What are quantum computers and how do they affect crypto?

Could a computer find your wallet’s key without you handing it over? That’s the core concern behind the debate about quantum computers and crypto.

Ordinary computers use bits with a value of 0 or 1. Quantum computers use quantum bits (qubits), which can exist in a superposition of states. Suitable algorithms exploit this property to solve specific mathematical problems far more efficiently. But they don’t become faster at every task, nor do they magically try every password at once.

Think of a lock we consider secure because a conventional burglar would need far too long to open it. A different tool could change that assessment. In crypto, the equivalent “lock” includes, among other things, the math that links the public key to the private key.

Why it matters

A sufficiently powerful quantum computer, with proper error correction, could use Shor’s algorithm to compute private keys from public keys for signature schemes used on many blockchains. That would allow forging digital signatures and potentially unauthorized transfers.

Hash functions, which blockchains also use, are affected differently. It isn’t true that a single quantum attack automatically “breaks” every security mechanism. Nor is the number of qubits alone enough to judge what a machine can do.

There are post-quantum cryptographic methods, designed to resist known quantum attacks. Integrating them into a blockchain requires review, upgrades and coordination. We believe that’s where the real issue lies: in how well networks prepare, not in sensational headlines.

What to watch out for

A hardware wallet protects your private key from many practical risks, but it doesn’t change the network’s signature algorithm. If that algorithm becomes vulnerable, offline storage alone doesn’t solve the problem.

Also, a wallet address isn’t always the same as the public key. When the public key is revealed depends on the network and the address type. So claims about a “quantum-safe” wallet need a specific technical explanation, not just a label.