[DigitalToday reporter Jinju Hong (홍진주)] A warning has emerged that if quantum computers become reality, the safety of private keys, a core premise of Bitcoin security, could collapse.

Bitcoin Magazine on Sept. 10 explained how quantum computing differs from existing computers and why that difference poses a tangible threat to Bitcoin.

The core issue lies in the structure that underpins Bitcoin ownership. Bitcoin operates on the assumption that only the person with the private key can move the asset. The outlet noted that unless a copy of the private key itself is leaked, no one other than the key holder can sign, and that is the basis of holding bitcoin. Quantum computing calls that assumption into question.

The difference between conventional computers and quantum computers comes down to how they compute. Conventional computers store all information as bits of 1s and 0s and process them sequentially, step by step. Creating a private key and calculating a public key is ultimately a series of procedures that change bits in order. That means to discover someone else’s private key, every possible case must be tried one by one.

The problem is the number of possibilities. The number of candidate Bitcoin private keys reaches 2 to the 256th power. A conventional computer would have to check them one by one, and even if parallel processing is expanded, the computing resources required still explode. The outlet explained it as requiring a computational cost that cannot be handled even by mobilising every computer on Earth, and that even in time terms it would be at a level where it could not be checked before all the stars in the universe disappear.

Quantum computers take a different approach at that point. Qubits, the basic unit of a quantum computer, exist in a superposed state of 1 and 0 until observed. With entanglement added, computation proceeds not by plugging in specific values in sequence but by adjusting the probabilities of possible outcomes. The outlet said quantum algorithms work by raising the probability of the correct answer and lowering the probability of wrong answers.

As a result, quantum computers do not need to test every private key one by one like classical computers. Bitcoin Magazine said, "A quantum computer does not check all possibilities at once, but with the right algorithm it can reach the correct answer after running multiple times." That means Bitcoin’s security assumptions based on elliptic-curve cryptography could be broken.

Bitcoin Magazine did not treat the risk lightly. It said that if a practically working quantum computer is built, the foundational assumption that has protected bitcoiners’ assets would be broken and the funds would no longer be safe. At the same time, it stressed that the situation is not yet completely defenceless. It said the problem is understood, the points of exposure are known, and solutions are gathering across several fronts.

From a market perspective, the discussion is closer to structural risk than price volatility. No immediate numerical change or fund flow was presented, but it is clear that the private-key and signature system at the core of Bitcoin security is becoming a subject of long-term verification. It also said the essence of the threat is not a simple improvement in processing speed, but the emergence of a computing system that can solve certain kinds of cryptographic problems in a completely different way.

Against that backdrop, there are two points to watch. One is when a "properly working" quantum computer will actually appear. The other is what response measures the Bitcoin ecosystem will organise before then. The article focused on laying out the basic structure of why quantum computing is a threat to Bitcoin, rather than amplifying fear. It said the quantum risk is still unfolding, but has entered a stage where it is difficult to leave it as merely a peripheral issue in debates over Bitcoin security.