Quantum Computers Could Crack Bitcoin Security by the 2030s

IBM materials on Eagle and Quantum System Two
(Image credit: IBM)

Today, the Bitcoin network's security, using a cryptographic algorithm called SHA-256, would be insurmountable for a computer as we know it to crack. But quantum computing may change that within the next decade. Scientists at the University of Sussex now estimate that quantum computers are likely to become powerful enough to crack the security that protects Bitcoins sometime in the next decade. New Scientist first reported on the study.

Bitcoin is based on a blockchain, essentially a ledger of who owns what, protected by the SHA-256 algorithm. If you could crack the key revealed during Bitcoin transactions, you could change ownership of a Bitcoin. The Sussex scientists, led by Mark Webber, explain that every Bitcoin transaction is assigned a cryptographic key, which is vulnerable for a finite time, which might vary from 10 minutes to an hour, to a day.

The researchers estimate that a quantum computer with 1.9 billion qubits would be necessary to crack a Bitcoin's encryption within 10 minutes. To manage the feat within an hour, a machine with 317 million qubits would be required. However, if you had a full day to try and crack the security, a system packing just 13 million qubits would be capable of the task.

Right now, the most potent quantum computer, developed by IBM, boasts 127 qubits. We are obviously a long way from machines with 13 million qubits becoming available, and a 317 million+ qubit machine is a much better bet in practical cracking of Bitcoins, as things stand. The Sussex scientists reckon that with the pace of advances we see now, sufficiently powerful quantum computers will not be realized for "potentially over a decade," putting us firmly into the 2030s.

Any projected calamitous D-Day for Bitcoin is very much a moving target. The scientists note that the Bitcoin network "could nullify this threat by performing a soft fork onto an encryption method that is quantum secure, but there may be serious scaling concerns associated with the switch." On the other side of the tug-o-war, developments in quantum computing could easily accelerate progress towards being able to hack Bitcoin security. The researchers mention the potential of trapped ion-based quantum computers, for example.

Indirect Attacks Are Growing in Popularity

Absorbing the huge numbers discussed by the scientists, plus pondering over concepts of quantum supremacy and quantum advantage, it is easy to forget that the current tech news landscape is littered with news of various crypto currencies and exchanges being hacked, or investor or speculator funds being otherwise purloined. How is this happening with such strong encryption deployed?

Any secure system is only as secure as its weakest point, as were were reminded by the very recent Wormhole crypto hack. Earlier today we reported that Wormhole, one of the most popular bridges linking the Ethereum and Solana blockchains, leaked $320 million to hackers. Blockchain protocols like Wormhole are necessary to the system for cross currency transactions, and other purposes, but have become an increasingly popular target in recent months.

Mark Tyson
News Editor

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.

  • InvalidError
    I had a feeling it wouldn't be much longer before someone published a paper about the potential vulnerability of crypto to quantum computing.

    Attacking the block chain itself isn't particularly useful since you are competing against the network hash rate for the next block, which means you need a quantum computer powerful enough to achieve a 51% attack to hijack the block chain. The more interesting thing to attack IMO would be wallet encryption. Solve that and then you have all of the time within reason to drain every wallet with sufficient data on the blockchain to factor out the wallet's private key into your own wallets.
  • TJ Hooker
    This article has mixed up a few details. SHA-256 is not a form of encryption, it is a hashing algorithm. When the paper talks about quantum computers one day being able to break Bitcoin's encryption, they're referring to the 256 bit ECC (elliptic curve cryptography) public key cryptography that Bitcoin uses.

    It has been well known for many years that current public key cryptography algorithms (ECC and RSA) will be vulnerable to quantum computers. And when that does happen, it'll have a much larger impact than just Bitcoin. Most secure networking relies on public key cryptography. E.g. HTTPS, which uses public key cryptography to verify the identify of the website you're connecting to (via its digital signature) and to establish a secure communication channel. All of these protocols will need to switch over to quantum resistant algorithms prior to quantum computers getting too fast, or we're all going to have a bad time.
  • Giroro
    If your goal is to simply "break" bitcoin, then you don't even need to crack the cryptography. You just need need to be able to reliably predict which blocks will get a payout.
    That's not the only step, but the ensuing arms race would make BTC virtually untradeable within a few months.
  • TJ Hooker
    Giroro said:
    You just need need to be able to reliably predict which blocks will get a payout.
    What "payout" are you referring to? Every new block that is mined results in the miner earning a block reward (plus transaction fees).
  • eltoro
    I sure hope that all cryptocurrencies get cracked and become worthless ASAP.
    I also hope that news like this is going to push their worth down even right now.
    They are the reason behind the huge video card price and availability problems, and that is my only interest in this field.
    For all I care, people who are making an income out of this should start working like the rest of us.