Quantum computers likely to reveal if Satoshi is alive — Adam Back

Early cypherpunk Adam Back, cited by Satoshi Nakamoto in the Bitcoin white paper, suggested that quantum computing pressure may reveal whether the blockchain’s pseudonymous creator is alive.

During an interview after a Q&A session at the “Satoshi Spritz” event in Turin on April 18, Back suggested that quantum computing may force Nakamoto to move their Bitcoin (BTC). That’s because, according to Back, Bitcoin holders will be forced to move their assets to newer, quantum-resistant signature-based addresses.

Back said that current quantum computers do not pose a credible threat to Bitcoin’s cryptography but will likely threaten it in the future. Back estimated that quantum computers may evolve to that extent in “maybe 20 years.”

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When the threat becomes real, Back said the Bitcoin community will have to choose between deprecating old, vulnerable addresses or letting those funds be stolen:

“If the quantum computers are here, and people at universities and research labs have access, the network has a choice to either let people steal them or to freeze them — to deprecate the signature.“

Back expects the community to go with the former option, forcing Bitcoin’s pseudonymous creator to move their funds if they wish to avoid losing them.

Privacy upgrades could complicate proof

Still, Back said that whether such a situation will reveal if Satoshi Nakamoto is alive also depends on Bitcoin’s future privacy features.

“It depends a bit on the technology, there are some research ideas that could add privacy to Bitcoin,” Back said. “So, possibly there might be a way to fix quantum issues while keeping privacy.“

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Still, not everyone is convinced that — privacy enhancements or not — such a scenario would reveal whether Nakamoto was alive. An anonymous early Bitcoin miner and member of the Bitcoin community told Cointelegraph that he does not expect Nakamoto’s coins to be moved:

“Even if he is alive and holds the private keys, I do not think he’d move them. Based on how he acted so far I would rather expect him to let the community to decide.”

He added that, since this is a controversial choice, it makes sense to let the community decide. He said that he’d be surprised if Nakamoto came out of the woodwork to move the assets.

A quantum-resistant Bitcoin

Back explained that most quantum-resistant signature implementations are either unproven in terms of security or very expensive from a data perspective. He cited Lamport signatures as an old and proven design, but pointed out that they weigh tens of kilobytes.

Consequently, he suggested that Bitcoin should be prepared to switch to quantum-resistant signatures but only do so when necessary. He suggested a Bitcoin taproot-based implementation allowing addresses to switch to quantum-resistant signatures when needed.

Magazine: Bitcoin vs. the quantum computer threat: Timeline and solutions (2025–2035)