“Quantum supremacy.” The terminology instigates images of a giant world-brain supercomputer that can number the grains of sand on every beach on Earth. But what does Google’s official actual claim of supremacy imply, and how will practical quantum computing alter the cryptocurrency world?
After a long period of waiting, Google announced that it has developed and tested a 54-qubit quantum processor known as “Sycamore.” The processor, which appears to be covered in a mass of serpents within its super-cooled cryo-chamber, was able to execute a complex computation in 200 seconds.
“From measurements, in our experiment, we determined that it would take the world’s fastest supercomputer 10,000 years to produce a similar output,” wrote Sycamore’s creators in a blog post.
Quantum processors work by using superposition and entanglement. These unique quantum features allow a quantum chip to process large amounts of data concurrently. To better comprehend it, assume that, like Dr. Strange, a quantum processor can “see” every likely outcome at once and then, statistically, select the most likely answer. This implies time-consuming programs like factoring large numbers- establishing the two large numbers that, when multiplied, makes another large number- is insignificant for a quantum computer.
Quantum supremacy implies that Google has been able to execute a calculation that is not possible on traditional computing hardware. In other words, no “classical” computer- from the fastest mainframe to an Atari 800XL- would ever be able to perform the calculation within a reasonable period, aka before the heat death of the universe or 10,000 years, whichever comes first.
But what does quantum supremacy mean for crypto and crypto mining, where having a highly effective computer gives you an edge over everyone else?
The greatest threat posed by quantum computing to blockchain networks is its ability to break traditional encryption. If you wanted to ultimately damage cryptocurrencies, you would use a quantum computer at SHA-256, a standard hashing algorithm that creates 32-byte “hashes” of passwords, essentially converting them into unreadable gibberish.
Quantum computing professionals see SHA-256 as a proverbial canary in a coal mine. When a true quantum execution starts invading systems globally, researchers will know to panic.
“Quantum computing will impact many forms of encryption, including SHA-256, which is used by bitcoin. Since Bitcoin has value, people will have more of an incentive to attack it. However, I believe many easier encryption algorithms will be broken first and alert the community that it’s time for a change,” said Patrick Dai, founder, and CEO of Qtum, a business-focused blockchain provider. “Breaking SHA-256 isn’t something that happens overnight. We will have many warnings. Ultimately miners will pay the price when the switch happens because they are stuck with incompatible hardware, but bitcoin will continue to progress.”
Ultimately researchers think we are on track to break hashing algorithms and even the asymmetric cryptography systems that power our public and private keys.
Vitalik Buterin, for his part, isn’t bullish on quantum computing.
“My one-sentence impression of new 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,” he wrote.
David Chaum, the creator of Praxxis, believes that proof-of-work systems will be more resistant to quantum attacks, even though wallets and keys won’t.
“The hashing algorithms in Proof of Work (PoW) protocols that require mining are generally resistant to quantum computing. The more likely angle of attack for an adversary with a quantum computer is to break the security of wallets in PoW or Proof of Stake (PoS) protocols,” he said.
Quantum computers can employ Shor’s algorithm factor- the long integers utilized by cryptocurrencies to secure wallets. The expectation is that any individual able to use quantum computing to break RSA- the cryptographic standard for most platforms- will probably keep quiet.
“Given the unpredictability of scientific progress, and the likelihood of secrecy, forecasting exactly when quantum computers will break blockchain crypto is a fool’s errand. With that said, while the barriers to quantum computer development are difficult to overcome, there is no evidence that they are insurmountable.”
HE ADDED: “One day soon, a quantum computer capable of using Shor’s algorithm to defeat many cryptosystems will be produced. The blockchain community would be foolish to ignore this threat until that day comes. The NSA directed government agencies to halt work on quantum-susceptible cryptosystems more than four years ago. The NSA is taking quantum computing seriously. So should we,” said Chaum.
The bottom line is simple: once quantum supremacy starts to touch real-world implementations- including crypto- all hell will break loose. The only way to minimize harm is to be prepared.