase the difficulty of mining by upgrading the SHA256 algorithm (such as upgrading to SHA384, SHA512).

It should be noted that the above discussion is based on the premise that "quantum computers are very mature and cheap."

The reality is that quantum computers are still in the laboratory. Google researchers also said that Google's quantum computers can only perform a single, highly technical calculation, and it will take years to solve practical problems. As of now, no universal quantum computer has emerged, and reliable dedicated quantum computers have not yet appeared.

The magic algorithm is one foot high and the road height is one foot. While the quantum computer is moving forward, the encryption algorithm will continue to improve.

In "Getting" "Zhuoke Cryptography 30", the famous science writer Zhuo Ke mentioned the seventh-generation encryption method against quantum computers – quantum encryption .

Unlike other encryption methods, quantum encryption uses not only mathematics, but also quantum theory in physics. Quantum computers are also likely to be impossible to crack, because if they are cracked, they violate the basic principles of quantum mechanics.

After reading this article, are you still worried about the encryption assets in your hand? Feel free to share your opinion in the message area.

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Author | JackyLHH

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