We live in a world where the minute devices are performing gigantic tasks within the twinkling of an eye. This is far different from what we had decades ago where a single computer occupies a room large enough to comfortably accommodate 100 adults and perform tasks at an incredibly low speed. No doubts, advancements in technology have made the world a better place, but there seems to be a lot of rivers to cross that are beyond the capacity of the most powerful computers we have today. Time will definitely tell whether these tasks ahead will be achieved or not.
If you have a science background, you certainly know what an atom is. In case you don’t know, perform this quick experiment: Pick a piece of cookie and divide it into pieces. Further break the resultant pieces until you get to point where it is no longer possible to do so. Those indivisible small particles you ended up having are what atoms are likened to be. Now, picture your computer having memory units and transistors as minute as those pieces of cookies. This is the era we are currently approaching with what is known as Quantum Computing. While the speed and potentially smaller computers are worthy of looking out for, the complexity compared to classic computing and its implications for the blockchain technology have generated some concerns.
Conventional VS Quantum Computing
As we all know, conventional computers are amazing storage and processing devices. Computer’s main functions – storage and processing – are enabled by transistors. They are like switches represented by binary numbers 1 and 0 or on and off. Information sent to a computer is converted to these binary digits also known as bits. A combination of a number of transistors forms logic gates, which the computer uses for calculations. Several logic gates form an electronic circuit (EC) by which a certain calculation is performed.
The breakthrough associated replacing vacuum tubes with transistors which also forms integrated circuits (micro-chips) came with limitations. Conventional computers require more transistors to store more binary digits, resulting from more information. Also, it can only work in series (process one thing at a time). This means complex problems require more computing power and steps to solve.
Quantum computers on the other hand have every backend feature of a conventional computer. However, instead of bits, Quantum computers utilize Qubits (Quantum Bits) which are capable of storing and processing a one, zero and a superpositioned multiple of both simultaneously. In other words, a Quantum Computer operates in parallel, meaning it is capable of executing several tasks at the same time. So, it is faster than any classical computer. Also, a Quantum computer’s computational capacity is proportional to the number of qubits.
The idea of Quantum computers remained a mere theory until 1994 when Shor’s algorithm which was capable of computing prime factors of large numbers was developed. Given this breakthrough, the race to build the first Quantum computer has been intense as cryptographers also began looking for Quantum-resistant antidotes to counter it.
Till date, programmable 5-qubit computers and 10 to 20-qubit test systems have been fully built. Achieving a threshold, otherwise known as “quantum supremacy” of 50qubits is currently being worked upon by researchers. At this point and beyond, it would be impossible for any existing classical supercomputer to match up with what such computers can achieve in memory, computing power and speed. Quantum computers are deemed to have commercial value at between 30-100 qubits and researchers have projected this will be happening in the next 2-5 years.
Quantum Computing and the Blockchain
Public key cryptography is an invention of the 1970s, aimed at securing internet transactions. At the moment, most blockchain technology relies on public key cryptography, which encrypts information using a pair of keys – private and public keys. The security of the entire system largely depends on the difficulty in determining the private keys by which the encrypted message can be decoded.
Usually, public and private keys are connected by the factors of the product of two large prime numbers. Therefore, accessing the private keys from the public keys would mean finding out the factors. This is quite impracticable with a classical computer based on the size of prime numbers in question and the time it would take to accomplish such tasks. However, with a Quantum computer wielding massive computing power and speed, it might be possible. So, current public key cryptography becomes vulnerable and this voids the blockchain security.
While many are of the opinion that Quantum computers are still far ahead of us and by the time it arrives, it will be met by a more secured signature scheme, cryptographers have gone to work. Significant progress in the quest to create a quantum-resistant cryptographic system has been made. For instance, Russian researchers recently announced the development of the World’s first quantum-resistant blockchain. According to them, digital signatures were completely eliminated in the new model and instead, quantum cryptography is used for authentication. This form of cryptography is built round entangled particles utilizing “quantum key distribution” to create immunity against attacks by quantum computers.
Another move is by the Quantum Resistant Ledger team whose solution will be built around complex hash-based cryptographic structures which will enable the generation of private keys from public keys in a more complex manner. As a result, this form of post-quantum cryptography eliminates the reliance on prime factorization.
Therefore, with emerging trends indicating the reality of Quantum computers and its imminent effects on blockchain security, there seems to be a lot to think about. Obviously, this won’t be hitting us by surprise, so in the long-run, we might have a suitable antidote before arrival of these superfast computers.