Quantum-resistant algorithms — also known as post-quantum, quantum-secure, and quantum-safe — are cryptographic algorithms that can fend off attacks from quantum computers.
Quantum computers are machines whose processing power far outstrips even the most powerful supercomputers available today.
Traditional computers process information in bits — strings of 1s and 0s represented as electrical or optical pulses. By contrast, quantum computers use qubits. These are subatomic particles, typically electrons or photons.
Today’s public blockchains, including Bitcoin, are secured using asymmetric cryptography. This means a user needs a public key and a private key to access their wallet.
The mathematical relationship between users’ private and public keys is too complex for traditional computers. But a quantum computer could figure it out and gain access to users’ wallets in a matter of days.
Quantum computers are still a highly specialised area. But experts think they could become commonplace and, so, an imminent threat to cryptographic security by the end of the 2020s. Blockchain networks will need upgrading before this happens.
A number of projects aimed at increasing cryptographic security and creating blockchain networks that can resist quantum computers’ attacks are already underway.
The first quantum computing algorithm was published by Peter Shor in 1994 — three years before the first quantum computer was built. But the idea that quantum computers could solve problems traditional computers can’t was first put forward by Richard Feynman, Paul Benioff, and Yuri Manin in the early 1980s.
While the first quantum computer was built in 1997, the field became an arms race during the 2010s.
IBM unveiled the first quantum computer for scientific and commercial use — IBM Q System One — in January 2019. In October of the same year, Google made history by announcing they’d achieved quantum supremacy. Their quantum computer had solved a mathematical problem it would take a traditional machine 10,000 years to solve.
Researchers at the University of Singapore have said that Bitcoin’s cryptographic algorithm could be under threat by quantum computers as soon as 2027.
But some crypto experts aren’t especially worried. When Google announced it had achieved quantum supremacy, Ethereum’s founder Vitalik Buterin was unimpressed. He tweeted:
“My one-sentence impression of recent quantum supremacy stuff so far is that it is to real quantum computing what hydrogen bombs are to nuclear fusion. Proof that a phenomenon and the capability to extract power from it exist, but still far from directed use toward useful things.”
Want to know more?
- This article by Deloitte explains the threat quantum computers pose for the blockchain in great detail. The authors speculate that about 4 million Bitcoin, currently worth $40 billion, are vulnerable to a quantum computer attack.
- Want to learn more about quantum computers? This article from MIT Technology Review is a highly readable explainer. Quantum computers are especially promising when it comes to improving electric vehicles’ performance and creating new drugs.
The METACO view
“Wherever there’s a threat, there’s also an opportunity to innovate. The risks presented by quantum computing are a chance to devise ever more secure infrastructure which will strengthen cryptocurrencies and boost their legitimacy as an asset class.”