The notion that quantum computers will soon compromise the security of the bitcoin network has been gaining traction, with some claims suggesting that these machines could rapidly crack the cryptocurrency's cryptography or overwhelm the network. However, recent academic research presents a more nuanced picture, highlighting that some widely cited 'breakthroughs' are based on simplified problems that do not accurately reflect real-world cryptography. Furthermore, the energy required for a quantum attack on the bitcoin network is estimated to be equivalent to that of a small star, according to research papers shared by Bitcoin hardware entrepreneur Rodolfo Novak. The security of bitcoin relies on two types of mathematics, and quantum computers pose a threat to them in different ways.
One method, known as Shor's algorithm, targets wallet security by potentially allowing a powerful quantum computer to derive a private key from a public key, thereby giving an attacker control over funds. The other method, known as Grover's algorithm, applies to mining and offers a theoretical speedup in the trial-and-error search process that miners use to find valid blocks.
However, the advantage provided by Grover's algorithm largely disappears when attempting to build the machine. Two recent papers, one a sober engineering analysis and the other a satirical piece, make the case from opposing directions that the current panic on crypto Twitter conflates a legitimate long-term concern with a news cycle driven by sensationalism. The first paper, published in March 2026 by Pierre-Luc Dallaire-Demers and the BTQ Technologies team, examines whether a quantum computer could out-mine BTC using Grover's algorithm.
The researchers argue that the answer collapses once the hardware and energy requirements are considered, as running Grover against the SHA-256 math formula used by bitcoin miners would be physically impossible. The process would require quantum hardware on a scale that is currently unknown, with each step involving hundreds of thousands of delicate operations, each needing its own dedicated support system of thousands of qubits to keep errors in check. Given bitcoin's production of a new block every ten minutes, an attacker would have a narrow window to complete the task, forcing them to run enormous numbers of these machines side by side.
At Bitcoin's January 2025 difficulty, the authors estimate that a quantum mining fleet would need roughly 10²³ qubits drawing 10²⁵ watts, approaching the energy output of a star. This makes a quantum 51% attack not just expensive but physically unattainable at any scale a real civilization could power. The second paper, by Peter Gutmann of the University of Auckland and Stephan Neuhaus of Zürcher Hochschule in Switzerland, targets the steady stream of headlines claiming that quantum computers are already starting to break encryption.
The authors set out to replicate every major quantum factoring 'breakthrough' of the past two decades using a 1981 VIC-20 home computer, an abacus, and a dog named Scribble. They succeed in making the point that factoring, the math problem at the heart of most modern encryption, is often made easy by picking numbers with prime factors that are only a few digits apart, making them simple to guess with a basic calculator trick. The researchers focus on one recent paper that claimed a Chinese team had used a D-Wave machine to make progress toward breaking RSA-2048, the encryption standard that protects most of the internet's banking, email, and e-commerce traffic.
The authors ran the numbers through a VIC-20 emulator and recovered the answers in about 16 seconds each, demonstrating that the primes had been chosen to sit just a few digits apart, making them easy to find with an algorithm adapted from an abacus technique. The takeaway is not that quantum computing is harmless but that every 'breakthrough' headline does not represent real progress toward breaking modern encryption. The real vulnerability is bitcoin wallets, not mining, with millions of bitcoin sitting in older or reused addresses where key information is already exposed on the blockchain, making them the most likely long-term target if quantum machines improve. Recent research suggests that the computing power needed for such an attack could fall sharply, with the encryption that secures the Bitcoin blockchain vulnerable in an attack that takes minutes.
However, building such a machine is currently physically impossible and requires engineering advances that have not been achieved yet. Developers are already working on fixes, including ways to reduce key exposure and new types of signatures designed to withstand quantum attacks. Markets reflect the view that this threat is still theoretical, with traders seeing little chance that bitcoin will replace its mining algorithm before 2027 but assigning higher odds to upgrades aimed at reducing wallet risk.