Quantum computers could kill off traditional cryptocurrencies within a few years. Cryptocurrency transactions are impossible to hack with conventional computers, but they could soon be exposed to the processing power of quantum computers.

Most cryptocurrencies, including bitcoin, are blockchain-based, an encrypted data chain maintained by a network of tens of thousands of computers. All bitcoin mining, buying and selling operations have to be validated by 51% of the computers in this network.

That is why it is such a secure system: with conventional computers, no hacker has enough computing power to hack or replace 51% of the computers in a blockchain network. They would need “thousands of years”, Canudas explains.

However, this could change with the progression of quantum computers, which have already reached “private hands”, according to this 11Onze agent. In 2019, for example, Sycamore was presented, a 54-qubit quantum computer capable of performing in 200 seconds a calculation for which the most powerful traditional computer of the moment would need 10,000 years. Eagle, a quantum computer with more computing power than all conventional computers combined, was also recently made public.

What about trying with quantum computers?

National University of Singapore researcher Divesh Aggarwal predicted that quantum computers would be able to decrypt bitcoin’s elliptic curve digital signature system by 2027.

The computational power of these computers puts traditional cryptography in a difficult situation. In each transaction, a public key is generated from the private and secret key of the owner of each cryptocurrency. Figuring out a private key from a public key would require thousands of years of calculations with conventional computers, but only seconds or minutes with a quantum computer.

Cryptocurrencies will not be the only ones to suffer from the emergence of quantum computers. Their threat extends to all cryptographic keys: mobile phone passwords, router passwords, bank account passwords… “Quantum computers, like artificial intelligence, will change our reality in many more ways than we imagine,” concludes Canudas.

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