Dawn of the Qubit: Quantum Computers Bring Change to Cryptography

Quantum computers are cool, literally. Operating at around 15 millikelvin (that’s nearly absolute zero), quantum computing is one of the hottest topics in tech despite (or perhaps because of) its near atomically seizing temperatures. But with all the hype it can be a bit confusing to understand exactly what is going on, which companies are building what, and what it will mean for the general public in the future. A lot of current news may be guiding you to believe that quantum threats are going to start appearing next week, but rest assured, your bitcoins are safe for now.

To understand where the imminent threat will develop it is important to take a deeper look into the tech and methods that are fueling the quantum computing revolution. It would be foolish to say that blockchains and cryptography in general will be safe and secure forever, but only by understanding the true threat can we start to form appropriate solutions. By the end of this article you’ll be able to hold your own the next time a friend shares a FUD inspired article with you. Afterall, it is only through knowledge that we can expunge ignorance.

Quantum Computers – A Basic Primer

Achieving a basic understanding of quantum physics is not a simple feat by any standards, but there are a few key principles that need to be understood in order to grasp the fundamentals of quantum computing.

Don’t worry, we’ll avoid PhD level terminology to keep things fresh and easily discussible in future conversations with your friends.
Quantum bits (or Qubits) are the smallest known unit of quantum information, essentially the quantum analog of a traditional computer bit. Imagine them like fancier, more capable 3-Dimensional computer bits that can exist in two+ positions at once.

Source: Nicholas Teague – Medium.com

This is known as superposition and it is the key to quantum computing. This can be a bit to wrap your head around, but it basically means that because the qubit is not limited to two states it can hold more information.

These qubits must be entangled for optimal performance, which essentially means that what is done to one qubits instantaneously happens to the other. Qubits stack exponentially, and although they are hard to directly compare to traditional machines, a 50 entangled qubit machine is expected to be able to surpass the ominous (and sometimes misleading) line into ‘quantum supremacy.’

“A 50-qubit machine can do things that are extremely difficult to simulate without quantum technology.”Will Knight, technologyreview.com

All potential quantum computers are based on the principles of entangling qubits in superposition, but though they may share that key characteristic, not all quantum computers are built the same. In order of least-to-most useful, we have Quantum Annealer, Analog Quantum, and Universal Gate Quantum computers.

Quantum Annealer computers are the least powerful, most restricted, and easiest to build version. These QCs are designed to perform one specific function, and even within that function they are not proven to outperform current supercomputers in identical tasks.

The current leader in quantum annealing computers is D-Wave, a canadian company that made big waves when it released its “2,000 qubit” machine. However, independent research has been unable to prove the effectiveness of this machine over traditional computing methods. It is important to note that no matter how advanced quantum annealing computers become, they will NEVER be able to run Shor’s algorithm, and thus, will never be a threat to modern cryptography.

Analog Quantum computers are what we are currently trying to achieve, and probably won’t surpass for at least 5-10 years. Analog QCs are able to simulate complex quantum interactions that are far too complex for modern traditional computers, no matter how powerful they are.

Analog QCs are currently being built by IBM, Google, Intel, Microsoft, and even China has a horse in the race. The reason these analog QCs are being built is because we have essentially reached the pinnacle of modern traditional computer power: we cannot physically make microchips any smaller, and thus, not any faster. The research and funding currently being poured into quantum computing is targeted mostly towards analog QCs because they are thought of as a crucial step on the path to creating a Universal Gate Quantum Computer.

Universal Gate QCs are the holy grail of the industry, but they are also 10+ years from becoming a reality. UGQCs are by far the hardest to build, and it is theorized that they will contain more than 100,000 physical qubits. These types of computers are the end goal, and with them we will be able to run computations that will make our modern supercomputers seem as advanced as an abacus.
There are currently no companies building UGQCs, but all of the companies working on Analog QCs hope to expand into this more purified version of quantum computing. When you hear about threats to cryptography and cryptocurrencies, this is the culprit. Remember Shor’s algorithm? Universal Gate Quantum Computers will be able to make Shor’s, as well as our our current cryptographic security, seem like child’s play.

Quantum Computing vs Cryptography

As we mentioned before, current QCs aren’t a threat to cryptography, but as QCs evolve and more qubits are entangled we will certainly start to see the changes in our daily security practices. Google has successfully constructed a 72 qubit QC, but it will take around 4,000 qubits before cryptography is in danger. In the modern world the majority of the internet, and data in general, is secured using mathematical algorithms that are essentially impossible to brute force solve.

“Modern algorithms with suitable key lengths (e.g. AES-128, RSA-2048, ECDSA-256, etc.) are not susceptible to brute force attack – even with massive amounts of computing power, they would take centuries or, in some cases, even longer than the lifetime of the universe to break.” – Rob Stubbs, cryptomathic.com

Given the nature of cryptocurrencies and blockchains, they are in danger for different reasons and to varying degrees. There are a lot of clickbait articles floating around discussing the “end of blockchain,” many of which are ignoring a few crucial facts.

  • Universal Gate Quantum Computers (the only ones viably capable of breaking cryptography) are 10+ years away, and even then they won’t be in every household – far from it.
  • Blockchain technology can incorporate quantum practices to ensure they are not made obsolete. This will help prevent a 51% attack if proof-of-work algorithms are altered to be “quantum proof.”
  • The real threat will be that of digital signature security, and will be not be exclusive to blockchains. Because QCs will be able to run Shor’s algorithm we will have to rethink the way we validate public/private keys as well as the hashing protocols we use.

Some companies, like the Kelvin Blockchain, are preparing for the future by working to ensure that when we enter a post quantum blockchain world, we are as secure as possible. They are doing this by focusing primarily on the weakness presented through signatures, and will offer 10+ signature options during the launch of their blockchain.

The beauty of offering so many varying types of signatures lies in two parts:

  1. Anyone trying to crack a public key would have to know the type of encryption you used to hash.
  2. Many of the offered signature encryption options will be verified to be nearly uncrackable, even with Shor’s algorithm, thanks to their greater variable number quantities.

To add increased security, Kelvin will also be utilizing post-quantum zero knowledge ring signatures, a method that will anonymize transactions apart from a wallet – thus making it impossible to know what specific wallet to attack when seeking funds. It would be like trying to rob a house without knowing the address, even if you knew the house was full of gold you’d never be able to steal it without knowing where it was.

Post-Quantum World

BTC, ETH, BCH, and other major chains will all certainly make improvements to their security through forks as the QC revolution becomes more of a reality, implementing various anti-quantum practices to ensure data stays safe. But as we’ve seen in the past, it can sometimes take too long for these chains to update protocols given their size.

No one can say for certain how exactly quantum computers will change our lives. Although they probably won’t be as widespread as traditional computers, the general population will almost certainly benefit from their discoveries in science, medicine, technology, and more. From machine learning to quantum simulations, improvements in cryptography, the ability to run immense computations and more, quantum computers will herald a new era of human understanding.