Google’s quantum computer could break Bitcoin in two ways

Google announced a new quantum computing chip called Willow, and doomsayers already think it could break Bitcoin in at least two ways.

According to Google, Willow can solve in five minutes a problem that would take most supercomputers 10 septillion years to solve. Critics say that this power could overtake Bitcoin’s hashrate in a matter of minutes, rewrite the Bitcoin blockchain, or even steal Satoshi Nakamoto’s coins.

The price of bitcoin (BTC) dipped slightly yesterday around the time of Google’s 4pm post-market announcement and over the past 24 hours, remains around 3% lower.

Willow reportedly reduces the rate at which qubits “leak” information to the outside, non-quantum environment, improving the chip’s ability to retain information needed for quantum computations. This improves the new chip’s ability to remain quantum instead of becoming a classical chip after too much data leakage.

With its breakthrough, Google moved quantum computing one step closer to becoming a practical reality and potential threat to Bitcoin’s security.

The first threat would be to Bitcoin’s mining network. Bitcoin is secured by a globally distributed network of computer operators who expend time, electricity, and machinery to hash numbers and compete for the right to add and order new transactions atop Bitcoin’s blockchain.

If a quantum computer could suddenly perform most of this computational work at a fraction of the network’s existing time, electricity, and machinery, that computer could overtake the network and censor, reorder, or even double-spend BTC transactions.

Read more: Crypto reacts to superconductor claims that made front-page news

Could Willow steal Satoshi Nakamoto’s bitcoin?

Beyond a hashrate takeover, the second threat people flagged was to Satoshi Nakamoto’s BTC. The Bitcoin creator still owns over 1 million BTC and used a rudimentary pay-to-public-key (P2PK) format to store unspent transaction outputs (UTXOs), which reveals the public address on-chain.

Because Satoshi’s public keys are public, this could give a quantum computer a chance to crack its associated private keys with brute force effort.

Unlike classical chips, quantum chips could execute an exponential amount of computation — as evidenced by Google’s reduction of a 10-septillion-year task to five minutes.

Bitcoin developers abandoned the P2PK format for a system that only reveals the public address during a transaction. Even then, the modern format generates a hash of a hash of the public key receiving the coins.

This not only improves privacy but also limits the allure of brute force attacks, since the attacker would have to decrypt the public key first, and then further proceed to decrypting its private key.

In short, modern standards reduce the chances of exposing the actual public key during most BTC transactions and are, therefore, more quantum-resistant than earlier standards. However, Satoshi’s coins — all of which were mined prior to 2012 — are still vulnerable to this P2PK format attack.

Ava Labs co-founder Emin Gün Sirer recommended freezing Satoshi’s coins and sunsetting P2PK transactions altogether. He also, of course, boasted that he has a method to make digital assets more quantum-resistant.

However, no one has stolen Satoshi’s private keys yet.

Bitcoin hasn’t fallen to a quantum computer yet

Most people, even after Google’s announcement, still doubt that quantum computing actually poses any near-term threat to Bitcoin’s hashrate or Satoshi’s coins.

Google also plans to research potential real-world applications for Willow, which indicates that its accomplishments are impressive yet narrow in scope. It’s not quite ready to leave the lab yet, so to speak. 

It serves as a good reminder, however, to blockchain developers. It’s important to make digital assets more quantum-resistant, and Bitcoin will probably need to hard fork a protocol change in the future to adopt quantum-resistant cryptography.

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