Research: Quantum Computer Could Break Bitcoin Security Faster
Alice & Bob estimates that a quantum computer with around 30,000 qubits could break Bitcoin cryptography in just over an hour. Addresses whose public key is already visible are especially at risk.
Key Takeaways
- Researchers at Alice & Bob estimate that about 29,588 physical qubits could break Bitcoin cryptography in a little over an hour.
- The study mainly warns about addresses whose public key is already visible; according to the researchers, more than 6 million bitcoin sit behind them.
- The research increases pressure on Bitcoin to move to quantum-resistant security in time, while the threat and timing remain uncertain.
Researchers at quantum company Alice & Bob warn that a machine with about 30,000 physical qubits could break Bitcoin cryptography in just over an hour. That estimate is much lower than earlier calculations and adds to concerns about how quickly Bitcoin needs to defend itself against quantum attacks.
Lower Threshold Than Expected
Alice & Bob arrives at 29,588 qubits, about 17 times less than Google's earlier estimate in March. That difference is partly due to different assumptions and a different hardware design, but the conclusion is the same: the computing power needed to threaten Bitcoin may be smaller than previously thought.
The researchers used Shor's algorithm, a method that on a sufficiently powerful quantum computer can solve certain cryptographic problems that classical computers cannot practically crack. According to senior cryptanalyst Dahmun Goudarzi, that is why the move to stronger protection needs to start now.
Especially Exposed Keys Are at Risk
The study also draws a distinction between two types of risk. A transaction that is still waiting for confirmation is hard to attack, because the attack would take about 62 minutes according to the researchers and Bitcoin adds a block every 10 minutes on average. But bitcoin in addresses whose public key is already visible remains vulnerable for longer.
That is where the biggest concern lies: more than 6 million bitcoin sit behind those exposed public keys. A powerful quantum computer could in theory work backward to the private key and steal the coins. The researchers call their work theoretical, but they also say hardware improvements and lower required computing power could come closer together in the early 2030s.
What This Means for Bitcoin
For European crypto followers, this is especially relevant because the debate over quantum safety is already broader than Bitcoin alone. EU authorities have previously pointed to the possible threat of quantum computing to blockchain encryption, while NIST is also working on post-quantum cryptography. That shows the industry is not only looking at price or adoption, but also at how long current security will remain viable.
Pressure is also growing within the industry to take steps now. Coinbase wants Bitcoin prepared for the quantum threat now recently called for post-quantum signatures, a phased wallet migration, and special treatment for old or lost coins that could be extra vulnerable.
For Bitcoin developers, this means a move to quantum-resistant signatures could take years, while the threat itself is still evolving. The timing remains uncertain, but the research does add extra pressure to the debate over a future security migration.
