Quantum computing will break the blockchain and QKD can save it

Blockchain technology has proved to be one of the most disruptive and innovative technologies to emerge in the last decade. But just as companies and governments around the world are beginning to explore ways they can harness the blockchain to push their organizations and processes to the next level, a debilitating threat is on the horizon.

In order to understand the challenges organizations face in securing their data, it’s important to understand what the blockchain is and how it works. A blockchain is a digital ledger that records data across a network. Rather than storing a piece of information in one place, a blockchain replicates that information across a massive network of distributed computers. It does this by enlisting a network of specialized computers to solve a cryptographic algorithm, authenticating transactions between two individuals. That solution is then added to the record in what’s called a block. Blocks are publicly available records of blockchain transactions that are not hosted by any one individual yet are available to all.

Because the data exists in so many instances, that data is both easily verifiable and virtually unhackable by even the world’s most powerful computers. This impenetrable level of security and ability to maintain anonymity made it a fundamental building block for cryptocurrency, and its meteoric rise in popularity is due almost exclusively to Bitcoin trading. And while cryptocurrency is still the killer application for blockchain today, companies and organizations are beginning to explore other ways to use the same core technology. Blockchains could soon be used to manage everything from supply chains and medical records to more traditional financial transactions.

But for all its promise, blockchain technology isn’t perfect. Another groundbreaking technology looming in the not-so-distant future will undermine the security of any system built upon blockchain architecture. That technology is quantum computing.

In today’s technology landscape, the blockchain promises unbreakable data security, but that will all be undone as soon as quantum computers come on the scene. Blockchain security is based on mathematical puzzles that are incredibly difficult for even the best conventional computers to crack. One commonly used puzzle is to determine which two prime numbers have been multiplied together to create a new number, a challenge that gets nearly impossible as the numbers get bigger. In 1994, mathematician Peter Shor devised a way—called Shor’s algorithm—to quickly find a number’s prime factors and solve the puzzle. However, that algorithm requires a quantum computer to run.

Quantum computers will be able to perform calculations far faster than modern computers, and the math-based encryption that is so difficult for modern-day computers to break will be vulnerable to attack by a quantum computer in mere moments. To date, no one has shown they’ve built a viable quantum computer, but with big tech players like Alibaba, IBM, and Microsoft working on commercial versions, as well as governments of major superpowers like the United States and China sponsoring quantum research, the eventual arrival of fully functioning quantum computers is inevitable.

Quantum technology presents a very real threat to any system that relies on mathematical algorithms for its security. Quantum Key Distribution (QKD) however takes advantage of the laws of quantum mechanics, allowing two parties exchanging secure data to detect whether a third party is attempting to eavesdrop on their exchange. Using quantum keys in conjunction with a blockchain network could be one way to help secure against attacks from both classical and quantum computers.

Organizations exploring innovative uses for blockchain technology are on the cutting edge and relying on blockchain technology to securely manage your data might be sufficient now. But staying a step ahead of bad actors in the cybersecurity space is a perpetual challenge. In this case, we know what the future has in store; the only question is when it will arrive. Those who need to ensure their data is safe tomorrow and beyond will want to consider the inevitable challenges quantum computing will bring.



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