Google's Quantum Supremacy Provides Fresh Challenges for Blockchain Cryptography

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Google's Quantum Supremacy Provides Fresh Challenges for Blockchain Cryptography
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Last month, Google revealed that it had achieved “quantum supremacy” in its on-going quantum computing program. When a quantum device can complete a computation faster than a classical computer (your smartphone, laptop, an IBM supercomputer, etc) it is said to have demonstrated “quantum supremacy.” In an article published in Nature, the company disclosed that it had engineered a quantum processor dubbed “Sycamore.” This processor then performed a computation that would have taken 10,000 years to complete on the world’s fastest supercomputer, and it did so in a mere 200 seconds.

This is no doubt a remarkable scientific achievement for Google and the world, but the advent of quantum computing presents existential threats to our current encryption technologies and blockchain cryptography itself.

Blockchain technologies continue to expand their applications into various industries, whether that be healthcare or gaming. The technology is frequently in the crosshairs of financial regulators, the news media, and world governments. A World Economic Forum report predicted that 10% of the global GDP will be stored on blockchain or blockchain-related technologies by 2027.

Blockchain works by linking a chain of “blocks” of information together. Each block contains a cryptographic hash of the previous block. This structure makes blockchain virtually unbreakable by classical computers because the time needed to crack the encryption is impractically enormous; 0.65 billion years, for example.

Image: Paweł Czerwiński on Unsplash

Yet, what about a quantum computer that could complete 10,000-year calculations in a few seconds? Well, It is within the realm of possibility that it can crack private blockchain keys given its superior computational speed. Researchers have recently issued dire warnings that quantum computing is only a decade away from the capability of breaking blockchain’s cryptographic codes and encryptions. If we are indeed only a decade away from encryption-breaking quantum computers, what could this mean for blockchain? Could confidence in the technology evaporate if malicious actors can break into peoples’ wallets with ease? 

The answer, unfortunately, is yes. If cryptographic solutions to the challenges posed by quantum computers are not developed, untold amounts of economic damage could be done, and the technology could be abandoned if things get too out of hand. However, with so much of the global economy relying on blockchain, the community is developing encryption methods that could be resistant to theoretical attacks by quantum computers. Quantum computing calls for quantum cryptography and a quantum-resistant blockchain. Even today, there are quantum-resistant blockchain technologies available, such as Praxxis and the Quantum Resistant Ledger (QRL). These technologies use something called “hash-based cryptography” for its digital signatures (i.e., the public and private keys used for crypto wallets) to make itself resistant to quantum computing. These hash-based signature schemes make the time required to break the private keys impractically long, once again, even for quantum computers.

Following Google’s announcement, it is inevitable that more quantum-resistant solutions will emerge before viable quantum computers hit the market or become available to malicious actors. Developers in the space have no illusions about what quantum supremacy means for blockchain cryptography. Even if its actualized threats are many years away, developers now know they have no choice but to make their blockchain encryption methods resistant to unavoidable future attacks.

Also, quantum computing is still extremely young, and its current capabilities and applications are limited. It’ll be many decades before any quantum computer is viable for a commercial market. Blockchain, on the other hand, while still having its own limitations, has been around for some time. It still has the headstart to beef up its cryptography, especially now that Google revealed what’s coming, and what’s coming soon. The community will continue to implement and develop new quantum-resistant cryptography, and instead of presenting a devastating existential threat, quantum supremacy will result in a much stronger and more encrypted blockchain.

Anthony Pellegrino

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