Quantum Computers Not a Threat to Bitcoin: MIT Review

Sankar Das Sarma – a physicist from the University of Maryland – recently wrote at length about why the capabilities of quantum computing are overhyped at the moment. Specifically, he clarifies that quantum computing has evolved nowhere close to the stage required to break the public key cryptography used in popular technologies today – such as Bitcoin.
A Long Way to Go for Quantum Computing
As written in an opinion piece for Technology Review, Sarma suggests that ‘Quantum Computing’ has become the second most overhyped buzzword next to ‘Artificial Intelligence’. Yet despite the substantial investments into quantum R&D from major institutions like Alphabet, Amazon, and Microsoft, it’s unlikely they’ll be able to produce something of use any time soon.
“Established applications for quantum computers do exist,” states Sarma. For example, there’s a theoretical application of Quantum computing for finding the prime factors of large numbers exponentially faster than existing schemes. This, he explains, is at the heart of breaking RSA-based cryptography widely used for both email and cryptocurrency transactions.
As such, national governments everywhere have devoted great attention and funding to quantum computing. However, what can be conceptualized in theory isn’t always easily built-in practice.
“The most advanced quantum computers today have dozens of decohering (or “noisy”) physical qubits,” said the professor. These qubits are used primarily for a process called “quantum error correction”, which compensates for the fact that quantum states are fast to disappear.
However, a computer that could actually crack RSA would require many millions or even billions of qubits. Only tens of thousands would be used for real computation, while the rest would be used for error correction.
While Sarma calls qubit systems today a “scientific achievement” they cannot yet solve a problem “that anybody cares about.”
“It is akin to trying to make today’s best smartphones using vacuum tubes from the early 1900s… What is missing is the breakthrough of integrated circuits and CPUs leading to smartphones.”
Bitcoin’s Public Key Cryptography
Most cryptocurrencies today use public keys as “crypto addresses” to which any outside party can send their digital assets. However, to send a transaction from that address, one is required to know the private key from which that public key was derived.
While a private key can easily identify a public key it is compatible with, it is currently impossible to decipher a private key just by knowing someone’s public key alone.
Nevertheless, not everyone is careful to keep their private keys safe. A hacker managed to steal $600 million in funds from the Ronin network this week by securing the private keys belonging to 5 of 9 validator nodes on the network.