Quantum computing and Bitcoin security

Recent developments in quantum computing have become a central topic in discussions about Bitcoin. While quantum computing may seem like a looming threat, there’s already progress toward solutions that will keep your Bitcoin secure, and there are a few things you can already do to make yourself less vulnerable to a potential attack by a quantum computer.

In this article, we’ll explain what quantum computing is, what the quantum threat to Bitcoin security means, and what’s being done to address it.

What is quantum computing?

Quantum computing is a new type of computing that uses the rules of quantum physics to solve certain problems much faster than regular computers. For specific tasks, quantum computers can be exponentially faster, solving in seconds what might take a regular computer thousands or even millions of years.

Most modern quantum computers are extremely delicate and must be kept at temperatures near absolute zero (around −273 °C) just to remain stable. This means that a quantum computer can only operate in a state that is colder than outer space. However, this may change as quantum computers become more advanced in the future.

Even then, they can only function for a less than a second at a time before noise and interference cause errors. This makes today’s quantum machines highly experimental, and nowhere near ready to threaten Bitcoin’s security.

Quantum computers can solve certain types of equations significantly faster because their basic units, qubits, can exist in multiple states at the same time, thanks to a property called superposition. This is a strange concept because it goes beyond our conventional understanding of physics.

One of the most important quantum algorithms in this context is Shor’s algorithm, a method that could, in theory, break the cryptographic foundations of Bitcoin by calculating private keys from public keys.

This doesn’t mean a quantum computer tries every solution at once in a magical way. It manipulates these overlapping states using quantum rules to amplify the right answers and cancel out the wrong ones. This is an approach that works well for some problems, but not all.

What is a qubit?

The basic unit of information in a quantum computer is the qubit, as opposed to the bit used in traditional computers.

A bit can be either 0 or 1, and combined in large numbers, bits form the basis of all modern digital technology.

A qubit, on the other hand, can be 0, 1, or a combination of both states (until it is measured).

It’s important to distinguish between the two types of qubits: physical and logical. Physical qubits are used in today’s quantum computers. They’re functional but inherently unstable due to noise and decoherence.

Logical qubits, on the other hand, are far more stable. They maintain quantum coherence and superposition for longer periods. Achieving a single logical qubit typically requires between 1,000 and 10,000 physical qubits, depending on the error correction method and system noise.

Quantum threats to Bitcoin

Let’s get straight to the point: it is true that a sufficiently powerful quantum computer could theoretically break the cryptography that underpins Bitcoin. The question is - when could this happen, and can we do anything to get ahead of the issue?

First, we need to address the amount of quantum computing power required to actually break the encryption behind Bitcoin. It’s estimated that breaking Bitcoin’s encryption would require around thousands of logical, and between tens and hundreds of millions of physical qubits once error correction is factored in.

Scientists have created basic logical qubits in research labs, but they’re still fragile, short-lived, and far from ready for real applications. No one has built a working quantum computer with enough logical qubits to run large-scale programs, let alone one powerful enough to threaten Bitcoin.

Quantum computers which are powerful enough to crack Bitcoin’s encryption will most likely not arrive in the near future. However, they are undoubtedly getting more powerful as time goes on, and the safe thing to do is to assume that this will eventually happen.

This makes the topic an important one to pay attention to, as it will eventually require action from the Bitcoin community, both on the side of developers and users.

What can be done about the quantum threat?

Bitcoin has evolved over the years through numerous upgrades known as Bitcoin Improvement Proposals (BIPs). These proposals have helped make Bitcoin more user-friendly and practical, while increasing security and technical complexity behind the scenes.

BIP360 is one such proposal, focused specifically on quantum security. While the technical details require a deep understanding of quantum computing, the core idea is simple: it introduces a new type of Bitcoin address designed to resist attacks from future quantum computers that could potentially reverse-engineer a private key from a public key.

Dormant wallets

One of the most fascinating aspects of the quantum computing conversation is its potential impact on older Bitcoin wallets, including the first coins mined by Satoshi.

These coins have remained untouched since they were mined, but because they are tied to public keys that could eventually be exposed to quantum attacks, they would need to be moved to a new address format to remain secure.

This leads to two possibilities: either Satoshi would need to move the coins, marking his first public activity since 2010, or the coins could become vulnerable to theft by anyone with a sufficiently powerful quantum computer. Either outcome would have serious implications for Bitcoin.

Should you be worried?

While quantum computing does pose a real risk in the long term, it remains a theoretical threat for now. Today’s quantum computers are nowhere near powerful enough to break Bitcoin’s cryptography.

For now, the risk is hypothetical.