1980s, physicist Paul Benioff first proposed the concept of quantum computing. Soon after, theoretical physicist richard feynman and mathematician Yuri Manning took the lead in proposing that quantum computers could solve problems that classical computers could not. In fact, in the 1990' s, mathematician Peter Shore developed an algorithm that quantum computers can use to crack public key cryptography: "Shore algorithm"-if quantum computers become powerful enough.
20 19 10 After decades of research, Google officially announced that it has reached "quantum hegemony". This essentially means that quantum computers have solved problems that classical computers cannot solve. Or rather, it solved a problem in 200 seconds, and even the most powerful classic supercomputer took 65,438+00,000 years to solve.
Although this is a major breakthrough, it seems that there is still a long way to go before quantum computers can run Shor's algorithm. On the one hand, the current quantum computer is not powerful enough, and it is not clear how easy it is to expand this technology. In addition, to really play a role, quantum computers rely on a technical solution called "error correction", which remains a challenge.
It is difficult to predict the future development of this technology, but it may take years or even decades for a quantum computer to run the Shor algorithm-perhaps it is impossible to achieve it at all.
If the quantum computer can run the Shor algorithm and crack the public key password, then bitcoin may indeed be attacked. Specifically, some coins may be stolen.
But some people think that theft will be restricted to a certain extent. Although all coins are protected by public key encryption (currently ECDSA algorithm), most coins are also protected by SHA256 hash algorithm. Only by cracking these two algorithms can all coins be stolen completely, but at present it seems that SHA256 (or any other hashing algorithm) cannot be cracked by quantum computers.
In other words, a large number of coins can only be protected by public key cryptography. Current estimates show that if the public key cryptosystem is cracked, about 5 million bitcoins will be stolen. Here are some situations where Bitcoin may be at risk:
In fact, even if Bitcoin is protected by both public key and hash, it may be a challenge to use it safely in the "quantum world". When users try to spend their bitcoin and transmit transactions through the bitcoin network, attackers will have the opportunity to try to steal funds. At this point, the attacker can try to crack the public key encryption before the transaction is confirmed, and then resend the bitcoin to one of his own addresses.
I just want to say that if quantum computers suddenly become more powerful than anyone expected, Bitcoin will have a problem.
It should be noted that if a quantum computer that can run Shore algorithm suddenly appears, Bitcoin is unlikely to become the first or main target. Public key encryption can protect almost all other digital information in the world, including military intelligence, bank data and other existing financial infrastructure, communication networks and so on.
Yes, the Bitcoin protocol can be upgraded to anti-quantum.
In short, the signature algorithm of Bitcoin will have to be replaced by the anti-quantum signature algorithm. Due to the activation of isolated witness, the signature algorithm of Bitcoin can be replaced by backward compatible soft fork upgrade relatively easily. (The current ECDSA signature algorithm may be partially replaced by Schnorr signature algorithm through soft bifurcation in the near future. )
After the upgrade, users should move their bitcoin to a new address in order to be protected by the anti-quantum signature algorithm. Before the quantum computer can run the Shor algorithm, users who have not migrated in time will face the risk that bitcoin will be stolen in some way.
If bitcoin is not transferred to a safe address in time, the bitcoin protocol may also be upgraded to prevent bitcoin from being consumed. This measure means that the original owners will also lose Bitcoin-but, of course, they are likely to lose Bitcoin to attackers. (It has been suggested that these bitcoins may be unlocked by their legitimate owners through zero-knowledge proof cryptography-but this is still very speculative. )
In view of the current development of quantum computing, it is expected that Bitcoin will have enough early warning that it needs to be upgraded. Experts believe that we are not close to that time.
Quantum computers may be able to mine bitcoin faster than traditional computers. However, because bitcoin mining is based on hash (rather than public key cryptography), it may not be destroyed to any meaningful extent.
On the contrary, the emergence of quantum computing may lead to a new arms race to build the fastest mining hardware until a new balance point is found. When GPU replaced CPU and ASIC replaced GPU, Bitcoin mining mode also experienced a similar evolution.