## Quantum Computers Threaten to Break Blockchain Encryption

### The introduction of quantum computers has made cryptocurrencies and blockchains vulnerable, as the vast computational resources of quantum computers can be used to break a blockchain’s encryption.

While this problem has been theorized for years, it may have become one step closer to reality after a new scientific paper released by Google says that the company has reached “Quantum Supremacy”.

Google’s claims to have used a quantum computer to achieve quantum supremacy by running a quantum algorithm that classical supercomputers simply cannot run. The report says that Google’s 53-qubit quantum machine (called Sycamore) was able to complete a calculation that would take the world’s fastest supercomputer (IBM’s Summit) 10,000 years to complete in just 200 seconds. If the reports are true, then Google’s achievement will be first time a quantum computer has outperformed a classical supercomputer.

If quantum supremacy has been reached then the feat is a milestone in quantum computing, ushering in an era where quantum computers can out-performing classical supercomputers for various applications. It remains to be seen if quantum computers develop to a point where they can run simulations, applications and computations that classical computers cannot.

Techworm reporter Kavita Iyer reports that,*“The (Google) team also indicated the accomplishment of quantum supremacy to be “a milestone towards full-scale quantum computing”. They also predicted that the power of quantum computers will increase at a “double exponential rate”, in comparison to the exponential rate of Moore’s Law (Iyer, 2019).”*

Quantum computers offer the promise of being significantly faster than classical computers by operating at a particle level, improving on the performance of conventional computers by taking advantage of complex quantum phenomena.

Private and public keys are used in securing blockchains. Three mathematical problems are used in a blockchain's encryption, and all three of them share the same property. By knowing the mathematical problem’s inputs (encryption key), their output can generally be easily calculated. But by only knowing the mathematical problem’s output, it can be extremely difficult to guess the corresponding inputs. Quantum computing can potentially solve this problem.

In theory, quantum computers will possess enough processing power to reverse the calculation of the inputs in less time than classical computers. Quantum computers could crack regular encryption by executing each mathematical combination one-by-one.

*StreetInsider explains the potential severity of the problem quantum computers pose to blockchain encryption by saying, “By its nature, quantum computing is highly effective at factorizing numbers, which means quantum computers will be many orders of magnitude faster at the calculations necessary to break the RSA and ECC (Elliptic Curve Cryptography) encryption that underpins our digital systems today. This efficiency gain is so monumental that increasing the key sizes of these cryptographic schemes is not a viable solution. Rather, the world’s Public Key Infrastructure (PKI) systems will have to migrate to one or more new, quantum-resistant encryption algorithms before quantum computers break current encryption methods (Business Wire, 2019).”*

The immense processing power of quantum computers is measured in qubits. Qubits have been proven to be as fast as normal bits for some types of computations and an order of magnitude faster for other computations. Classical computers use bits. Bits can be either 0 or 1. Qubits are different from regular bits because they can be 0, 1, or anything else in between. Quantum computers can be both 0 and 1 at the same time but with different likelihoods. This unique property is called superposition. It means that Qubits can store much more information than regular bits, allowing quantum computers to compute certain things much faster than classical computers.

One of the biggest obstacles in the development and distribution of quantum computers is their cooling requirement. Quantum computers need to be close to absolute 0 to operate, which is -273 degrees Celsius. At lower temperatures, electrons move slower. The cooling requirement of quantum computers has made them very expensive to develop and operate. As a result, the potential of an average person having their own quantum computer is still years (possibly decades) away. Ultimately, the goal is for future developers to create quantum-safe encryption before quantum computers before it is too late.

*Street Insider says, “The search for algorithms is underway. Thought leaders from industry, academia, and government are combining efforts to discover and deploy quantum-resistant cryptographic solutions across our global digital systems. The National Institute for Standards and Technology (NIST) has been leading an effort to identify one or more cryptographic approaches that can substitute for RSA and ECC. The community participating in NIST’s process now has a list of more than 20 candidate algorithms that are undergoing scrutiny of their suitability for this task.*

*Successful quantum-resistant algorithms must be difficult to break using brute-force attacks by both traditional and quantum architectures while still meeting performance standards similar to today’s algorithms. To be viable for widespread use, the algorithm must deliver on criteria such as:*

• *Fast Encryption using traditional computers*

• *Fast decryption (with private keys) using traditional computers*

• *Impractical to decrypt (without private keys) using quantum or traditional architectures*

• *Able to generate encrypted data of a size that is reasonable for storage and transmission across networks and the internet*

• *Compatible with a vast range of software, hardware, and services*

• *Well-understood and checked against potential attack*

• *Understanding the challenge*

One possible solution to the quantum computer problem is to add a secure quantum layer to existing blockchains. Using a secure quantum layer produces an outcome where existing blockchain encryptions can be used and updated to prevent a quantum computer attack.

Another potential solution is to use quantum blockchains. More specifically, a blockchain that is built for (and explicitly used by) quantum computers. In this example, all nodes of the blockchain would have to be used by quantum computers as well, requiring a quantum network to connect the nodes.

As Google’s claim of quantum superiority suggests, we are on the doorstep of a new era in computing. The race will be on to see if future developers, programmers and blockchains will be able to withstand a new era of quantum technologies and the threats they pose to the cryptocurrency community.

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