Does Quantum Computing Threaten Bitcoin? The Reality Is Calmer Than You Think

Does Quantum Computing Threaten Bitcoin? The Reality Is Calmer Than You ThinkIn the world of digital cryptography, quantum computers are often portrayed as a ferocious wolf, foreshadowing the demise of cryptocurrencies like Bitcoin. Following Google's 2019 announcement of achieving "quantum supremacy," Bitcoin's price briefly plummeted, triggering market panic

Does Quantum Computing Threaten Bitcoin? The Reality Is Calmer Than You Think

In the world of digital cryptography, quantum computers are often portrayed as a ferocious wolf, foreshadowing the demise of cryptocurrencies like Bitcoin. Following Google's 2019 announcement of achieving "quantum supremacy," Bitcoin's price briefly plummeted, triggering market panic. However, five years later, Google's announcement of a breakthrough with its latest quantum chip, Willow, elicited a remarkably calm market response. What accounts for this difference? Can quantum computers truly easily breach Bitcoin's security defenses? This article delves into the actual threat quantum computers pose to Bitcoin's security and analyzes the underlying reasons behind the muted response.

Bitcoin's security system primarily relies on two cryptographic techniques: the Elliptic Curve Digital Signature Algorithm (ECDSA) and the hash algorithm (SHA-256). ECDSA, a public-key cryptosystem, is responsible for encrypting and decrypting data; SHA-256 secures Bitcoin mining. Theoretically, quantum computers pose a threat to public-key cryptography. Shor's algorithm can significantly reduce the number of operations required to crack ECDSA, making it theoretically feasible. However, on classical computers, breaking ECDSA requires approximately 2¹²⁸ basic operationsan astronomical number. Even with Shor's algorithm, a quantum computer would need approximately 2^128/3 basic quantum operations. While the order of magnitude is reduced, this remains a monumental challenge.

On the other hand, SHA-256, as a hash algorithm, is not effectively threatened by quantum computers, even theoretically. On classical computers, finding data corresponding to a specific SHA-256 hash value requires 2²⁵⁶ basic operations, and Grover's algorithm on a quantum computer would still require 2¹²⁸ operations. These immense numbers of operations indicate that the threat of quantum computers to Bitcoin mining is negligible.

However, a vast chasm exists between theoretical feasibility and engineering realization. To practically use a quantum computer to crack Bitcoin, four key challenges must be overcome:

1. Qubit Count: Current state-of-the-art quantum chips, such as Google's Willow chip, possess 105 qubits. However, running Shor's algorithm to break Bitcoin's 256-bit ECDSA encryption would require millions of logical qubits, each requiring multiple physical qubits. A significant gap exists between current technological capabilities and the required scale.

2. Qubit Error Correction: While the Willow chip achieved an exponential reduction in errors alongside an increase in qubit count, this technology is still in its prototype stage. Cracking Bitcoin requires prolonged computation, demanding extremely high stability and precision from qubitsa level far beyond current error correction capabilities.

3. Quantum Gate Speed: While the Willow chip can perform specific computations in minutes that would take a classical supercomputer trillions of years, this refers to highly specific random circuit sampling. The gate operations required to crack ECDSA are entirely different and currently extremely slow.

4. Feasibility of Shor's Algorithm: Running Shor's algorithm to break a 256-bit key requires a much larger and more stable programmable quantum computer than Willow. Such a quantum computer is currently far beyond reach. Shor's algorithm has been around for over three decades, and yet no desktop-sized prototype capable of verifying its practical application in breaking ECDSA has emerged, hinting at the immense engineering difficulties involved.

• These challenges have deep physical roots, making them difficult to overcome solely through technological advancements. Many experts are pessimistic, believing that large-scale, stable, general-purpose quantum computers may never materialize. For instance, mathematician and computer scientist Gil Kalai expressed caution regarding Google's claimed quantum supremacy, suggesting it might stem from methodological errors and an exaggeration of actual results [1]. Physicist Sabine Hossenfelder also criticized Google's claims, pointing out their zero impact on daily life [1]. A recent important paper published in Science fundamentally challenges the notion of quantum supremacy [2].

It's noteworthy that Bitcoin developers have long been aware of the potential threat of quantum computers. As early as 2010, Satoshi Nakamoto addressed this issue, and in 2016, a page addressing quantum computing was created on the Bitcoin website. The Bitcoin system design incorporates mechanisms to mitigate quantum threats, such as single-use addresses and displaying only the public key and signature before transaction confirmation, minimizing potential risks.

Furthermore, next-generation post-quantum cryptography (PQC) technologies are continually evolving, offering new avenues for countering quantum computer threats. The Bitcoin system framework likely already accommodates PQC, allowing for technological upgrades to address quantum threats if necessary. However, upgrading public-key cryptography is an extremely complex and time-consuming undertaking, requiring substantial financial and human resources. The significant vested interests involved also explain the persistence of hype surrounding quantum technology.

In conclusion, the actual threat of quantum computers to Bitcoin's security is currently negligible. While the cry of "wolf" may continue, a deeper understanding of the current state of quantum computing technology will likely dissipate this fear. Those who truly understand quantum computing technology won't be easily frightened by a paper wolf. You may have a hundred reasons to dislike Bitcoin, but a quantum computer is definitely not a sufficient one.

[1] In a blog post on the day of Google's Willow announcement, mathematician and computer scientist Gil Kalai urged caution, stating: Claims of Google quantum supremacy should be treated with caution, especially the extremely exaggerated claims. These claims might stem from major methodological errors; they might reflect more the researchers expectations than objective scientific reality. Physicist Sabine Hossenfelder criticized Google's quantum supremacy claims as overblown. She pointed out that similar claims made in 2019 involved a 50-qubit chip; a result quickly disputed by IBM. Researchers obtained the same computational results using classical methods within a similar timeframe. According to her, while the claims about Willow are scientifically impressive, their impact on daily life is zero. [2] Sudden death of quantum advantage in correlation generation

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