A superconducting quantum computer with 1.200 error-corrected qubits – in real hardware, this corresponds to fewer than 500.000 physical qubits – and 90 million computational steps could calculate a Bitcoin user’s private key – thus breaking the cryptographic basis of Bitcoin’s security.
Bitcoin's average "block time," the interval between two permanently stored transaction bundles, is ten minutes.
According to a whitepaper from Google Quantum AI, the encryption could be bypassed in just nine minutes in the best case scenario. The researchers also provide the associated zero-knowledge proof and source code.
Bitcoin’s security is based on a mathematical promise: each user has two associated keys – a public key, which anyone can see, and a private key, which only the owner knows. Anyone who wants to spend Bitcoin must prove with a digital signature that they know the private key. Calculating the private key from the public key is considered practically impossible for classical computers.
Quantum computers break this one-way street with the so-called Shor algorithm – developed in 1994 by mathematician Peter Shor. It can directly identify and exploit certain mathematical structures that form the basis of classical cryptography. What is a seemingly infinite search task for regular computers becomes a solvable computational problem for a large enough quantum computer.
When a Bitcoin user sends a transaction, it first ends up in the so-called mempool – a publicly visible waiting area for all unconfirmed transactions. The sender’s public key is visible to everyone from there. Only after an average of ten minutes is the transaction permanently stored in a block by a miner – a computer participating in the network. This is exactly the window in which the described attack works: a quantum computer reads the public key, calculates the private key from it and sends a fake transaction with a higher fee – the miners will prefer it and the original transaction will be displaced.
whitepaper from Google Quantum AI
Although the press releases will range from very select to rare, I said I'd pass...because sometimes the editors hide.
