A very real concern for the realization of Quantum Computing is that it will be able to hack hard cryptography. That means that quantum computers will put currency blockchain cryptography at risk.
Before you have an anxiety attack, let me assure you that we are not there yet.
And as excited as IBM is about the new Q System One, they are also not there yet. Quantum scientists are very excited about the potential available from the capacities of quantum computing, but there are still some very real hurdles that need to be overcome.
So what is the hype and stress about then?
Essentially, quantum computers can process computations much faster than any computer presently in existence. Theoretically, these computational processes will make it possible to break hard cryptography.
If you are interested in knowing more about quantum computing, I suggest you stop reading this and head over to the article on how quantum computing works.
Blockchain and Quantum Computers
Presently any tech-savvy person is totally and rightfully hyped on blockchain technology. Blockchain seems like it has the potential to answer so many of the problems we face when dealing with the digital world and information security. And since the creation of Satoshi Nakamoto’s Bitcoin, we have realized that we are living in the future, a world where blockchain and the cryptography it uses are essentially unbreakable.
Blockchain is so successful because it is an error-proof ledger that is maintained and secured with hard cryptography. Hard cryptography refers to the application of complex public keys and private keys which make addresses essentially unbreakable.
Each cryptographic block of a blockchain has a timestamp, a link to the previous block using a cryptographic hash function. These blocks form a chronological chain unchangeable through complex, interconnected cryptography. This ensures that the records kept on a blockchain cannot be altered once they have been added to the chain, you can only add more blocks.
Blockchain has what seems like an endless potential to improve the systems we rely on, such as:
- error-proof record keeping
- supply-chain coordination
- functional digital currencies like Bitcoin
The attacks on blockchains that have had some success and deleterious effects are the following:
- Sybil attack: this attack involves an attacker flooding the network with nodes he has control of
- A DDoS attack: this is an attack which overloads a server by working collectively to flood it with serious traffic.
- The routing attack: This is when 30% of the Bitcoin network has its nodes hosted by 13 different ISP’s. Simultaneously, over 60% of the Bitcoin’s traffic are nodes controlled by only 3 ISPs.
So how much would quantum computing affect the functionality and security of the immutable blockchain? And what would that mean for the cryptographic functions it relies on?
Cryptography works well because it relies on the factorization of large numbers which are difficult for computers to solve. This is because, with hard cryptography, computers need to factorize very large numbers. And the larger the number, the harder it is to factorize. This is one of the core functions of cryptography; applying a function that is computationally difficult enough to circumvent and discourage attackers.
Something is computationally difficult means that it is computationally challenging enough that attempts at guessing a private key or reverse engineering a digital address are ineffective and often impossible. That means that it would simply take too long for an attacker to guess at the right answer. This is just how passwords or private keys and digital signatures work.
We all dream of better, faster, and smarter computers, but we also want stronger more impermeable cryptography to protect our information. It almost seems like we cannot have it both. Well, frankly I don’t know if we can, and neither do top the computer scientists at Massachusetts Institute of Technology or the University of Waterloo. They are of course optimistic, but there is a very real difference between the theoretical and practical application.
Quantum computers are presently able to perform factorization exponentially faster than your everyday computer. The catch is that quantum computers are not yet ready as a consumer product. Not even IBM is selling actual quantum computers. They are just offering access to a “quantum cloud.”
Cloud computing is problematic because unlike blockchain, clouds are largely uninsured and risk-prone technology. Moreover, any blockchain does not require millions of dollars to be spent, as quantum computing presently does. Most importantly, IBM is offering a centralized server, unlike a decentralized blockchain, which is much more secure from ransoms and crashes.
Granted this is a technological step forward in many respects, it is not offering access to the decked-out quantum computers of our 90s sci-fi fantasies.
Bad News for Blockchain
Although quantum computers are not ready for mass markets, or even operating at their full theoretical potential, as I mentioned, once they have been perfected quantum computing will affect classical cryptography. And here is why.
Quantum computers have the benefit of putting the qualities of superposition and entanglement to work. This makes quantum computers especially sensitive to attackers or eavesdroppers. Because quantum computers take advantage of qubits, it also makes quantum computing incredibly efficient at factorization. That means that quantum computers will be able to decrypt classical encryption; possibly even computations as difficult as Bitcoin’s SHA-256 hash function.
Good News for Blockchain
Once quantum computers are in full swing, it is pretty clear that they will affect the way cryptography works now. Right now, blockchains rely on the sensitivity of hard cryptography and private key functions. That means that the cryptography that secure blockchains rely on will also have to adjust.
Quantum computers bring with them Quantum Key Distribution (QKD). This ability makes possible the distribution of completely random keys over great distances. Because they can harness superposition and entanglement, this means that large messages can be shared safely over long distances. This is because of decoherence, which makes these messages incredibly sensitive to interference.
QKD will allow for Ultra Secret Keys (USK), where any attempt to observe or measure a quantum system disturbs it, making it hard to attack, and easy to notice corruption.
It is exciting times for quantum computing and blockchain alike. However, at least for now, blockchain technology is miles ahead of quantum computing in terms of usability, and scalability. But I certainly look forward to seeing what computer scientists will do next!