Quantum computers have been received as cryptocurrency killers because they are great at solving multiple tasks simultaneously. Many fear that the Bitcoin network, among many others, will fail. However, that's not the entire truth. There are many more aspects to consider. In this article, you'll understand why quantum computing is not there yet and what you can expect from our current computing advances.
Before understanding why quantum computing cannot break any type of cryptocurrency yet, we have to understand a significant key aspect of this technology: Quantum computers are good at a few selected tasks while being extremely bad at many others.
Specifically, current implementations are too specialized to be used on a commercial level. They result from investigations and are just not good at 99% of the things we are interested in. We need a more complete type of quantum computer even to consider the possibility of cracking blockchain encryption.
See, quantum computers are based on the direction of atoms when you measure them. There are laws in physics that allow computers to measure atoms knows qubits at massive rates. You can easily calculate the position of many qubits at the same time.
This allows us to execute parallel computing at insanely fast speeds compared to traditional computers. It’s like moving at light speed. So if they are so fast at testing multiple possible results for a given encryption algorithm, shouldn't we be afraid of them breaking Blockchain's encryption? No, here's the first reason why:
Innovation is Still Slow in Quantum Computing
There aren't good quantum computers yet, and that kind of innovation will take us years to attain. Even a good quantum computer can only halve the difficulty of the SHA-256 algorithm used on the entire Bitcoin network, among many other Blockchains.
SHA-256 works by replacing each letter of your Blockchain transaction with a unique sequence of numbers and letters to generate an encrypted string using mathematical functions and its own algorithm.
In reality, the complete implementation of SHA-256 is relatively more complex. All you have to know regarding this particular algorithm is that Bitcoin and other Blockchains use it to secure the network by encrypting a block after another which in turn “links” all the blocks together, thanks to encryption.
It’s extremely strong to brute force attacks where computers try to guess the right encrypted hash because the mathematical functions used to encrypt it make it physically impossible to crack.
This means, the SHA-256 algorithm will become equivalent to the SHA-128, which is still unbreakable so there's nothing to worry about. Yet.
You see, quantum computers are measured by how many qubits they can process at a given moment which is an entirely new system based on physics at the atomic level. Even if we had the most theoretically powerful quantum computer right now, it would be almost impossible to break those existing algorithms. You’d need to make 2166guesses on a quantum computer to crack SHA-128 which is larger than the time of the known universe since the big bang.
SHA-256 and others are so incredibly strong that we can't even fathom how many iterations we need to generate our desired hash. Besides, even if such a strong computer existed in the hands of big corporations and agencies.
Bitcoin and other blockchains will most likely simple hard-fork into a more reliable system that can't be broken that easily since cryptocurrencies are based on trust at the core.
We Can Fight Quantum Technology With Quantum Algorithms
If quantum computers become strong enough to crack existing encryption systems, we will be able to fight back by using something known as post-quantum cryptography.
Which is a field that studies how we can create quantum-resistant algorithms by using those quantum computers themselves. It’s a field with active research where cryptographers are building new systems that will be unbreakable even by the strongest computers.
Many companies are investing into the research and development of these new post-quantum elliptic-curve encryptions to solve this potential issue in case we end up creating powerful enough quantum computers.
On the other hand, those agencies capable of creating such a strong computer won't focus their attention on Bitcoin and blockchain because if you think about it, they have more than enough funds to not care about the money they could possibly make out of crypto hacking.
Big Companies Won't Have the Need to Hack Cryptocurrencies
If you have so much capital to create a computer that breaks one of the strongest algorithms in existence, then you probably don't care about cracking a blockchain, you'll probably focus on other aspects related to security and surveillance or whatever interests you.
These computers are good at solving algorithms based on elliptic curves such as ECDSA which an elliptic curve type of algorithm for encrypting your digital signature on the blockchain to generate your account.
If they are able to break them, we can use quantum computers to create quantum-resistant elliptic curve algorithms. Using quantum to fight quantum.
Banks also use SHA-256 which means they are also safe from quantum computing although they have other encryption systems that may be vulnerable so it's up to each bank software system.
In the blockchain, the private keys are passed through many layers of encryption, something is known as hash-chaining to increase the security of these keys making them even more unlikely to be hacked.
By the nature of encryption algorithms, every hash has a corresponding key that can be calculated by brute force, testing all the possible combinations in the universe until you find one matching your expected key.
The algorithms used to generate public keys can be cracked using Shor's algorithm, which uses quantum positioning to make multiple guesses at once on quantum computers. That way you can un-encrypt an RSA or ECDSA type of algorithm without waiting years.
Researchers all over the world are working on improving quantum computing while at the same time, others are working on implementing quantum resistant cryptography to guarantee that we can continue using cryptocurrencies without any major consequences. Innovation is slow and it will take decades before we can understand the possible consequences of such a revolutionary technology.