The tech giant Google announced a breakthrough this week with the introduction of the "Willow" chip. The computing power of the quantum computer is exponentially stronger than that of a conventional supercomputer, raising questions about the security of Bitcoin and blockchain technology.
Quantum computers perform complex calculations by utilizing the principles of quantum mechanics. This allows them to solve specific tasks like optimization, cryptography, and simulations much faster than classical computers. According to Google, their Willow chip can solve complex problems in less than five minutes, which would take a supercomputer approximately 10 quadrillion years to process. However, the threat to Bitcoin is smaller than some skeptics might assume.
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Bitcoin wallets remain secure against quantum computers
Bitcoin uses the cryptographic hash function SHA-256 to secure transactions and generate new blocks by solving complex mathematical puzzles. Many other systems, such as SSL certificates and secure data storage, also rely on this function for encryption. Quantum computers could potentially threaten the security of SHA-256 by breaking its underlying cryptographic algorithms, which would allow a quantum computer to crack the private key of an address. Satoshi Nakamoto's wallet, containing over one million Bitcoin (valued at $100 billion today), would be a prime target.
On the one hand, today's quantum computers are nowhere near powerful enough to break Bitcoin's encryption. The processing power of this technology is measured in quantum bits ("qubits"). Estimates suggest that more than 13 million qubits would be needed to compromise Bitcoin wallets. By comparison, Google's Willow chip achieves fewer than 105 qubits. Moreover, Bitcoin could protect itself by transitioning its blockchain to quantum-resistant cryptographic algorithms, which researchers have already developed.
The Threat to Bitcoin Mining
Quantum computers could pose a threat to mining if they solve proof-of-work puzzles exponentially faster than traditional miners. This could lead to a 51% attack, where a single entity controls the majority of the mining power. In this scenario, the quantum computer could alter the network's rules and enrich itself.
Although advanced quantum computers could theoretically solve these puzzles much faster than conventional machines, several factors mitigate this threat. First, quantum computing performance is expected to improve gradually over the years due to technical challenges in scaling the number of qubits and implementing robust error correction.
When early quantum computers enter the market, their impact will be limited. Additionally, quantum computers today run for only a few seconds. Extending this runtime would require advanced error correction techniques and millions more qubits, which limits the immediate threat to Bitcoin until quantum-resistant mechanisms are deployed.
Malicious actors have other targets
Attackers in possession of a quantum computer would likely target systems with more immediate value before attacking SHA-256 blockchains like Bitcoin. A far easier target would be breaking RSA encryption, which is widely used for secure communication, banking, and government data. Those who store their wealth in banks instead of Bitcoin are at greater risk from quantum computers.
Malicious actors might also exploit vulnerabilities in critical infrastructure or steal sensitive corporate information. These targets are far more valuable in terms of economic and strategic impact than Bitcoin.
