Quantum hackers could crack bitcoin in minutes, but don’t panic just yet

Over the past decade, computer programming has steadily evolved and reached into the quantum realm, producing mind-blowing devices that promise unthinkable levels of power.

In 2020, for example, Chinese scientists harnessed a quantum computer to run a math problem that would have taken a typical supercomputer 2.5 billion years to solve. The quantum machine solved it in 200 seconds.

But the hype goes far beyond superhero calculations. Quantum computing has the potential to transform the way we interact with nature.

It could accelerate drug discovery by sift through molecular structures, a feat that IBM has partnered with the Cleveland Clinic to explore. It could strengthen Internet security towards a virtual impossibility of hackingto earn the attention of the United States Department of Energy. Even manufacturing companies, such as automotive giant BMW, have entered the quantum game as they could perfect materials science and rewrite the framework for artificial intelligence.

We could be on the edge of a quantum revolution where scientists can develop drugs at record speed, predict the weather with incredible certainty, and discover new angles on physics.

There is a catch, however.

Quantum computer prototypes still operate at relatively small scales. Qubits, the basic units of the quantum version of computing language, drive the power of a quantum PC. Most current quantum processors exceed a few tens of qubits, and the largest processor, built by IBM, is currently at 127 qubits. These figures are far from sufficient for quantum breakthroughs.

But what would it be? In an attempt to judge the current state of quantum chronology, Mark Webber, quantum architect of the English startup Universal Quantum, and his team calculated the amount of qubits that should theoretically be hacked the formidable security system used by bitcoinsdecentralized digital currency which has been a volatile investment, caught the eye of Elon Musk and become the symbol of an impending financial revolution.

Short answer? Several million more than the single 127 qubit processor from IBM lighting the way.

Bitcoin’s Quantum Weakness

Bitcoin’s security system is considered ultra-secure against conventional computers, which is why it offers a great way to gauge quantum computing power. It’s very complex, but here’s what you need to know for our purposes.

Every time a transaction is made, two important things happen.

A public key, accessible to all, and a secure private key, visible only to the spender, are generated. This key combination is then digitally “written” to a monetary transaction ledger within the system, aka a blockchain.

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After that, the transaction kind of freezes, preventing anyone from doing anything with the associated funds. But there is a flip side: “When someone makes a transaction in bitcoin, it is announced to the world, but it is not completely secure until it is integrated into the blockchain” , Webber said.

In other words, between the public declaration of a transaction and the integration, there is a window of vulnerability. In this window, funds can technically be manipulated. I say technically because it would require such complex algorithms that even the most powerful supercomputers don’t have enough computing power to run them – and you can forget about humans trying to do it manually. Quantum computers can, eventually.

“If you had a quantum computer and it could run fast enough, you could theoretically apply it to transactions routinely to redirect [them] at a different address, for example,” Webber said.

Although the general rough stage of the window ranges from 10 minutes to a day, Webber says its finiteness makes it a particularly good test for “We have a desired runtime, how many qubits do we need?”

But before we go any further, let’s discuss where all that qubit power is coming from. It’s thanks to two dazzling quantum features that you won’t believe are science fiction: superposition and entanglement.

Quick trip to the land of qubits

Suppose I toss a coin on a table and ask, “Is it heads or tails?” You would probably say, “What?” because my question doesn’t make much sense. Before the coin settles to one side, it essentially exists as the two options simultaneously. Think of this vertiginous piece as being in a “layering”.

If you interrupt its overlay to examine its fate — that is, cause the room to stop spinning — you cannot bring back the exact state of limbo. Once you break the overlay, it’s broken forever.

Now let’s modify the case to include two pieces that rotate next to each other. This time, I have one condition: if coin A lands heads, coin B will also. These parts are now interdependent, so to speak. The superposition of each piece is “entangled” in that of the other.

Adjustments to Part A Overlay instantly affect parts B. Even if only part A stops spinning, for example, you gain knowledge about part B – thereby breaking its superposition as well. This would ring true even if the pieces were at opposite ends of the universe.


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OK, you’re probably thinking: these analogies are kind of in the mind of the beholder. You are right. But that’s because we’re talking about coins. With quantum particles like electrons and photons, these things actually happen, physically.

Going back to quantum computing, superposition determines the state of a bit. Classical bits exist as 0 or 1, but qubits, made of quantum particles, can be superimposed – 0 and 1 at the same time. More importantly, they recover the data while still in this state.

As you can imagine, qubits run through computations at unfathomable speeds, testing multiple iterations simultaneously and tangle with other qubits to convey information instantly. It is essential.

For context, Google and IBM quantum computers evenly distribute qubits on a grid, using what is called superconducting quantum material. Adjacent qubits can intertwine to communicate information. Webber’s company focuses on trapped ionic material, which allows qubits to move freely and collaborate anywhere on a grid. Either way, though, more qubits equals exponentially more computing power.


IBM’s quantum computer.

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But how many of these qubits need to sync to take advantage of Bitcoin’s window of vulnerability?

Challenge accepted: hack bitcoin

Here’s what we know so far: Bitcoin transactions have a window during which they are vulnerable to quantum computers, but not classical computers and certainly not people. Indeed, quantum systems are filled with qubits, firing and performing calculations at speeds that the human brain can barely comprehend.

Using external research, Webber explained how many qubits are needed to enter this window, revealing solid estimates. But remember the delicacy of qubits. If something goes wrong in a quantum computer, the overlay is interrupted and all valuable quantum data can be lost forever. And things go wrong.

To avoid this disaster, quantum programmers do something quite intuitive. They just use more qubits. This is called quantum error correction.


A conceptual illustration of quantum particles working and intertwining with each other.

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Saving to simplify, they launch an army of qubits with each calculation to increase the chances of correct data. For example, if 9/10 qubits offered the same solution, it would be safe to say that it is correct.

“To have a fairly high-quality logical qubit — it’s not perfect, but it’s fine — it’s something like 1,000 physical qubits to one,” Webber said. So he multiplied his initial estimate by 1,000 to get a final answer.

Bingo, it would take around 317 million qubits to hack bitcoin in one hour. If you look at a 10-minute window, “it would just be a bigger number,” he said. “Probably six times more.” This would put the number of qubits in the billions. We’re not even close to that point yet.

“If you want to crack it slower,” Webber added, “it takes fewer qubits overall – so something like 13 million to crack it in a day.”

Webber isn’t the only one thinking about how quantum computing could bypass cryptocurrency security. The US National Institute of Standards and Technology, for example, is researching quantum-proof cryptography algorithms to keep cryptocurrency secure, while the Ethereum Foundation is researching notions of resistance. quantum.

While we still have a long way to go before we get to a quantum bitcoin hack, Webber urges thinking about advances now: “Look at the transition from classical computing to 10-bit vacuum tubes, or the number that they had in the beginning, to the extremes that we have now.

“Quantum computing will surely go through a similar transition.”

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